In a paper published in Science Advances, he proposes that mass extinction occurs if one of two thresholds are crossed: For changes in the carbon cycl e that occur over long timescales, extinctions will follow if those changes occur at rates faster than global ecosystems can adapt. For carbon perturb ations that take place over shorter timescales, the pace of carbon-cycle ch anges will not matter; instead, the size or magnitude of the change will de termine the likelihood of an extinction event.
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