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<div class="header reader-header reader-show-element"> <a
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href="https://www.theguardian.com/environment/2021/jun/23/climate-change-dangerous-thresholds-un-report?CMP=Share_AndroidApp_Other">theguardian.com</a>
<h1 class="reader-title">IPCC steps up warning on climate tipping
points in leaked draft report</h1>
<div class="credits reader-credits">Fiona Harvey</div>
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<div class="reader-estimated-time" dir="ltr">5-7 minutes</div>
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<p><font size="+1"><b>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.</b></font></p>
<p>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.</p>
<p>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 Most of the report will not be
published in time for consideration by policymakers at <a
href="https://www.theguardian.com/environment/cop26-glasgow-climate-change-conference-2021"
data-link-name="in body link">Cop26</a>, the UN climate
talks taking place in November in Glasgow.</p>
<p>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.”</p>
<p><a
href="https://www.theguardian.com/environment/2021/jun/03/climate-tipping-points-could-topple-like-dominoes-warn-scientists"
data-link-name="in body link">Tipping points are
triggered</a> 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
<a
href="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."
data-link-name="in body link">unfreezing soil releases
methane</a>, a powerful greenhouse gas that in turn
causes more heating.</p>
<figure id="574b53e9-2a63-4eaf-8e70-4ca39c6a7575"></figure>
<p>Other tipping points include the <a
href="https://www.theguardian.com/environment/2016/nov/25/arctic-ice-melt-trigger-uncontrollable-climate-change-global-level"
data-link-name="in body link">melting of polar ice
sheets</a>, which once under way may be almost <a
href="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"
data-link-name="in body link">impossible to reverse</a>
even if carbon emissions are rapidly reduced, and which
would raise sea levels catastrophically over many decades,
and the possibility of the <a
href="https://www.theguardian.com/environment/2019/oct/23/amazon-rainforest-close-to-irreversible-tipping-point"
data-link-name="in body link">Amazon rainforest
switching suddenly to savannah</a>, which scientists
have said <a
href="https://www.theguardian.com/environment/2020/oct/05/amazon-near-tipping-point-of-switching-from-rainforest-to-savannah-study"
data-link-name="in body link">could come quickly</a> and
with relatively small temperature rises.</p>
<p>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.”</p>
<p>Previous work by the IPCC has been <a
href="https://www.theguardian.com/environment/2018/oct/09/tipping-points-could-exacerbate-climate-crisis-scientists-fear"
data-link-name="in body link">criticised for failing to
take account</a> of tipping points. The new report is
set to contain the body’s strongest warnings yet on the
subject.</p>
<p>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.”</p>
<figure id="3e5edfc1-5b20-4c59-ae07-3360ad6e81bc"></figure>
<p>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.”</p>
<p>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.</p>
<p>According to AFP, the IPCC draft details at least 12
potential <a
href="https://www.theguardian.com/science/2020/sep/19/the-tipping-points-at-the-heart-of-the-climate-crisis"
data-link-name="in body link">tipping points</a>. “The
worst is yet to come, affecting our children’s and
grandchildren’s lives much more than our own,” the report
says.</p>
<p>The reportmay be subject to minor changes in the coming
months as the IPCC shifts its focus to a key executive
summary for policymakers.</p>
<p>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.</p>
<p>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.</p>
<p>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.”</p>
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