Jul 11, 2015 02:54 PM EDT By Staff Reporter, UniversityHerald Reporter

Climate change is having a significant impact on bumble bees in North America and Europe.

Researchers from the Universities of Calgary and Ottawa found that the bumblebee species are losing vital habitat in the southern regions of North America and Europe. This, in and of itself, is a cause for concern, but another pressing issue is that the bumblebee species generally haven't expanded north.

"Climate change may be making things too hot for them in the south, but is not pulling them north as expected, Paul Galpern, co-author of the study, said in a statement.

When climate warms, many wildlife species expand into areas that used to be too cold for them. They are usually forced to move into areas that are closer to the North Pole in response to climate change, but bumble bees are experiencing a different fate. They are being held at the northern most range while losing ground rapidly in the south.

"Picture a vice, now picture the bumble bee habitat in the middle of the vice," said Jeremy Kerr, lead researcher of the study and University Research Chair in Macroecology and Conservation at the University of Ottawa. "As the climate warms, bumblebee species are being crushed as the 'climate vice' compresses their geographical ranges. The result is widespread, rapid declines of pollinators across continents, effects that are not due to pesticide use or habitat loss. It looks like it's just too hot."

It is this revelation that is the most concerning because a very important piece of the ecological puzzle is under threat.

"Bumblebee species play critical roles as wild pollinators, not just for crops but of all sorts of plants," Galpern said. "They provide an important service to ecosystems. They help plants produce fruits, seeds and this in turn provides both food and habitat for other animals, and so on."

With nearly half a million observations compiled from museum collections and citizen scientist collectors from North America and Europe over the last century, researchers were able to track 31 bumblebee species in North America and 36 in Europe.

"We don't know for sure what is causing a stagnation at the northern end of things. Bees should be able to start new colonies in places they did not historically occupy. But we don't know why this is happening so slowly that it looks like the ranges are not moving at all," Galpern added. "This all points to the fact that bumble bees are at risk, and the services that they provide are increasingly threatened by human-caused climate change."

Their findings are detailed in the journal Science.

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