The next frontier for climate change science : insights from the authors of the IPCC 6th assessment report on knowledge gaps and priorities for research.
Date: 2024-02-16
Institutions: Directorate-General for Research and Innovation
Subjects: agricultural policy, climate change, climate change policy, earth sciences, energy policy, environmental cooperation, environmental research, equal treatment, international cooperation, nature-based solution, research and development, risk management

The Next Frontier 
for Climate Change 
Science

Insights from the authors of the  
IPCC 6th Assessment Report on knowledge 
gaps and priorities for research

Independent 
Expert 
Report

Research and 
Innovation 

The Next Frontier for Climate Change Science: 
Insights from the authors of the IPCC 6th Assessment Report on knowledge gaps and priorities for research
European Commission
Directorate B — Healthy Planet
Unit B.3 — Climate & Planetary Boundaries

Contact 
Email 

MOUSSON Mathilde
 Mathilde.MOUSSON@ec.europa.eu 
 RTD-PUBLICATIONS@ec.europa.eu

European Commission
B-1049 Brussels

Manuscript completed in February 2024. 
1st edition.

This document has been prepared for the European Commission, however it reflects the views only of the authors, and the European Commission 
shall not be liable for any consequence stemming from the reuse.

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EUROPEAN COMMISSION

The Next Frontier for Climate 
Change Science

Insights from the authors ofthe IPCC 6th Assessment 
Report on knowledge gaps and priorities for research

Birgit Bednar-Friedl, Goran Berndes, Joern Birkmann, Luisa F. Cabeza, 
Felix Creutzig, Delphine Deryng, Wolfgang Kiessling, Silvia Kreibiehl, 
Volker Krey, Gerhard Krinner, Simone D. Langhans, Franck Lecocq, Elena 
Lopez Gunn, Jochem Marotzke, Valérie Masson-Delmotte, Jan Christoph 
Minx, Anna Pirani, Alexander Popp, Hans-Otto Pörtner, Roshanka 
Ranasinghe, Keywan Riahi, Joeri Rogelj, Sonia Seneviratne, Jim Skea, 
Trude Storelvmo, Peter Thorne, Maarten Van Aalst

edited by
 Anna Pirani, Katarzyna Drabicka, Mathilde Mousson,  
Margarita Ruiz Ramos, Robin Markowitsch  
with the support of Larissa Lorinczi, Adrian Leip and Paola Lepori

2024

Directorate-General for Research and Innovation
Healthy Planet

TABLE OF CONTENT

INTRODUCTION �����������������������������������������������������������������������������������������������������������������������������������������������������4

CLUSTER 1:  
EARTH SYSTEM PROCESSES, CLIMATE FEEDBACKS AND CLIMATE SENSITIVITY ��������������������8
1.1   Understanding and quantifying near-surface fluxes of heat, moisture and momentum  ...............................10
1.2   Assessing feedback mechanisms in the climate system and their dependence on climate state .............11
1.3   Quantifying the methane budget and monitoring progress on methane reductions .........................................12
1.4  Better understanding early instrumental period changes .................................................................................................13
1.5   Understanding how the Earth system components will respond to a state of net zero emissions ...........14

CLUSTER 2:  
CHANGES IN THE CLIMATE SYSTEM, INCLUDING ABRUPT AND IRREVERSIBLE CHANGE �15
2.1   Modeling atmospheric circulation and precipitation changes in a warming climate ..........................................17
2.2   Representing the Atlantic Meridional Overturning Circulation (AMOC) in climate models ..............................18
2.3   Identifying abrupt, irreversible, and committed changes in the cryosphere ...........................................................19
2.4   Extending high-resolution proxy reconstructions with a focus on the mid-Holocene ........................................20

CLUSTER 3:  
RISKS AND VULNERABILITY ACROSS TIME AND SPACE ������������������������������������������������������������������21
3.1   Understanding future global climate risks for individual systems, sectors and for compound risks ........23
3.2   Understanding the dynamics of exposure and human vulnerability at regional and local scales ..............24
3.3   Cascading, compound and transboundary risks and adaptation ...................................................................................25
3.4   Evaluating the intrinsic risks of climate change responses  .............................................................................................26
3.5   Advancing knowledge on risks from overshooting 1.5°C and  

options to bring temperatures back down ..................................................................................................................................27
3.6   Exploring societal resilience in a volatile world amplified by climate change ........................................................28
3.7   Utilising paleo records of past impacts of climate changes to refine future scenarios ...................................29

CLUSTER 4:  
ADAPTATION: EFFECTIVENESS, PATHWAYS AND LIMITS, LOSSES AND DAMAGES ���������������������������30
4.1   Understanding adaptation effectiveness and limits at different degrees of warming ......................................32
4.2   Probing the limits of nature-based solutions under different climate-change scenarios ................................33
4.3   Considering population response and coastal adaptation strategies in the face of rising sea levels ......34
4.4  Advancing climate science relevant for loss and damage ................................................................................................35
4.5   Integrating climate resilience in post-extreme events reconstruction ........................................................................36
4.6  Linking early warning to long-term adaptation .......................................................................................................................37

CLUSTER 5:  
WATER, BIODIVERSITY, NATURE-BASED SOLUTIONS AND  
THE COASTAL ENVIRONMENT IN A CHANGING CLIMATE ����������������������������������������������������������������������������������38
5.1   Projecting climate impacts across natural systems: terrestrial, marine, and freshwater................................40
5.2   Integrating water management and adaptation responses .............................................................................................41
5.3   Projecting and monitoring soil moisture and ecosystem drought processes to build resilience .................42
5.4   Strengthening best-practices for freshwater ecosystems, biodiversity and  

climate response strategies ................................................................................................................................................................43
5.5   Improving projections of future coastal change with Earth observations ................................................................44
5.6   Multi-scale modeling coastal changes in Arctic regions under warming conditions ..........................................45

2

CLUSTER 6:  
TOWARDS MORE COHERENCE IN CLIMATE POLICIES:  
INTEGRATING IMPACTS-ADAPTATION-MITIGATION ����������������������������������������������������������������������������������������������46
6.1  Integrating mitigation and adaptation action across scales ............................................................................................48
6.2   Bridging the gap from Earth system science to impacts and  

low-emissions climate resilient scenarios ..................................................................................................................................49

6.3   Investigating the interplay of mitigation and adaptation through integrated scenarios with improved 

representation of climate impacts ..................................................................................................................................................50

CLUSTER 7:  
SECTORAL AND SYSTEMS TRANSITIONS ������������������������������������������������������������������������������������������������������������ 51
7.1   Improving global assessments of urban responses to climate change .....................................................................53
7.2   Investigating the contribution of demand-side measures in expediting the shift toward  

climate neutrality, with a particular focus on the role of digitalisation .....................................................................54
7.3   Informing the politics and economics of phasing out fossil fuel infrastructures .................................................55
7.4   Reducing energy demand and quantifying materials and embodied carbon in the building stock and 

other infrastructure .............................................................................................................................................................................................56

CLUSTER 8:  
LAND USE, AGRICULTURE AND CARBON DIOXIDE REMOVAL ��������������������������������������������������������57
8.1   Nurturing the potential of land-based mitigation and adaptation ...............................................................................59
8.2   Fostering sustainable use of biomass for climate change mitigation ........................................................................60
8.3   Achieving global climate, biodiversity, and health objectives by optimising  

the management of food systems..................................................................................................................................................61
8.4   Assessing long-term viability of agroforestry as a solution to climate change and food security  ...........62
8.5  Designing carbon dioxide removal policies and governance ............................................................................................63

CLUSTER 9:  
EQUITY AND JUST TRANSITIONS ���������������������������������������������������������������������������������������������������������������64
9.1  Attributing climate impacts in a climate justice context ....................................................................................................66
9.2   Improving the consideration of equity and justice in adaptation strategies to build resilience ...................67
9.3   Improving integrated assessment models to represent different dimensions of justice and equity ........68
9.4   Designing just transition policies for agriculture, forests and other land use ........................................................69

CLUSTER 10:  
ACCELERATING CLIMATE ACTION: LEVERS AND ENABLERS ����������������������������������������������������������70
10.1   Communicating and translating climate science to policymakers and general public ...................................72
10.2   Understanding social dynamics, including tipping points, as drivers of climate action .................................73
10.3   Accelerating near-term climate action to meet long-term goals ...............................................................................74
10.4   Assessing the performance of climate policy instruments using  

rigorous evidence synthesis methods ........................................................................................................................................75
10.5   Shifting to climate-resilient development ................................................................................................................................76
10.6   Investigating how global shocks (fail to) enable climate action .................................................................................77
10.7   Mobilising climate finance through improved understanding of financial sector behaviour .......................78

CLUSTER 11:  
CLIMATE INTERVENTION �������������������������������������������������������������������������������������������������������������������������������������������������������79
11.1   Assessing interdisciplinary research on solar radiation modification .......................................................................81

ACRONYMS AND ABBREVIATIONS �������������������������������������������������������������������������������������������������������������82

3

INTRODUCTION

2023 is now confirmed as the warmest year on record. This period was marked by unparalleled 

temperature anomalies and witnessed a disturbing escalation in the frequency and magnitude 
of devastating climate impacts. In Europe, Slovenia was hit by the worst-ever floods on record with 
a month’s worth of rain falling in less than a day; Spain, Portugal and Greece experienced extreme 
heat and were badly scarred by wildfires and Switzerland recorded a new altitude record for the 
freezing point of well above 5,000 meters. Many parts of the Middle East saw temperatures 
of above 50°C. The global ocean witnessed unprecedented sea surface temperature anomalies, 
fuelling  numerous  typhoons,  cyclones,  and  hurricanes.  In  parallel,  global  GHG  emissions  and 
atmospheric concentrations of carbon dioxide (CO2) also hit new highs, putting the world on track 
for a temperature rise far above the goals of the Paris Agreement, underscoring the urgent need 
to step up adaptation action, while at the same time making rapid, immediate, and deep economy-
wide cuts in greenhouse gas (GHG) emissions.

Accelerating the transition to climate neutrality and resilience is at the heart of the European 
Green Deal. By placing environmental sustainability at the centre of the European policy agenda, 
this ambitious initiative aims to provide a holistic response not only to global warming, but also 
to biodiversity, pollution, and resource depletion crises. Informed by science, the implementation 
of  the  Green  Deal  will  continuously  rely  on  robust  scientific  evidence  to  guide  policymakers, 
businesses, and citizens in the massive transformations ahead. 

By helping us understand how the climate system works, how it will change over time and how the 
impacts of climate change will materialise, climate science is fundamental for enabling informed 
decisions about how to reduce emissions and how to adapt to a warmer, more unpredictable, and 
more inhospitable world. The work of the Intergovernmental Panel on Climate Change (IPCC) 
is an example of how instrumental science is for shaping effective policies and mobilising action. 
The IPCC reports not only represent an essential source of information about climate change, but 
they also help to forge consensus among governments and play a central role in international 
climate diplomacy. 

TOTAL BUDGET
~€100 billion

HORIZON 
EUROPE
the EU’s research 
and innovation 
programme
 2021-2027

CLIMATE ACTION

~35% 

over €1 billion 
will be invested into 
advancing 

climate science
The results of this research 
will inform future 
IPCC assessments

4

The  journey  towards  sustainability  calls  for  a  major  research  and  innovation  effort  not 
only  to  provide  a  robust  scientific  basis  to  guide  the  transition  process,  but  also  to  assess, 
develop,  deploy,  and  scale  up  the  solutions  and  to  nurture  the  behavioural  change  and 
political  will  on  which  the  transition  hinges.  Horizon  Europe,  the  European  Union’s  (EU) 
current  research  and  innovation  (R&I)  funding  programme,  acknowledging  the  importance 
of  the  R&I  contribution  to  fighting  climate  change,  earmarks  at  least  35%  of  its  nearly  
EUR 100 billion budget to climate action, out of which over EUR 1 billion will be invested in climate 
science.

It is the role of Directorate-General for Research and Innovation (DG RTD) to maximise the impact 
of the programme by financing activities that are scientifically, socially and politically relevant 
and by focusing the available funding on the most critical areas. In the domain of climate science 
this means addressing knowledge gaps and advancing our understanding on how the climate 
system works, how it is influenced by climate change, what options we have to pursue ambitious 
mitigation and adaptation action, and how to mobilise society towards transformative change.

To inform the design of future calls on climate science, DG RTD has assembled a group of leading 
European scientists involved in the IPPC 6th assessment cycle, to identify the most pressing research 
themes in climate change arising from the latest IPPC reports. This document compiles a synthesis of 
independent recommendations spanning the physical climate science, impacts and risks, adaptation, 
and mitigation, while promoting multi-disciplinarity and synergies between the various themes. 
The report is structured by key themes (“clusters”), many of which tackle the topics assessed by the 
different IPCC Working Groups and address cross-cutting or particularly pressing policy issues such 
as equity and justice, losses, and damages1, overshoot of temperature targets, transitions in the land 
sector, limits to adaptation or climate intervention. As a result, this compilation represents a precious 
resource for shaping a more strategic approach towards EU investment in climate research under  
Horizon Europe and beyond.

Investing in climate science is investing in our future by 
securing the necessary knowledge to shape the climate 
action that is required.

This report, building on state-of-art scientific expertise, 
is invaluable for maximising the impact of EU-funded 
R&I and for generating the evidence-base for guiding the 
implementation of the European Green Deal.

Marc Lemaître, 
Director-General for Research and Innovation (DG RTD)

1.  “Losses and damages” refer broadly to harm from observed impacts and projected risks whereas “Loss and Damage” refers to political debate under the 
UNFCCC, which is to address loss and damage associated with impacts of climate change in developing countries that are particularly vulnerable to the 
adverse effects of climate change. In the research context of this report, unless specified otherwise, we primary focus on “losses and damages”.

5

The Intergovernmental Panel on Climate Change (IPCC)

The IPCC, to which many of the world’s leading climate scientists contribute, plays a unique 
role within climate science and in informing policy decisions. First convened in 1988 by the 
United Nations Environment Programme and the World Meteorological Organisation, the 
IPCC is tasked to provide policymakers with regular (circa every 5-7 years), comprehensive, 
and authoritative assessments of the scientific basis of climate change and its impacts 
as well as available human response options, building on the research and technical work 
of thousands of scientists, and increasingly also practitioners, worldwide. The IPCC does 
not carry out any research of its own and the authors work pro bono to provide an expert 
assessment of the published literature.

The Panel’s work has been instrumental in establishing unequivocally the link between 
human activity and climate change. With each successive assessment cycle, reports have 
seen an increased confidence in the findings, based on continuous progress in climate 
science, including modeling, process understanding, observations, and empirical studies, 
and have provided the knowledge basis for reinforced warnings and calls for action. The 
IPCC reports thus represent an essential source of information for the implementation of 
the Paris Agreement. 

The latest IPCC 6th Assessment Report (AR6), consists of three special reports on global 
warming of 1.5°C2; climate change and land3; and the ocean and cryosphere in a changing 
climate4, and a three-part "climate report": the first instalment, on the physical science of 
climate change5, was published in August 2021, delivering the starkest warning so far, and 
described by the United Nations Secretary-General António Guterres as a “code red for 
humanity”. The second part, approved in February 2022 and focusing on impacts, adaptation 
and vulnerability6 warns that any further delay in climate action “will miss a brief and rapidly 
closing window of opportunity to secure a liveable and sustainable future for all”. The third 
report7 that came out in April 2022 is centred on mitigation and highlights how the world 
must take deep and rapid cuts in emissions to keep global warming in check. 

Finally, the Synthesis Report8 concluding the 6th assessment cycle was adopted in March 
2023 and summarises the main messages from across the entire AR6.

2.   https://www.ipcc.ch/sr15/
3.   https://www.ipcc.ch/srccl/
4.   https://www.ipcc.ch/srocc/
5.   https://www.ipcc.ch/report/ar6/wg1/
6.   https://www.ipcc.ch/report/ar6/wg2/
7.   https://www.ipcc.ch/report/ar6/wg3/
8.   AR6 Synthesis Report: Climate Change 2023 (ipcc.ch)

6

HOW TO READ THIS DOCUMENT

This  document  is  a  comprehensive  although  non-exhaustive  summary  of  independent  expert 
recommendations on research priorities in climate science, inspired by, but not limited to, IPCC 
authors’ experience in contributing to the 6th assessment cycle. It means to provide inspiration for 
Directorate-General R&I and other funding bodies in the identification and selection of research 
priorities.

The  research  gaps,  presented  in  a  form  of  one-pagers,  have  been  grouped  together  around 
common areas to form 11 thematic clusters. Each one pager briefly describes the nature of the 
research gaps and its policy relevance and signals how the thematic is pertinent for the three 
IPCC Working Groups (Earth system science (WGI); Impact, risks and adaptation (WGII); Mitigation 
(WGIII)). The order of presentation is random, with no prioritisation between or within Clusters.

For each research gap the relevance for five cross-cutting policy issues as set out in the Horizon 
Europe  legal  basis  is  flag(s)ged  to  signal  that  the  gap  has  high  potential  for  tackling  these 
horizontal priorities. The five flag(s) categories include: 

 ▶ international cooperation (see below)

 ▶ digitalisation  and  artificial  intelligence  (AI)  (e.g.,  where  advanced  computing  and  digital 
technologies, incl. machine learning, sensors, and satellites, can enable advances in climate 
research)

 ▶ ecosystems and biodiversity (e.g. climate-biodiversity nexus, including NBS for mitigation and 

adaptation) 

 ▶ social sciences and humanities (e.g., where human behaviour, policy, governance, economics 

etc. are at stake)

 ▶ gender (e.g., where distributional aspects are discussed)

It  should  be  clarified  that  whereas  international  cooperation  on  any  topic  addressing  climate 
change might seem by default applicable given the global nature of the problem at stake, in 
the report we apply a more restrictive approach by flag(s)ging only topics where participation of 
non-EU countries as essential members of research consortia would be necessary for successfully 
tackling the specific research issue at stake. By extension, an absence of such a flag(s) does not 
mean  that  international  cooperation  would  not  be  needed  or  welcome  to  address  the  gap  in 
question.

By design, the fiches within clusters are closely interrelated. In addition, where strong thematic 
links exist between research gaps across the different clusters, these have been signaled by means 
of cross-references to facilitate the readability of the report.

7

CLUSTER 1:  
EARTH SYSTEM PROCESSES, CLIMATE 
FEEDBACKS AND CLIMATE SENSITIVITY

The latest IPCC report concludes that: human activities have unequivocally caused widespread 

and rapid changes in all components of the Earth system. The pace and scale of the observed 
changes across the climate system are unprecedented over many thousands to millions of years, 
with recent intensification of these trends. Advancements in comprehending the Earth system 
are imperative to assess how the climate may change in the future, to understand the regional 
implications,  and  to  formulate  effective  strategies  for  both  adaptation  and  mitigation  action.  
Research on multiple lines of evidence will be key for narrowing uncertainties in estimates of key 
variables such as climate sensitivity, Earth system feedbacks, and biogeochemical cycles.

Observations and paleoclimate records together with climate models are all essential tools to 
advance our understanding of the changing climate. Progress is required to secure high quality 
stable and sustained observational measurements over multiple decades, to increase the quality 
and exploitation of reanalyses, and to develop integrated composite products that bring added 
value and address data and knowledge gaps. Past climatic changes can provide uniquely valuable 
context - enhanced and extended paleoclimate records are needed to help us understand how 
the components of the climate system work, how unusual present and future conditions are and 
what the committed climate change is, particularly in the slowly responding ocean and cryosphere. 

8

Better understanding of key processes and feedbacks in the climate system and our ability to 
model and observe them is necessary to understand past and current changes in the climate 
system, and to explore future scenarios. For example, near-surface fluxes between the ocean and 
atmosphere are still not well known with broad ranging 
implications,  including  for  quantifying  global  surface 
temperature  changes.  Another  fundamental  source  of 
uncertainty  in  climate  sensitivity  and  for  estimating 
carbon budgets are cloud feedbacks.

Core challenges persist in the development and utilisation 
of  diverse  datasets,  arising  particularly  from  in-situ 
observations,  satellite  products,  paleoclimate  proxies, 
modeling  exercises,  and  other  research  activities  that 
generate data as part of their deliverables. Collaborative 
efforts  are  essential  to  improve  the  development,  use 
and interoperability of these datasets, addressing issues 
related  to  heterogeneity,  sustainability,  and  curation. 
Such improvements would also benefit the Copernicus 
Climate Change Service and other similar products. 

Advancements in 
comprehending the 
Earth system are 
imperative to assess 
how the climate may 
change in the future, 
to understand the 
regional implications, 
and to formulate 
effective strategies 
for both adaptation 
and mitigation action�

Tracking progress in stabilising global temperatures is 
critical for guiding climate policy and requires the ability 
to accurately assess and monitor natural and human caused sources and sinks of GHGs, the 
related processes and feedbacks as well as the carbon budgets. As net zero targets are becoming 
increasingly prominent in the EU and international policymaking, we also need to better understand 
how the Earth system will respond to a state of net zero CO2/GHG emissions. This knowledge will 
be critical for defining the future emission reduction efforts under the Paris Agreement.  

.

9

1.1   Understanding and quantifying near-surface fluxes of heat, 

moisture and momentum 

Earth system science

Impacts, risks and adaptation

Mitigation

There are substantial gaps in our observational and theoretical understanding of near-surface 
fluxes, with broad ranging implications for the quantification of key processes and their future 
projections in climate models. This is the case over both the ocean and land surface, with sparse 
direct measurements of near-surface fluxes, particularly over the ocean. The related key processes 
are  parameterised  in  climate  models,  often  based  on  similar  assumptions.  There  are  major 
opportunities for progress in measuring these fluxes. For example, large-scale wind farm facilities 
include  high  quality  meteorological  instrumentation  that  can  augment  sparse  measurement 
capabilities. Higher resolution models may also allow for key processes to be explicitly modelled 
rather than be parameterised.

A critical knowledge gap is how the relationship between sea-surface temperatures (SST) and 
marine air temperatures (MAT) has evolved and will continue to evolve in a warming climate. It 
is critical to reconcile these observations to understand and improve early estimates of observed 
changes. Climate model simulations consistently suggest that MATs should be warming faster 
than SSTs. However, all models parametrise the processes at this scale and all parameterisations 
are based upon the same similarity theory, leaving open the possibility of a common systematic 
bias in the simulations. Observationally-based estimates, for which MAT-based estimates are 
considerably  less  mature  than  their  SST-equivalents,  suggest  the  opposite  behaviour  –  that 
SST warms more than MAT in the long term. Theoretical understanding of the expected spatio-
temporal behaviour is overall lacking, leading to uncertainties in long-term surface temperature 
change estimates.

Policy relevance
Surface flux exchanges are a key part of the meteorological 
and climatic conditions at the surface where we live and work, 
and  their  better  understanding  will  substantially  improve 
regional projections and help to address overall model biases. 
Changes  in  surface  fluxes  will  directly  affect  human  health 
and comfort, bio-spheric health, and agricultural production 
amongst others.

Flag(s)

Digitalisation/AI

Related fiche(s) 
5.5

10

1.2   Assessing feedback mechanisms in the climate system and 

their dependence on climate state

Earth system science

Impacts, risks and adaptation

Mitigation

Climate feedback mechanisms in the Earth system need to be well understood to robustly quantify 
Earth’s climate sensitivity to increasing temperatures. While many of the feedbacks have reduced 
uncertainties  over  recent  years  thanks  to  scientific  progress  and  are  now  assessed  with  high 
confidence, others remain uncertain. This is particularly the case for cloud feedback mechanisms, 
for which a strong dependence on climate state and patterns of warming have been identified. 
Whilst there has been progress in understanding marine low-cloud feedbacks, historically a major 
contributor to the total cloud feedback uncertainty, other cloud regimes remain major sources of 
uncertainty, for example the climate feedback resulting from the amount of tropical high-clouds.

Furthermore, climate models still have considerable biases in climatological temperature and 
cloud macroscopic properties, in particular over land and over the Southern Ocean. There are 
confounding  issues,  on  the  one  hand  between  the  number  of  different  cloud  regimes  in  the 
climate system and the challenge of representing these in climate models and, on the other hand, 
the need for a consistent treatment of clouds in models. Observational campaigns necessarily 
focus on one specific cloud type, while climate modeling is geared at representing different cloud 
processes and regimes, and their aggregate effects across scales. Research strategies for how 
to propagate process understanding from individual cloud regimes into demonstrated climate 
modeling improvements across multiple cloud regimes would be highly valuable. 

The reduction of uncertainties related to cloud feedbacks since IPCC 5th assessment cycle has 
contributed to the reduced uncertainty of the assessed equilibrium climate sensitivity (ECS) in the 
latest IPCC report. However, the assessment also noted a distinct possibility of a warming climate 
increasing the strength of these feedbacks. This means that the upper end estimates of the likely 
ECS range are weakly constrained. More research is also needed into how future changes of SST 
patterns could determine the “effective” climate sensitivity, with implications for the assessment 
of ECS.

Policy relevance
Assessments  of  the  Earth  climate  sensitivity  are  of  great 
relevance for understanding how the climate will respond to 
increasing warming, as well as for estimating the remaining 
carbon  budgets  in  the  context  of  meeting  the  goals  of  the 
Paris Agreement. Improvements in the understanding of cloud 
processes are also central for better representing the water 
cycle in climate models, which, in turn, enables more accurate 
assessment of future changes in precipitation.

Flag(s)

Digitalisation/AI

Related fiche(s) 
5.3, 6.3 

11

1.3   Quantifying the methane budget and monitoring progress on 

methane reductions

Earth system science

Impacts, risks and adaptation

Mitigation

Methane is the second largest contributor to global warming. Its atmospheric concentration has 
increased by around 170% since pre-industrial times. Owing to its relatively short lifetime, changes 
in methane concentration exhibit substantial inter-annual to multi-decadal variations. The global 
methane cycle remains relatively poorly understood with challenges in determining the causes of 
many year-to-year and even longer timescale variations, including the role of natural variability, 
feedbacks, and permafrost thawing.

There is a substantial opportunity to reduce uncertainty in critical aspects of the global methane 
cycle, such as better monitoring and quantifying anthropogenic emissions from diffuse sources 
which are thus far poorly quantified. This will support the development of policy-relevant indicators 
of the magnitude and speed of climate and methane cycle interactions that may, in turn, reinforce 
human-caused  warming.  Accordingly,  there  is  a  need  to  develop  a  European-wide  methane 
assessment capacity, building on advances in modeling and observation of the methane cycle 
and on improved cooperation and communication between the relevant scientific communities.

Policy relevance
A  better  understanding,  monitoring,  and  modeling  of 
atmospheric  chemical  processes  will  result  in  improved 
science  base  for  methane  cycle  analysis,  enhancing  the 
quality of emission inventories reported to the United Nations 
Framework Convention on Climate Change (UNFCCC). This will 
be  critical  for  verifying  national  and  regional  contributions 
towards the Global Methane Pledge agreed at the COP26 in 
Glasgow, led by the United States and the EU and for forming 
a robust policy advice.

Flag(s)

International 
cooperation

Digitalisation/AI

Related fiche(s) 
2.3 

12

1.4  Better understanding early instrumental period changes

Earth system science

Impacts, risks and adaptation

Mitigation

There is a rich history of observing weather and climate globally, particularly over Europe. However, 
much of this data exists solely in hard copy or image form and thus is presently unexploitable. It 
is likely that as much data exists for the period prior to 1950 as is currently in digital form. These 
“unknown knowns” from the observations can be resolved through their rescue and integration 
into national, regional, and global holdings.

There are efforts underway to rescue data across Europe, but scaling up is needed using novel 
approaches  such  as  classroom-based  exercises  while  taking  care  to  address  the  quality  and 
homogeneity of the early observations. This could be extended to also rescue data from Africa 
based upon the recently recovered fiche and film records from the African Centre of Meteorological 
Application for Development effort led by the Belgian meteorological service, as well as efforts to 
digitise comprehensively European records. Once digitised, these data could be analysed to form 
both new and extended observational datasets of a broad range of essential climate variables. 
It would also provide an improved observational constraint to reanalysis products at global and 
regional scales.

Policy relevance
Longer-term  and  higher  quality  datasets  on  retrieved  past 
observations and records will enable greater insights into past 
significant  climatic  events.  It  will  increase  climate  literacy 
through  participatory  learning  techniques  across  countries 
and  offers  significant  potential  to  strengthen  international 
cooperation, in particular with Africa.

Flag(s)

International 
cooperation

Digitalisation/AI

Related fiche(s) 
2.4, 3.7 

13

1.5   Understanding how the Earth system components will 

respond to a state of net zero emissions

Earth system science

Impacts, risks and adaptation

Mitigation

Net  zero  targets  are  being  used  to  guide  climate  policy  in  the  coming  decades  and  as  such, 
they are taking an increasingly prominent place in national and international climate debates. At 
present, however, it is unclear how exactly the Earth system will respond to a state of net zero 
CO2 or GHG emissions.

The  latest  IPCC  report  assessed  the  "zero  emissions  commitment"  (ZEC)  of  CO2,  which  is  the 
additional  warming  projected  to  occur  after  a  net  zero  CO2  emissions  state  is  achieved  and 
maintained, with a best estimate of zero additional warming, but with an uncertainty range of 
up to 15% of further warming. Much of the evidence underpinning this ZEC assessment has an 
incomplete representation of potentially important Earth system feedbacks with climate modeling 
tools most often showing a slight cooling after net zero CO2 emissions are reached.

Research is needed to better constrain, quantify, and identify key contributing factors of ZEC 
uncertainty  and  to  improve  modeling  tools  to  allow  applying  new  ZEC  insights  to  mitigation 
analysis. Progress is also necessary on enhanced understanding of global warming and other 
committed changes in a net zero world, including improved representation of processes that drive 
future ocean heat uptake, carbon uptake in land and ocean, and in atmospheric physical feedback 
processes. Additional aspects come into play when net zero GHG is considered and are equally 
important to research, including the need for net negative CO2 emissions.

Policy relevance
Furthering the understanding of the Earth system response 
to declining and net zero emissions of CO2 and other GHGs is 
critical for understanding the emission reduction efforts, as 
well as the role of CO2 removal, required to meet the Paris 
Agreement.

Flag(s)
Digitalisation/AI

 Biodiversity/
Ecosystem

Related fiche(s) 
3.1, 3.5 

14

CLUSTER 2:  
CHANGES IN THE CLIMATE SYSTEM, 
INCLUDING ABRUPT  
AND IRREVERSIBLE CHANGE
Although  the  origin  and  magnitude  of  Earth’s  warming  are  now  firmly  established,  major 

uncertainties persist about the resulting consequences and their effects on regional climate. 
Changes in both atmospheric and ocean circulation need to be better understood and represented 
more  accurately  in  climate  models.  This  includes  the  causes,  rate  and  consequences  of  past 
changes - for example, the Atlantic Meridional Overturning Circulation (AMOC) collapsed abruptly 
during the last glacial period, but our ability to determine the likelihood of such collapse under 
increasing  global  warming  remains  limited.  The  European  climate,  in  particular  precipitation 
patterns, is strongly affected by variations in atmospheric circulation, mid-latitudes trends and 
changes  in  the  AMOC.  Yet,  present  climate  models  still  grapple  with  uncertainties  regarding 
whether precipitation will locally increase or decrease with additional warming. This underscores 
the need for advancements in our understanding of atmospheric circulation changes in a warming 
climate, including the impacts of Arctic amplification on global warming in mid-latitudes.

The increasing pace of climate change combined with insufficient progress in reducing emissions 
escalates the need to better understand the emergence of novel conditions, including the probability 
and quantification of abrupt, high-impact, large-scale and potentially irreversible changes. Notably, 

15

despite recent progress and ongoing efforts, uncertainties persist so as to the likelihood, timing 
and amplitude of the thresholds beyond which tipping points may occur. Understanding these 
changes  and  the  related  processes  is  crucial  for  long-term  climate  action  planning,  including 
adaptation efforts.

The  response  of  the  cryosphere,  most  notably  ice 
sheets  and  permafrost,  can  be  both  abrupt  and 
irreversible, and lead to committed long-term changes 
in the future. Thawing in the cryosphere can amplify 
global  or  regional  climate  feedbacks  -  for  example, 
large  meltwater  fluxes  into  the  North  Atlantic  from 
Greenland have the potential to affect the deep ocean 
circulation (AMOC). High uncertainty exists regarding 
the  response  of  the  Antarctic  Ice  Sheet,  but  also 
regarding carbon release from permafrost thaw since 
the related processes are generally not represented 
in climate models. Therefore, the understanding of all 
these complex processes and their monitoring must be 
significantly advanced.

The increasing pace 
of climate change 
combined with 
insufficient progress 
in reducing emissions 
escalates the need to 
better understand the 
emergence of novel 
conditions, including 
the probability and 
quantification of abrupt, 
highimpact, large-
scale and potentially  
irreversible changes�

More research is also needed on proxy reconstructions 
that  provide  valuable  historical  climate  information 
extending  beyond  the  period  for  which  we  have 
direct  records.  These  reconstructions  help  scientists 
understand past climate variations and patterns, which 
is essential for estimating natural climate variability, 
calibrating climate models, identifying climate trends or contextualising recent changes. Targeted 
efforts are needed on prior warm periods in the paleoclimatic record to better understand how 
the climate was behaving globally and regionally in a multi-millennial context. This will inform 
our understanding in terms of both the novelty of the current climate system state and the rate 
of ongoing climate change.

16

2.1   Modeling atmospheric circulation and precipitation changes 

in a warming climate

Earth system science

Impacts, risks and adaptation

Mitigation

Future changes in atmospheric circulation and the resulting precipitation changes are subject to 
substantial knowledge gaps. There are structural and systematic uncertainties in representing 
changes  in  the  21st  century  atmospheric  circulation  changes  in  the  North  Atlantic/European 
sector and there remains substantial uncertainty in assessing the interactions between climate 
change and in particular Arctic warming, and mid-latitude variability. There are contrasting lines 
of evidence that cannot yet be reconciled on the linkages between the Arctic warming and the 
mid-latitude atmospheric circulation. Furthermore, climate models agree only in a few regions 
on how (in which direction) trends in mean precipitation will change during this century. Hence, 
based on the current generation of climate models, we do not know for most regions whether 
mean precipitation will increase or decrease, let alone knowledge of more sophisticated climate 
indicators related to precipitation.

Strong arguments can be made that these substantial uncertainties can be reduced through a 
decisive increase in spatial resolution and hence quality of the climate models used. Progress will 
require flexible experimentation with the recently developed very-high-resolution coupled climate 
models increasingly feasible in the context of the upcoming European exascale High Performance 
Computing efforts.

Policy relevance
Reducing uncertainties in predicting atmospheric circulation 
and precipitation changes is vital for informed policymaking 
across  sectors  to  enhance  resilience,  sustainability,  and 
preparedness in the face of a changing climate, via a shift to 
higher-resolution climate models.

Flag(s)
Digitalisation/AI

Related fiche(s) 
5.3, 8.4 

17

 
2.2   Representing the Atlantic Meridional Overturning Circulation 

(AMOC) in climate models

Earth system science

Impacts, risks and adaptation

Mitigation

Our current knowledge on the AMOC is insufficient. The best assessment is that the AMOC will 
weaken in the future, but we do not know by how much and for how long, nor how much this 
weakening depends on the mix and rate of future GHG emissions. It is generally understood that 
the AMOC collapsed abruptly during the last glacial period, but the likelihood of collapse this 
century under global warming is currently assessed as a low likelihood outcome with considerable 
uncertainty. While proxy records indicate that the AMOC was relatively stable during the past 8000 
years, there is some evidence, but low confidence, of a decline during the 20th century. To what 
extent observed change is due to natural variability or human-caused change remains uncertain.

These knowledge gaps highlight the critical importance of continuous high-quality monitoring, yet 
the future of subpolar AMOC measurements is unclear. A systematic exploration of reducing the 
dependency upon short-term funding support of subpolar observations by individual entities and 
teams is needed to ensure long-term continuous monitoring. There is also a need for systematic 
exploration of physical, chemical, and perhaps biological proxies of recent AMOC changes. 

The magnitude and mechanisms of AMOC internal variability show inconsistent behaviour across 
existing climate models and remain underestimated despite most recent model development. 
The observations in the subpolar North Atlantic show that the importance of Labrador Sea deep 
convection for AMOC variability is substantially overestimated in standard climate models. This 
suggests  that  coupled  climate  models  must  be  run  at  much  higher  spatial  resolution  than  is 
currently standard to simulate air-sea interactions in the water-mass formation regions and to 
properly assess the impact of future changes. Flexible experimentation with recently developed 
very-high-resolution climate models is needed for the assessment of likeliness of future collapse.

Policy relevance
AMOC  changes  influence  regional  ocean  changes  in  the 
North  Atlantic/European  realm  and  have  far-reaching 
effects on precipitation patterns. A complete AMOC collapse 
would  fundamentally  alter  the  North  Atlantic  regional 
climate with broad ranging impacts for Europe and beyond. 
Better  understanding  the  likelihood  and  warning  signs  of 
an  AMOC  collapse  is  critical  for  robust  policies  for  building  
climate resilience.

Flag(s)
Digitalisation/AI

18

 
2.3   Identifying abrupt, irreversible, and committed changes in 

the cryosphere

Earth system science

Impacts, risks and adaptation

Mitigation

The climatic responses of cryospheric elements like ice sheets and permafrost can be both abrupt 
and irreversible, lead to committed long-term changes, and contribute to global or regional climate 
feedbacks. However, despite recent progress, large uncertainties remain on the likelihood, timing, 
and amplitude of abrupt and irreversible changes in the cryosphere. This is also the case for the 
amplitude of committed future changes in the context of stabilising global temperatures at a 
given warming level.

There  is  an  urgent  need  to  improve  our  capabilities  to  observe,  model  and  identify  signs  of 
destabilisation of the Antarctic and Greenland Ice Sheets to constrain uncertainties in projections 
of global sea level rise.

The  Greenland  Ice  Sheet  could  be  subject  to  abrupt  changes  in  a  warmer  climate,  however, 
there is low agreement including on the processes determining the evolution of surface mass 
balance  (meltwater  formation,  storage,  and  drainage  at  the  surface  and  below),  and  their 
potential interaction with ice dynamics. The West and East Antarctic ice sheets are considered 
to be susceptible to develop instabilities linked to critical thresholds. However, there are large 
uncertainties in modeling marine instability due to warming oceans, subsurface melting, and ice 
shelf fractures, impacting future ice-mass projections.

Conflicting observations and limited accessibility hinder accurate modeling. Permafrost thawing 
with global warming will decrease the frozen soil volume, releasing carbon, yet the timing and 
extent of carbon dioxide versus methane release remain uncertain. Inadequate representation 
of processes like abrupt thaw and limited observational data in climate models contribute to 
this uncertainty. Variability in surface conditions complicates understanding and modeling carbon 
pools, while some models overlook the existing permafrost carbon pool crucial for estimating  
its feedback.

Policy relevance
Ice-sheet melt has direct implications on the global scale due 
to  the  influence  on  global  mean  sea  level.  Abrupt  changes 
can lead to accelerated changes; committed and irreversible 
changes with long-term effects, including on regional climate. 
Having a better understanding of how such changes might and 
will occur will help design the necessary adaptation responses, 
with a greater knowledge of implied impacts for ecosystems 
and populations, both relevant for region-specific policies and 
for international cooperation.

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International 
cooperation

Digitalisation/AI

Related fiche(s) 
1.3, 3.1, 5.5, 5.6. 

19

 
2.4   Extending high-resolution proxy reconstructions with a focus 

on the mid-Holocene

Earth system science

Impacts, risks and adaptation

Mitigation

Proxy reconstructions of past climate with a yearly temporal resolution only reach back to the 
Common Era at global and hemispheric scales. Further back in time the reconstructions become 
progressively sparser in time, at decadal, centennial, and then even millennial temporal scales. 
This limits how our rapidly changing climate state can be compared with earlier periods, and thus 
the quantification of both the unusualness of the current state of the climate system, and the rate 
of ongoing climate change in a multi-millennial context. There is considerable potential to extend 
back in time high resolution proxy reconstructions through a combination of reanalysis of existing 
proxy records and the development of new and improved techniques.

A focus on the mid-Holocene thermal maximum period is particularly valuable as a comparison to 
current climate. During that epoch, the global surface temperature maximum – driven by seasonal 
insolation changes from orbital variations – may have reached sustained temperatures above 
pre-industrial  levels,  potentially  only  surpassed  in  the  most  recent  decade.  However,  there  is 
considerable ambiguity over the synchronicity of reconstructed changes and incomplete knowledge 
of implied changes in other climatic variables.

Improving  the  temporal  resolution  of  reconstructions  around  the  last  interglacial  peak,  when 
the climate was warmer than today, with a higher global sea level and smaller ice sheets, but 
with much lower CO2 concentrations  in the  atmosphere, is important  to help answer  to what 
degree climate change experienced in the coming decades is unique in the context of the current 
interglacial. The currently available reconstructions for this last warm period around 125,000 
years ago are at solely centennial to multi-centennial resolution.

Policy relevance
This enables a longer-term view of changes, which is important 
to exploit existing proxies and undertake targeted additional 
studies.  Improving  our  knowledge  about  the  past  periods 
similar to today’s in terms of climatic and non-climatic aspects 
will  aid  planning  and  decision-making  across  scales  with  a 
greater granularity.

Flag(s)
Digitalisation/AI

Related fiche(s) 
1.4, 3.7. 

20

CLUSTER 3:  
RISKS AND VULNERABILITY ACROSS 
TIME AND SPACE
The latest IPCC assessment finds that dangerous climate risks will occur at lower warming levels 

and earlier than assessed in previous reports. With additional warming, risks are becoming 
increasingly intense, complex and more difficult to manage. In addition, societal systems and 
their economies are more and more exposed to compounding risks arising from multiple climate 
hazards occurring together and concurring with a range of other, non-climatic factors such as 
land use and habitat destruction. Transboundary and trans-sectoral risks related to, for example, 
global supply chains, financial markets, non-linear socioeconomic responses, or loss of ecosystem 
services, can significantly amplify losses, as has been dramatically illustrated by the recent COVID-
19 pandemic. 

The dynamics of compounding and cascading risks are still poorly understood and require further 
investigation to inform pathways for building societal resilience in the long term. The propagation 
of risks and their interactions with adaptation and mitigation options should be analysed from a 
more holistic perspective. More evidence is needed to characterise and quantify the development 
and  transmission  pathways  of  risks  for  specific  systems  under  different  scenarios  of  future 
climatic, adaptation, mitigation, and societal development pathways.

Reducing the vulnerability of ecosystems and people to climate hazards also requires more and 

21

better data on climate-related risks, with a commitment to widespread accessibility, as pursued 
by the Risk Data Hub and ClimateAdapt initiatives. Equally important is the development of robust 
methodologies and frameworks for the quantification of risk sensitivity. This involves addressing 
the characterisation, monitoring and quantification of the many nonlinear interactions involved. 
These advances are pivotal for evaluating the effectiveness of mitigation, adaptation, and risk 
reduction strategies.

Adaptation also needs to be better characterised under a variety of future scenarios, with new 
data and knowledge on the response of both human and natural systems to adaptation options. 
Research should explore how the adaptation potential of societies for risk reduction varies with 
local and temporal context, depending on the dynamics of human vulnerability and exposure 
to climate change and extreme events, their interaction 
and  interdependence  with  ecosystem  vulnerability, 
and  with  other  non-climatic  factors  and  hazards. 
A  comprehensive  approach  is  required  to  inform 
adaptation strategies that are not only incremental but 
also transformative to build lasting resilience embedded 
in broader development policies. 

With additional 
warming, risks 
are becoming 
increasingly intense, 
complex and more 
difficult to manage

With  global  warming  likely  to  exceed  1.5°C  in  this 
century  given  the  slow  pace  of  progress  on  reducing 
GHG  emissions,  there  is  an  increasing  interest  in  the 
exploration of overshoot scenarios with a subsequent decline in global temperatures. In fact, the 
majority of emission scenarios limiting global warming to 1.5°C by 2100 analysed in the latest 
IPCC assessment involve a temperature overshoot. There is an urgent need to better understand 
risks associated with such scenarios, including exploration of climate and Earth system feedbacks, 
the feasibility and impacts of large-scale carbon dioxide removal (CDR) that would be needed 
to bring the temperatures back down, and the wider implications for mitigation and adaptation 
strategies.

22

3.1   Understanding future global climate risks for individual  

systems, sectors and for compound risks

Earth system science

Impacts, risks and adaptation

Mitigation

Climate  risks  intensify  with  rising  temperatures,  especially  affecting  vulnerable  groups  and 
systems. As temperatures rise, managing impacts becomes more challenging due to complex 
interactions between multiple hazards and other threats. The ability to minimise risks varies by 
location and depends on adaptation efforts.

Research is needed to better understand the development of risks over time for different possible 
future climate and mitigation scenarios, the surpassing of temperature dependent adaptation limits 
for ecosystems and human systems, and what effective response options can be deployed both for 
human society and communities, and also in terms of constraints on individual actors. Developing 
robust projections of future compounding global climate risks requires further basic research 
about mechanisms and underlying causes and effects concerning 1) the vulnerability of species, 
biodiversity, ecosystems, dependent humans and societies at regional scale at different warming 
levels; 2) the occurrence, including “when” and “why”, of biological tipping points (ecosystems) and 
tipping points for societal functioning, and; 3) the limits to adaptation (evolutionary adaptation) of 
species, ecosystems and of dependent societies with various economic backgrounds.

Furthermore, IPCC reports include an iconic representation of rising climate risk as a function of 
temperature rise – figures called "burning embers". These represent the relationship between risk 
development and degree of global warming. It would be valuable to develop approaches that 
would enable visualisations akin to the burning embers, with and without adaptation, for various 
development pathways, and including consideration of regional risks and also embracing other 
indicators of climate change beyond the warming levels alone (such as temperature humidity 
combinations,  extreme  events  including  drought  and  flood,  sea  level  rise,  ocean  oxygen  loss  
and acidification).

Policy relevance
Expanded risk-scenarios, including compound risks and nature’s 
and societies’ capacities to respond, will enable policymakers 
to  make  robust  decisions  about  mitigation,  adaptation  and 
climate resilient development.

Flag(s)
Digitalisation/AI

 Biodiversity/
Ecosystems

 SSH

Related fiche(s) 
1.5, 2.3, 4.2, 6.3. 

23

3.2   Understanding the dynamics of exposure and human  

vulnerability at regional and local scales

Earth system science

Impacts, risks and adaptation

Mitigation

In assessing climate risk, both exposure and vulnerability, as well as their interlinkages, need to be 
taken into account. Notably, vulnerability and exposure cannot be considered as static, and their 
variability in both space and time needs better understanding and assessment. 

Despite changes in exposure, present studies tend to assess exposure to heat stress based on 
static  information,  without  accounting  for  daily  mobility  and  other  population  dynamics.  For 
example, during the day, increased heat stress exposure can be experienced outside of the place 
of residence, as well as during any commute. The development of adaptation and early warning 
systems in the context of extreme events would benefit significantly from more sophisticated 
understanding and treatment of daily, weekly and monthly dynamics of population movements in 
terms of exposure. A comprehensive and improved consideration of population dynamics requires 
updated methodologies, advanced modeling, and planning tools. 

Changes in vulnerability, in turn, are especially induced by evolving socio-demographic and socio-
economic structures or framework conditions. Better understanding of the associated dynamics 
is a pressing research need given the potentially significant implications for adaptation responses 
in the context of mitigation action, as well as the broader equity and justice dimensions. Today, 
3.6 billion people are already considered highly vulnerable to climate change due to overlapping 
challenges  and  effects  of  compound  risks.  But  how  will  their  adaptation  capacity  and  limits 
change depending on the progress on poverty reduction, equity, justice, resource distributions and 
mitigation? Research is needed to elucidate these questions by providing more insights into issues 
such as vulnerability of human society at regional and local scales; interactions between heat 
stress, human thermal performance and levels of societal functioning; the environmental criteria 
for human well-being and health, but also for ecosystem health and biodiversity; trajectories that 
integrate human into ecosystem and planetary health through climate resilient development; the 
gender dimension of vulnerability and adaptive capacity.

Policy relevance
More  accurately  representing  societal  and  ecosystem 
vulnerability and exposure in time and space, will allow for 
better tailoring of early warning systems (of direct relevance 
for  the  World  Meteorological  Organisation  (WMO)  “Early 
Warnings for All” initiative), risk management strategies and 
other adaptation measures at different levels of mitigation, 
significantly improving their effectiveness and helping to avoid 
maladaptation.

Flag(s)

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International 
cooperation

 Biodiversity/
Ecosystems

 Gender

Related fiche(s) 
4.3, 4.6, 9.3. 

24

3.3   Cascading, compound and transboundary risks and  

adaptation

Earth system science

Impacts, risks and adaptation

Mitigation

Cascading and compound risks of climate change are potentially very damaging to economies 
and societies, including across sectors and international borders. The latest IPCC report has found 
that increasing transboundary risks are projected across the food, energy, and water sectors as 
impacts from more frequent and severe weather and climate extremes increasingly propagate 
through supply chains, financial markets, and natural resource flows, and may also increasingly 
interact with impacts from other crises such as pandemics.

While  the  conceptual  understanding  of  cascading  and  compound  risks  and  adaptation  has 
improved, systems-wide research quantifying how commodity and trade networks, the financial 
system, natural resource flows (e.g. rivers and watersheds) and the movement of people and 
species propagate impacts and risks across sectors, regions and borders has only recently started 
to emerge. Substantially more evidence is needed to understand risk transmission pathways. 
Several gaps remain also for specific compound risks, for instance how the interaction of multiple 
risks across sectors may result in displacement, migration, or immobility of people both within 
and from outside Europe. Finally, while there is generally good conceptual understanding of how 
adaptation can reduce risks at the source, research is needed to identify the effectiveness of 
different adaptation options in reducing these cascading, compound, and transboundary risks 
across different levels of mitigation action.

Policy relevance
Most  European  adaptation  strategies  are  still  heavily 
focused on sectoral, regional, and national risks and thereby 
underestimate the true costs and disruption of climate change. 
This  research  will  inform  cross-sectoral,  cross-boundary 
and  better  coordinated  international  adaptation  responses 
to  diverse  combinations  of  climatic  and  non-climatic  risks. 
It  will  also  contribute  to  understanding  adaptation  limits 
and  the  requirements  for  transformational  rather  than  
incremental adaptation.

Flag(s)

International 
cooperation

 SSH

 Biodiversity/
Ecosystems

Related fiche(s) 
4.1, 4.2, 8.3. 

25

3.4   Evaluating the intrinsic risks of climate change responses 

Earth system science

Impacts, risks and adaptation

Mitigation

The way we respond to climate change can itself generate new risks. The IPCC defines risk as “the 
potential for adverse consequences for human or ecological systems, recognising the diversity 
of values and objectives associated with such systems”, encompassing risks from both potential 
impacts of climate change and human responses to it. These may include: 1) maladaptation (and/
or trade-offs between adaptation to various increasing hazards, e.g., adaptation to increasing 
extreme  precipitation  leading  to  a  higher  vulnerability  to  drought);  2)  mitigation  options  that 
unintentionally increase physical climate risk or other crises like pollution or biodiversity loss (e.g., 
biofuel production competing with food security, driving land use change and limiting options for 
more effective mitigation).

With  the  scale  of  implementation  of  responses  required,  such  risks  will  become  increasingly 
likely and potentially severe, hence also constraining future options for climate action. A core 
research priority is to develop a systematic inventory of such risks, and, where possible, their 
quantification.  Accordingly,  research  is  needed  to  strengthen  the  methodological  toolbox  for 
complex climate risk assessment, to increase public understanding and policy awareness of such 
risks, and to quantify the most important complex risk feedbacks, particularly when it may result 
in significant constraints on options for climate action. In this context, monitoring and evaluation 
of the effectiveness of mitigation and adaptation measures, policies, and actions is needed on a 
local, regional, and national scale. 

Policy relevance
In-depth understanding of side-effects associated with climate 
action  can  help  eliminate  the  response  options  that  are 
ineffective or even counterproductive and identify the most 
effective solutions for both mitigation and adaptation.

Flag(s)
Digitalisation/AI

 Biodiversity/
Ecosystems

  SSH

Related fiche(s) 
4.1, 6.1, 8.1, 8.2, 10.4. 

26

3.5   Advancing knowledge on risks from overshooting 1.5°C and 

options to bring temperatures back down

Earth system science

Impacts, risks and adaptation

Mitigation

The latest IPCC reports conclude that global warming of 1.5°C is likely to be reached early in 
the 2030s. Yet there is limited understanding of the implications of exceeding a level of global 
warming  of  1.5°C  and  the  extent  to  which  a  reversal  in  global  surface  temperatures  can  be 
achieved. This includes characterising the physical and social risks associated with exceedance 
and return below a specified level of global warming, including a better understanding of carbon 
cycle feedbacks and of the socio-economic, technical, and institutional feasibility of drawing down 
temperatures by removing CO2 from the atmosphere, requiring new modeling frameworks. This 
would include systematic approaches to modeling risks of different durations and magnitudes of 
overshoot, including fast and slow onset processes, low-likelihood high-impact events, and the 
risk of irreversible impacts.

A better understanding of overshoot and (ir)reversibility of its long-term impacts beyond 2100 
need to be considered to account for the slowly varying components of the climate and natural 
systems in the light of the consequences on the well-being of future generations. While many 
hazards decrease with lower temperatures, vulnerability and exposure are not linearly related to 
global surface temperatures and will depend on impacts that occur during an overshoot period 
and on adaptation measures implemented and their cost. Irreversible impacts and ineffective 
adaptation may lead to a situation where impacts remain high even once temperatures return to 
lower levels. 

The feasibility and sustainability of a globally attainable level of CDR also needs to be better 
understood, considering carbon cycle feedbacks and land and ocean impacts, together with an 
improved representation of CDR options and their implementation barriers in global mitigation 
pathways. The potential for stepping up near-term action (including governance and institutional 
barriers) needs to be explored, to understand how much further temperatures could be reversed, 
at what costs and how this would limit residual climate risks.

Policy relevance
Every  increment  of  global  warming  has  major  implications 
for  global  and  regional  climate  and  related  risks  in  the 
coming decades. Both mitigation and adaptation policies will 
benefit from assessing the potential for enhanced near-term 
mitigation, long-term CDR and the associated impacts, risks 
and feasibility of returning temperatures to lower levels.

Flag(s)

  SSH

 Biodiversity/
Ecosystems

Related fiche(s) 
1.5, 4.1, 8.5.

27

 
3.6   Exploring societal resilience in a volatile world amplified by 

climate change

Earth system science

Impacts, risks and adaptation

Mitigation

The causes, risks, and consequences of climate change are well established. Addressing the climate 
challenge is also increasingly seen as a key enabling factor to achieve other societal objectives that 
are part of a broader sustainable development agenda, and vice versa. It is therefore clear that 
societal choices about how to respond to the climate change challenge are intricately interlinked 
with our wider societal system. A key knowledge gap, however, is how other crises can amplify 
climate risk or are exacerbated by climate impacts or adaptation and mitigation responses, when 
they occur simultaneously or in short succession. This state, where disparate crises can interact 
such that the overall impact far exceeds the sum of each part is called a poly-crisis. Interlinked 
crises that were identified in expert elicitations include environmental (climate change, biodiversity 
and ecosystem collapse, natural resource crisis), societal (public health and pandemics, cost of 
living, mis- and disinformation), technological (breakdown of critical infrastructure), economic and 
geopolitical crises (armed conflicts).

Illustrative examples of the interactions between different crises that need to be better understood 
in  the  context  of  adaptation  are  the  role  of  non-climate  crises  in  changing  exposure  and 
vulnerability patterns that affect loss and damage, including through the impact of multiple crises 
on biodiversity and access to environmental services. A crisis that increases vulnerability presents 
an additional driver of risk and further exacerbates the impacts of climate shocks. Adaptation 
options that exist otherwise may not be available under these conditions. Compound and cascading 
risk assessments and analyses of multi-dimensional climate risk in areas of high vulnerability (and 
often limited data) are needed. In the context of mitigation, the interactions and linkages between 
different crises need to be better understood in how the transformations required to reach a net 
zero world change society’s vulnerability and exposure to critical infrastructure, geopolitical or 
other risks. It is equally important to address how climate (mitigation and adaptation) policies can 
create synergies and trade-offs in addressing other crises, and vice versa. 

Policy relevance
Current  research  and  research  tools  are  not  equipped  to 
explore the interdisciplinary questions that must be answered 
to  understand  complex  and  cascading  multi-dimensional 
climate risks, their interaction with societal vulnerability and 
exposure, as well as potential societal solutions. However, a 
better  understanding  of  these  risks  at  different  spatial  and 
temporal scales is crucial to ensure a resilient future society 
through informed decision-making.

Flag(s)

 Gender

  SSH

Related fiche(s) 
4.4, 5.1, 9.3, 10.2, 10.6. 

28

3.7   Utilising paleo records of past impacts of climate changes to 

refine future scenarios

Earth system science

Impacts, risks and adaptation

Mitigation

The unfolding climatic changes are not unique and there have been equivalents in the prehistoric 
past.  Although  climatic  changes  of  the  last  2.5  million  years  have  largely  been  driven  by 
astronomical  cycles,  there  are  examples  from  the  more  distant  past  when  large  releases  of 
GHGs caused global ecological crises and even mass extinctions. The rich record of ecosystem 
responses in the deep past is currently poorly integrated in the assessment of climate risks and 
vulnerabilities. The study of past warming periods can help assess the vulnerability of groups of 
species and ecosystems, identifying those which may be most vulnerable to global warming in 
the long run, including where the impacts of climate change are expected to be most severe and 
which climatic thresholds may lead to mass extinctions.

The  latest  IPCC  report  includes  a  better  coverage  of  paleontological  records  of  impacts  than 
before, but due to lack of targeted research few statements could be made with high confidence. 
Exploring  climate  impacts  in  the  geological  past  can  reveal  climate  change  impacts  with  no 
confounding human impacts such as habitat destruction, pollution and overexploitation that are 
the main sources of modern biodiversity decline. Another advantage is that ecosystem states can 
be compared for different stages of past climate-induced crises – before, during, and after. A key 
challenge to compare these past impacts with current climate change is the different timescales 
over which such comparisons can be made. Bridging the gap requires a combined effort to find 
mechanisms that are scale-independent and to use modeling and simulations. Regarding models, 
the most widely used approaches to predicting biodiversity losses due to climate change are 
species distribution models. Simulations are needed to interpolate longer term observations of 
climate impacts to shorter time scales. Challenges also exist with reference to the spatio-temporal 
link between warming and biological responses.

Policy relevance
Deepening  the  understanding  of  species  and  ecosystems’ 
vulnerability  to  climate  change  based  on  multiple  lines 
of  evidence,  including  paleo  records,  is  critical  for  refining 
conservation  planning  and  directing  it  towards  species 
and  ecosystems  that  are  likely  to  be  most  impacted  under 
projected warming scenarios.

Flag(s)

 Biodiversity/
Ecosystems

Digitalisation/AI

Related fiche(s) 
1.4, 2.4. 

29

CLUSTER 4:  
ADAPTATION: EFFECTIVENESS, PATHWAYS 
AND LIMITS, LOSSES AND DAMAGES
Widespread adverse impacts, including related losses and damages to people and nature, are 

already occurring in countries and regions hit by climate hazards, affecting disproportionately 
vulnerable communities and ecosystems. Impacts will escalate with every increment of global 
warming, making the case for adaptation increasingly urgent. The IPCC cautions, however, that 
there are limits to how much adaptation can reduce climate risks - as climate change progresses, 
human and natural systems increasingly face adaptation limits, where adaptive measures become 
ineffective in reducing risk and safeguarding against harmful consequences. There is also a need 
to learn from the increasing evidence of maladaptation across sectors and regions that creates 
lock-in of vulnerability and makes exposure and risks more difficult and costly to manage.

In  addition  to  the  continued  benefits  of  incremental  adaptation,  the  IPCC  report  introduces  a 
paradigm shift towards transformational adaptation that builds resilience in the long term in 
synergy with sustainable development, helping to overcome soft adaptation limits. Sustainable 
development  for  all  is  also  the  foundation  of  the  concept  of  climate  resilient  development, 
integrating adaptation with mitigation action to deliver benefits for human well-being and health of 
the planet. However, important barriers that undermine adaptive capacity remain to be overcome, 
including  in  Europe,  to  accelerate,  monitor  and  assess  the  development  and  implementation 
of effective and transformative adaptation actions. Examples of such barriers include missing 

30

data, inadequate institutional and governance arrangements or gaps in our capacity to assess 
climate risk and the effectiveness of adaptation strategies. The links between risk preparedness 
and response, including early warning, climate resilient reconstruction, grey and nature-based 
solutions (NBS) for adaptation and sustainable development also need to be strengthened, and 
incorporated into the EU core policies such as the Common Agricultural Policy and the Water 
Framework Directive.

Understanding the role of human activities through climate 
attribution becomes increasingly important for informed 
risk  management  and  policy  development  and  is  key  to 
progress in strengthening the preparedness for extremes, 
reducing  losses  and  damages.  It  is  important  to  clarify 
here  the  distinction  between  “losses  and  damages”  and 
“Loss  and  Damage”  -  the  IPCC  uses  the  former  to  refer 
broadly  to  adverse  (observed)  impacts  and  (projected) 
risks whereas the latter is linked to political debate under 
the  UNFCCC  on  addressing  climate-related  destruction 
in  developing  countries  in  the  context  of  the  Warsaw 
International Mechanism. In the research context of this 
report, the primary focus is on the wider notion of “losses 
and damages”, with the potential to inform the “Loss and 
Damage” policy and legal dimensions. Advances are needed 
in our understanding and quantification of losses and damages, including cross-cutting issues 
related to climate justice and responsibility, distributional aspects, and stakeholder engagement, 
as well as non-economic aspects such as ecosystem functions, culture and heritage. The potential 
legal implications of Loss and Damage under the UNFCCC, as well as at other scales (e.g., local 
and national) and other legal regimes, also need to be further explored.

Human and natural 
systems increasingly 
face adaptation 
limits, where 
adaptive measures 
become ineffective 
in reducing risk 
and safeguarding 
against harmful 
consequences�

Filling these gaps will secure more and better data on climate-related losses and damages, help 
validate effective adaptation options and provide state-of-art knowledge on adaptation best-
practises, strengthening repositories such as Climate-ADAPT.

31

 
4.1   Understanding adaptation effectiveness and limits  

at different degrees of warming

Earth system science

Impacts, risks and adaptation

Mitigation

Despite a notable increase in evaluations of the implementation and effectiveness of adaptation in 
the latest IPCC report, the assessment primarily focused on responses to past or present climatic 
conditions and did not consider increasing temperatures. However, most adaptation options to the 
four key risks in Europe (heat, drought, flooding, water scarcity) depend on water and land, the 
availability of which will be diminished with increasing global warming. The current adaptation 
implementation  gap  is  therefore  likely  to  increase  with  higher  warming,  but  quantification  is 
missing.

The latest IPCC report also found increasing evidence for hard limits to adaptation being surpassed 
already at current warming levels. Such hard limits are related to biological tolerance thresholds, 
including  human  physiological  limits  (such  as  under  hot  and  wet  conditions)  and  biological 
physiological limits leading to species mass mortality and degradation of ocean, aquatic, and 
terrestrial ecosystems. With further warming, it is expected that context-specific hard limits will 
increasingly be encountered due to biogeophysical constraints, e.g. on water availability, carbon 
storage and biomass production. However, the scientific evidence underpinning the identification 
of  such  hard  limits  remains  limited,  facilitating  lock-in  effects,  maladaptation,  and  negative 
mitigation responses. 

Better  knowledge  about  adaptation  feasibility  and  limits  and  effectiveness  of  adaptation  for 
different global warming levels and socio-economic contexts is necessary. Advancements are 
needed in assessing possible adaptation responses to numerous climatic impact-drivers across 
a  comprehensive  range  of  warming  levels,  sectors  (energy,  agriculture,  building,  transport, 
industry, ecosystems…), and regions, but also in better including adaptation in climate impact and 
Integrated Assessment Models (IAMs). Regions of particular interest for exploration of adaptation 
limits include those affected by the loss of high mountain cryosphere for water availability, small 
islands and low-lying areas and coasts (changing profiles of coastal hazards including salinisation), 
and the Mediterranean region (biogeophysical constraints e.g., on greening due to limited water 
availability).

Policy relevance
This knowledge is highly relevant for informing the development 
of comprehensive, context-specific, and effective adaptation 
strategies, including evaluation of adaptation options in light 
of limitations, feasibility, and effectiveness, and how to avoid 
maladaptation.

Flag(s)

 Biodiversity/
Ecosystems

Related fiche(s) 
3.1, 3.3, 3.4, 3.5,  
5.2, 8.2, 10.4. 

32

 
4.2   Probing the limits of nature-based solutions under different 

climate-change scenarios

Earth system science

Impacts, risks and adaptation

Mitigation

Nature-based solutions (NBS) are clearly preferable over grey solutions, both by virtue of their 
co-benefits to biodiversity and human health, and also because they sometimes are simply better 
climate mitigation and adaptation solutions. However, the latest IPCC report suggests that while 
NBS as well as most water-related adaptation options are effective, they are vulnerable to climate 
change impacts and their effectiveness may drop with increasing global warming. Effectiveness 
and full exploitation of the potential of NBS therefore relies on ambitious emissions reductions.

As the limits to NBS depend on context and intended benefit, there is need for a more rigorous 
assessment of their feasibility for climate resilience and mitigation at different levels of warming, 
at different timescales, and across a wide range of regions and sectors, addressing questions such 
as when, where and for whom these options can be most effective. Research is needed on the 
benefits and costs of NBS in different settings (e.g., coastal, terrestrial) and for different purposes 
(e.g., mitigation, adaptation, biodiversity conservation) under different warming scenarios and to 
identify best-practice pathways towards design and implementation in different socio-economic 
contexts. In addition, more effort is needed to quantify the efficacy of NBS for adaptation (as 
has been done for mitigation) at various warming levels, and including co-benefits for mitigation  
and biodiversity.

Policy relevance
Understanding how NBS will respond to a warming climate 
and  how  their  potential  will  be  impacted  will  inform  the 
timely development of resilient climate strategies (combining 
adaptation and mitigation dimensions) that are robust against 
various  warming  levels  and  promote  implementation  of 
climate resilient NBS in the broader sustainable development 
context.

Flag(s)

 SSH

 Biodiversity/
Ecosystems

Related fiche(s) 
3.1, 3.2, 5.4. 

33

4.3   Considering population response and coastal adaptation 

strategies in the face of rising sea levels

Earth system science

Impacts, risks and adaptation

Mitigation

Understanding and predicting coastal change is severely limited by incomplete or insufficiently 
tested models, incomplete understanding of nearshore wave processes and unreliable satellite-
derived shoreline estimates. Calibration to local scales is generally needed. A coupled approach 
promises a better handle on both data and model reliability for sandy open coasts, at scales from 
municipalities to regions and continents. Whether this can be extended to mud/mangrove coasts 
that comprise a very substantial part of the global coastlines is an open question. A universal 
approach would be useful to assess long-term strategies of erosion prevention and coastline 
management.

Shortcomings also remain in how national to continental scale assessments of future coastal 
risk can support long-term coastal adaptation pathways. First, they lack consideration of human 
population dynamics and of the interactions between decisions at different scales. While national 
level socio-economic development has generally been included in the assessments, these mostly 
do not take into account subnational spatial and temporal patterns of human development, such as 
urbanisation and migration. Furthermore, assessments generally do not link higher level adaptation 
decisions (e.g., to protect or retreat) with decisions associated with population development.

Assessments have generally not included decision-making frameworks that fit the dynamic and 
adaptive nature of coastal pathways. Adaptation pathway analysis is a helpful tool but lacks 
integration with modeling frameworks. Generally, there is a need to move from static approaches 
(cost-benefit analysis) to dynamic and adaptive approaches that consider the spatial and temporal 
patterns of sea-level rise and socio-economic development. Research should develop a relocatable 
workflow for assessment of past and future coastal evolution at a timescale of decades under 
global and local scenarios of coastal and urban development and climate change. We also need 
to learn more about social acceptability and population responses to coastal adaptation as part 
of broader adaptation pathways across various contexts.

Policy relevance
The outcomes will serve to better appraise the effectiveness 
and  efficiency  of  coastal  adaptation  policy  options  that 
take  into  account  the  essential  development  dynamics  and 
are tailored for different contexts. Improved coastal change 
projections  will  inform  risk  assessment  and  shape  policies 
such as coastal management plans and zoning.

Flag(s)
Digitalisation/AI

  SSH

 Gender

Related fiche(s) 
3.2, 5.1, 5.5, 5.6, 10.2. 

34

4.4  Advancing climate science relevant for loss and damage

Earth system science

Impacts, risks and adaptation

Mitigation

There is an urgent need for a more systemic and, where possible, quantified assessment of current 
and future losses and damages. This includes the extent to which future losses and damages can 
be avoided by mitigation and adaptation and at what costs, as well as limits to adaptation. This 
calls for updated assessments of observed impacts, including their attribution to climate change, 
associated  limits  to  adaptation,  and  adaptation  options  and  constraints.  Second,  it  requires 
progress in modeling of future losses and damages in relation to mitigation, adaptation, and 
development pathways, linking to research on wider climate risk assessment.

Research needs range from basic climate research and advances in the interplay between natural 
variability and human-induced global climate change (both in the recent past and in the near-term 
future), to research focused on responses, to inform how impacts are shaped by the interactions 
between local responses with human-induced exacerbation of climate hazards. Detection and 
attribution of climate-specific losses and damages can be enabled by delivering datasets and 
enhanced methods to separate influences of climate trends (including in extreme events) from 
trends in exposure and vulnerability, both in observed datasets and in model scenarios.

Combining the methodologies of attribution and emergence could help better inform when and 
where unprecedented conditions potentially leading to major losses and damages are expected to 
occur (including using initialised predictions and scenario-based projections).

Policy relevance
Advancements in attribution science can inform and improve 
the effectiveness of early warning and humanitarian strategic 
planning in a changing climate, country- and region-specific 
planning for both adaptation and management of residual risk, 
including in the context of the UNFCCC Santiago Network on 
loss and damage, as well as mitigation choices.

Flag(s)

International 
cooperation

Digitalisation/AI

 Gender

  SSH

 Biodiversity/
Ecosystems

Related fiche(s) 
3.6, 9.1, 9.2. 

35

4.5   Integrating climate resilience in post-extreme events  

reconstruction

Earth system science

Impacts, risks and adaptation

Mitigation

Strengthening the integration of climate resilience and adaptation into reconstruction and loss and 
damage programmes is needed, including in the context of climate resilient development. In most 
cases loss and reconstruction funds primarily provide funding for the rebuilding of what has been 
there before. Improvements towards climate resilience, in different phases of reconstruction, are 
often underfunded or not part of the funding schemes (private insurance as well as state funding 
schemes).  New  data,  methods  and  tools  are  needed  to  improve  the  consideration  of  climate 
resilience within different phases and sectors of reconstruction after extreme events, considering 
differences in climatic hazards, but also in vulnerability and exposure of people, infrastructures, 
and services.

In addition to the integration of climate resilience and adaptation into reconstruction programmes, 
there is also the need to better understand synergies and trade-offs between adaptation and 
mitigation actions. For example, synergies can be strengthened when improving climate resilience 
with new green/blue infrastructures in cities, but specific insulation materials for houses to reduce 
energy consumption might increase loss and damage once the house gets flooded.

Policy relevance
Building  climate  resilience  into  reconstruction  and  loss  and 
damage  programmes  enhances  preparedness  and  adaptive 
capacity  in  synergy  with  sustainable  development.  It  also 
contributes  to  sound  financial  management  in  the  face  of 
non-linear  risks  associated  with  future  climate  change  and 
supports  improved  definition  of  adaptation  and  resilience 
goals, and cooperation formats.

Flag(s)

International 
cooperation

 Gender

  SSH

Related fiche(s) 
6.1, 9.2, 9.3, 10.6. 

36

4.6  Linking early warning to long-term adaptation

Earth system science

Impacts, risks and adaptation

Mitigation

With the impacts of extreme climate events becoming a highly political issue, there is a growing 
interest in examining the role of early warning to protect lives and assets and to support wider 
adaptation efforts. However, there has so far been little systematic exploration of the extent to 
which early warning systems link to adaptation planning, including issues such as how information 
about exposure and vulnerability can be useful across timescales, whether it is shared across 
institutions and if limits to adaptation emerge when considering response to an early warning of 
an unprecedented extreme event.

Case-study based assessments are needed to investigate the adequacy of early warning systems 
in a changing climate, and how they can be improved to enhance preparedness to future events. 
The assessments should identify the limitations of such systems - for example, with the short 
lead-time between warning and extreme weather event (typically a few hours or days notice), 
people may be able to move out of harm’s way, but many assets will still be lost, with no time 
for more structural adaptation such as changes in land use planning, construction of protective 
infrastructure or public awareness raising. The outcomes should underpin the design of better 
early warning systems and point to areas where other adaptation solutions are necessary.

Policy relevance
Results will serve to strengthen the coherence between short-
term  disaster  risk  management,  longer-term  disaster  risk 
reduction, and more systemic climate change adaptation as 
called for by the Cancun Agreement and the Sendai Framework 
for Disaster Risk Reduction. At the global level, the outcomes 
will  support  the  efforts  on  addressing  “Loss  and  Damage”, 
including  under  the  UNFCCC,  where  early  warning  systems 
have been suggested as a key mechanism, and encompassing 
the “Early Warnings for All” initiative of the WMO.

Flag(s)

International 
cooperation

 Gender

Digitalisation/AI

  SSH

 Biodiversity/
Ecosystems

Related fiche(s) 
3.2, 9.1, 9.2.

37

CLUSTER 5:  
WATER, BIODIVERSITY, NATURE-BASED  
SOLUTIONS AND THE COASTAL 
ENVIRONMENT IN A CHANGING CLIMATE
Water is a dual force in the fight against climate change, acting as both a source of hazards 

through  floods,  droughts,  and  extreme  weather  events,  and  a  vital  component  of  both 
adaptation and mitigation responses. As highlighted at the 2023 United Nations Water Conference, 
“Water is a dealmaker for the Sustainable Development Goals, and for the health and prosperity 
of people and planet. But our progress on water related goals and targets remains alarmingly off 
track”. Indeed, the world is already facing an unprecedented water crisis, with global freshwater 
demand predicted to exceed supply by 40% by 2030. The latest IPCC report warns that continued 
warming is poised to further disrupt the global water cycle, impacting its variability, monsoon 
precipitation, river flows, seasons as well as very wet and very dry extremes. The IPCC report warns 
that increases in frequency, intensity, and severity of droughts, floods, and heatwaves, combined 
with sea-level rise will expose millions of people to acute water and food insecurity with a high 
risk of triggering conflicts, political instability, and refugee crises.

Water and food security greatly depend on functioning freshwater ecosystems in streams, rivers, lakes, 
and wetlands, which are vital for sustainable development, climate resilience and as carbon sinks. In 
2022, the Convention on Biological Diversity (CBD) emphasised their crucial role by establishing targets 

38

that specifically focus on the conservation, restoration, and sustainable management of inland waters. 
However, the latest IPCC report shows that freshwater ecosystems are under threat from climate 
induced changes in the hydrological cycle. With additional global warming, ecosystems may reach or 
surpass hard adaptation limits. 

Around 10% of the world's population – close to 1 billion people – resides in low-lying coastal areas 
hosting significant infrastructure, economic and ecosystem assets that are at significant risk from 
sea-level rise, storms, and storm surges, but also from saltwater intrusion into coastal ecosystems, 
increased water temperatures and ocean acidification. Whereas many coastal cities and settlements 
are already experiencing severe climate impacts, the latest 
IPCC report warns that coastal climatic impact-drivers – sea-
level rise, coastal flooding, and coastal erosion - are projected 
to increase by mid-century. Coastal flood damage alone is 
projected to increase at least tenfold by the end of the 21st 
century.

Continued warming 
is poised to 
further disrupt 
the global water 
cycle, impacting its 
variability, monsoon 
precipitation, river 
flows, seasons as 
well as very wet and 
very dry extremes�

Understanding of the changes in the global water cycle and the 
interdependencies between climate change, water dynamics, 
and biodiversity is essential for crafting effective response 
strategies, which should include nature-based solutions (NBS) 
among other approaches to support ecosystem adaptation. 
Strengthening the evidence base regarding the efficacy of NBS 
in a warming climate is crucial. Ecosystem adaptation must 
be driven by improved knowledge about the ramifications of 
management and restoration actions on ecosystem functions, 
services,  and  biodiversity.  Coastal  ecosystems  adaptation 
can  be  advanced  by  comprehending  and  quantifying  the 
future risks and impacts of changing coastal conditions and the effectiveness of related adaptation 
strategies, not least by combining modeling studies with satellite observations and by expanding 
comprehensive local to global assessments. Enhancing the resolution and representation of coastal 
processes is also crucial for actionability at a local scale. All these aspects should be considered as 
research needs and take into account the needs of the Water Framework Directive in a changing 
climate, by addressing a variety of issues from water-related extremes (e.g., floods and droughts) to 
water as a resource (e.g., groundwater, urban water and water reuse) and water in the ecosystems  
(e.g., marine water and nitrates).

39

 
5.1   Projecting climate impacts across natural systems:  

terrestrial, marine, and freshwater

Earth system science

Impacts, risks and adaptation

Mitigation

When it comes to risk reduction, our knowledge on how nature-based solutions, in terms of both 
adaptation and mitigation measures, integrate is limited. To guarantee a liveable future for all, we 
need to rebuild destroyed or degraded ecosystems for biodiversity and carbon storage. To do so 
successfully, we need improved projections of future possible impacts and to develop adaptation 
pathways across ecosystems and dependent societies more comprehensively.

Current research is improving the understanding around which climate-dependent mechanisms 
are  underpinning  biodiversity  shifts,  and  which  physiological  trade-offs  and  constraints  must 
be  considered,  explaining  species  interactions,  competitiveness,  abundance  in  relation  to 
environmental parameters, and overall, ecosystem structure and functioning. However, to cover 
global biodiversity in freshwater or marine environments a significant expansion of modelled 
scenarios should consider abrupt changes, thresholds and possible tipping points of ecosystems 
and dependent societies (which are system properties), their (lack of) capacities to adapt and 
mitigate, as well as the responses of ecosystems and societies to shocks under extremes, and 
water-related risks associated with adaptation and mitigation responses. Scenario development 
needs to reflect this integration, considering land, freshwater and ocean “scapes”.

Furthermore, the climate change-biology interface needs further investigation to broaden our 
understanding regarding evolutionary responses in complex and long-lived marine organisms to 
identify which changes in ecosystems lead to ecosystem failure.

Policy relevance
A better understanding of climate change related impacts on 
ecosystems and dependent societies can lead to an improved 
quality  and  acceptability  of  climate  policies.  Improved 
understanding  of  tipping  points  and  limits  to  adaptation 
supports the development of adaptation trajectories that are 
better tailored to ecosystems and societies.

Flag(s)

  SSH

 Biodiversity/
Ecosystems

Related fiche(s) 
3.6, 4.3, 6.3, 9.1.

40

5.2   Integrating water management and adaptation responses

Earth system science

Impacts, risks and adaptation

Mitigation

In its latest report, the IPCC has underscored that 60% of climate change adaptation measures are 
intricately tied to water. Furthermore, a multitude of climate impacts are also mediated through 
water, including but not limited to floods, droughts, and the melting of glaciers, highlighting the 
importance of improving our understanding of the effectiveness, robustness, and limitations of 
water-related adaptation strategies.

There is a need to advance integrated water management for adaptation purposes through a 
context-specific, portfolio-based approach that considers all aspects of the water cycle, from 
atmospheric rivers, to soil moisture and groundwater storage. This would require a systematic 
review  of  observed  and  projected  climate  impacts  in  the  hydrological  cycle  together  with 
identification of water-based adaptation options and limits (at different levels of mitigation and 
warming) as well as risks of maladaptation. For example, salinisation of coastal aquifers and 
upstream migration of salt wedge in rivers due to sea-level rise may limit the available adaptation 
options. 

Research should include better understanding of the interaction between water-based adaptation 
and mitigation options to strengthen their synergies - for example, in water scarce areas some 
adaptation responses (e.g., desalination) could undermine decarbonisation efforts. There is also 
a  need  to  explore  the  interdependencies  more  thoroughly  within  water-related  sustainable 
development  objectives,  notably  in  the  context  of  the  water-energy-food  nexus,  such  as  the 
relationship between soil moisture and land use. 

Policy relevance
A  more  comprehensive  understanding  of  how  climate 
change affects the entire water cycle will enable a portfolio 
of strategies for better managing water resources, including 
options for climate-proofing the existing EU water policies, and 
reinforcing  synergies  with  sectoral  adaptation  (e.g.,  energy, 
agriculture). It will also help avoid maladaptation and support 
better  integration  of  ecosystem-based  adaptation  and  NBS 
into water management strategies.

Flag(s)

 Biodiversity/
Ecosystems

Related fiche(s) 
4.1, 6.1, 6.3.

41

5.3   Projecting and monitoring soil moisture and ecosystem 

drought processes to build resilience

Earth system science

Impacts, risks and adaptation

Mitigation

Soil moisture is a crucial regulatory variable affecting water resources, ecosystems, and land-
climate  feedbacks.  Its  interaction  with  other  variables  such  as  soil  organic  carbon  plays  an 
important role in determining soil GHG emissions, though quantification of these interactions 
comes with large uncertainties. Within the water cycle, soil moisture plays a significant role in 
various natural processes, including plant growth, groundwater recharge, runoff generation, and 
climate interactions. Accurate monitoring of soil moisture offers therefore significant potential 
skill for short-term and sub seasonal weather and hydrological forecasting. However, soil moisture 
initialisation  is  generally  not  fully  incorporated  in  forecasting  systems.  The  development  of 
robust initialisation capabilities is crucial, as it sets the initial state of soil moisture in a model or 
simulation.

Better and extended monitoring systems are needed for soil moisture and environmental drought 
status combining in-situ measurements, remote sensing, and land surface models, both in Europe 
and at the global scale. Improvements are necessary in land surface, hydrological and climate 
models in their representation of soil moisture dynamics and soil moisture-climate feedbacks, 
including progress on understanding and quantifying the implications for land-carbon sinks in terms 
of drivers and future trends. The collaboration between relevant research communities (climate 
science, meteorology, hydrology, ecosystem science, physiology of relevant organisms, agronomy 
and forestry, soil science, land surface modeling, remote sensing) should be strengthened.

Assessing  the  soil  moisture  status  and  associated  ecosystem  and  atmospheric  responses  is 
particularly important in Southern, Central and Western Europe, hosting regions that are projected 
to be affected by increasing soil moisture deficits with climate change. 

Policy relevance
An improved understanding of the evolution of soil moisture 
and  ecosystem  drought  in  a  warming  climate  will  provide 
policymakers  with  essential  information  for  effective  water 
resource  management,  drought  preparedness,  land  use 
planning,  and  climate  change  adaptation  and  mitigation 
strategies, notably in the agriculture and forestry sectors.

Flag(s)
 Digitalisation/AI

 SSH

 Biodiversity/
Ecosystems

Related fiche(s) 
1.2, 2.1, 6.3, 8.4, 9.4.

42

5.4   Strengthening best-practices for freshwater ecosystems,  

biodiversity and climate response strategies

Earth system science

Impacts, risks and adaptation

Mitigation

Biodiversity is declining globally and one of the most species-rich ecosystems - fresh waters - are 
being especially threatened. Freshwater vertebrates have faced an average population decline 
of 84% since 1970. Today, roughly one third of all known freshwater species face the threat of 
extinction, including one third of all known freshwater fish species. Under future climate change, 
the pressures on freshwater ecosystems and their species are expected to further increase with 
habitat loss and barriers to migration routes among major threats. Loss of freshwater biodiversity 
will directly lead to a decline in ecological functions, threatening the multitude of natural benefits 
that freshwater biodiversity and ecosystems provide for people.

Nature-based solutions (NBS) have been identified as a cornerstone for protection and restoration 
of  biodiversity  and  ecosystem  services.  To  fully  realise  their  potential  benefits,  it  is  essential 
that  they  are  deployed  in  the  right  places  and  with  the  appropriate  approaches  based  on  a 
scientifically  robust  decision-making  framework  that  integrates  interdisciplinary,  local,  and 
indigenous knowledge with practical expertise while accounting for uncertainty. For highly context-
specific local policy challenges, building of typologies, case studies and their synthesis, as well 
as knowledge sharing, is critical. However, there is still limited evidence on the effectiveness of 
NBS adaptation measures, especially for freshwater ecosystems. In addition, despite the fact 
that participatory (i.e., collaborative) processes are emphasised as part of the development of 
the  EU  Water  Framework  River  Basin  Management  Plans,  there  is  still  a  considerable  lack  of 
consolidated knowledge that defines best practices of collaborative decision-making processes 
for the development and implementation of freshwater adaptation. Such practices encompass 
catchment  restoration,  management,  NBS  plans,  for  example  at  different  spatial  scales,  with 
different spatial resolutions, and ecological and cultural backgrounds.

Policy relevance
Furthering our understanding of the different elements that 
comprise the value of freshwater restoration, management, 
adaptation,  and  NBS  plans  and  strategies,  including  when, 
where,  what  and  how  to  co-develop,  implement,  and  refine 
them, will be imperative to mitigate and to adapt to a warmer 
climate.

Flag(s)

 Biodiversity/
Ecosystems

Related fiche(s) 
4.2, 9.2, 10.4.

43

5.5   Improving projections of future coastal change with Earth 

observations

Earth system science

Impacts, risks and adaptation

Mitigation

Coastal climatic impact-drivers (relative sea level change, coastal flooding, coastal erosion) and 
related  impacts  are  projected  to  increase  almost  all  over  the  world  by  the  mid-21st  century. 
Committed sea level rise requires effective local coastal adaptation measures in addition to the 
global effort to reduce GHG emissions to limit the magnitude and the rate of sea level rise, allowing 
for more time for coastal responses. Progress is needed in modeling the related processes (e.g., 
permanent inundation, episodic flooding, coastal erosion) and associated impacts, together with 
an assessment of risk reduction adaptation measures (e.g., protection structures, NBS, managed 
retreat, etc.).

While advances have been made in recent years on exploiting the ever-increasing Earth observation 
(EO) data, high resolution global datasets of coastal type (sandy, muddy, rocky, etc.), nearshore 
bathymetry and coastal topography are needed for integration with modeling studies to inform 
adaptation planning at local scales. Research is needed on the one hand to benchmark EO baseline 
data with model applications to assess changes in climate hazards, impacts, and risks. On the 
other hand, stakeholder engagement, including the effective involvement of social sciences, is 
needed to develop adaptation options and strategies for implementation.

Policy relevance
Coastal  communities  are  increasingly  at  risk  from  the 
consequences of sea level rise. The local-scale assessment 
of  risk  reduction,  enabled  through  a  range  of  adaptation 
measures, is highly relevant for tailoring policy formulation, 
helping allocate resources efficiently, promoting community 
engagement, enabling data-driven decision-making, building 
resilience, and reducing vulnerability.

Flag(s)
 Digitalisation/AI

 SSH

 Biodiversity/
Ecosystems

Related fiche(s) 
1.1, 2.3, 4.3.

44

5.6   Multi-scale modeling coastal changes in Arctic regions under 

warming conditions

Earth system science

Impacts, risks and adaptation

Mitigation

Global warming accelerates thawing rates in Arctic regions. Permafrost thaw is occurring in an 
increased number of areas, exposing the landscape more and more to cyclic frost patterns and 
prolonged periods of above freezing temperatures. These changing conditions are expected to lead 
to an expanded exploitation of these areas for socio-economic purposes, a process that has already 
started. However, the suitability of the coastal zones of such regions for these developments is 
relatively understudied, in particular, the physical processes that shape these coasts, and their 
dynamics  on  various  temporal  and  spatial  scales  are  largely  unknown.  More  research  is  also 
needed on the implications of an accelerated warming and erosion of presently frozen floodplains 
for the release of GHG into the atmosphere.

State  of  the  art  morpho-dynamic  models  can  reproduce  the  medium  to  long  term  evolution 
of  unconsolidated  coasts  consisting  of  a  silty  and/or  sandy  substrate.  However,  currently  no  
morpho-dynamic model can simulate the evolution of a (partially) frozen coastline under the 
action of tides, waves, and ice, largely due to a lack of process knowledge. This gap may be 
filled by leveraging existing datasets of morpho dynamics of Arctic coastal zones, collecting new 
detailed data on freezing/thawing related dynamics in field and/or lab settings, and by developing 
suitable parameterisations that can be built into existing coastal morpho-dynamic models. 

Policy relevance
Evidence-based  decision  making  is  needed  to  address  new 
developments in the next decades that will likely occur in the 
warming Arctic including on issues such as suitability for civil 
construction,  increased  flood  risk  for  coastal  communities 
due to a larger exposure to coastal hazards and sustainable 
coastal zone management. 

Flag(s)
 Digitalisation/AI

 SSH

 Biodiversity/
Ecosystems

Related fiche(s) 
2.3, 4.3.

45

CLUSTER 6:  
TOWARDS MORE COHERENCE IN  
CLIMATE POLICIES: INTEGRATING 
IMPACTS-ADAPTATION-MITIGATION
Mitigation and adaptation are two sides of the same coin, but their interactions are inherently 

complex. The latest IPCC report is clear that progress on mitigation will largely determine 
the demand for and the effectiveness of adaptation, with limits being reached with increasing 
warming levels. At the same time, mitigation scenarios themselves must be resilient to changes 
in climate, particularly the occurrence of extremes. The IPCC stresses that the trends in adverse 
climate impacts, projected risks and vulnerability increase the urgency to advance climate resilient 
development that combines deep emissions reductions and climate adaptation together, making 
the case for coordination and integration of climate policies and actions even stronger. This is also 
important because approaches focusing on mitigation or adaptation in siloes may produce trade-
offs that undermine the overall progress of climate action.

Synergies  and  trade-offs  between  adaptation  and  mitigation  vary  across  sectors,  between 
and within regions and nations, depending on local contexts. For example, certain adaptation 
actions such as NBS can have positive effects on mitigation through increasing carbon stocks. 
Climate resilient urban planning also holds great potential for reducing emissions. Conversely, 
some  measures  such  as  (hard)  flood  protection,  desalination  or  expansion  of  air  conditioning 

46

can have negative impact in terms of emissions due to their high energy intensity. Furthermore, 
some mitigation strategies can be detrimental for adaptation. As an example, densification of the 
urban structure to reduce emissions from transportation can cause urban heat islands, and large-
scale bioenergy production can disrupt ecosystems and erode their adaptation services. Careful 
balancing between mitigation and adaptation objectives is therefore crucial for effective climate 
action but needs to overcome a scale challenge as the decisions on adaptation and mitigation are 
typically taken at different governance levels.

Opportunities  also  exist  to  better  integrate  adaptation 
and  mitigation  into  broader  development  strategies  in 
line with the United Nations 2030 Agenda for Sustainable 
Development,  which  recognises  that  ending  poverty  and 
delivering  on  social  needs  must  go  hand  in  hand  with 
tackling climate change and other environmental crises. The 
latest IPCC report has for the first time comprehensively 
assessed  the  interplay  between  adaptation,  mitigation, 
and  sustainable  development  in  terms  of  synergies  and 
trade-offs. The IPCC concludes that more synergies than 
conflicts  exist,  but  more  integration  is  needed  to  deliver 
climate resilient development. The IPCC also emphasises 
strong links between climate change and biodiversity loss, 
stressing  that  climate  related  impacts  on  ecosystems 
and biodiversity increase vulnerability and may limit our 
ability to adapt and mitigate. In higher warming scenarios 
the  feasibility,  effectiveness,  and  availability  of  NBS, 
agroforestry,  bioenergy  or  bio-based  materials  may  be 
(severely) constrained.

Trends in adverse 
climate impacts, 
projected risks 
and vulnerability 
increase the urgency 
to advance climate 
resilient development 
that combines deep 
emissions reductions 
and climate 
adaptation together�

Research  is  needed  to  support  a  more  strategic  approach  to  climate  action  and  sustainable 
development by providing a more complete overview of how adaptation and mitigation interact 
with each other and with other policy objectives, and by identifying transformative and equitable 
climate actions with most co-benefits. A better toolbox is needed to support linking policies and 
actions across different spatial and temporal scales and across sectors, underpinned by an effective 
monitoring and evaluation. Improving the representation of the interplay between mitigation and 
adaptation options in a warming world requires better linking mitigation pathways to climate 
impacts and adaptation. An improved assessment of optimal allocation and vulnerability of land-
use to climate change (forest cover, forest type, conservation, agricultural land, food production) 
is also required.

47

6.1  Integrating mitigation and adaptation action across scales

Earth system science

Impacts, risks and adaptation

Mitigation

As the urgency to step up climate action mounts, it is fundamental to adopt a more integrated 
approach to mitigation and adaptation interventions to maximise their effectiveness. This calls 
for a much better understanding of synergies and trade-offs between mitigation and adaptation 
responses. Improved coherence at all scales – from global through national to regional and local 
-  is  necessary  to  tap  into  potential  synergies,  to  avoid  and/or  minimise  trade-offs  while  also 
capturing the links with other Sustainable Development Goals (SDGs).

Research is needed to underpin operationalisation of integrating adaptation and mitigation both 
from design and tracking perspectives, and evaluation of which approaches are most effective. 
A significant challenge consists in the different spatial and temporal scales of mitigation and 
adaptation and in understanding how they interact. More insight is needed on the interaction 
dynamics within and across specific domains such as, for example, settlements (spatial planning, 
architectural design, blue/green infrastructure) and land use/agriculture (agroforestry, soil, and 
wetland management) based on real-life case studies and addressing various dimensions - legal, 
economic, technological, social (including gender) and environmental. There is also a need to 
better measure and monitor progress on adaptation effectiveness, which has traditionally been 
more challenging than tracking mitigation effectiveness. This includes generating comprehensive 
evidence-gap maps of the evidence on integrated adaptation-mitigation responses as well as a 
strategic approach to fill existing gaps by high-quality evaluation work.

Finally, research should improve our understanding on how the adaptation-mitigation nexus has 
(or has not) been built into existing policies and institutions, extracting the lessons learnt and 
replicable examples of best practice across sectors, ecosystems, countries, and communities.

Policy relevance
Improved understanding of the interplay between mitigation 
and adaptation will support the development of integrated, 
economy-wide resilient net zero pathways with clear metrics to 
evaluate progress from a social, environmental, and economic 
perspective.  It  can  also  increase  the  cost-effectiveness  of 
actions and make them more attractive to stakeholders.

Flag(s)
 Digitalisation/AI

 SSH

 Gender

 Biodiversity/
Ecosystems

Related fiche(s) 
3.4, 4.5, 7.2, 8.1, 10.4.

48

6.2   Bridging the gap from Earth system science to impacts and 

low-emissions climate resilient scenarios

Earth system science

Impacts, risks and adaptation

Mitigation

Climate resilient low-carbon development requires continuously updated assessments of climate 
risks, for which an accurate understanding of evolving climate hazards and their uncertainties is 
key. A central challenge is to accurately capture the changes in global to local climate responses, 
depending on the emission scenario followed, given a cascade of underlying uncertainties (including 
in climate sensitivity and effective radiative forcing at the global level, but also those related to 
local response patterns).

A novel dimension of the latest IPCC report was the assessment of global Earth system emulators 
to evaluate the climate outcomes of diverse mitigation pathways. This innovation, however, also 
highlighted important research gaps, notably in translating Earth system knowledge for integration 
into impact and adaptation assessments. 

To  tackle  these  challenges,  we  must  improve  the  availability  of  tools,  methods,  and  data  to 
incorporate  and  emulate  the  Earth  system  response  and  its  uncertainties,  especially  at  the 
regional  and  local  level.  The  most  critical  bottlenecks  include  the  scarce  data  availability  for 
model calibration and validation, limitations in tools to accurately represent complex systems 
(including high-impact tail risks), as well as integration of cutting-edge Earth system knowledge 
into adaptation strategies, climate resilience assessments and mitigation pathways. There is a 
need to bridge scales from global to regional, incorporating feedbacks and processes that are 
crucial for understanding impacts and the effectiveness of climate policy measures.

Policy relevance
This research will inform risk assessments across a wide range 
of stakeholders, from academia over decision makers to the 
private sector and the general public, enabling more effective 
and  more  coherent  mitigation  and  adaptation  strategies 
thanks to a comprehensive, holistic, and horizontal approach.

Flag(s)
 Digitalisation/AI

Related fiche(s) 
3.1, 6.3.

49

6.3   Investigating the interplay of mitigation and adaptation 

through integrated scenarios with improved representation 
of climate impacts

Earth system science

Impacts, risks and adaptation

Mitigation

The assumptions underlying integrated assessment models (IAMs) are insufficiently tested against 
projections of both regional climate changes and climate extremes. Research should investigate 
existing and develop new low-emissions pathways consistent with the temperature goals of the 
Paris Agreement that integrate and are resilient to climate impacts, including extreme events, to 
test their feasibility. This requires IAMs to better represent physical climate change and related 
extremes, including frequency and magnitude of change as well as a more granular representation 
of vulnerability, exposure and adaptive capacity that captures differences across populations and 
ecosystems,  as  well  as  adaptation  options  and  how  these  interact  with  mitigation  pathways. 
Relating climate change impacts, mitigation and adaptation measures to a broader range of SDGs 
is also highly desirable.

With respect to climate extremes, there is an urgent need to better understand how they interact 
with and constrain mitigation pathways - for example, how events such as droughts and wildfires 
affect afforestation and bioenergy scenarios, including potential indirect consequences for the 
population, food production, economy, financial systems, and political stability. This requires the 
development of new approaches for evaluating and interactively computing changes in extremes 
for emissions scenarios, such as regional climate model emulators, the integration of regional 
biophysical feedbacks from land use and should have the capability to address low-likelihood/
high-impact events.

Given a significant level of uncertainty surrounding the future effects of climate change on land 
and marine systems (e.g., permafrost thaw, tipping points, increased disturbances, intensified CO2 
fertilisation effect) and, by extension, on their capacity to contribute to mitigation and adaptation, 
further research into these mechanisms and integration of this knowledge into IAMs is also critical 
to better understand the potential of climate action measures in the land sector.

Policy relevance
Improving  the  representation  of  physical  climate  change 
and related extreme events in IAMs is of high relevance to 
risk-proof mitigation and adaptation pathways, enabling the 
development  of  Paris-aligned  strategies  that  are  feasible, 
realistic, and better capture the dynamics between mitigation 
and adaptation options.

Flag(s)
 Digitalisation/AI

 Biodiversity/
Ecosystems

Related fiche(s) 
1.2, 3.1, 5.1, 5.2, 5.3.

50

CLUSTER 7:  
SECTORAL AND SYSTEMS TRANSITIONS

Rapid and profound transformations are needed in all sectors and regions to reduce emissions 

and avoid the most serious impacts of climate change. The IPCC has assessed the substantial 
potential for reducing emissions in systems including urban, energy, buildings, transport, industry 
and land use through reducing energy demand and transitions to low- or zero-carbon technologies, 
materials and processes. It found that options to reduce emissions exist, costing less than $100 
per tonne of CO2, and which, cumulatively, could cut global GHG emissions by at least half by 
2030. Most notably, the cost of producing renewable electricity has become competitive with 
fossil fuels in many parts of the world, driving the deployment rates up and placing renewables at 
the heart of the transformation, next to energy efficiency, electrification, and circularity. The IPCC 
is also clear on fossil fuels – they must be phased out rapidly. The positive message is that there 
are many proven policy measures that can deliver deep emission reductions and build climate 
resilience if scaled up.

The  IPCC  also  found  that  changes  in  our  lifestyles  and  new  ways  of  delivering  services  enabled 
by the right policies, infrastructure and technologies can reduce global GHG emissions in end-use 
sectors (buildings, transport, food) by as much as 40-70% by 2050. A better understanding of the 
transformation of demand-side provisioning systems is necessary to tap into this significant potential. It 
requires research on key barriers and enabling conditions for a transition towards a shared and circular 
economy, including better understanding of the interactions between individual behaviour, social norms, 

51

technology/service options and available infrastructure, and how they shape consumer preferences.

In addition, there is  a  need  for  a  more systematic  exploration  of  the role of digitalisation in the 
transformation towards a net zero future, with particular focus on unlocking demand-side transitions. 
Notably, the convergence of advances in high resolution spatial data and the rapid progress in AI and 
machine learning, presents novel opportunities for strategies that not only maximise mitigation benefits 
but also increase climate resilience by fostering sustainable practices and informed choices at both 
individual and systemic levels. Examples include analysing consumer behaviour to tailor sustainable 
interventions, optimising transport, and energy management with co-benefits for flexibility of service 
provision and access equality, streamlining supply chains for reduced emissions, minimising waste-
generation, optimising recycling operations and informing climate risk assessments by mapping areas 
prone to extreme weather and other climate impacts.

In  the  context  of  systemic  transitions,  cities,  as  transition 
hubs,  will  play  a  very  central  role  in  driving  forward  the 
climate  agenda.  They  are  home  to  more  than  half  of  the 
world’s population and are responsible for three quarters of 
the  global  energy  consumption  and  GHG  emissions.  Cities 
are  also  hotspots  of  climate  impacts  with  higher  average 
temperatures  and  more  intense  heat  extremes.  Against 
this backdrop, they are emerging as pivotal actors in both 
mitigation and adaptation efforts and as key determinants 
of  human  well-being.  For  these  reasons,  cities  are  being 
increasingly recognised as key actors for climate action, with 
their role to be highlighted in a special report of the new IPCC 
7th assessment cycle.

Rapid and profound 
transformations are 
needed in all sectors 
and regions to reduce 
emissions and avoid 
the most serious 
impacts of climate 
change�

52

7.1   Improving global assessments of urban responses to climate 

change

Earth system science

Impacts, risks and adaptation

Mitigation

Urban  infrastructure  plays  a  crucial  role  in  achieving  net  zero  emissions  and  enhancing 
climate resilience. Nonetheless, there is an insufficient understanding of how cities and human 
settlements can be fully harnessed to expedite these transitions. The uniqueness of each city and 
its infrastructure, coupled with historically sparse and high-quality data on urban areas, makes 
meaningful  comparisons  challenging.  We  lack  rigorous  ex-post  evaluations  of  urban  climate 
responses, hindering our ability to understand the effectiveness of policies and their contextual 
nuances.  Given  the  complexity  of  large  urban  agglomerations,  there  is  a  pressing  need  for  a 
stronger focus on the metropolitan scale to discern their mitigation and adaptation options.

Modeling low-carbon and resilient urban planning with AI and the advancement of big spatial 
data offers new opportunities for research to guide urban form modification in the context of a 
changing climate: agile, AI-based, high-resolution tools can advance urban design at the scale of 
individual streets, locations, and buildings to reduce energy demand and emissions in buildings, 
urban  transportation  and  waste  while  rendering  cities  more  resilient  to  climate  change  and 
extreme  events.  Research  should  build  on  new  sources  of  data  and  rapid  progress  in  AI  that 
provides the required granular representations of the complex structures of cities and human 
settlements. Conceptual advances and most recent developments in AI (in particular, the advent of 
large-language models) and in evidence synthesis methodologies can gather the vast amount of 
scientific evidence on cities. Two challenges need to be overcome to leverage AI for urban planning: 
curating high resolution datasets and developing machine learning algorithms that provide useful 
insights for cities and municipal actors. 

Research in this domain should also address systematisation of critical and sensitive AI-based 
infrastructures that are key to support vital services and functions to urban systems and analyse 
how different societal groups (e.g., children, disabled persons, elderly, women, marginalised groups) 
use them differently. This will help draw conclusions towards urban development and planning that 
is compatible with Paris-aligned mitigation and adaptation requirements.

Policy relevance
This  area  of  research  will  generate  evidence  for  municipal 
decision-makers on most effective strategies and modifications 
to  the  existing  urban  form  that  would  maximise  climate 
benefits, while contributing to more liveable cities that provide 
a high quality of life to their citizens.

Flag(s)
 Digitalisation/AI

 SSH

 Gender

Related fiche(s) 
7.2, 7.4.

53

7.2   Investigating the contribution of demand-side measures in 
expediting the shift toward climate neutrality, with a  
particular focus on the role of digitalisation

Earth system science

Impacts, risks and adaptation

Mitigation

The latest IPCC report concludes that demand-side measures and new ways of service provision 
can considerably (40-70% by 2050) reduce global GHG emissions in end use sectors. Digitalisation, 
driven by revolutionary developments combining AI, deep learning, and large data sets, is already 
fundamentally  transforming  consumption  and  production  patterns  across  scales,  creating 
opportunities, but also risks for climate action. On one hand, it offers considerable potential for 
limiting growth in energy-demand, but on the other, it also risks inducing energy-intensive practices 
(e.g., online shopping), not to mention the ICT sector’s own emission footprint.

First,  a  better  understanding  of  the  transformation  potential  of  demand-side  provisioning 
systems towards climate-neutrality is necessary and requires research on behavioural, social, 
and other factors determining uptake of demand-side solutions, with particular focus on the role 
of digitalisation. Building on that, novel modeling tools need to be developed with a bottom-up 
representation  of  demand-side  aspects  in  transition  pathways.  Key  barriers  and  enabling 
conditions of shared and circular economy should be included in such a representation, capturing 
the interactions between individual behaviour, social norms, technology options, and available 
infrastructure in shaping consumer preferences.

Second, research should comprehensively investigate climate implications of the digital economy 
and evaluate the role of digitalisation in unlocking demand-side transitions. Progress is needed 
on identifying effective strategies for proactive climate-focused governance across actors, scales, 
and contexts, addressing issues of risk, trust, engagement, and access (incl. gender dimension) 
with an explicit consideration of institutional design. There is also room for progress on data and 
AI governance for making cities, settlements, and societies more climate resilient, for example, by 
mapping of heat, precipitation risks and other climate-related risks.

Policy relevance
Better capturing demand-side mitigation measures will widen 
the option space, enabling acceleration of the transformation 
towards  net  zero  emissions  while  minimising  trade-offs 
associated with supply-focused strategies. Careful governance 
of digitalisation will support climate change mitigation and 
adaptation efforts, including at municipal and national scale, 
with a focus on low energy demand, and sustainable, resilient 
service provisioning systems

Flag(s)
 Digitalisation/AI

 SSH

 Gender

Related fiche(s) 
6.1, 7.1, 7.4, 10.4.

54

7.3   Informing the politics and economics of phasing out fossil 

fuel infrastructures

Earth system science

Impacts, risks and adaptation

Mitigation

The  anticipated  emissions  from  existing  and  planned  fossil  fuel  infrastructures  are  projected 
to contribute 600-1100 Gt of future CO2 emissions, exceeding the remaining carbon budgets 
compatible with limiting warming to 1.5°C. There is hence a strong case for fossil fuel infrastructure 
phase out - encompassing exploration, production, refining, distribution and end-use, - and making 
the underlying political strategies an essential element of the transition process.

Research should map the current state of fossil fuel infrastructures both in terms of related CO2 
emissions and their economic value to define economically viable (or unviable) options and limits 
for phase-out, repurposing and retrofitting to stay in line with the goals of the Paris Agreement. 
Repurposing for “green” fuels, such as low-carbon hydrogen and synfuels, requires assessing 
the interplay between energy demand (including green carbohydrates that require high energy 
input but allow flexible storage/load) and renewable energy availability (including competition with 
alternative uses, and compatibility with efficient electrification strategies such as heat pumps). The 
existing evidence on the deployment limits of green fuels in the transition towards net zero should 
also be considered. It is also crucial to broaden the analysis to the political economy of fossil fuel 
infrastructures, including common narratives in the media (including social media) and options for 
circumventing the lobbying structures that work to prevent the phase-out.

Policy relevance
Progress in this area will guide the decisions on which fossil 
infrastructures should be decommissioned, which should be 
repurposed  or  retrofitted  with  carbon  capture  and  storage, 
under what kind of timelines, and who should bear the costs in 
support of overcoming the severe carbon lock-in of the global 
energy system.

Flag(s)

 SSH

55

7.4   Reducing energy demand and quantifying materials and  

embodied carbon in the building stock and other infrastructure

Earth system science

Impacts, risks and adaptation

Mitigation

Buildings are responsible - directly and indirectly - for 36% of the energy-related GHG emissions 
in the EU, thus playing a pivotal role in the transition to reaching net zero emissions. Whereas 
most European countries continue to invest in energy efficiency and renewable energy sources, 
it is equally important to place a focus on promoting energy sufficiency (avoidance of energy 
demand) and transforming the existing built environment in line with the net zero paradigm. More 
research is needed for innovative solutions that can be easily implemented in the already built 
environment and support energy sufficiency such as new wall concepts, new window frames, new 
building materials with more thermal inertia and lower carbon footprint, new insulation systems 
and integrated nature-based solutions (NBS) for refurbishing. This should be complemented by 
work on prioritising renovation needs in the built environment. In this context, it is also important 
that all public buildings in Europe become net zero as soon as possible to convince society to 
invest in improving their own housing. A better understanding of the interlinkages between a low 
emission built environment, urban planning and transport systems for people and merchandise is 
needed to support more integrative strategies.

Embodied energy and embodied carbon in the built environment, including buildings, industrial 
facilities, roads, and other infrastructure have now also been identified as an essential component 
of the transition to a net zero emissions. The assessment of embodied energy and carbon emissions 
relies on the understanding of the quantity of materials used or processed in the production phase 
per infrastructure type. To address the existing gaps, more work is needed on the classification of 
infrastructures in the built environment according to the types of buildings. The challenges that 
need to be overcome include a multitude of different construction types that change with location, 
age, final use, etc. as well as quantification of infrastructure by type. Then, research should support 
the clear identification and quantification of the materials used per built environment type (i.e., 
type of building, type of road), together with the production and/or transformation processes 
associated with each of them with a view to evaluate the embodied energy and carbon footprint 
more precisely.

Policy relevance
More reliable emissions data, including embodied carbon, will 
improve  the  precision  and  quality  of  models  that  underpin 
climate  policies,  supporting  a  whole-system  approach  to 
carbon  reductions  and  allowing  for  better  targeted  climate 
policies.  This  research  will  also  inform  strategies  on  how 
to efficiently improve, repurpose and/or retrofit the building 
stock, based on the Sufficiency, Efficiency, Renewables (SER) 
framework.

Flag(s)

 SSH

 Digitalisation/AI

Related fiche(s) 
7.1, 7.2.

56

CLUSTER 8:  
LAND USE, AGRICULTURE AND CARBON 
DIOXIDE REMOVAL
As demonstrated by the IPCC Special Report on Climate Change and Land, sustainable land 

management offers great potential contribution to mitigation and adaptation action. The land 
sector has the ability to act both as a source and a sink for emissions, with opportunities to provide 
biomass, mainly from forestry and residues, as a substitute for carbon intensive products. Globally, 
emissions from agriculture, forestry, and other land uses (AFOLU) contribute about 22% of total 
anthropogenic GHG emissions while terrestrial ecosystems sequester more than a third of CO2 
emissions. The largest near-term mitigation potential of the AFOLU sector comes from forests and 
other natural ecosystems, with land-use management critical for achieving a balance between 
anthropogenic GHG emissions and removals after 2050. The IPCC warns, however, that land-based 
mitigation cannot compensate for delayed action in other sectors.

The links between land (-use) and climate are complex. Higher levels of warming will impact 
the  ability  of  land  to  store  carbon,  its  productivity  (by  changing  levels  of  water  availability) 
and  the  resilience  of  ecosystems,  making  the  persistence  of  removals  highly  uncertain.  For 
example, an increase in droughts, wildfire damage, insect and fungus outbreaks, or permafrost 
thawing can decrease the role of land as a carbon sink. In turn, adaptive management to these 
impacts can also alter land mitigation potential. In addition, land also plays an integral role in 
regulating  temperature  and  precipitation  patterns  through  albedo  effects,  evapotranspiration,  

57

and aerosol loading.

Effective land-use management is also critically important for meeting the biodiversity targets 
under the Convention on Biodiversity (CBD) and plays a crucial role in achieving several of the 
Sustainable Development Goals (SDGs), including those on ending hunger (SDG 2), clean water 
(SDG 6), clean energy (SDG 7), and life on land (SDG 15). While many options offer co-benefits 
for adaptation, food security, biodiversity, health and livelihoods, there are also trade-offs and 
indirect land-use effects. Competition with food production is of particular concern. Therefore, 
exploring options to alleviate competition for land should be prioritised, such as reducing meat 
consumption and moving to more plant-based, balanced diets, reducing food waste, managing 
discarded products, and exploring innovative food and feed sources (e.g., insects, grass-based 
protein feeds, etc). 

Policies  targeting  land-use  need  to  be  synergistic 
with other policy objectives in the areas of climate, 
food  security,  biodiversity,  and  health.  A  better 
understanding  of  the  multidimensional  land-
climate-biodiversity-food-health nexus is necessary 
to  effectively  manage  the  underlying  synergies 
and tensions. Research should identify sustainable 
land-use  management  practices  and  define  what 
institutions,  strategies  and  policies  are  needed  at 
global,  national,  and  regional  levels.  This  requires 
a  more  in-depth  understanding  of  the  underlying 
including 
in  mitigation  pathways, 
dynamics 
improvements  in  sectoral  models  and  integrated 
assessment models (IAMs) to better reflect the diversity of priorities related to land and biomass 
use  options  and  investigation  of  the  political  economy  of  large-scale  land  and  biomass  use. 
Research should also support enhancing the consistency between global models and national 
GHG inventories under the UNFCCC on human-caused CO2 emissions and removals for the land 
sector to better evaluate the efficacy of land-based mitigation, particularly for the forestry sector.

A better understanding  
of the multidimensional  
and-climate-biodiversity-
food-health nexus is 
necessary to  
effectively manage  
the underlying synergies 
and tensions�

Mitigation pathways compatible with achieving the Paris Agreement assessed in the latest IPCC 
report include carbon dioxide removal (CDR) at scale in addition to accelerating near-term emission 
reductions, to achieve net zero CO2, and to move into net negative emissions thereafter towards 
net zero GHG emissions. Land-based approaches such as reforestation, afforestation, soil, and 
forest management, dominate today’s removals options, but novel technologies like direct air 
capture and storage (DACCS) or bioenergy combined with carbon capture and storage (BECCS), 
biochar, and enhanced weathering are also emerging. More is needed to explore CDR scaling as 
resolved by mitigation scenarios and the development of policies and implementation options. 
Finally, there is a need for research on realistic potentials, limitations, permanence, co-benefits 
and trade-offs with other policy objectives, as well as public acceptance, in order to inform global 
CDR policy design and governance.

58

8.1   Nurturing the potential of land-based mitigation  

and adaptation

Earth system science

Impacts, risks and adaptation

Mitigation

Given its significant anthropogenic GHG emissions and potential for carbon sequestration, the 
AFOLU sector is pivotal for achieving climate change mitigation targets. Contributions come from 
conservation and restoration of natural ecosystems, improvements in agriculture and forestry 
practices, as well biomass provision for mitigation in other sectors. While trade-offs may exist 
between the objectives to store carbon in ecosystems and to produce biomass as an alternative 
to fossil resources, these objectives are not always mutually exclusive, emphasasing the need for 
balanced decision-making that considers multiple goals. In addition to mitigation benefits, making 
agriculture and land-use climate-resilient is also crucial for protecting ecosystems and livelihoods, 
and for safeguarding food security.

Research should delve into the complex interlinkages between diverse sectors involved in landbased 
mitigation, including exploration of synergies and trade-offs between land carbon storage and 
biomass production across various forestry and agriculture systems across a spectrum of different 
net zero scenarios, while also considering adaptation, biodiversity, and other outcomes. There is a 
need to better understand how the interplay between bio-based and other low-carbon alternatives, 
policy, governance, land-use practices, private investments and public spending collectively shape 
mitigation and adaptation efforts in the AFOLU sector. This requires advancements in both sectoral 
and cross-sectoral modeling at national, regional, and global scales to better integrate climate 
change dynamics with land-use and other sectors, while also enhancing consistency between 
model outcomes and national statistics of GHG emissions and sinks. Advances in agent-based 
modeling are also crucial for studying the implications of different transition pathways and policy 
measures  on  farms,  regional  agricultural  structures,  and  production  activities.  The  significant 
anticipated  contribution  of  the  AFOLU  sector  to  the  EU's  pursuit  of  net  zero  emissions,  with 
consequences for other regions, makes the EU a valuable case study. 

Policy relevance
Effective  mitigation  strategies  in  the  AFOLU  sector  require 
a coordinated policy design across climate, agriculture, and 
other land-use relevant domains, in full consistency with other 
than climate policy objectives such as food, energy security, 
and  biodiversity  related,  whilst  properly  accounting  for  the 
limitations and trade-offs associated with the contributions 
from the land-use sector.

Flag(s)

International 
cooperation

  SSH

 Gender

 Biodiversity/
Ecosystem

Related fiche(s) 
 3.4, 6.1, 9.4.

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8.2   Fostering sustainable use of biomass for climate  

change mitigation

Earth system science

Impacts, risks and adaptation

Mitigation

While fostering food and nutrition security, sustainable management of natural resources, and 
reducing reliance on fossil fuels, a sustainable bioeconomy also provides multiple avenues for 
mitigating GHG emissions in the context of the transition to net zero. Mitigation opportunities are 
twofold: a) carbon storage in ecosystems (vegetation and soils) through a wide range of diverse 
land  management  measures  and  with  multiple  co-benefits  (e.g.  adaptation,  biodiversity,  soil 
quality), though this is subject to reversals and disturbances (climate events, insect infestations); 
b) use of biomass across different sectors as bio-based products, storing carbon and displacing 
fossil-based alternatives, also susceptible to leakage as well as, in regard of storage, to reversals. 
Although the two approaches are not mutually exclusive, they face trade-offs that need to be 
accounted for in the policy design.

Governance  and  policymaking  addressing  the  bioeconomy  is  generally  challenging  since  the 
optimal  development  of  a  bioeconomy  varies  geographically  due  to  multiple,  heterogeneous 
conditions. Consequently, the expansion of sustainable biomass utilisation across sectors must 
reflect a diversity of priorities and conditions, which must be viewed in an integrated manner.

Research should develop a new generation of global mitigation pathways that consistently cover 
biomass demand and supply of different sectors. Such pathways should encompass the whole 
biomass  value  chain  (production,  processing,  and  consumption  aspects),  account  for  indirect 
land use changes and leakage effects,  notably  those related  to deforestation  and  ecosystem 
degradation, and address political economy issues associated with large-scale land and biomass 
use. This will require improvements in IAMs as well as sectoral models to better capture the complex 
dynamics associated with the bioeconomy, including better consideration of the competition and 
synergies between different biomass and land uses in the exploration of mitigation pathways while 
also accounting for the necessity to safeguard biodiversity, food security and ecosystem-based 
services.

Policy relevance
This  research  will  produce  science  foundations  to  inform 
sustainable biomass supply and use strategies in the EU and 
beyond, maximising contributions to climate change mitigation 
and adaptation, but also focusing on the broader sustainability 
dimension, and accounting for climate impacts.

Flag(s)

International 
cooperation

  SSH

 Biodiversity/
Ecosystem

Related fiche(s) 
3.4, 4.1, 9.4.

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8.3   Achieving global climate, biodiversity, and health objectives 

by optimising the management of food systems

Earth system science

Impacts, risks and adaptation

Mitigation

Climate  change,  along  with  associated  adaptation  and  mitigation  efforts  affect  the  state  of 
biodiversity as well as the social and environmental determinants of food systems and health, 
which, in turn, affect societies’ capacity for effective climate action. Food systems are associated 
with 23–42% of global GHG emissions while also causing severe biodiversity impacts, including 
from agriculture’s spatial shifts as an adaptive response to climate change. The food-climate-
biodiversity-health nexus is hence growing in attention and requires a coordinated policy response.

Accurately  measuring  the  scale  and  impact  of  the  interactions  between  climate  change, 
biodiversity loss and human health remains challenging whereas integrated assessments fall 
short of accurately (or at all) representing those complex interfaces and associated land-use 
consequences. Further research is crucial to enhance our understanding of the interplay between 
the  climate,  biodiversity,  and  health  dimension  of  food  systems.  This  includes  the  direct  and 
indirect effects and cross-sectoral linkages and evaluating mitigation and adaptation strategies in 
local and regional contexts within an evolving state of climate and biodiversity.

Improvements  in  integrated  assessment  and  sectoral  modeling,  sub-system  and  single 
technology  assessment  are  essential  to  improve  knowledge  of  emission  trends  and  drivers, 
adaptation and mitigation costs and potentials, regional specificities, sector-specific barriers and 
enabling conditions related to mitigation and adaptation options in the realm of food systems. 
Complementary approaches, drawing on disciplines such agronomy, engineering, natural sciences 
as well as social sciences can also offer comprehensive insights into food systems and should be 
explored to bridge system-level and bottom-up perspectives, addressing issues related to human 
behaviour, lifestyles, gender, culture, and socio-technical transitions in both producer consumer 
sides of food systems.

Policy relevance
Definition of consistent and realistic transformation pathways 
within the integrated framework of the climate-biodiversity-
health-food  nexus  is  essential  for  optimising  governance 
of  food  systems  and  land-use  to  achieve  climate-  and 
biodiversity-friendly, as well as healthy, futures.

Flag(s)

  SSH

 Gender

 Biodiversity/
Ecosystem

Related fiche(s) 
3.2, 9.4. 

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8.4   Assessing long-term viability of agroforestry as a solution  

to climate change and food security 

Earth system science

Impacts, risks and adaptation

Mitigation

Agroforestry is widely cited as a promising solution for addressing low yields, climate change, 
biodiversity loss, land degradation, water scarcity, food insecurity and rural poverty altogether. 
Yet, the evidence on the resilience potential of agroforestry systems, which is a precondition for 
delivering all these benefits, remains scattered, and the understanding of climate change impacts 
on agroforestry remains limited. There is a large body of literature stating the effect of tree-crop 
interaction on local evapotranspiration and microclimate, with corresponding benefits on farming 
systems, but research behind this evidence is typically conducted at small/local scale and would 
require larger scale assessments to strengthen the evidence base. Furthermore, the long-term 
nature of tree physiology, and thus actual benefits provided by agroforestry systems require a 
better representation of the complex interaction between long-term vegetation-climate interaction 
and short-term socio-economic challenges to better characterise the feasibility and effectiveness 
of this measure for a wide range of environments.

Many case studies that focus on agroforestry struggle to integrate the planetary dimension of 
the impacts such as feedback effects resulting from land-climate interaction. Furthermore, the 
magnitude of the effect of agroforestry on the water cycle and climate feedback is generally 
overlooked in large scale modeling assessments. Research is needed to improve the representation 
of agroforestry systems in global climate impacts and agroecosystem models capable of simulating 
large scale vegetation-climate interactions, together with the implementation of these advances 
into IAMs as well as land-sector models. Improvements are also needed in representing layered 
vegetation  structures  in  many  land-surface  modules  of  climate  models.  Specific  agroforestry 
systems and their role in food security and nutrition need to be studied with more granularity. In 
addition, there can be synergies and trade-offs with other climate solutions - for example, large-
scale forestry may affect the viability and yield of wind and solar in some regions, yet they can 
also co-exist as integrated systems.

Policy relevance
Robust  evidence  on  the  benefits,  disadvantages  and  trade-
offs associated with agroforestry systems will help address 
the food security and climate change nexus, fostering more 
effective land-use management strategies, especially if the 
modeling  work  is  accompanied  by  policy  and  governance 
research. This research will also shed light on whether benefits 
from agroforestry are greater than those of alternative land-
uses, supporting the realisation of multiple SDGs.

Flag(s)

 Biodiversity/
Ecosystem

Related fiche(s) 
2.1, 5.3, 9.2, 9.4.

62

8.5  Designing carbon dioxide removal policies and governance

Earth system science

Impacts, risks and adaptation

Mitigation

The latest IPCC report emphasises that achieving the goals of the Paris Agreement will require CDR 
at scale for counterbalancing hard-to-abate residual emissions to get to net zero CO2. Net negative 
CO2 emissions will also be needed to compensate for remaining non-CO2 emissions to reach net 
zero GHG emissions. CDR methods include conventional (afforestation, soil carbon sequestration) 
and  novel  bioenergy  with  carbon  capture  and  storage  (BECCS),  direct  air  carbon  capture  and 
storage (DACCS), ocean alkalinisation, enhanced weathering, biochar). These approaches differ in 
technological maturity, deployment levels, cost, scaling potential, durability, and reversibility of CO2 
storage, as well in terms of side-effects and trade-offs with adaptation and other development 
objectives. Overall, more knowledge is needed on future CDR availability, not least due to the 
challenges and risks associated with many of the methods. 

A considerable gap exists between how much CDR is required in the modelled net zero pathways 
and what the countries are planning in the medium (2030) and long-term (2050), in particular 
regarding less conventional options. For example, achieving net zero CO2 emissions in the EU 
by  2050  would  require  several  hundred  million  tonnes  of  CO2  per  year  of  CDR,  well  above  
current levels. 

Better knowledge, particularly from the social sciences, is needed to support the design of effective 
CDR policies and governance frameworks. Research should enhance the understanding of the 
state of art and pace of innovations in CDR, different CO2 storage times, levers for acceleration, 
management of side-effects, options for maximising synergies and co-benefits with other policy 
objectives such as food security and biodiversity protection and the implications for policy design, 
institutions, and governance. Other evidence gaps relate to the political economy of CDR including 
distributional aspects and consequences for regional development as well as the role of CDR in 
international climate policy with particular emphasis on feasible deployment levels and options 
for a just national, regional, and international effort sharing .

Policy relevance
This research will inform global efforts on how to develop robust 
CDR governance frameworks, including careful management 
of uncertainties and risks, whilst avoiding overreliance. It will 
also  support  institutional  design  to  successfully  incentivise 
the scale-up process needed to grow a new industry. Scientific 
assessment of different monitoring, reporting, and verification 
schemes  to  inform  the  EU’s  carbon  removal  certification 
framework is also high on the research agenda.

Flag(s)

International 
cooperation

  SSH

 Biodiversity/
Ecosystem

Related fiche(s) 
3.5, 9.4.

63

CLUSTER 9:  
EQUITY AND JUST TRANSITIONS

Climate change is already negatively affecting inequality and poverty, both within and between 
countries. It hurts the poorest and most vulnerable the most, undermining the efforts to achieve 
justice  and  equity  across  the  world.  Climate-induced  resource  stresses  -  including  on  water, 
agricultural crops, or other biotic resources - increasingly drive conflict, threatening the peace 
and inclusivity of societies, and undermining social justice. Climate change-related impacts and 
disasters  are  also  key  drivers  of  human  displacement  and  migration  and  can  worsen  gender 
inequalities. The transition to a net zero emissions society will also have significant distributional 
consequences across countries, sectors, businesses, and households.

Against this background, the latest IPCC report emphasises the importance of prioritising equity, 
social  justice,  inclusivity  and  just  transition  when  addressing  climate  change.  This  fosters 
transformative change, drives support for high-ambition climate policies by building consensus 
and social trust across the society, helps to resolve trade-offs with other SDGs and leads to better 
outcomes in general. The IPCC also underscores the importance to strengthen the consideration 
of justice and equity in the formulation and execution of adaptation strategies, particularly when 
addressing extreme events, to achieve greater outcomes by supporting highly vulnerable regions.

The Paris Agreement recognises the principle of common but differentiated responsibilities and 
respective capabilities among nations, aiming to ensure that wealthier nations support developing 
countries in their efforts to mitigate and adapt to climate change, and encouraging countries to 

64

consider equity and fairness when implementing climate policies. The importance of ensuring a just 
transition is being increasingly acknowledged by governments worldwide and mainstreamed into 
climate plans and strategies. The European Green Deal, with its overarching objective of “leaving 
no one behind”, is a good example. It aims at shielding regions, communities, and industries from 
adverse social and economic impacts, and highlights the need to ensure a fair distribution of both 
benefits and burdens of the EU’s transformation towards climate neutrality. 

Therefore, the assessment of climate change impacts, risks and future development pathways 
needs to be grounded in the context of the distributional aspects and equity. However, the complex 
linkages between climate action and justice are still not well understood nor fully addressed in policy 
responses and require more research. For example, there 
is a need to develop mitigation scenarios with greater 
attention to equity and justice that better reflect regional 
and sub-regional development priorities, as well as the 
conditions and constraints of the poor  and  vulnerable 
communities and societal groups. The consideration of 
equity,  justice  and  climate  resilient  development  also 
needs to be strengthened in disaster risk reduction and 
adaptation strategies, which frequently do not properly 
consider the needs of the poorest and most vulnerable 
groups or lack the gender dimension. Progress is also 
a  need  in  the  exploration  of  inequity  and  injustice  as 
constraints to individual and collective climate action.

Prioritising equity, 
social justice, 
inclusivity and just 
transition fosters 
transformative change 
and drives support for 
high-ambition climate 
policies by building 
consensus and  
social trust�

justice  principles  are  relevant  to 
Given  that 
mitigation,  adaptation,  and  other  sustainability 
transitions,  and  to  all  sectors,  research  should  support  a  more  integrated  treatment.  The 
AFOLU  sector  is  one  example  where  the  immense  and  potentially  competitive  demand 
for  land  and  biomass  assumed  by  low-emission  scenarios  makes  equity  and  justice  even 
more  vital  for  designing  feasible  and  fair  policies.  Research  is  needed  to  better  understand 
the  distributional  implications  of  climate  strategies  in  diverse  agricultural,  forestry,  
and land use contexts. 

65

9.1  Attributing climate impacts in a climate justice context

Earth system science

Impacts, risks and adaptation

Mitigation

The issue of climate justice and procedural and distributional impacts is becoming critical as 
impacts increase both in Europe and across the world. Extreme event attribution has advanced the 
understanding of how human influence has affected the likelihood of occurrence and intensity of 
climate and weather extreme events, increasingly leading to widespread impacts on ecosystems, 
economies, and societies, disproportionately affecting vulnerable communities. While the science 
of attribution has advanced, numerous gaps remain which require major scientific advances. These 
gaps include the impacts and hazards being investigated, in particular compound and cascading 
events, the interplay between slow and fast onset events, the regional focus on events being 
investigated, and the relationships between insights from attribution studies relevant for today’s 
climate and the potential high impact events or combinations of events expected to emerge in 
the near-term (for example in a 1.5°C warmer world, relevant for this decade). Advances are 
also needed to link information about changes in extreme event characteristics in the context of 
wider sustainability challenges, for example including the water-land-climate nexus, taking into 
consideration the related vulnerability and exposure.

While climate change disproportionately affects vulnerable communities and societal groups (e.g., 
children, disabled persons, elderly, women, marginalised groups), consideration for climate justice 
in the context of the equitable distribution of burdens and benefits allows for an optimised way of 
addressing the climate crisis. Policies and actions that integrate climate justice require science-
based attribution of climate events, and the advancement of research relevant for climate legal 
frameworks, specifically relating to the emergence of responses to climate change in complex 
societal, political, and legal systems. The analysis should consider comprehensively the attribution 
of damages, costs and benefits and legal responsibilities in complex systems.

Policy relevance
Improving  the  science  of  attribution  will  advance  our 
understanding  of  the  anthropogenic  signal  in  climate 
phenomena and impacts. This will not only impact policy, and 
potentially early warning systems, but also serve as a basis 
for establishing legal responsibility in a fair and proportionate 
manner.

Flag(s)

International 
cooperation

  SSH

 Gender

Related fiche(s) 
4.4, 4.6, 5.1.

66

9.2   Improving the consideration of equity and justice  

in adaptation strategies to build resilience

Earth system science

Impacts, risks and adaptation

Mitigation

There is an emerging recognition that successful adaptation needs to properly integrate equity and 
justice considerations to be effective and contribute to building lasting resilience. However, present 
adaptation strategies at national and local levels often focus primarily on climatic hazards (floods, 
extreme  precipitation,  heat  stress,  droughts,  etc.)  and  first  order  impacts  with  standards  and 
methods to account for equity and justice dimension often missing. Much less attention is paid to 
vulnerability reduction although it is central for adaptation measures given that adaptive capacities 
differ according to the level of vulnerability. Consequently, just, and equitable reconstruction and 
adaptation requires better consideration and reduction of risks particularly for the most vulnerable 
groups and sectors.

Equity  and  justice  need  to  be  further  operationalised  to  be  relevant  for  practical  adaptation 
programmes, for example, by defining concrete indicators, quality standards and criteria. Research 
is needed to analyse selected adaptation strategies and programmes and their impacts on climate 
justice and equity across different societal groups (children, disabled persons, elderly, women, 
marginalised groups etc.) and sectors. The analysis should capture not only first, but also second 
order impacts of adaptation strategies, as well as their cascading effects. For example, relocation 
has severe social impacts whereas large protection measures such as storm barriers may decrease 
economic activities. These examples raise important questions about justice and equity in terms of 
both access to adaptation measures and their differential consequences that research could shed 
some light on. In addition, adaptation enablers and barriers often present a gender dimension, 
which should also be investigated.

Policy relevance
This  research  will  enable  planners  and  decision  makers  to 
better consider equity and justice in adaptation, risk reduction 
and reconstruction strategies in the broader context of climate 
resilient development, enhancing their acceptability.

Flag(s)

International 
cooperation

 Gender

  SSH

Related fiche(s) 
4.3, 4.4, 4.6, 5.4, 8.4, 10.2.

67

9.3   Improving integrated assessment models to represent  

different dimensions of justice and equity

Earth system science

Impacts, risks and adaptation

Mitigation

The current generation of global mitigation pathways lacks a systematic consideration of justice 
or  equity.  Even  though  these  pathways  incorporate  assumptions  about  distributional  aspects 
and result in declining levels of absolute poverty across all scenarios they have faced criticism 
for a continuing “equity deficit”. This deficit concerns, for example, slow convergence of gross 
domestic product per capita, perceived inattention to common but differentiated responsibilities 
and respective capabilities, and a lack of transparency.

A new generation of scenarios is needed, capable of more effectively representing justice and 
equity considerations. This involves moving beyond pure economic convergence assumptions and 
embracing all different dimensions of justice, spanning from procedural to distributive justice and 
also addressing aspects of political economy. The new scenarios should be carefully co-designed 
with key stakeholders and regional experts as part of a transparent and inclusive community 
process including a review of key input assumptions and main elements of the narratives.

The representation of justice and equity in these scenarios should extend beyond the conventional 
Integrated Assessment Models' (IAM) focus on interregional equity and burden sharing assumptions 
for  emissions  reductions.  It  should  include  a  bottom-up  representation  of  well-being  (social 
and physical) and how mitigation and adaptation efforts affect the living standards in diverse 
circumstances. It is also crucial to better integrate institutional effectiveness and governance in 
the models to improve the representation of differentiated capacity and policy feasibility. This 
requires a more robust integration of social sciences and empirical research into the IAM models.

Policy relevance
A  wider  range  of  socio-economic  pathways  with  attention 
to  equity  and  justice  that  better  reflect  the  conditions  and 
constraints  of  the  Global  South  will  help  promote  broader 
international acceptance of scenario findings with potential to 
unlock momentum in global climate negotiations.

Flag(s)

International 
cooperation

  SSH

Related fiche(s) 
3.2, 3.4, 4.5.

68

9.4   Designing just transition policies for agriculture, forests and 

other land use

Earth system science

Impacts, risks and adaptation

Mitigation

Agriculture  and  patterns  of  land  use  will  need  to  change  significantly  in  any  scenario  taking 
the world to net zero GHG emissions, with implications for global inequalities across and within 
individual countries. Just transition principles have been applied to energy transitions, but less 
attention has been given to the AFOLU sector, despite the immense demand for land and biomass 
implied by low-emission scenarios, leading to social and economic challenges. In those scenarios 
bioenergy remains a major energy source, and additional land is required for CDR technologies and 
renewables such as solar and wind. Simultaneously, demand for biomass is expected to increase 
for food, including higher shares of animal-based foods, and material use. Such developments 
might lead to the conversion of agricultural land to other uses, with implications on patterns of 
land tenure, risking to further exacerbate justice issues through changes in the size of holdings, 
ownership models, and landowner-tenant relationships.

On the one hand, farmers may diversify their land use and benefit from new income sources, 
and  the  introduction  of  new  cultivation  systems  (agroforestry  systems,  perennial  plants)  into 
agricultural landscapes can enhance landscape diversity, habitat quality, retention of nutrients, 
erosion control, climate regulation, pollination, pest and disease control, and flood regulation. Other 
influencing factors with relevance for justice also encompass regulation and financial incentives 
for actions that deliver climate outcomes, including the sharing of mitigation burden and benefits 
(e.g., ownership of credits, liabilities for emissions).

Research needs to assess the implications of the transition to net zero for actors in the AFOLU 
sectors,  by  interpreting  mitigation  and  adaptation  scenarios,  and  by  assessing  a  variety  of 
stakeholder perspectives (e.g., elderly or gender) on the implied changes and identifying synergies 
between climate actions and other policy objectives such as food security, biodiversity conservation 
and human development. The International Labor Organisation’s principles - social dialogue, social 
protection, rights at work and employment - should be an integral part of the research.

Policy relevance
This  research  will  support  more  effective  and  equitable 
climate policy design by promoting and operationalising just 
transition  principles  for  land  use.  It  will  guide  the  creation 
of effective financial incentives and strategies that address 
both adaptation and mitigation, while ensuring the equitable 
sharing of greenhouse gas mitigation costs and benefits.

Flag(s)

  SSH

 Gender

 Biodiversity/
Ecosystem

Related fiche(s) 
5.3, Cluster 8.

69

CLUSTER 10:  
ACCELERATING CLIMATE ACTION: 
LEVERS AND ENABLERS

The window of opportunity to secure a liveable and sustainable future for all is closing rapidly, 
the latest IPCC report warns. Yet, despite the existing commitments and availability of multiple 
feasible, proven, and effective options that can significantly reduce emissions in all sectors, global 
emissions continue to rise. The pace and scale of climate action is deeply inconsistent with the 
goals of the Paris Agreement, making these ambitious objectives increasingly challenging to meet.

This underscores the need for greater prioritisation of near-term climate action, with rapid, deep 
reductions in GHG emissions in this critical decade, as this will largely determine whether warming 
can be limited to 1.5°C or 2°C this century. The closing of implementation and ambition gaps in 
climate policy requires research that draws more attention to the levers and enablers of near-term 
action, and their incorporation into the development and exploration of possible future scenarios. 
This includes optimising policy interventions to ensure they are fit for purpose to address multiple 
global crises, environmentally effective, economically efficient, socially acceptable and rooted in 
the best available scientific evidence.

For assessing the performance of policy instruments, rigorous methods are needed to learn which 
strategies work and under what conditions. Feasibility and implementation potential are particularly 
important criteria, especially in the context of key social drivers, dynamics, and tipping points to 

70

achieve deep decarbonisation actions, together with a comprehensive assessment of enabling 
conditions and barriers. Recent shocks such as COVID-19 pandemic, wars, energy, and cost of life 
crises, can also provide lessons as to the ability to implement drastic policy interventions regionally 
or globally (e.g., travel bans, lockdowns, shifts in energy trade patterns, mobilising trillions for 
investments in safety nets and bailouts, etc.).

Amongst the essential enablers of climate action, finance has potential to serve as a major catalyst 
for societal transformation. Adequate funding is crucial for the development and deployment of 
effective, flexible, and affordable net zero solutions and 
adaptation measures. Investors, both public and private, 
have  the  power  to  mobilise  and  channel  resources 
towards  climate-related  initiatives,  influencing  and 
enabling the society-wide adoption of more sustainable 
practices.  Nonetheless,  substantial  knowledge  gaps 
persist in our comprehension of the interplay between 
climate change and the financial sector, constituting a 
critical barrier and a potential lever to scaling mitigation 
and  adaptation  investments  to  the  levels  compatible 
with the Paris Agreement.

There is a need for 
greater prioritisation 
of near-term climate 
action, with rapid, 
deep reductions in 
GHG emissions in this 
critical decade, as this 
will largely determine 
whether warming can 
be limited to 1�5°C or 
2°C this century�

Communication is another key agent for climate action. In 
absence of a common understanding of the key scientific 
messages, there is a significant barrier for society and 
policymakers to make science-based decisions and have 
an  informed  dialogue  on  the  causes,  consequences, 
and responses for climate change. The propagation of 
disinformation, for example via social media and traditional media, also causes confusion and 
hampers efforts to communicate science effectively. In this context, research on more impactful 
communication of climate science emerges as an important area of scientific inquiry.

Finally, acceleration of climate action will occur when it is made meaningful to people's daily 
lives and incorporated into their thinking, behaviour and daily choices. This requires awakening 
motivation in people and a deep desire for personal and social transformation, accompanied by 
a sense of urgency, which fuel demand for changes from policy makers and the private sector. 
Central to this is fostering the perception that climate justice not only exists but is actively pursued. 
This requires avoiding the creation of climate elites that turn climate action into a luxury and 
addressing intergenerational justice by strengthening the connection with younger generations 
and incorporating their demands. Research on just climate transitions is thus a pivotal priority, as 
detailed in the preceding cluster.

71

10.1   Communicating and translating climate science to  

policymakers and general public

Earth system science

Impacts, risks and adaptation

Mitigation

The  relevance  of  climate  change  science  for  people's  daily  lives  is  growing,  yet,  for  many,  it 
remains difficult to understand, in part due to challenges in communicating complex scientific 
concepts. Despite the IPCC's efforts to clearly convey the assessment outcomes, the messaging 
often remains technically complicated. The propagation of disinformation, identified as a top short-
term risk in the 2024 Global  Risk Report of the  World Economic  Forum, further  hampers the 
communication of science-based evidence to decision-makers and the public. 

Within  the  IPCC  context,  the  science  of  communication  suggests  replacing  passive  strategies 
with  more  engaging  and  dialogic  approaches.  Research  is  required  to  operationalise  these 
recommendations and, more broadly, to understand how communication can enhance awareness 
and  climate  literacy  to  enable  effective  climate  action.  This  involves  delving  into  cognitive 
processes of understanding and absorbing complex information, the influence of socio-cultural 
factors, development status and values on perception and learning.

Improving  knowledge  on  how  communication  can  stimulate  various  actions,  how  to  measure 
outcomes, and understanding the interplay of behavioural change and wider societal choices 
within broader political, governance, economy, and policy context, is also crucial. Research should 
also identify the most impactful tools, messages, and co-design processes for communicating 
about climate change, with links to journalism and the media. 

Recognising the power of storytelling to instill agency, research should explore narratives that 
integrate  climate  change  information  into  people's  lives,  focusing  on  solutions-orientated 
messaging  that  people  can  identify  with.  Beyond  the  array  of  available  climate-related 
visualisations, there is a need to bridge the gap on making data relevant to people's everyday 
existence. Social science research is essential to determine the most effective messages and tools, 
while cognitive psychology can contribute to understanding how individuals receive messages and 
how these messages transform or influence their experiences. 

Policy relevance
Absence  of  a  common  understanding  of  the  key  scientific 
messages  about  climate  change  is  a  significant  barrier  for 
society and policymakers to make science-aligned decisions. 
More effective communication is vital for aligning the society 
behind  ambitious  and  far-reaching  responses,  inspiring  the 
policymakers to make courageous decisions.

Flag(s)

 Gender

  SSH

72

10.2   Understanding social dynamics, including tipping points, as 

drivers of climate action

Earth system science

Impacts, risks and adaptation

Mitigation

The current pace of mitigation and adaptation is falling short of the transformational change 
needed now and in this decade to address climate change and its consequences. The barriers to 
climate action need to be identified through monitoring and evaluation of past measures/policies, 
together with the societal thresholds that can unlock rapid action. In the latest IPCC report, social 
movements are considered as a catalyst for social tipping points, which either positively unlock 
rapid social action or lead to system destabilisation. Empirical evidence shows that social tipping 
points can be triggered before tolerance thresholds are reached, yet much better understanding 
of these processes is needed.

We need to learn more about the relationships between adaptive capacity, social capital and social 
tipping points, both positive (e.g., transformational structural changes for fast decarbonisation 
and resilience) and negative (e.g., system destabilisation, social unrest, migration), the political 
economy, structural power issues, perceptions, and also climate justice and distributional aspects 
(including both costs and benefits of the transition). Migration decisions, for example, can be based 
on perceptions of environmental changes by local populations rather than on actual changes 
themselves. There is a need to better understand social perceptions and psychological aspects 
of  climate  change,  as  well  as  the  role  of  education  in  closing  information  gaps  and  bringing 
motivation and societal readiness.

Future societal decisions are impossible to predict due to the deep uncertainty associated with 
social  structures,  the  many  interacting  processes,  abrupt  changes  in  other  fields,  unintended 
consequences  of  certain  policy  decisions,  and  other  factors.  While  the  latest  IPCC  report  has 
comprehensively assessed the feasibility of mitigation or adaptation options, societal dynamics 
(including social inertia, path dependency, disruptive change, user practices, actor constellations, 
and regulatory environment) determine the plausibility of these measures being implemented and 
deserve more in-depth exploration.

Policy relevance
Investigating the activation of social dynamics towards net 
zero  will  help  to  design  effective  policies  for  low  carbon 
climate resilient transformation. It will also expedite the pace 
of climate action by providing insights on how to trigger social 
mobilisation and pro-environmental behaviour.

Flag(s)

 Gender

  SSH

Related fiche(s)  
3.6, 4.3, 9.2.

73

10.3   Accelerating near-term climate action to meet  

long-term goals

Earth system science

Impacts, risks and adaptation

Mitigation

The  EU  and  other  jurisdictions  have  established  near-term  emission  targets  that  represent 
important milestones on the path towards net zero CO2 emissions by 2050. Meeting these targets 
would  put  the  world  on  a  path  towards  meeting  the  Paris  Agreement  goals  whereas  failure 
risks closing/narrowing down options and may place long-term goals beyond reach. Successful 
implementation  of  climate  policy  requires  research  that  draws  more  attention  to  the  factors 
influencing near-term climate actions and their incorporation into modeling tools.

Modeling activities that underpin transition pathways tends to focus on longer-term time horizons 
and proceeds through multi-year time steps (5 or 10 years). The feasibility of emissions pathways 
is  another  issue  of  key  importance  for  defining  effective  and  realistic  response  strategies, 
including  for  the  short-term.  There  has  been  some  good  progress  over  the  past  few  years 
with research addressing geophysical, technological, economic, socio-cultural, and institutional 
feasibility dimensions. The existing emissions scenarios have been benchmarked against these 
considerations, but what is now needed from the scenario framework is more focus on near-term 
perspectives and extended plausibility analysis. By plausibility analysis we mean the extent to 
which societal dynamics will plausibly activate enabling conditions or barriers, and hence the 
credibility  of  mitigation  measures  actually  being  implemented.  Plausibility  builds  on  history, 
context, and agency, each conceptualised based on theories of change, drawn, for example, from 
social movement theories or organisational theories. 

Issues  such  as  labour  markets  (mismatches)  and  supply  chains,  finance,  policy  information, 
institutional capacity, social acceptance, distributional and equity considerations, the influence 
of  and  interplay  with  non-climate  policies,  political  economy,  and  power  structures  (including 
incumbents)  also  need  to  be  addressed.  This  research  could  benefit  from  expert  and  local 
knowledge to feed into near-term scenario development.

Policy relevance
This work will result in a better understanding of the feasibility 
and  plausibility,  as  well  as  challenges  and  barriers  to  the 
acceleration  of  climate  action  in  the  near-term,  and  of  the 
capacity to enhance implementation. It will give policymakers 
tools to assess the effectiveness of various policy interventions 
to unlock ambitious near-term climate action.

Flag(s)

  SSH

 Gender

74

10.4   Assessing the performance of climate policy instruments 

using rigorous evidence synthesis methods

Earth system science

Impacts, risks and adaptation

Mitigation

In times of multiple global crises and increasingly tight public finances, it is ever more important to 
ensure that policy interventions are environmentally effective, economically efficient, and socially 
acceptable and are rooted in the best available scientific evidence.

A growing number of scientific studies evaluate mitigation and adaptation interventions in terms 
of how successful they have been in reducing GHG emissions and/or enhancing climate resilience, 
but also relevant outcomes such as economic costs, distributional implications, social acceptance, 
impact  on  labour  markets,  innovation  dynamics,  economic  competitiveness,  health,  and  well-
being etc. What is missing are rigorous evidence syntheses of this exponentially growing body of 
evidence to assess the performance of policy instruments and policy instrument packages. Such 
a synthesis exercise would enable accelerated learning in science and policy on which strategies 
actually work, under what conditions, while identifying critical synergies and trade-offs with other 
policies or policy objectives.

The assessment should be focussed on evidence from ex-post evaluations and cover a broad 
range of policy instruments (e.g., market-based, regulatory, and voluntary instruments, information 
and education programmes) across relevant outcomes and address compound effects on other 
policy objectives. Climate-relevant policies with a different primary objective such as improvement 
of air quality, protection of the ozone layer or biodiversity/ecosystems should also be covered. 
With rapid advancements in AI, new potentials for accelerating or partially automating evidence 
synthesis methodologies should be further explored as well as related research frontiers such as 
“living evidence”.

Policy relevance
By enabling a comprehensive assessment of climate policy 
performance via a consistent systematic review ecosystem, 
this  work  will  generate  rigorous,  context-specific,  and 
actionable knowledge for decision-makers, thus contributing 
to  the  effectiveness  of  climate  action.  The  identification  of 
gaps in evidence including the lack of high-quality monitoring 
and  research  will  contribute  to  a  more  efficient  knowledge 
generation process around climate policies.

Flag(s)
Digitalisation/AI

 Gender

  SSH

Related fiche(s)  
3.4, 4.1, 5.4, 6.1, 7.2.

75

10.5   Shifting to climate-resilient development

Earth system science

Impacts, risks and adaptation

Mitigation

Limiting global warming in line with the Paris Agreement requires comprehensive change that 
is achieved not only by addressing the direct causes of emissions and immediate barriers to 
adaptation, but also via understanding and addressing the foundational drivers of development 
patterns, with consideration of distributional aspects and transformative levers.

Critical research questions remain open, firstly, to understand how development pathways have 
evolved in the past. The literature on past systems change, notably at large scale, remains limited. 
Understanding how past changes have been driven, and to what extent, is also critical to inform 
policymaking today, including where climate was less of a focus. Secondly, we need to investigate 
how current development pathways (across scales and contexts) affect our capacity to mitigate and 
adapt. This is to identify where current development pathways constitute a barrier to mitigation 
and/or adaptation and assess what could be achieved by changing them. Finally, research should 
analyse  how  development  pathways  can  shift  towards  sustainability  and  resilience,  and  how 
that would affect progress towards development goals, in addition to our ability to mitigate and 
adapt. It asks which alternative pathways exist for a given barrier, what are the implications, and 
what is necessary (in terms of institutions, policies, finance, innovation, cross-sector, international 
cooperation) to effectively implement such a change.

Addressing these questions requires drawing on many fields of knowledge beyond the boundaries 
of climate research, such as development studies or sector-specific literature. Economics, social 
sciences and humanities are central to this analysis, but within a pluri-disciplinary framework that 
captures scientific and technical realities and acknowledging that there are competing visions of 
how change can be achieved across disciplines. Energy- economy-environment modeling is one of 
the relevant tools to address the second and third questions. A challenge is that unlike the climate 
community, the development community has produced few forward-looking studies.

Policy relevance
Answering these questions will provide a better understanding 
of  how  development  pathways  drive  emissions,  mitigation 
and adaptive capacities. In turn, these are essential to shift 
development pathways towards sustainability and resilience 
across a broad range of development goals, including but not 
limited to climate.

Flag(s)

International 
cooperation

  SSH

 Gender

76

10.6   Investigating how global shocks (fail to) enable climate 

action

Earth system science

Impacts, risks and adaptation

Mitigation

Experience from recent global shocks (e.g., responses to the COVID-19 pandemic; the Russia’s war 
of aggression against Ukraine, the energy and cost of living crisis) has shown that despite regional 
or global ability to implement drastic interventions (such as travel bans, lockdowns, dramatic shifts 
in energy trade patterns, mobilising trillions for investments in safety nets and bailouts, etc.), 
these shocks have not been used effectively to achieve the objectives of the Paris Agreement, 
sometimes even adding fossil fuel capacity and deepening lock-ins. Similar patterns often emerge 
in the context of smaller or more localised shocks, including partly climate-induced ones, such as 
in the case of weather-related disasters.

Research should investigate how we have dealt with these shocks to (avoid failing to) implement 
the transformational change needed to avoid catastrophic climate change and how to make better 
use of the opportunity windows provided by such shocks for more radical strategies/measures. 
Deeper knowledge and planning are needed to inform policymakers on how to most effectively and 
durably respond to shocks to harness their momentum for the benefits of climate action.

A methodological development of typology of possible shocks, from known unknowns to unknown 
unknowns, could lead to an adaptive decision-making and operating framework. There is a role 
for ex-post evaluation to learn from responses; equally we want to learn on how models, such as 
integrated assessment models (IAMs), can be used to explore shocks, as well as updating scenarios 
to take into account recent occurrences. There are also new concepts that have emerged. For 
example, in health, COVID-19 triggered the "living evidence/living systematic reviews" paradigm, 
where scientific knowledge gets continuously updated to enable an immediate response based on 
the best available information.

Policy relevance
The  aim  of  the  research  is  to  prepare  decision  makers  for 
shocks, both in the sense of managing the direct consequences, 
and to enable transformative climate action in those defining 
phases requiring major societal and governmental responses. 
This will provide relevant climate policy responses beforehand 
to leverage the momentum of a shock, rather than focusing 
on the short-term needs, reactively.

Flag(s)

  SSH

Related fiche(s)  
 3.6, 4.5.

77

10.7   Mobilising climate finance through improved understanding 

of financial sector behaviour

Earth system science

Impacts, risks and adaptation

Mitigation

The latest IPCC report underscores the necessity for significantly increased financial flows to the 
Global South to meet mitigation and adaptation needs. However, challenges like high capital costs, 
high levels of indebtedness and economic vulnerability hinder the ability of developing countries 
to mobilise the required funds. Substantial climate-related regulatory interventions targeting the 
financial industry in the Global North, including the EU Sustainable Finance Taxonomy, present an 
opportunity to shape investment choices and enhance climate finance outcomes for the Global 
South. The IPCC also identifies knowledge gaps in the assessment of climate related financial risk 
as a major barrier to achieving ambitious climate finance flows in the near term. Underestimation 
of transition risks by public and private financial actors often leads to inefficient capital allocation 
that is inconsistent with the mitigation objectives. 

Research should address knowledge gaps regarding how regulatory interventions targeting the 
financial sector can contribute to a more efficient allocation of capital for climate action. It should 
address various dimensions of impact, including additionality and liquidity in local capital markets, 
particularly vital in the Global South. It is crucial to also investigate whether and how new data 
points such as on taxonomy compliance and Green Asset Ratios, can be effectively leveraged. 
Regarding financial risks, there is a need for a broader analysis of transition risks and opportunities 
that considers a classification of all economic activities that could be affected, well beyond the 
current focus on stranded assets in the fossil fuel industry. Research is also needed on bridging 
climate change economics and asset pricing to assist the financial industry in better understanding 
the weaknesses in their transition risk assessments and valuations.

Policy relevance
Understanding  the  implications  of  current  regulatory 
interventions  in  the  financial  sector  will  help  developing 
more efficient policy packages, better capable of leveraging 
increased levels of financial flows into climate action in both the 
Global North and the Global South and including North-South 
transfers.  More  realistic  corporate  finance  valuation,  better 
capturing climate-related risks, will facilitate a redirection of 
financial flows towards Paris-aligned investments.

Flag(s)

International 
cooperation

78

CLUSTER 11:  
CLIMATE INTERVENTION
As impacts of climate change unfold, and the efforts to curb carbon emissions prove inadequate, 

interest in geoengineering is on the rise. The IPCC used to define geoengineering as a broad 
set of methods and technologies that aim to deliberately alter the climate system - atmosphere, 
land or ocean - in order to alleviate the impacts of climate change. The two key characteristics 
of geoengineering are its global or regional influence on the climate system and the potential for 
significant unintended effects that transcend national boundaries. Geoengineering comprises a 
diverse array of options, but the literature commonly divides them into two main categories: solar 
radiation modification (SRM) and carbon dioxide removal (CDR).

SRM methods seek to reduce the amount of solar energy absorbed in the climate system by reflecting 
the incoming sunlight back into space through techniques such as artificial injection of stratospheric 
aerosols, marine cloud brightening or space-based mirrors. Yet, SRM is fundamentally distinct from 
mitigation action since it does not address the root cause of the problem - continued GHG emissions 
- nor does it tackle other critical issues such as ocean acidification associated with high atmospheric 
CO2  concentrations.  This  makes  SRM  the  most  contentious  and  potentially  the  most  risk-laden 
geoengineering technique. On the other hand, CDR intends to increase net carbon sinks from the 
atmosphere at a scale sufficiently large to alter climate and includes a variety of methods, both natural 
and technological, ranging from afforestation, direct air capture, to ocean fertilisation and enhanced 
weathering. Both SRM and CDR can have multifaceted impacts on the climate system, influencing 
regional  albedo,  altering  atmospheric  chemistry,  disrupting  circulation  patterns,  affecting  nutrient 

79

cycles, and introducing other, less predictable changes. These complexities justify the necessity for a 
precautionary approach.

The controversy surrounding SRM arises from its potentially 
very  significant  yet  still  poorly  understood  impacts  and 
unintended  consequences,  introducing  novel  risks  to  both 
the  environment  and  society.  Furthermore,  uncertainties 
extend to the institutional, economic and technical feasibility 
of SRM measures, their social acceptance, and the hazards 
related to (abrupt) termination of interventions or a reduced 
commitment  to  proven  mitigation  methods.  The  risks 
associated with the cross-border effects of some of these 
technologies, national political and economic interests, the 
possibility  of  weaponisation,  and  private  sector  initiatives 
driven  by  purely  commercial  interests,  are  all  possible 
sources of global tensions or conflicts, further exacerbated 
by the absence of international rules, institutions and proper 
governance structures.

There is high 
uncertainty around 
the response of the 
climate system to 
SRM, its side effects 
on economies, 
ecosystems, crop 
yields, and human 
health, on top of the 
challenges related to 
international equity, 
security, governance 
and ethics

The latest IPCC report, while acknowledging that SRM may 
reduce  some  climate  impacts  if  surface  temperatures 
are  decreased,  qualifies  it  as  part  of  “more  speculative” 
technologies  for  tackling  climate  change.  The  assessment 
underscores high uncertainty around the response of the climate system and the side effects on 
economies, ecosystems, crop yields, and human health, on top of the challenges related to international 
equity, security, governance and ethics. The IPCC also expresses concern over, amongst other things, 
residual and overcompensating climate change and the likelihood of abrupt water cycle changes if SRM 
techniques were to be deployed at scale.

A  more  comprehensive  understanding  of  the  risks,  uncertainties  and  limitations  associated  with 
geoengineering techniques is essential to facilitate an open and transparent debate that could lead to 
a global consensus on their use, including development of common rules, and, if deemed appropriate, 
implementation of moratoria.

80

11.1   Assessing interdisciplinary research on  

solar radiation modification

Earth system science

Impacts, risks and adaptation

Mitigation

Solar  Radiation  Management  (SRM)  remains  controversial  but  is  gaining  increased  attention 
from both the public and policymakers. There is a scope for more coordinated and transparent 
interdisciplinary  research  on  proposed  SRM  strategies  with  public  institutions  in  the  lead  to 
comprehensively and critically assess viability, impacts and risks. Knowledge gaps identified in 
the IPCC reports should be addressed, such as the limited understanding of the climate system’s 
response to SRM, especially at the regional scale, the risks and risk reduction potential to people, 
biodiversity, and ecosystems, both marine and terrestrial. The following aspects should be tackled9:

 ▶ Context  and  goals,  including  modeling  scenarios,  strategies  for  decision-making  under 

uncertainty, and the capacity needed for all countries to engage meaningfully.

 ▶ Impacts and technical dimensions, including the properties of injected aerosol particles and 
their interactions with radiation, clouds and atmospheric chemistry, possible climate outcomes 
and subsequent impacts on socio-ecological systems, advancing monitoring and attribution 
capabilities, as well as techno-economic feasibility of various SRM methods.

 ▶ Social dimension, including research on domestic and international conflict and cooperation, 
options for effective governance, and integration of justice, ethics, and equity considerations.

A  truly  transdisciplinary  approach,  integrating  aspects  from  Science,  Technology,  Engineering, 
and  Mathematics,  to  SSH  (with  elements  from  governance,  conflict  and  cooperation,  societal 
acceptance, environmental law, equity, and ethics) is necessary, leveraging collaboration between 
the respective research communities. It should be non-experimental and far from actual SRM 
deployment (laboratory research would be acceptable).

Policy relevance
This  research  will  provide  policymakers  with  a  toolbox 
necessary to perform risk-risk analysis on SRM, i.e., weighing 
the risks of under-mitigated climate change against the risks 
of SRM implementation. It will support advancing the efforts 
on establishing more robust arrangements and frameworks 
for  SRM  governance,  including  research  related  aspects,  in 
accordance with the precautionary principle.

Flag(s)

International 
cooperation

  SSH

 Biodiversity/
Ecosystem

9.  Building on: National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and 

Research Governance. Washington, DC: The National Academies Press.

81

ACRONYMS AND ABBREVIATIONS

AFOLU 

Agriculture, Forestry and Other Land Use

AI 

AMOC  

AR6  

BECCS 

CBD  

CDR  

CO2 
DACCS 

EU 

GHG  

IAM  

IPCC  

Artificial Intelligence 

Atlantic Meridional Overturning Circulation 

6th Assessment Report of the IPCC 

Bioenergy with Carbon Capture and Storage 

Convention on Biological Diversity 

Carbon Dioxide Removal 

Carbon Dioxide 

Direct Air Carbon Capture and Storage

European Union

Greenhouse Gas(es)

Integrated Assessment Models 

Intergovernmental Panel on Climate Change 

LULUCF   

Land Use, Land Use Change and Forestry

MAT  

NBS  

R&I 

SDG  

SRM  

SST  

Marine Air Temperatures 

Nature-Based Solutions 

Research and Innovation

Sustainable Development Goals 

Solar Radiation Modification 

Sea-Surface Temperatures

UNFCCC   

United Nations Framework Convention on Climate Change 

WGI/ II/ III  

Working Groups of the IPCC 

WMO 

ZEC  

World Meteorological Organisation

Zero Emissions Commitment 

82

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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As climate change impacts intensify globally in both frequency and 
magnitude, and with scientific consensus on what is yet to come if the 
world fails to act, the imperative to step up our collective response has 
never been more pressing.

By providing the knowledge necessary to formulate effective mitigation 
and adaptation strategies, climate science serves as a critical enabler of 
climate action and a vital input to evidence-based policymaking. Bridging 
the knowledge gaps in climate change research is crucial for guiding the 
transition towards a low-carbon climate resilient future, for fostering 
consensus and alliances, for empowering global cooperation and for 
mobilising stakeholders across the society.

This report draws attention to where additional research is required to 
effectively and adequately address climate change, aiming to inform 
future calls under the EU Horizon Europe R&I Programme and beyond. 

Studies and reports