Transforming human systems tosafeguard the Global Commons
An integrated assessment of deep transformations in human energy, land use,and production and consumption systems towards keeping the Global Commons
within the safe space of the Planetary Boundaries

March 2024

This report was prepared by the Potsdam Institute for Climate Impact Research (PIK) and the Center
for Global Commons (CGC) at the University of Tokyo. The analysis and report production were
undertaken by Gabriel Abrahão, Dorothee Keppler, Simón Moreno, Isabelle Weindl, Jessica Strefler,
Bjoern Soergel, Lavinia Baumstark, Christoph Bertram, Michael Crawford, Jan Philipp Dietrich, Alois
Dirnaichner, Robin Hasse, Jens Heinke, Florian Humpenöder, David Klein, Gunnar Luderer,
Christoph Müller, Michaja Pehl, Robert Pietzcker, Franziska Piontek, Alexander Popp, Sebastian
Rauner and Renato Rodrigues, under the direction of Elmar Kriegler (PIK), Johan Rockström (PIK)and Naoko Ishii (CGC).

Please cite this report as:
Abrahão et al. 2024. Transforming human systems to safeguard the Global Commons: A report by PIK
and CGC. Potsdam, Germany and Tokyo, Japan.

The Global Commons Stewardship Project
The Global Commons Stewardship (GCS) project, initiated and led by the Center for Global
Commons (CGC) at the University of Tokyo, in partnership with PIK, SDSN, WRI and SYSTEMIQ,
aims at the development of a conceptual framework and strategies for Global Commons
Stewardship.
Within the GCS project, the Potsdam Institute for Climate Impact Research (PIK) is responsible for
conducting interdisciplinary modelling, performing a comprehensive assessment of how thesystem transformations identified in the GCS project can contribute to the stewardship of the
Global Commons.

The Global Commons Stewardship Framework

Executive Summary
Current policies and the Global Commons
Safeguarding the Global Commons requires a global perspective. The Global Commons, thebiophysical systems that as a whole keep the Earth System stable and resilient, consisting of several
global commons domains, are the foundation of human development and prosperity.. Currently,
human activities have already pushed several of these systems outside the safe operating space of
the Planetary Boundaries.
Our integrated assessment results show that, with current policies, humanity is on track to worsen
the state of most Global Commons domains and cross several Planetary Boundaries by
mid-century (Fig A). The boundaries for Nitrogen Flow, Land System Change and Biosphere Integrity
have already been transgressed today, and continuing current policies would not reverse theunderlying trends by returning the associated indicators to a position substantially closer to their
Planetary boundaries by 2050. With just the controls currently in place on emissions of CO2 andother greenhouse gases, the Planetary Boundaries for Climate Change and Ocean Acidification would
also be crossed by 2050.1 The only indicator that is set to improve is the one for the Ozone Layer,with the successful implementation of the Montreal Protocol bringing ozone depletion back inside
the Planetary Boundary.
A complete worldwide implementation of the Nationally Determined Contributions (NDC) on
emissions reduction, land protection and afforestation by 2030 and the continuation of this levelof ambition until 2050 would not substantially change the worsening trends under current policies.
Only small progress back towards the Planetary Boundaries for Climate Change, Ocean Acidificationand Land System Change would be made, which is not enough to remain inside the Planetary
Boundaries or even stop degradation at current values. Furthermore, the pressures of increased
land scarcity and a possible reliance on bioenergy for reducing emissions would lead agriculture tofurther worsen the state of the Nitrogen Flow indicators.

A holistic transformation pathway
A scenario in which transformations of energy use, land use, and production and consumption
patterns are implemented jointly would allow humanity to reverse the degradation of the Global
Commons domains to levels very close to or within the Planetary Boundaries by 2050. Althougheven these deep systems transformations would not be able to keep warming below 1.5°C without asmall overshoot in 2050, a combination of CO2 removal and continued reduction of non-CO2
emissions would revert warming, so that global mean temperatures would stay below the Paris
Agreement target by 2100 and beyond. However, CO2 concentrations and radiative forcing would still1

As described in Section 2.3, we define the Planetary Boundary as 1.5°C warming over the preindustrial value, the target
set by the Paris Agreement. As current warming is around 1.1°C, the target has not been crossed yet, but would be in 2050
if current policies continue. In this point we deviate from the Planetary Boundaries framework (Steffen et al. 2015) which
defines Climate Change as an atmospheric CO2 concentration of 350 ppm. Based on this indicator and value, the Planetary
boundary for Climate has already been crossed, and even all the transformations investigated here cannot bring CO2
concentrations back below that value.

only be stabilized at around current levels, at which changes in climate harmful to human and natural
systems are already observed.
In the scenarios considered, the proposed interventions lead to dramatic changes in the energy,
land and production and consumption systems. In our modeling framework, these changes are a
combination of direct model assumptions and endogenous responses to them. Some of the most
relevant are:
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The average global price on GHG emissions in both the energy and land sectors reaches
around 90 U.S. dollars per ton of CO2eq in 2050. These levels are relatively low, being
enough to limit warming to 1.5°C by 2100 (with limited overshoot) only in combination withall other transformations. Prices are phased in more slowly in developing countries. In theabsence of these other transformations, the prices required for the same temperature limit
are over three times higher
Diets worldwide move towards more healthy and sustainable patterns, along the lines of the
EAT-Lancet diet recommendations, by 2050. Global consumption of livestock products,
which is currently increasing, decreases by around half, especially moving away fromruminant meat. Most of this reduction comes from developed countries with meat-rich diets.
Food waste is halved by 2050
Global average crop nitrogen use efficiency (NUE), the fraction of nitrogen in fertilizer that istaken up by the crops, improves from the current 50% to 70%. .
All areas currently listed as protected in the World Database of Protected Areas (WDPA) are
effectively protected, plus all intact forest landscapes and biodiversity hotspots, in total
protecting around 30% of the global land environment by 2030. This value is in line with thecommitments in the Kunming-Montreal Global Biodiversity Framework. GHG pricing isapplied to land use change to disincentive loss of carbon, natural vegetation and biodiversity
in non-protected areas.
The share of electricity in the global final energy supply increases from currently below 20%
to ~25% in 2030, to 45% in 2050. A combination of reduction in the cost of renewables andcarbon pricing leads to an almost complete phase out of coal and oil use in electricity
generation, and reliance on gas falls below 2% of the electricity supply in 2050.
The per-capita demand for cement is reduced by 20%, as a result of price changes in theenergy system and through the promotion of higher material efficiency in the buildings
sector.

Fig. A: Effects of the continuation of current policies (from 2015 to 2050, top row) and of varioustransformations (in 2050) on keeping the Global Commons domains within selected the Planetary Boundaries.
Inner dotted lines mark the Planetary Boundary value (or the 1.5C global mean temperature change limit in thecase of the Climate Change boundary). Green (red) arrows indicate an improvement (worsening) of an indicator
due to a certain transformation in 2050 in relation to either 2015 (blue lines in NPi) or to the current policies
continued scenario in 2050 (black lines). Wedges show the relative value of each indicator, with green (orange)
portions showing the part inside (outside) the defined safe space. The starting points of the wedges at thecenter were chosen so as to visually emphasize the effects and their relation to the Planetary Boundary value,
and are not comparable across indicators. Effects on the Air Pollution and Freshwater Use boundaries were notexplicitly quantified in this study.

Modelling transformations
In this study, we used the REMIND-MAgPIE
integrated assessment framework to simulate
scenariosthat
implement
different
combinations of these transformations inaddition to existing policies. Results show how
they affect the future development of five
GlobalCommons
Domains,(Climate,
Cryosphere, Oceans, Ozone Layer and Land
Biosphere) relative to the Planetary Boundaries
over the course of the next century.
Due to the high relevance of the land andindustry sectors for the pressure on several
planetary boundaries, special sets of scenarios
also offer insights into the effects andtrade-offs
ofdedicated
landandindustry-specific transformations. In the land
sector, options for changing current foodsystems, improving resource efficiency inagriculture, and land-based solutions forclimate change were investigated. In theindustry sector, reductions in the demand formaterials, the introduction of carbon captureand storage (CCS) technologies, and widespreaduse of hydrogen were analyzed in combination
with GHG pricing in the sector. Additionally, thepotential of circular economy strategies in theplastics sector was examined in relation to the Fig. B: System Transformations implemented inplanetary boundaries of climate change and the the REMIND-MAgPIE modelling framework
introduction of novel entities.

Effects of individual transformations
Implemented individually, the transformations of energy use, land use, and production andconsumption patterns have different effects on safeguarding the Global Commons. Most but not
all of them are positive.
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The Energy Systems Transformation has strong effects on safeguarding the Climate, Cryosphereand Oceans, but can have detrimental effects on the Land Biosphere Global Commonsdomains. Transforming the energy systems towards sustainable energy sources and shifting
towards more sustainable transport modes would reduce GHG emissions by 39 Gt CO2eq/year in
2050, a 60% reduction relative to a scenario with only the currently implemented policies. This
would prevent around 0.19°C of warming. Most of the avoided emissions would be of CO2,
keeping Ocean Acidification at relatively safe levels inside the Planetary Boundary throughout
the century. However, an increased reliance on bioenergy ultimately has detrimental effects on
the Land Biosphere, leading to higher deforestation rates, use of nitrogen fertilizers, agricultural
consumption and degradation of biodiversity.

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The Land Systems Transformation is fundamental for preserving the Land Biosphere, but also
has substantial positive impacts on the other Global Commons domains. By 2050, it would halt
the loss of natural forest, reduce agricultural water consumption and improve human-induced
nitrogen fixation and biodiversity intactness to conditions superior to those of today. This would
bring Land System Change, Nitrogen Flow and Biosphere Integrity back within their Planetary
Boundaries. These effects are more than enough to counteract negative effects from theEnergy Systems transformation in these Global Commons domains. The combination of landinterventions would also reduce GHG emissions by 19 Gt CO2eq/year. Methane emissions would
be particularly reduced, preventing 0.18°C of warming in the medium term (2050) andminimizing overshoot of the 1.5°C Paris Agreement target. The avoided CO2 emissions would
have positive impacts on Ocean Acidification, but not enough to prevent it from degrading tolevels outside the Planetary Boundary.

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Individual components of the Land Systems Transformation focusing on resource-efficient
production, reduction of GHG emissions, and dietary changes, differ in terms of their individual
impact on safeguarding the Global Commons domains, and exhibit synergies and tradeoffs
between them and with other transformations.
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Transitioning to resource-efficient production systems is a key supply-side intervention to
reduce human-induced nitrogen fixation and agricultural water use. However, reducing water
consumption by limiting irrigation can increase pressures on Land System Change andBiosphere Integrity, as replacing irrigated systems with relatively lower-yielding rainfed ones
requires more land area.

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Pricing GHG emissions from land use change can prevent leakage effects from otherinterventions, including those that can occur if regulation-based land protection orafforestation schemes like current NDCs miss sufficient coverage in terms of regional
distribution and types of included ecosystem.,○

Each of these land protection measures are of paramount importance if interventions inother sectors further increase biomass demand, e.g. for energy use. On the other hand,land-based solutions alone can push unsustainable intensification practices and can create
tradeoffs with water use.
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In contrast, transforming food demand towards more sustainable diets and reducing foodwaste leads to strong beneficial impacts across most Global Commons domains. It can
combine synergistically with other land interventions, leading to more than additive
outcomes in Land Systems Change and Biosphere Integrity, as reduced demand for foodfrees more land to be used for mitigation and conservation. Its beneficial effect on reducing
emissions and the use of nitrogen and water are slightly diminished when evaluated inconjunction with the other land interventions, which ultimately make the food system moreenvironmentally efficient and therefore reduces the burden of additional food demand.
However, it still positively affects economic variables such as food and bioenergy prices,which are mostly negatively influenced by the other land interventions. It is also key tofacilitating a multi-dimensional transformation to sustainability that also addresses humanwell-being and development.

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The Sustainable Production and Consumption Transformation has some effects on
safeguarding the Climate, Cryosphere and Oceans, but is not enough to protect them on its
own. The improvements in material efficiency and more sustainable consumption habitsultimately lead to lower industrial production and energy demand, which reduces GHG emissions
by 16 Gt CO2eq/yr relative to current policies in 2050. These reductions can prevent 0.09°C ofwarming overshoot in 2050 and have benefits for Ocean Acidification. When combined withother transformations, Sustainable Production and Consumption can further limit peak warming,
facilitate the Energy Systems Transformation and ease the pressure on the Land Biosphere.

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The transformations have little to no effect on the Ozone Layer beyond the Montreal Protocol.
With continued compliance to the Montreal Protocol on the emissions of ozone-depleting
substances, the ozone layer should return to pre-1980 levels between 2030 and 2050.

The role of demand reductions
Interventions that reduce demand for goods and services, be it for industrial materials (such as theSustainable Production and Consumption Transformation), or for unsustainable food products(Sustainable Food demand) can have very substantial effects on safeguarding the Global Commons.
But even within our deep transformations, demand-side interventions alone will not be sufficient
to reach any of the assessed targets. Furthermore, when coupled with structural changes in thesystems themselves, such as the decarbonisation of energy supply and more resource-efficient
agricultural production, these demand-side interventions tend to have a smaller effect than when
considered alone. This arises from the fact that these transformed production systems can fulfill thesame demand with less impact on the Global Commons.
However, reductions in demand can be fundamental in reducing the socioeconomic burden ofthese production systems transformations, making the same targets achievable with lower prices
for food, energy and GHG emissions for example. Since most of the demand reductions assessed
require deep behavioural changes, implementing them is posing a major policy challenge.

Industry transformation
Industry-specific modelling shows that carbon pricing is essential for reducing the sector’s
environmental impacts, but implementing industry-specific policies enables faster and deeper
de-carbonization of the sector.
Reducing the material demand of the economy through sustainable production and consumption
practices offers significant reductions of the pressure that industry puts on the Global Commonsdomains. However, the feasibility of deep dematerialization remains uncertain.
Carbon capture and storage (CCS) is important for deep decarbonization of the global industry totackle process emissions, as these cannot be mitigated by means of low-carbon energy carriers.
However, CCS technology is not a viable replacement for phasing out fossil fuels for energy use.
Robust policy making for deep decarbonization cannot be avoided.
The adoption of hydrogen-driven technologies in the industry sector should concentrate on thespecific applications where electrification is not feasible, as it is generally not the mostcost-effective solution .
Circular approaches for plastic waste mitigation can help mitigate the introduction of novel entities
in the earth system while avoiding putting further pressure on the climate and the energy transition
but further research is required that defines the technical, economic, and environmental limits ofthis alternative.

Policy recommendations
An integrated, comprehensive design of policies is needed for a Global Commons stewardship:
Global Commons stewardship needs combined and comprehensive policy settings, targetingtransformations on multiple sectors at the same time. To protect and preserve the Global Commonsand planetary integrity, such an integrated approach is of utmost importance. The interventions
considered in our scenario analysis are mutually supportive in preserving the Global Commons inmany cases, and can avoid or compensate for policy trade-offs if applied together. This is of particularimportance between and within the Energy and Land Systems Transformations, to avoid trade-offs
between land-based mitigation, growing bioenergy crops and nature conservation.
Current policies and commitments need to be substantially strengthened and increase theircoverage of the broad set of changes and transformations required for safeguarding the Global
Commons: Current commitments should not only be implemented, but strengthened with more
ambitious targets in terms of emissions reductions by 2030 and 2050, but also of land andbiodiversity protection. The recently adopted Global Biodiversity Framework represents a major stepin this direction. Policy measures should also have a more comprehensive focus on multiple sectors
and producer and consumer-facing interventions. This could help fill gaps in policy coverage, forexample, with regard to better taking into account the effects of agricultural systems on the waterand nutrient cycles, inducing a change towards more sustainable consumption patterns, andincreasing the material efficiency of production.
An emissions pricing scheme to safeguard the Global Commons should play a critical role topenalize actions that lead to more GHG emissions and reward those that reduce emissions. It
should be designed to cover all emitting sectors, have prices that rise over time, and explicitly
address its own equity and distributional impacts: Measures that effectively put a price on emitting
GHGs can have large positive effects on many Global Commons domains. Actual measures can
include direct carbon pricing or taxation, but also carbon markets (such as the EU Emissions Trading
Scheme) or regulations. Emission pricing directly targets the protection of the climate, and thus also
the preservation of ice sheets and glaciers and the prevention of further Ocean Acidification. It also
discourages the use of coal and other fossil fuels, thus improving air quality especially in cities andcommunities. Including the land use sector in such a pricing scheme creates incentives to protect
and expand forests. It also disincentivizes an excessive reliance on bioenergy for decarbonizing theenergy sector. Including GHGs other than CO2 in the pricing scheme also favours less meat
consumption and fosters a more sustainable use of nitrogen fertilizers. However, GHG pricing
should be accompanied by specific land protection measures to alleviate the pressure that someclimate mitigation options such as bioenergy use and afforestation can cause on natural andsemi-natural land, which is critical for halting and reversing biodiversity loss. GHG pricing instruments
should address their equity and distributional impacts by design to ensure their acceptance,
directing their revenues to lower income regions and households and phasing in prices more slowly
in developing countries.
The GHG price levels required for safeguarding the Global Commons domains, especially the
Climate, depend crucially on all other measures implemented: In the absence of any othermeasures, energy system GHG prices in our scenarios would have to reach around 350 U.S. dollars
per ton of CO2 equivalent by 2050 to reach the 1.5°C climate goal. Combining it with other policies,
especially encouraging the reduction of total demand for high emissions products and services,such as industrial materials, energy and animal-source foods, and pricing emissions in the land
sector lowers the GHG prices necessary to achieve the same climate target. Demand reductions,although difficult to implement, ease the cost of transition and have several co-benefits for the land
biosphere. Combined with strong levels of demand reduction, a comprehensive GHG pricing scheme
in the energy and land use could achieve the 1.5°C climate goal with prices as low as 90 U.S. dollars
per ton of CO2 equivalent by 2050.
The role of bioenergy in decarbonising the energy system should be limited and coupled with landconservation policies: Bioenergy production can lead to severe trade-offs, threatening the integrityof the land biosphere and increasing food prices. Many of these effects could be counteracted byvery ambitious conservation policies and a shift towards more sustainable food consumption
behaviour, which are challenging to implement at a global scale. Therefore, a mix of regulations onenergy markets to limit their reliance on bioenergy and comprehensive conservation policies on
bioenergy producing regions is recommended.
Foster sustainable production and consumption of industrial goods: A reduction in per-capita
production of material goods in high-income countries facilitates the decarbonization of the energy
supply, thus contributing directly to the protection of climate, cryosphere and oceans, as well as to a
reduction of air pollution and associated health effects and the amount of waste to be disposed of.
Part of these reductions can be achieved through material efficiency measures and technologicalimprovements in the producing industries. But promoting a shift to more sustainable consumption
patterns, with a focus on sharing and circular economies, could also lead to massive benefits.
A sound strategy for the sustainable transformation of the global industry requires a set of
sector-specific policies to overcome potential bottlenecks and carbon lock-ins. Incentives thatspeed up the development and rapid scale-up of Carbon capture and storage technologies areneeded to mitigate process emissions in industry. However, deploying CCS is not a license tocontinue to use fossil fuels, as it cannot provide full decarbonization. Robust policy making for theindustry transformation should hedge against the deep uncertainties underlying both newtechnologies and reductions in demand. More research must be done to define thetechno-economic boundaries of dematerialization and material efficiency, as well as advancing theunderstanding of cross-sectoral interactions. Incentives that foster the scale-up of hydrogen areneeded, but should be targeted to applications where electrification of processes is technicallyconstrained. Subsidizing the deployment of hydrogen beyond the necessary scope risks triggering
additional transformational challenges which can hinder the transformation of industry.
Promotion of healthy and sustainable diets and a reduction of food waste: The food system is oneof the key drivers for environmental degradation. A transition to lower meat and dairy consumption,
as recommended by the ‘Planetary Health’ diet of the EAT-Lancet expert commission, improves
human health and has far-reaching positive consequences for the Global Commons. Together with areduction of food waste, an adoption of the Planetary Health diet reduces food sector emissions of
CH4 and N2O drastically. By reducing land requirements for food production, in addition to inputs for
agriculture such as irrigation and nitrogen fertilizer, sustainable diets are key to facilitating ambitious
climate targets and preserving biodiversity.
Pull all levers to make land and food systems more sustainable: Although supply-side measures tomake agricultural production systems more resource-efficient, demand-side transitions to healthy
diets and low food waste, and systemic solutions to disincentive land system change and associatedGHG emissions are each yielding substantial progress on some Global Commons domains, none canon their own achieve - despite their ambitious design - the vision of returning within those Planetary
Boundaries that are closely tied to land use and agriculture. Thus, policy coherence is key toharnessing the many synergies between individual strategies and is likely to have many co-benefits inother areas, such as nitrogen-related air and water pollution and public health.
Beyond the physical dimensions of the Global Commons domains assessed, we also recommend tofurther take into account measures that primarily target societal development goals and that canalso have substantial impacts on the Global Commons. Many of these interventions can directly or
indirectly affect the justice, acceptability and feasibility of policies targeting the Global Commonsdomains, such as improving global justice in sharing the burden for implementing transformations,gender equality and access to education.
The feasibility of the implementation of such ambitious measures will depend on well-working
governmental institutions and strong international cooperation. Although each government should
control its own transformation strategy, coordination and compensation mechanisms at the global
level are critical given the significant challenges arising from the profound transformations in theenergy, agricultural and industrial systems, particularly in the global south. International cooperationand strong regional institutions will be needed to prevent leakages in the impact of policies,
especially in the land sector and between the Global South and Global North. Moreover, due to thenon-predictability of all impacts of certain measures, monitoring and readjustment strategies will benecessary and should be included in the conception of governance strategies aiming to keep the
impacts of human activities on the Global Commons domains within Planetary Boundaries.

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