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https://www.theguardian.com/environment/2025/aug/19/a-climate-of-unparalleled-malevolence-are-we-on-our-way-to-the-sixth-major-mass-extinction>
"Daniel Rothman works on the top floor of the building that houses the
Massachusetts Institute of Technology (MIT) Department of Earth, Atmospheric
and Planetary Sciences, a big concrete domino that overlooks the Charles River
in Cambridge, Massachusetts. Rothman is a mathematician interested in the
behaviour of complex systems, and in the Earth he has found a worthy subject.
Specifically, Rothman studies the behaviour of the planet’s carbon cycle deep
in the Earth’s past, especially in those rare times it was pushed over a
threshold and spun out of control, regaining its equilibrium only after
hundreds of thousands of years. Seeing as it’s all carbon-based life here on
Earth, these extreme disruptions to the carbon cycle express themselves as, and
are better known as, “mass extinctions”.
Worryingly, in the past few decades geologists have discovered that many, if
not most, of the mass extinctions of Earth history – including the very worst
ever by far – were caused not by asteroids as they had expected, but by
continent-spanning volcanic eruptions that injected catastrophic amounts of CO₂
into the air and oceans.
Put enough CO₂ into the system all at once, and push the life-sustaining carbon
cycle far enough out of equilibrium, and it might escape into a sort of
planetary failure mode, where processes intrinsic to the Earth itself take
over, acting as positive feedback to release dramatically more carbon into the
system. This subsequent release of carbon would send the planet off on a
devastating 100-millennia excursion before regaining its composure. And it
wouldn’t matter if CO₂ were higher or lower than it is today, or whether the
Earth was warmer or cooler as a result. It’s the rate of change in CO₂ that
gets you to Armageddon.
This is because the carbon cycle is happy to accommodate the steady stream of
CO₂ that issues from volcanoes over millions of years, as it moves between the
air and oceans, gets recycled by the biosphere, and ultimately turns back into
geology. In fact, this is the carbon cycle. But short-circuit this planetary
process by overloading it with a truly huge slug of CO₂ in a geologically brief
timespan, beyond what the Earth can accommodate, and it may be possible to set
off a runaway response that proves far more devastating than whatever
catastrophe set off the whole episode in the first place. There could be a
threshold that separates your run-of-the-mill warming episodes in Earth history
– episodes that life nevertheless absorbs with good humour – from those that
spiral uncontrollably toward mass extinction.
While it has been more than 60m years since the planet surpassed such a
threshold, by Rothman’s calculation we are about to set the planet on just such
an ancient and ominous trajectory, one that may take millennia to eventually
arrive at the destination of mass extinction, but that may be all but
inevitable once we have pushed off from shore.
It turns out that there are only a few known ways, demonstrated in the entire
geologic history of the Earth, to liberate gigatons of carbon from the planet’s
crust into the atmosphere. There are your once-every-50m-years-or-so spasms of
large igneous province volcanism, on the one hand, and industrial capitalism,
which, as far as we know, has only happened once, on the other."
Via Susan ****
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
