Short, rapid warming events, known as interstadials, coincided with major extinction events, according to a team of scientists from Australia and the United States.
This image depicts a Pleistocene landscape in northern Spain with woolly mammoths (Mammuthus primigenius), equids, a woolly rhinoceros (Coelodonta antiquitatis), and European cave lions (Panthera leo spelaea). Image credit: Mauricio Anton.
“Abrupt warming has repeatedly played a key role in mass extinction events of large animals in Earth’s past,” said the scientists, led by Prof Alan Cooper from the University of Adelaide.
“By contrast, extreme cold periods, such as the last glacial maximum, do not appear to correspond with these extinctions.”
They came to their conclusions after detecting a pattern, a decade ago, in ancient DNA studies suggesting the rapid disappearance of large species. At first they thought these were related to intense cold snaps.
However, as more fossil-DNA became available from museum specimen collections and through improvements in carbon dating and temperature records that showed better resolution through time, they were surprised to find the opposite.
It became increasingly clear that rapid warming, not sudden cold snaps, was the cause of the extinctions during the last glacial maximum.
The results, published online in the journal Science, help explain the sudden disappearance of mammoths and giant sloths that became extinct around 11,000 years ago at the end of the last Ice Age.
“It’s important to recognise that man still played an important role in the disappearance of the major mega fauna species,” said study co-author Prof Chris Turney from the University of New South Wales.
“The abrupt warming of the climate caused massive changes to the environment that set the extinction events in motion, but the rise of humans applied the coup de grâce to a population that was already under stress.”
“Even without the presence of humans we saw mass extinctions,” Prof Cooper added.
“When you add the modern addition of human pressures and fragmenting of the environment to the rapid changes brought by global warming, it raises serious concerns about the future of our environment.”
In addition, the new statistical methods used to interrogate the datasets and the new data itself has created an extraordinarily precise record of climate change and species movement over the Pleistocene.
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Alan Cooper et al. Abrupt warming events drove Late Pleistocene Holarctic megafaunal turnover. Science, published online July 23, 2015; doi: 10.1126/science.aac4315
