陸と海の動物の大量絶滅の規模と気候変化の関係

抄録

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 loss corresponding to major mass extinctions so called “big five” correlate 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 with ± 1 °C error in the temperature anomalies as the global average, although number 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 Anthropogenic future extinction magnitude will not reach the major mass extinction magnitude, when the extinction magnitude parallelly changes with global surface temperature anomaly. In the linear relationship, I found lower tolerance of terrestrial tetrapods than that of 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 to the ongoing extinctions.