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SUNDAY SCIENCE: HOW MAINSTREAM CLIMATE SCIENCE ENDORSED THE FANTASY
OF A GLOBAL WARMING TIME MACHINE  
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Wim Carton, Andreas Malm
October 9, 2024
The Conversation
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_ Nearly all modelled pathways for limiting global heating to 1.5°C
above pre-industrial levels involved temporarily transgressing this
target. A new study published in Nature confirmed that this was
nothing more than a fantasy. _

People fleeing the landfall of Hurricane Milton near Naples,
Florida., EPA-EFE/Cristobal Herrera-Ulashkevich

 

When the Paris agreement
[[link removed]] on
climate change was gavelled into being in December 2015, it briefly
looked like that rarest of things: a political victory for climate
activists and delegates from the poorest regions of the world that,
due to colonisation by today’s wealthy nations, have contributed
little to the climate crisis – but stand to suffer its worst
ravages.

The world had finally agreed an upper limit for global warming. And in
a move that stunned most experts, it had embraced the stretch target
of 1.5°C, the boundary that small island states, acutely threatened
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by sea-level rise, had tirelessly pushed for years.

Or so, at least, it seemed. For soon, the ambitious Paris agreement
limit turned out to be not much of a limit at all. When the
Intergovernmental Panel on Climate Change (or IPCC, the world’s
foremost body of climate experts) lent its authority to the 1.5°C
temperature target with its 2018 special report
[[link removed]], something odd transpired.

Nearly all modelled pathways for limiting global heating to 1.5°C
above pre-industrial levels involved temporarily transgressing this
target. Each still arrived back at 1.5°C eventually (the deadline
being the random end point of 2100), but not before first shooting
past it.

Scientists responsible for modelling the response of Earth’s climate
to greenhouse gas emissions – primarily caused
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by burning fossil fuels – called these “overshoot” scenarios.
They became the dominant path along which mitigating climate change
was imagined to proceed, almost as soon as talk of temperature limits
emerged.

De facto, what they said was this: staying below a temperature limit
is the same as first crossing it and then, a few decades hence, using
methods of removing carbon from the atmosphere to dial temperatures
back down again.

From some corners of the scientific literature came the assertion that
this was nothing more than fantasy. A new study
[[link removed]] published in
Nature has now confirmed this critique. It found that humanity’s
ability to restore Earth’s temperature below 1.5°C of warming,
after overshooting it, cannot be guaranteed. Many impacts of climate
change are essentially irreversible. Those that are might take decades
to undo, well beyond the relevant horizon for climate politics. For
policy makers of the future, it matters little that temperatures might
eventually fall back again; the impacts they will need to plan for are
those of the overshoot period itself.

[A bleached coral reef.]

Not coming back: tropical coral reefs face permanent destruction.
Sabangvideo/Shutterstock
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The rise of overshoot ideology

Even if global average surface temperatures are ultimately reversed,
climate conditions at regional levels might not necessarily follow the
global trend and might end up different from before. Delayed changes
in ocean currents, for instance, could mean that the North Atlantic or
Southern Ocean continue warming while the rest of the planet does not.

Any losses and damages that accumulate during the overshoot period
itself would of course be permanent. For a farmer in Sudan whose
livestock perishes in a heatwave that would have been avoided at
1.5°C, it will be scant consolation to know that temperatures are
scheduled to return to that level when her children have grown up.

Then there is the dubious feasibility of planetary-scale carbon
removal. Planting enough trees or energy crops to make a dent in
global temperatures would require whole continents of land. Direct air
capture of gigatonnes of carbon would consume prodigious amounts of
renewable energy and so compete with decarbonisation. Whose land are
we going to use for this? Who will shoulder the burdens for all this
excess energy use?

If reversal cannot be guaranteed, then clearly it is irresponsible to
sanction a supposedly temporary overshoot of the Paris targets. And
yet this is exactly what scientists have done. What compelled them to
go down this dangerous route?

Our own book
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topic (Overshoot: How the World Surrendered to Climate Breakdown,
published last week by Verso) offers a history and critique of the
idea.

When overshoot scenarios were summoned into being in the early 2000s,
the single most important reason was economics. Rapid, near-term
emissions cuts were deemed prohibitively costly and so unpalatable.
Cost optimisation mandated that they be pushed into the future to the
extent possible.

The models for projecting possible mitigation trajectories had these
principles written into their code and so for the most part could not
compute “low” temperature targets like 1.5 or 2°C. And because
modellers could not imagine transgressing the deeply conservative
constraints that they worked within, something else had to be
transgressed.

One team [[link removed]]
stumbled upon the idea that large-scale removal of carbon might be
possible in the future, and so help reverse climate change. The EU and
then the IPCC picked up on it, and before long, overshoot scenarios
had colonised the expert literature. Deference to mainstream economics
yielded a defence of the political status quo. This in turn translated
into reckless experimentation with the climate system. Conservatism or
fatalism about society’s capacity for change flipped into extreme
adventurism about nature.

Time to bury the time machine

Just as the climate movement scored an important political victory,
compelling the world to rally behind an ambitious temperature limit,
an influential group of scientists, amplified by the world’s most
authoritative scientific body on the subject, effectively helped water
it down. When all is said and written about the post-Paris era, this
surely should stand as one of its greatest tragedies.

By conjuring up the fantasy of overshoot-and-return, scientists
invented a mechanism for delaying climate action and unwittingly lent
credibility to those (and they are many) who have no real interest in
reigning in emissions here and now; who will seize on any excuse to
keep the oil and gas and coal flowing just a little longer.

[An offshore oil platform.]

A stable climate is not compatible with rising oil profits. Igor
Hotinsky/Shutterstock
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The findings of this new paper
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clear: There is no time machine waiting in the wings. Once 1.5°C lies
behind us, we must consider that threshold permanently broken.

There then remains only one road to ambitious mitigation of climate
change, and no amount of carbon dioxide removal can absolve us of its
inconvenient political implications.

Avoiding climate breakdown demands that we bury the fantasy of
overshoot-and-return and with it another illusion as well: that the
Paris targets can be met without uprooting the status-quo. One limit
after the other will be broken unless we manage to strand fossil fuel
assets and curtail opportunities for continuing to profit from oil and
gas and coal.

We will not mitigate climate change without confronting and defeating
fossil fuel interests. We should expect climate scientists to be
candid about this.

[Imagine weekly climate newsletter]

_DON’T HAVE TIME TO READ ABOUT CLIMATE CHANGE AS MUCH AS YOU’D
LIKE?_
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[[link removed]]
Every Wednesday, The Conversation’s environment editor writes
Imagine, a short email that goes a little deeper into just one climate
issue. Join the 35,000+ readers who’ve subscribed so far.
[[link removed]]_[The
Conversation]

_Wim Carton [[link removed]],
Associate Professor of Political Ecology, Lund University
[[link removed]] and
Andreas Malm
[[link removed]], Associate
Professor of Human Ecology, Lund University
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_This article is republished from The Conversation
[[link removed]] under a Creative Commons license. Read
the original article
[[link removed]]._

Do Evolution and Natural Selection Occur Cosmically?
[[link removed]]
Ethan Siegel
Starts With A Bang/Big Think
The Universe changes remarkably over time, with some entities
surviving and others simply decaying away. Is this cosmic evolution at
work?
October 11, 2024

* fossil fuels
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* Climate Change
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* carbon capture
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* Paris Agreement
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* IPCC report
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*
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