Scientists have discovered evidence pointing to a strong relationship in geologic time between the magnitude of mass extinctions and global temperature changes. This intriguing correlation indicates a more optimistic view of future extinction events.
A Tohoku University professor emeritus has discovered evidence pointing to a strong relationship between the magnitude of mass extinctions and global temperature changes throughout geologic time.
The findings were reported in the journal Biogeosciences. According to the study, the primary causes of potential mass extinctions would be climate-driven ocean warming and oxygen depletion. Furthermore, direct human impacts such as habitat destruction, overfishing, and coastal pollution endanger marine species.
Throughout the Phanerozoic Eon (539 million years to the present), abrupt climate change, combined with environmental destruction caused by large volcanic eruptions and meteorites, has resulted in major mass extinctions.
There have been few quantitative assessments of the relationship between land temperature anomalies and terrestrial animal extinctions to date. Furthermore, the extinction rates of marine and terrestrial animals have diverged, and this phenomenon is still being studied.
These findings indicate that the bigger the shifts in climate, the larger the mass extinction. They also tell us that any prospective extinction related to human activity will not be of the same proportions when the extinction magnitude changes in conjunction with global surface temperature anomaly.
Professor Emeritus Kunio Kaiho
The combustion of fossil fuels such as oil, gas, and coal, which power our world, emits greenhouse gases such as carbon dioxide and methane into the Earth’s atmosphere and oceans. According to the study, as ocean temperatures rise and oxygen availability decreases, the abundance of marine life decreases.
Professor Emeritus Kunio Kaiho demonstrated that marine invertebrates and terrestrial tetrapods’ extinction rates corresponded to deviations in global and habitat surface temperatures, regardless of whether it was cooling or warming. Loss of species during the ‘big five’ major extinctions correlated 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.
“These findings indicate that the bigger the shifts in climate, the larger the mass extinction,” Kaiho said. “They also tell us that any prospective extinction related to human activity will not be of the same proportions when the extinction magnitude changes in conjunction with global surface temperature anomaly.”
Kaiho cites an earlier study that claimed a 5.2°C increase in average global temperature would result in a mass extinction event comparable to previous ones. However, according to this study’s analysis, the temperature will need to rise by 9°C, which will not occur until 2500 in the worst-case scenario.
Extinctions could occur within the next 100-300 years: “By 2100, in a high-emissions scenario, extinction risks could rival all human threats in the ocean as they currently stand, including overfishing and marine pollution, among others,” Penn said. “By 2300, these extinctions could rival those of the geologic past, unless trends in greenhouse gas emissions are reversed.”
According to the study, under “business as usual” global temperature increases, marine ecosystems planetwide are likely to experience mass extinctions potentially rivaling the size and severity of the end-Permian extinction – the “Great Dying” – which occurred roughly 250 million years ago and led to the demise of more than two-thirds of marine animals.
“Although predicting the extent of future extinctions is difficult because causes will differ from previous ones,” Kaiho said, “there is enough evidence to suggest that any forthcoming extinction will not reach past magnitudes if global surface temperature anomalies and other environmental anomalies change correspondingly.”
Kaiho also discovered that terrestrial tetrapods have a lower tolerance for global warming events than marine animals. However, marine animals were less tolerant of the same temperature changes as terrestrial animals. This is due to the fact that the temperature anomaly on land is 2.2 times greater than the sea surface temperature. These occurrences are consistent with ongoing extinction patterns.
Looking ahead, Kaiho hopes to forecast future animal extinction magnitudes between 2000 and 2500. Regardless of how scientists slice the data, it’s clear that unless we can stop climate change, many species are doomed. The precise percentage of losses and the timing of those losses are still being debated.
