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Science

Mammal Extinctions Linked to Climate Footprints

The mass extinction of mammal species 50,000 years ago possibly linked to continental climate footprints.

[social_buttons]An international team of scientists used global data modelling to construct continental “climate footprints” in an effort to determine the cause of the mass extinctions that took place 50,000 years ago.

“Between 50,000 and 3,000 years before present (BP) 65% of mammal species weighing over 44kg went extinct, together with a lower proportion of small mammals,” said lead author Dr David Nogues-Bravo from the Center for Macroecology, Evolution and Climate in University of Copenhagen. “Why these species became extinct in such large numbers has been hotly debated for over a century.”

The study, published in the journal Evolution, used global data modelling to take a different look at a debate arguing whether it was humans or the environment that ended the lives of so many species of mammals.

Some scientists believe in the theory of overkill, where as humans made their way out of the trees decided that the big wooly and meaty animals walking around would be good sport and food. Palaeontologist Paul S. Martin is one of the leading advocates of this theory points, amongst other evidences, to the fact that 80% of North American large mammal disappeared within a thousand years of the arrival of humans.

The new research however shows significant linkages between the climate footprint of a location and its level of 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,” said Dr Nogues-Bravo. “Our approach is completely different. By dealing with the issue at a global scale we add a new dimension to the debate by showing that the impact of climate change was not equal across all regions, and we quantify this to reveal each continent’s “footprint of climate change.”

The team’s results showed that continents with larger climate changes suffered a large extinction of small mammals, while those with smaller climate changes suffered a smaller extinction. It is the small mammals – compared to the large mammals – that is the keystone of this latest research. If humans were the result of the mass extinctions, then only the large mammals would have been seriously affected. However if climate change was the cause, then both large and small mammals would have been affected.

“Our results show that continents with the highest ‘climate footprints’ witnessed more extinctions then continents with lower ‘climate footprints’. These results are consistent across species with different body masses, reinforcing the view that past climate changes contributed to global extinctions.”

“While climate change is not the only factor behind extinction, past, present or future, we cannot neglect in any way that climate change, directly or indirectly, is a crucial actor to understand past and future species extinctions.”, said Miguel Araújo, a co-author of the paper from the National Museum of Natural Sciences in Spain.

This research once again falls under the “gaining more knowledge of our world” category. Studies like this help us better understand what has happened so that we can begin to get a grasp on what might happen in the future.

Source: Wiley-Blackwell




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