[D66] [JD: 122] IPCC steps up warning on climate tipping points in leaked draft report

[R.O.]

theguardian.com
<https://www.theguardian.com/environment/2021/jun/23/climate-change-dangerous-thresholds-un-report?CMP=Share_AndroidApp_Other>



  IPCC steps up warning on climate tipping points in leaked draft report

Fiona Harvey
5-7 minutes
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*Climate scientists are increasingly concerned that global heating will
trigger tipping points in Earth’s natural systems, which will lead to
widespread and possibly irrevocable disaster, unless action is taken
urgently.*

The impacts are likely to be much closer than most people realise, a a
draft report from the world’s leading climate scientists suggests, and
will fundamentally reshape life in the coming decades even if greenhouse
gas emissions are brought under some control.

The Intergovernmental Panel on Climate Change is preparing a landmark
report to be published in stages this summer and next year. Most of the
report will not be published in time for consideration by policymakers
at Cop26
<https://www.theguardian.com/environment/cop26-glasgow-climate-change-conference-2021>,
the UN climate talks taking place in November in Glasgow.

A draft of the IPCC report apparently from early this year was leaked to
Agence France-Presse, which reported on its findings on Thursday. The
draft warns of a series of thresholds beyond which recovery from climate
breakdown may become impossible. It warns: “Life on Earth can recover
from a drastic climate shift by evolving into new species and creating
new ecosystems … humans cannot.”

Tipping points are triggered
<https://www.theguardian.com/environment/2021/jun/03/climate-tipping-points-could-topple-like-dominoes-warn-scientists>
when temperatures reach a certain level, whereby one impact rapidly
leads to a series of cascading events with vast repercussions. For
instance, as rising temperatures lead to the melting of Arctic
permafrost, the unfreezing soil releases methane
<https://www.theguardian.com/science/2020/oct/27/sleeping-giant-arctic-methane-deposits-starting-to-release-scientists-find#:~:text=Scientists%20say%20they%20have%20found,coast%2C%20the%20Guardian%20can%20reveal.>,
a powerful greenhouse gas that in turn causes more heating.

Other tipping points include the melting of polar ice sheets
<https://www.theguardian.com/environment/2016/nov/25/arctic-ice-melt-trigger-uncontrollable-climate-change-global-level>,
which once under way may be almost impossible to reverse
<https://www.theguardian.com/environment/2020/sep/23/melting-antarctic-ice-will-raise-sea-level-by-25-metres-even-if-paris-climate-goals-are-met-study-finds>
even if carbon emissions are rapidly reduced, and which would raise sea
levels catastrophically over many decades, and the possibility of the
Amazon rainforest switching suddenly to savannah
<https://www.theguardian.com/environment/2019/oct/23/amazon-rainforest-close-to-irreversible-tipping-point>,
which scientists have said could come quickly
<https://www.theguardian.com/environment/2020/oct/05/amazon-near-tipping-point-of-switching-from-rainforest-to-savannah-study>
and with relatively small temperature rises.

Bob Ward, the policy and communications director at the Grantham
Research Institute on Climate Change and the Environment at the London
School of Economics, said: “Scientists have identified several potential
regional and global thresholds or tipping points in the climate beyond
which impacts become unstoppable or irreversible, or accelerate. They
could create huge social and economic responses, such as population
displacements and conflict, and so represent the largest potential risks
of climate change. Tipping points should be the climate change impacts
about which policymakers worry the most, but they are often left out of
assessments by scientists and economists because they are difficult to
quantify.”

Previous work by the IPCC has been criticised for failing to take
account
<https://www.theguardian.com/environment/2018/oct/09/tipping-points-could-exacerbate-climate-crisis-scientists-fear>
of tipping points. The new report is set to contain the body’s strongest
warnings yet on the subject.

Simon Lewis, a professor of global change science at University College
London, said: “Nothing in the IPCC report should be a surprise, as all
the information comes from the scientific literature. But put together,
the stark message from the IPCC is that increasingly severe heatwaves,
fires, floods and droughts are coming our way with dire impacts for many
countries. On top of this are some irreversible changes, often called
tipping points, such as where high temperatures and droughts mean parts
of the Amazon rainforest can’t persist. These tipping points may then
link, like toppling dominoes.”

He added: “The exact timing of tipping points and the links between them
is not well understood by scientists, so they have been under-reported
in past IPCC assessments. The blunter language from the IPCC this time
is welcome, as people need to know what is at stake if society does not
take action to immediately slash carbon emissions.”

Myles Allen, a professor of geosystem science at the University of
Oxford, declined to comment on the draft report but stressed that
avoiding dire impacts was still possible. “It’s important people don’t
get the message ‘we’re doomed anyway so why bother?’. This is a fixable
problem. We could stop global warming in a generation if we wanted to,
which would mean limiting future warming to not much more than has
happened already this century. We also know how. It’s just a matter of
getting on with it,” he said.

According to AFP, the IPCC draft details at least 12 potential tipping
points
<https://www.theguardian.com/science/2020/sep/19/the-tipping-points-at-the-heart-of-the-climate-crisis>.
“The worst is yet to come, affecting our children’s and grandchildren’s
lives much more than our own,” the report says.

The reportmay be subject to minor changes in the coming months as the
IPCC shifts its focus to a key executive summary for policymakers.

It says that with 1.1C of warming above pre-industrial levels clocked so
far, the climate is already changing. A decade ago, scientists believed
that limiting global warming to 2C above mid-19th-century levels would
be enough to safeguard the future.

That goal is enshrined in the 2015 Paris agreement, adopted by nearly
200 nations who vowed to collectively cap warming at “well below” 2C –
and 1.5C if possible. On current trends the world is heading for 3C at best.

Earlier models predicted that Earth-altering climate change was not
likely before 2100. But the UN draft report says prolonged warming even
beyond 1.5C could produce “progressively serious, centuries-long and, in
some cases, irreversible consequences.”

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