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we know enough – climate scientists share key new insights from the ipcc’s latest report

the global temperature is likely to fall Moreover, this report assesses climate warming, changes in extremes continue
later in the century and to stabilise impacts by region, providing regional to become larger. For example, every
just below 1.5°C. This is in striking information that can be used for climate additional 0.5°C of global warming
contrast to scenarios with weak or no risk assessment, which goes beyond causes clearly discernible increases
further mitigation where we can expect what any previous IPCC report has done. in the intensity and frequency of hot
to see warming of 2.5-4°C by the end of This will definitely help decision making extremes, including heatwaves (very
this century. in the different countries, especially in likely), and heavy precipitation (high
We also show that many changes, the Global South. confidence), as well as agricultural and
such as ice loss and sea level rise, are ecological droughts in some regions
irreversible for centuries or millennia. So, DR EMILY SHUCKBURGH (high confidence)”.
even if we succeed with stabilising global Director of Cambridge Zero This report is historic, establishing
temperature, we will need to adapt to University of Cambridge human influence on the climate as a
ongoing changes for some time to come. Ever more certain, ever more detailed. fact, bringing precise understanding
That’s the brief summary I would of the state of the climate, and what to
PROF TIANJUN ZHOU give the AR6 WG1 summary for expect in the future, depending on our
Professor (AR6 WG1 Chapter 4 lead author) policymakers (SPM). Once again it actions. Let’s hope the resulting action
Chinese Academy of Sciences and provides a comprehensive chronicle of will be as historic.
University of Chinese Academy of extreme weather induced by climate
Sciences, Beijing change and the risk of catastrophic PROF WEN WANG
To me, one key finding of the report is future impacts. It estimates the Professor (AR6 WG1 Chapter 12 lead author)
the new estimation of the equilibrium remaining carbon budget from 2020 Hohai University, Nanjing
climate sensitivity (ECS), which is an for a reasonable chance (67 per cent) of A risk framework was used for
important quantity used to estimate limiting warming to 1.5°C is 400 billion assessing risks from climate changes
how the climate responds to radiative tonnes of CO₂ (GtCO₂). With global in previous IPCC assessment reports,
forcing. Based on multiple lines of emissions in 2020 of 40 GtCO₂, this re- focusing on adverse consequences
evidence, the best estimate of ECS is emphasises that this decade is critical. for human or ecological systems. That
3°C with a likely range of 2.5 to 4°C, In the Decline and Fall of the Roman sometimes leads to criticisms of IPCC
compared to 1.5 to 4.5°C in AR5. The Empire, historian Edward Gibbon for being too alarmist.
new estimate represents a major wrote that history is “little more than As the effects of climate change
reduction in uncertainty. the register of the crimes, follies and can be detrimental, beneficial, or
The new estimate of ECS helps us to misfortunes of mankind”. Our history inconsequential, alongside a revised
constrain future climate projections. is being written. For three decades, the risk framing, the report adopted a
For the first time, the assessment of IPCC has been warning of the dangers Climatic Impact-Driver (CID) framework
three key aspects of the climate system of climate change, yet the world has for assessing changing climate
response to scenarios – global mean not taken strong enough action to conditions in a more neutral way. CIDs
surface temperature, ocean heat uptake halt it. This report is clear that unless are physical climate system conditions
and global mean sea level rise – has there are immediate, rapid and large- (e.g., averages, and extremes) that
combined multiple lines of evidence, scale reductions in greenhouse gas affect society or ecosystems. Every
including the updated assessment of emissions, limiting warming to close to sector can be affected by multiple
climate sensitivity. This has helped us to 1.5°C or even 2°C will be beyond reach. CIDs, each CID affects multiple sectors
reduce the uncertainty range of warming and can cause different responses in
expected under specific scenarios and different circumstances.
provide more reliable projections that This report allows us to show We believe that the CID framework
are crucial for policymaking. that climate change is affecting can provide useful information for
every region on earth and that sectoral applications and decision
DR PAOLA ARIAS making without pre-determining the
Associate Professor these changes will become more effects of changing climate phenomena.
(AR6 WG1 Chapter 8 lead author) severe if global temperatures
University of Antioquia, Medellín continue to increase MAISA ROJAS CORRADI
This report allows us to show that Director (AR6 coordinating lead author)
climate change is affecting every Center for Climate and Resilience
region on earth and that these changes DR CELINE GUIVARCH Research, Santiago
will become more severe if global Research Director Unlike AR4 and AR5, which had
temperatures continue to increase. CIRED, Ecole des Ponts ParisTech dedicated palaeoclimate chapters,
This is very important since we are The report states that “reaching net paleo information in the AR6 can be
now able to link global-scale changes zero anthropogenic CO₂ emissions is a found across the report. Palaeoclimate
such as the increases in global requirement to stabilise human-induced information is integrated into
surface temperatures with changes global temperature increase at any assessment findings as one of the “multi
that translate very differently at level”. This point is not totally new, as, lines of evidence”. This AR6 approach
regional scales, such as the occurrence after all, this report is not new science, had its risks, but, ultimately, I believe
of heatwaves, droughts, extreme but I think it is extremely important and the result has been very successful.
precipitation and fire weather. We backed by compelling evidence. Many of the palaeo findings are the
also have a better understanding and It gives an extremely clear guide for basis for the key message: “Many of
attribution of the human influence on what our collective actions should aim the changes observed in the climate
the climate system, particularly for at, together with the statement: “With are unprecedented in thousands, if not
extreme weather events. every additional increment of global hundreds of thousands of years…”

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