Thresholds of catastrophe in the Earth system
September 21, 2017 6:48 AM   Subscribe

"Five times in the past 542 million years, more than three-fourths of marine animal species have vanished in mass extinctions. Each of these events is associated with a significant change in Earth’s carbon cycle. ... The modern critical size for the marine carbon cycle is roughly similar to the mass of carbon that human activities will likely have added to the oceans by the year 2100. ... Although the uncertainty of [these predictions are] considerable, all scenarios for cumulative uptake at the century’s end either exceed or are commensurate with the threshold for catastrophic change."

The author notes that "the strictest emission scenario [RCP2.6] results in oceanic carbon uptake whose mean falls just below the critical mass," but even that scenario is rapidly becoming implausible if not outright impossible.
posted by jedicus (9 comments total) 20 users marked this as a favorite
posted by Melismata at 7:36 AM on September 21, 2017 [2 favorites]

Hmmmm, an article on mass extinctions that doesn't mention asteroid strikes....
posted by storybored at 7:42 AM on September 21, 2017

Surely this...
posted by chavenet at 7:47 AM on September 21, 2017 [1 favorite]

Wow, what a scientific opportunity, what times we live in. It'll be like marine hunger games, seeing which species eventually gets the upper flipper...
posted by Laotic at 7:47 AM on September 21, 2017

So Long And Thanks To All The Fish
posted by The Card Cheat at 7:51 AM on September 21, 2017 [3 favorites]

Hmmmm, an article on mass extinctions that doesn't mention asteroid strikes....
Modern investigations of mass extinctions often emphasize a plurality of causes. Erwin’s “complex web of causality” addresses how a combination of volcanism, climate change, marine anoxia, methane release, and other environmental stressors may have contributed to the end-Permian extinction. Recent studies of the end-Cretaceous extinction consider massive volcanism in addition to a bolide impact.
(emphasis added)

The Cretaceous-Paleogene extinction was one of the 31 carbon isotopic events that the study considered. Most of those were relatively benign, but 5 extreme events were associated with a mass (i.e. >75%) extinction of marine animal species.
posted by jedicus at 8:46 AM on September 21, 2017

Ah, bolide = asteroid! My mistake.
posted by storybored at 9:16 AM on September 21, 2017

To be fair, adding a new asteroid to earth is essentially a carbon change.
posted by curious nu at 9:20 AM on September 21, 2017

posted by twsf at 12:27 PM on September 21, 2017

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