| Title | Mass Extinctions on Earth Coincided with Out-of-Whack Carbon Cycles | |
| Date | Sunday September 24 2017, @08:28PM | |
| Author | martyb | |
| Topic | ||
| from the better-whack-it-back dept. | ||
Seeker reports on the finding of Daniel Rothman, a geophysicist at the MIT. The layman version in Seeker
...Daniel Rothman, [is] a geophysicist at the Massachusetts Institute of Technology, who built a database of fossil records going back half a billion years. Rothman found the periods in which large percentages of existing species died off coincided with big swings in the carbon isotopes found in those records, suggesting the planet's carbon cycle was out of whack.
[...] human civilization has been pumping more carbon into the environment by burning carbon-rich fossil fuels like coal, oil, and natural gas. On the current trajectory, the oceans are expected to absorb at least another 300 billion tons of carbon by 2100 — an amount that could end up producing long-term changes to the environment, Rothman concluded.
[...] Rothman isn't alone in warning of a potential extinction. Some scientists argue a sixth such event is under way already, with about two species a year disappearing and thousands seeing their populations and ranges shrink.
The more arid study is published in Science Advances and the full text is freely available.
The abstract goes like this (with my emphasis):
The history of the Earth system is a story of change. Some changes are gradual and benign, but others, especially those associated with catastrophic mass extinction, are relatively abrupt and destructive. What sets one group apart from the other? Here, I hypothesize that perturbations of Earth's carbon cycle lead to mass extinction if they exceed either a critical rate at long time scales or a critical size at short time scales. By analyzing 31 carbon isotopic events during the past 542 million years, I identify the critical rate with a limit imposed by mass conservation. Identification of the crossover time scale separating fast from slow events then yields the critical size. 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.
I hope our grandchildren will be able to live, even if I have doubts they'll be able to forgive us.
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