Science and IPCC, where do we standDr Stephan SingerMay 2022

April 2022

420.23

Early Homo Sapiens

"If humanity wishes to preserve a planet
similar to that on which civilization developed
and to which life on Earth is adapted,
paleoclimate evidence and ongoing climatechange suggest that CO2 will need to be
reduced from its current 385 ppm to at most
350 ppm.“ Jim Hansen, 2008• „CO2 atmospheric concentrations are likely the highest on
Earth since at least 3 mio years“ (SCIENCE, Nov. 2019)“ or thehighest since at least 2 mio years (IPCC, 2021)• University of Louisiana at Lafayette concluded 2020 that today's
carbon dioxide (CO2) levels are actually higher than they have been
for the past 23 million years.
• “About 15 to 40% of emitted CO2 will remain in theatmosphere longer than 1,000 years” (IPCC AR5 WGI, 2014)• “In the past 200 years alone, ocean water has become 30
percent more acidic—faster than any known change in ocean
chemistry in the last 50 million years” (Smithonian Institute,2016)• Rate of ocean surface water acidification is the highest since atleast 2 mio years (IPCC, 2021)

The rate of global warming today is about five to fifty times faster thanin historic/palaeontological times of periods of rapid natural globalwarming• 2019 and 2020, again as in in previous years, global warming of 1°C to
1.1°C (compared to the 1901 – 2000 average), has been much higher
over land (1.42° C) than over the oceans (0.7°C) and stronger in theNorthern (1.15° C) than in the Southern (0.7°C) hemisphere. But bynow, oceans have accumulated the highest heat content sincerecordings started.
• Since about 20-30 years, annual regional warming with up to 3°C andmore had been almost three times as high than global average inparticular in regions in North, Central and Mediterranean Europe, inparts of the Middle East, and spread across the entire Arctic zone
from Greenland to Northern Canada and Russia to Alaska.

Global Tipping Points

Source: Steffen et al., 2018• „The Greenland Ice Sheet (GrIS) and its outlying ice caps were losing mass
at a rate of about 102 Gt/y in early 2003, but 10 y later this rate had
increased nearly fourfold to about 393 Gt/y, accounting for much of theobserved acceleration in sea level rise…” (PNAS, Jan 2019)• While the Greenland ice melting had increased six times between the1980s and today as a result of global warming, the contribution to sea level
rise was about half of all in only the last eight years 2010 – 2018. In theseeight years the net cumulative loss of ice from Greenland was about 2200
billion tons (April 2019: https://www.theatlantic.com/science/archive/2019/04/how-much-icehas-greenland-lost-climate-change/587431/
https://www.pnas.org/content/early/2019/04/16/1904242116)• “In the Antarctic, the total ice mass loss increased from 40 Gt/y on averagein 1979–1990 to 50 Gt annually in 1989–2000, jumping to 166 Gt/y in
1999–2009, and were about 252 Gt annually in recent years of 2009–2017….” (PNAS, Jan 2019) - An increase of 6 times (in 20-30 years).
A non-linear but exponential trend – Sea level rise projections by
IPCC are probably highly underestimatedSource:Accelerating annual sea level rise 1993 - 2022

Source: “State of Climate 2021”; World Meteorological Organisation (WMO) 2022

1.7 m ?

and confirmed for low-carbon
Scenarios as well

The dangers of uncontrollable carbon feed backs“….permafrost is thawing much more quickly than models have predicted, with unknown
consequences for greenhouse-gas release.”“ We estimate that abrupt permafrost thawing in lowland lakes and wetlands, together
with that in upland hills, could release between 60 billion and 100 billion tonnes ofcarbon by 2300 (200 – 370 billion tonnes CO2). This is in addition to the 200 billion
tonnes of carbon (740 billion tonnes CO2) expected to be released in other regions thatwill thaw gradually. Although abrupt permafrost thawing will occur in less than 20% offrozen land, it increases permafrost carbon release projections by about 50%. ““Furthermore, because abrupt thawing releases more methane than gradual thawing
does, the climate impacts of the two processes will be similar. So, together, the impacts ofthawing permafrost on Earth’s climate could be twice that expected from current
models”
Source: NATURE 2019 https://www.nature.com/articles/d41586-019-01313-4?utm_source=Nature+Briefing&utm_
campaign=9d991fd363-briefing-dy-20190430&utm_medium=email&utm_term=0_c9dfd39373-9d991fd363-43943857

Direct quotes from the IPCC report on oceans and the cryosphere 1• It is virtually certain that the global ocean has warmed unabated since 1970 andhas taken up more than 90% of the excess heat in the climate system (highconfidence).
• Datasets spanning 1970–2010 show that the open ocean has lost oxygen by avery likely range of 0.5–3.3% over the upper 1000 m, alongside a likely expansionof the volume of oxygen minimum zones by 3–8%. (higher than observedbefore)• The ocean has taken up between 20–30% (very likely) of total anthropogenic CO2
emissions since the 1980s causing further ocean acidification. Open ocean
surface pH has declined by a very likely range of 0.017–0.027 pH units per
decade since the late 1980s (means a 30% increase of ocean acidification)• Sea-level rise has accelerated (extremely likely) due to the combined increased
ice loss from the Greenland and Antarctic ice sheets (very high confidence). Mass
loss from the Antarctic ice sheet over the period 2007–2016 tripled relative to
1997–2006. For Greenland, mass loss doubled over the same period.
Source: IPCC report on Oceans and Cryosphere, September 2019; highlights by meDirect quotes from the IPCC report on oceans and the cryosphere 2• Acceleration of ice flow and retreat in Antarctica, which has thepotential to lead to sea-level rise of several metres within a few
centuries, is observed in the Amundsen Sea, Embayment of West
Antarctica and in Wilkes Land, East Antarctica (very high confidence).
These changes may be the onset of an irreversible ice sheet
instability.
• The Greenland and Antarctic Ice Sheets are projected to lose mass at
an increasing rate throughout the 21st century and beyond (highconfidence). The rates and magnitudes of these cryospheric changes
are projected to increase further in the second half of the 21stcentury in a high greenhouse gas emissions scenario (highconfidence). Strong reductions in greenhouse gas emissions in thecoming decades are projected to reduce further changes after 2050
(high confidence).
Source: IPCC report on Oceans and Cryosphere, September 2019; highlights by meDirect quotes from the IPCC report on oceans and the cryosphere 3• The RCP8.5 scenario leads to the cumulative release of tens to hundreds ofbillions of tons (GtC) of permafrost carbon as CO2 and methane to theatmosphere by 2100 with the potential to exacerbate climate change• Sea level continues to rise at an increasing rate. Extreme sea level events
that are historically rare (once per century in the recent past) areprojected to occur frequently (at least once per year) at many locations by
2050 in all RCP scenarios, especially in tropical regions (high confidence).
• Many low-lying megacities and small islands (including SIDS) are projected
to experience historical centennial events at least annually by 2050 under
RCP2.6, RCP4.5 and RCP8.5.
• In the absence of more ambitious adaptation efforts compared to today,
and under current trends of increasing exposure and vulnerability ofcoastal communities, risks, such as erosion and land loss, flooding,salinization, and cascading impacts due to mean sea level rise and extreme
events are projected to significantly increase throughout this century
under all greenhouse gas emissions scenarios (very high confidence).
Source: IPCC report on Oceans and Cryosphere, September 2019; highlights by meThe real temperature differences between high- andlow emissions scenarios occur in the future decades

IPCC WG II – Highlights from SPM, direct quotes
In yellow – my emphasize• Beyond 2040 and depending on the level of global warming, climate change will lead to numerous risks to natural andhuman systems (high confidence). For 127 identified key risks, assessed mid- and long-term impacts are up to multiple
times higher than currently observed (high confidence). The magnitude and rate of climate change and associatedrisks depend strongly on near-term mitigation and adaptation actions, and projected adverse impacts and related
losses and damages escalate with every increment of global warming (very high confidence).
• Global warming, reaching 1.5°C in the near-term, would cause unavoidable increases in multiple climate hazards andpresent multiple risks to ecosystems and humans (very high confidence). The level of risk will depend on concurrent
near-term trends in vulnerability, exposure, level of socioeconomic development and adaptation (high confidence).
Near-term actions that limit global warming to close to 1.5°C would substantially reduce projected losses anddamages related to climate change in human systems and ecosystems, compared to higher warming levels, but cannot
eliminate them all (very high confidence)• Biodiversity loss, and degradation, damages to and transformation of ecosystems are already key risks for every region
due to past global warming and will continue to escalate with every increment of global warming (very highconfidence). In terrestrial ecosystems, 3 to 14% of species assessed will likely face very high risk of extinction at global
warming levels of 1.5°C…….
• Globally, population change in low-lying cities and settlements will lead to approximately a billion people projected to
be at risk from coastal-specific climate hazards in the mid-term under all scenarios, including in Small Islands (highconfidence).

• Projected estimates of global aggregate net economic damages generally increase non-linearly with global warming
levels (high confidence).
• Depending on the magnitude and duration of overshoot, some impacts will cause release of additional greenhousegases (medium confidence) and some will be irreversible, even if global warming is reduced (high confidence).
• Additional warming, e.g., above 1.5°C during an overshoot period this century, will result in irreversible impacts on
certain ecosystems with low resilience, such as polar, mountain, and coastal ecosystems, impacted by ice-sheet, glaciermelt, or by accelerating and higher committed sea level rise (high confidence). Risks to human systems will increase,including those to infrastructure, low-lying coastal settlements, some ecosystem-based adaptation measures, andassociated livelihoods (high confidence), cultural and spiritual values (medium confidence). Projected impacts are lesssevere with shorter duration and lower levels of overshoot (medium confidence).
• Most observed adaptation is fragmented, small in scale, incremental, sector-specific, designed to respond to current
impacts or near-term risks, and focused more on planning rather than implementation (high confidence). Observed
adaptation is unequally distributed across regions (high confidence), and gaps are partially driven by widening
disparities between the estimated costs of adaptation and documented finance allocated to adaptation (highconfidence). The largest adaptation gaps exist among lower income population groups (high confidence).

• Sea level rise poses a distinctive and severe adaptation challenge as it implies dealing with slow onset changes andincreased frequency and magnitude of extreme sea level events which will escalate in the coming decades (highconfidence). Such adaptation challenges would occur much earlier under high rates of sea level rise, in particular if lowlikelihood, high impact outcomes associated with collapsing ice sheets occur (high confidence).
• Approximately 3.4 billion people globally live in rural areas around the world, and many are highly vulnerable to climatechange. Integrating climate adaptation into social protection programs, including cash transfers and public works
programmes, is highly feasible and increases resilience to climate change, especially when supported by basic services
and infrastructure. Social safety nets are increasingly being reconfigured to build adaptive capacities of the mostvulnerable in rural and also urban communities. Social safety nets that support climate change adaptation have strong
co-benefits with development goals such as education, poverty alleviation, gender inclusion and food security.
• Within energy system transitions, the most feasible adaptation options support infrastructure resilience, reliable powersystems and efficient water use for existing and new energy generation systems (very high confidence). Energy
generation diversification, including with renewable energy resources and generation that can be decentralised
depending on context (e.g., wind, solar, small scale hydroelectric) and demand side management (e.g., storage, andenergy efficiency improvements) can reduce vulnerabilities to climate change, especially in rural populations (highconfidence).
• Unsustainable land-use and land cover change, unsustainable use of natural resources, deforestation, loss ofbiodiversity, pollution, and their interactions, adversely affect the capacities of ecosystems, societies, communities andindividuals to adapt to climate change (high confidence). Loss of ecosystems and their services has cascading and longterm impacts on people globally, especially for Indigenous Peoples and local communities who are directly dependenton ecosystems, to meet basic needs.

• With adaptation finance needs estimated to be higher than those presented in AR5, enhanced mobilization of andaccess to financial resources are essential for implementation of adaptation and to reduce adaptation gaps (highconfidence). Building capacity and removing some barriers to accessing finance is fundamental to accelerate
adaptation, especially for vulnerable groups, regions and sectors (high confidence). Public and private financeinstruments include inter alia grants, guarantee, equity, concessional debt, market debt, and internal budget
allocation as well as savings in households and insurance. Public finance is an important enabler of adaptation (highconfidence)• Levels of risk for all Reasons for Concern (RFC) [graphic next slide] are assessed to become high to very high at lower
global warming levels than in AR5 (high confidence). Between 1.2°C and 4.5°C global warming level very high risks
emerge in all five RFCs compared to just two RFCs in AR5 (high confidence).
• Climate resilient development pathways are progressively constrained by every increment of warming, in particularbeyond 1.5°C, social and economic inequalities, the balance between adaptation and mitigation varying by national,
regional and local circumstances and geographies, according to capabilities including resources, vulnerability, culture
and values, past development choices leading to past emissions and future warming scenarios, bounding the climate
resilient development pathways remaining, and the ways in which development trajectories are shaped by equity, andsocial and climate justice. (very high confidence).
• Recent analyses, drawing on a range of lines of evidence, suggest that maintaining the resilience of biodiversity andecosystem services at a global scale depends on effective and equitable conservation of approximately 30% to 50% ofEarth’s land, freshwater and ocean areas, including currently near-natural ecosystems (high confidence).
• The cumulative scientific evidence is unequivocal: Climate change is a threat to human well-being and planetary
health. Any further delay in concerted anticipatory global action on adaptation and mitigation will miss a brief andrapidly closing window of opportunity to secure a liveable and sustainable future for all. (very high confidence)CO2 remains the largest GHG with about 75%, and fossil fuels the largest sourceLargest historic total and per capita emissions in North America, lowest in Southern Asia

Largest mitigation potentials until 2030 for wind, solar, halting deforestation, energy
efficiency, restoration, shifting diets, carbon sequestration in agricultureDid not make it in the IPCC WG III report – but showing that world needs to grow investments
into clean technologies by up to six times annually between now and 2030

Conclusions “Code red”
• CO2 concentrations are the highest since at least two million years• Impacts across all continents do already and will happen faster, more extreme and exponential
than thought earlier, from food security, forest fires, sea level rise to heat and flood extremes• Exceeding 1.5°C increases the risks of irreversible changes and tipping points• Temporary 1.5°C overshoot is unavoidable in next decades, but return to 1.4°C possible• Much better and enhanced adaptation and Loss & Damage finance needed• Deep, early, continued GHG reductions are necessary, so are negative emissions after net-zero inmid-century• Fossil fuel phase out is mandatory, coal needs to be out of system in the 2030s• Financing for both adaptation and mitigation needs to be in the trillions to avoid havoc• Policies need to address the multiple crises of pollution, biodiversity loss, inequity etc.
• Largest technical and cost-effective potentials are solar, wind, ecosystem protection &restoration, energy efficiency in all economic sectors, diet shifts, reducing food waste• Nuclear and CCS only very limited options• Finance system and investment practices have to change radically – both internationally andnationally for drastically overcoming inequalities in almost all nations