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great report that has a wealth of exciting on weather and climatic extremes,
new findings and messages. It’s a report exploiting extended observational
that will strengthen global ambition at records, advances in physical
COP26. Over 120 national delegations understanding and benefiting from
participated and you could really tell that more comprehensive computer
they were really looking to the report to simulations. The newly assessed
help identify key messages for action. science is clear that without rapid
My own chapter looks at climate and sustained cuts in human-caused
feedbacks and, for the first time, we greenhouse gas emissions, water cycle
are able to quantify the role of clouds extremes will continue to intensify
in amplifying climate change with a with future increases in global surface
high degree of certainty. We use this temperature, along with more severe
information to substantially narrow associated flooding and drought events.
the range of our future temperature
projections. These projections give us
much stronger confidence that the plans “Eight years ago, the
being pushed for in COP26 are the right attribution of all these extreme
ones. If the world can substantially events to human-caused
reduce emissions in the 2020s and get
to net zero emissions by around 2050, climate change was less
temperature rise can still be limited to clear. Now, due to both an
1.5°C, but we need to act now. improvement in attribution
science but also the dispiriting
DR JESSICA TIERNEY
Associate Professor fact that climate change has
(AR6 WG1 Chapter 8 lead author) gotten so much worse, we
University of Arizona are sure that humans have
Something that is really different from contributed to extreme events”
the last IPCC report, AR5, is the increased
confidence we have in the attribution
of extreme events, such as heatwaves, DR AMANDA MAYCOCK
floods, droughts, to human influence. Associate Professor in Climate Dynamics
I worked on a lot of the text about and Director of the Institute for
drought in Chapter 8, the water Atmospheric and Climate Science
DROUGHT IN ETHIOPIA cycle chapter. We now know that the (AR6 WG1 Chapter 4 lead author)
severity of droughts in certain regions, University of Leeds
including western North America, the In the three years since work on
change in one of its key messages. Mediterranean and South Africa, can be the WG1 AR6 report began, the
Climate, by definition, is an average attributed to us. atmospheric CO₂ concentration has
of weather, and averages always hide The language in the report about increased by a further 7.5 parts per
the extreme values. Therefore, while heatwaves is even more confident. In the million by volume (ppmv) – 2.7 per cent
the current global mean warming of 1°C parlance of the report, it is “extremely higher than pre-industrial levels – and
may sound harmless, its manifestation unlikely” that some of the recent year-on-year we have observed record-
in the form of extremes is proving to be heatwaves we have seen would have breaking weather and climate extremes
disruptive and dangerous, as witnessed occurred without human influence. across the world.
by the widespread heatwaves and Eight years ago, the attribution of all It is stark to think of these changes
wildfires in recent years. these extreme events to human-caused occurring while authors have been hard
This fact appears in the IPCC’s key climate change was less clear. Now, due at work compiling the latest scientific
message on extremes, which is that to both an improvement in attribution evidence in AR6, which now shows
human influence is making extreme science but also the dispiriting fact that climate change is not something abstract
climate events, including heatwaves, climate change has gotten so much that will happen a long way in the future,
heavy rainfall and droughts, more worse, we are sure that humans have but that it is here with us now.
frequent and severe. These disruptive contributed to extreme events. The AR6 report adopts a more
events will only get worse with every bit comprehensive approach to projecting
of additional warming. PROF RICHARD ALLAN future warming under different
Professor of Climate Science emissions scenarios than was possible
PROF PIERS FORSTER (AR6 WG1 Chapter 8 lead author) in previous reports, by combining
Professor of Climate Physics and Director University of Reading information from climate models,
(AR6 WG1 Chapter 7 coordinating There is strengthened evidence that observed climate trends and energy
lead author and summary for human-caused warming of the climate balance models. These more nuanced
policymakers drafting author) is intensifying the global water cycle, projections show that in the five
Priestley International Centre for including its variability and the illustrative scenarios assessed we
Climate at the University of Leeds severity of wet and dry periods that are expect to reach or exceed the 1.5°C
I am tired after two weeks of online affecting all regions. warming threshold in the next 20 years.
plenary negotiations across time zones The new report includes distinct However, crucially, in the scenario
from my kitchen, but I think we have a chapters on water cycle changes and with strong greenhouse gas mitigation

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