In a May 2005 NASA image, the ocean break-off point of the Helheim Glacier is pictured in southeast Greenland. An international conference on global warming released a report April 6, 2007 warning of increases of world hunger, flooding, and species extinction unless world nations take action to adapt to climate change. (UPI Photo/NASA/Wallops) |
License Photo
COPENHAGEN, Denmark, May 25 (UPI) -- A Danish-led international team of scientists has linked climate change with the mass extinction of mammals during the late quaternary era 50,000 years ago.
"Between 50,000 and 3,000 years before present 65 percent of mammal species weighing over (97 pounds) went extinct, together with a lower proportion of small mammals," said University of Copenhagen researcher David Nogues-Bravo, the study's lead author. "Why these species became extinct in such large numbers has been hotly debated for over a century."
The researchers said the world's climate during the last 50,000 years became colder and drier, reaching full glacial conditions 21,000 years ago. Since then, the climate has become warmer. While both of these global changes played significant roles in species extinction, the researchers said their study reveals changing climate was a significant force driving the mass extinction.
"Until now global evidence to support the climate change argument has been lacking, a large part of existing evidence was based on local or regional estimates between numbers of extinctions, dates of human arrivals and dates of climate change," Nogues-Bravo said.
The researchers said their study shows the impact of climate change wasn't equal across all regions, but rather related to each continent's footprint of climate change. In Africa, where the climate changed to a relatively lesser extent, there were fewer extinctions. However, in North America, more species suffered extinction, as reflected by a greater degree of climate change.
The research is reported in the journal Evolution.
