Researchers at the Universities of York and Leeds have identified a close association between Earth's climate and mass extinction events in a study that examines the relationship between the two over the past 520 million years—almost the entire fossil record available.
Matching data sets of marine and terrestrial diversity against temperature estimates, evidence shows that global biodiversity is relatively low during warm greenhouse phases and extinctions relatively high, while the reverse is true in cooler icehouse phases.
The research, published in the latest issue of Proceedings of the Royal Society B, was carried out by University of York student Gareth Jenkins, together with his supervisor, Dr Peter Mayhew, and University of Leeds Professor Tim Benton, both of whom are population ecologists. Proceedings B is the Royal Society’s main biological research journal.
Our results provide the first clear evidence that global climate may explain substantial variation in the fossil record in a simple and consistent manner. If our results hold for current warming—the magnitude of which is comparable with the long-term fluctuations in Earth climate—they suggest that extinctions will increase.—Dr Peter Mayhew
Future predicted temperatures are within the range of the warmest greenhouse phases that are associated with mass extinction events identified in the fossil record.
Of the five mass extinction events(Cretaceous-Tertiary, End-Triassic, End-Permian, Late Devonian, Ordovician-Silurian), four—including the one that eliminated the dinosaurs 65 million years ago—are associated with greenhouse phases. The largest mass extinction event of all, the end-Permian, occurred during one of the warmest ever climatic phases and saw the estimated extinction of 95% of animal and plant species.
The long-term association has not been seen before, as previous studies have largely been confined to relatively short geological periods, limited geographical extents and few groups of organisms. But the evidence is striking.—Professor Tim Benton
|Five Worst Mass Extinctions|
Million years ago
|Cretaceous-Tertiary||65||Caused or aggravated by impact of large asteroid on the Yucatan Peninsula and beneath the Gulf of Mexico.||16% percent of marine families|
47% of marine genera
18% of land vertebrate families, including the dinosaurs.
|End-Triassic||200 - 214||Most likely caused by massive floods of lava erupting from the central Atlantic magmatic province - an event that triggered the opening of the Atlantic Ocean. The volcanism may have led to deadly global warming.||22% of marine families|
52% of marine genera
Vertebrate deaths are unclear
|End-Permian||251||Cause hotly debated. Earth’s worst mass extinction.||95% of all species|
53% of marine families
84% of marine genera
70% of land species such as plants, insects and vertebrate animals.
|Late Devonian||364||Cause unknown.||22% of marine families|
57% of marine genera
|Ordovician-Silurian||439||Caused by a drop in sea levels as glaciers formed, then by rising sea levels as glaciers melted.||25% of marine families|
60% of marine genera
Paleontologist Peter Ward of the University of Washington outlined some of the potential linkages between climate change and mass extinction events in his book published earlier this year, Under a Green Sky.