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Fossil record supports evidence of impending mass extinction
October 24, 2007Global temperatures predicted for the coming centuries may trigger a new 'mass extinction event', where over 50 per cent of animal and plant species would be wiped out, warn scientists at the Universities of York and Leeds.
The research team has, for the first time, discovered a close association between Earth climate and extinctions in a study that has examined the relationship 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.
Moreover, future predicted temperatures are within the range of the warmest greenhouse phases that are associated with mass extinction events identified in the fossil record.
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.
Dr Mayhew says: "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."
Of the five mass extinction events¹, 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 per cent 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," says Professor Benton. "But the evidence is striking."
The five worst mass extinctions:
Cretaceous-Tertiary - roughly 65 million years ago. Probably caused or aggravated by impact of large asteroid on the Yucatan Peninsula and beneath the Gulf of Mexico. Death toll: 16 percent of marine families, 47 per cent of marine genera (the classification above species) and 18 percent of land vertebrate families, including the dinosaurs.
End-Triassic - roughly 200 to 214 million years ago. 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. Death toll: 22 percent of marine families, 52 percent of marine genera. Vertebrate deaths are unclear.
End-Permian - about 251 million years ago. Cause hotly debated. Earth's worst mass extinction, killing 95 percent of all species, 53 percent of marine families, 84 percent of marine genera and an estimated 70 percent of land species such as plants, insects and vertebrate animals.
Late Devonian - about 364 million years ago. Cause unknown. Death toll: 22 percent of marine families and 57 percent of marine genera. Erwin said little is known about land organisms at the time.
Ordovician-Silurian - 439 million years ago. Caused by a drop in sea levels as glaciers formed, then by rising sea levels as glaciers melted. Death toll: 25 percent of marine families and 60 percent of marine genera.
University of York
Moreover, future predicted temperatures are within the range of the warmest greenhouse phases that are associated with mass extinction events identified in the fossil record.
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.
Dr Mayhew says: "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."
Of the five mass extinction events¹, 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 per cent 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," says Professor Benton. "But the evidence is striking."
The five worst mass extinctions:
Cretaceous-Tertiary - roughly 65 million years ago. Probably caused or aggravated by impact of large asteroid on the Yucatan Peninsula and beneath the Gulf of Mexico. Death toll: 16 percent of marine families, 47 per cent of marine genera (the classification above species) and 18 percent of land vertebrate families, including the dinosaurs.
End-Triassic - roughly 200 to 214 million years ago. 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. Death toll: 22 percent of marine families, 52 percent of marine genera. Vertebrate deaths are unclear.
End-Permian - about 251 million years ago. Cause hotly debated. Earth's worst mass extinction, killing 95 percent of all species, 53 percent of marine families, 84 percent of marine genera and an estimated 70 percent of land species such as plants, insects and vertebrate animals.
Late Devonian - about 364 million years ago. Cause unknown. Death toll: 22 percent of marine families and 57 percent of marine genera. Erwin said little is known about land organisms at the time.
Ordovician-Silurian - 439 million years ago. Caused by a drop in sea levels as glaciers formed, then by rising sea levels as glaciers melted. Death toll: 25 percent of marine families and 60 percent of marine genera.
University of York
Mass Extinction Current Events and Mass Extinction News RSSConservation targets too small to stop extinction
Conservation biologists are setting their minimum population size targets too low to prevent extinction.
The first neotropical rainforest was home of the Titanoboa
Smithsonian researchers working in Colombia's Cerrejón coal mine have unearthed the first megafossil evidence of a neotropical rainforest.
A new day dawned fast
In 1980, Luis Alvarez and his collaborators stunned the world with their discovery that an asteroid impact 65 million years ago probably killed off the dinosaurs and much of the the world's living organisms. But ever since, there has been an ongoing debate about how long it took for life to return to the devastated planet and for ecosystems to bounce back.
Surviving mass extinction by leading a double life
Drifting across the world's oceans are a group of unicellular marine microorganisms that are not only a crucial source of food for other marine life - but their fossils, which are found in abundance, provide scientists with an extraordinary record of climatic change and other major events in the history of the earth.
Ancient volcanic eruptions caused global mass extinction
A previously unknown giant volcanic eruption that led to global mass extinction 260million years ago has been uncovered by scientists at the University of Leeds.
Princeton geoscientist offers new evidence that meteorite did not wipe out dinosaurs
A Princeton University geoscientist who has stirred controversy with her studies challenging a popular theory that an asteroid wiped out the dinosaurs has compiled powerful new evidence asserting her position.
New blow for dinosaur-killing asteroid theory
The enduringly popular theory that the Chicxulub crater holds the clue to the demise of the dinosaurs, along with some 65 percent of all species 65 million years ago, is challenged in a paper to be published in the Journal of the Geological Society on April 27, 2009.
New theory on largest known mass extinction in the history of the earth
Did volatile halogenated gases from giant salt lakes at the end of the Permian Age lead to a mass extinction of species?
Study unravels why certain fishes went extinct 65 million years ago
Large size and a fast bite spelled doom for bony fishes during the last mass extinction 65 million years ago, according to a new study to be published March 31, 2009, in the Proceedings of the National Academy of Sciences.
No joy in discoveries of new mammal species -- only a warning for humanity, Paul Ehrlich says
In the era of global warming, when many scientists say we are experiencing a human-caused mass extinction to rival the one that killed off the dinosaurs, one might think that the discovery of a host of new species would be cause for joy.
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