The extinctions of large animals that occurred 100,000 years ago were caused by both man and climate change, according to a study in the journal PNAS .
The researchers, from the University of Cambridge, studied the extinctions that occurred during the Quaternary (from 700,000 years ago to the present), focusing especially on the last 100,000 years, when the disappearance of large animals such as the mammoths of North America and Eurasia, the mastodons and giant sloths of the Americas, the woolly rhinoceros of Europe, the giant kangaroos and wombats of Australia, and the giant moas of New Zealand.
For years these losses have been an enigma and it has been debated whether they were caused by climatic changes, or by human action. This study indicates that both factors combined had a devastating effect on the megafauna of the time. To reach these conclusions, the scientists analyzed a sample of Antarctic ice in which the changes in the Earth’s climate of the last hundreds of thousands of years have been recorded. This information, together with data on the movements of human populations, was analyzed in a statistical model.
“This previous combination of unusual patterns of climate change, and direct human pressure, is similar to what we are putting on nature today,” the authors note. The difference between 100,000 years ago and now is that, “this time, climate change is not caused by fluctuations in the Earth’s axis of rotation, but by the burning of fossil fuels and deforestation.”
For the researchers, “what happened before should be taken as a warning, we must learn the lesson and act urgently to moderate these two types of impact,” they have warned.
