When will the sixth mass extinction happen? A Japanese scientist may have an answer – Interesting Engineering
The largest mass extinction on record that occurred 250 million years ago took place over a period of 60,000 years. However, what we are facing now is happening much faster in a few centuries. The faster rate of this change may not give species sufficient time to adapt, and even though the warming may not be high, we might end up losing a higher number of species in the next extinction event. For that, humanity alone will be responsible.
Kahio’s calculations were published in the journal Biogeosciences.
Major mass extinctions in the Phanerozoic Eon occurred during abrupt global climate changes accompanied by environmental destruction driven by large volcanic eruptions and projectile impacts. Relationships between land temperature anomalies and terrestrial animal extinctions, as well as the difference in response between marine and terrestrial animals to abrupt climate changes in the Phanerozoic, have not been quantitatively evaluated. My analyses show that the magnitude of major extinctions in marine invertebrates and that of terrestrial tetrapods correlate well with the coincidental anomaly of global and habitat surface temperatures during biotic crises, respectively, regardless of the difference between warming and cooling (correlation coefficient R=0.92–0.95). The loss of more than 35 % of marine genera and 60 % of marine species corresponding to the so-called “big five” major mass extinctions correlates with a >7 ∘C global cooling and a 7–9 ∘C global warming for marine animals and a >7 ∘C global cooling and a >7 ∘C global warming for terrestrial tetrapods, accompanied by ±1 ∘C error in the temperature anomalies as the global average, although the amount of terrestrial data is small. These relationships indicate that (i) abrupt changes in climate and environment associated with high-energy input by volcanism and impact relate to the magnitude of mass extinctions and (ii) the future anthropogenic extinction magnitude will not reach the major mass extinction magnitude when the extinction magnitude parallelly changes with the global surface temperature anomaly. In the linear relationship, I found lower tolerance in terrestrial tetrapods than in marine animals for the same global warming events and a higher sensitivity of marine animals to the same habitat temperature change than terrestrial animals. These phenomena fit with the ongoing extinctions.