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上传时间: 2021-03-29 17:33:27
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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.