Study reveals alarming effects of climate change on bumblebees

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Calgary – Researchers from the University of Calgary and University of Ottawa have made an astonishing find when it comes to the habitat range of bumblebees, and the results are troubling.

Findings to be published in the Journal Science demonstrate that climate change is having a significant impact on bumblebee species in North America and Europe.

“Bumblebees are losing vital habitat in the southern regions of North America and Europe,” explains Paul Galpern, an Assistant Professor of Landscape Ecology in the Faculty of Environmental Design at the University of Calgary and a co-author of the study. “Climate change may be making things too hot for them in the south, but is not pulling them north as expected.”

For many wildlife species, when climate warms, they expand into areas that used to be too cold for them, pushing into areas that are closer to the North Pole in response. Bumblebee species are experiencing a different fate and being held at the northern most range while losing ground rapidly in the south.

“Picture a vice, now picture the bumblebee habitat in the middle of the vice,” says the study’s lead researcher Jeremy Kerr, a University of Ottawa Professor and the University Research Chair in Macroecology and Conservation. “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,” says Galpern. “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, this rich historical record enabled researchers 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,” says Galpern. “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. This all points to the fact that bumblebees are at risk, and the services that they provide are increasingly threatened by human-caused climate change.”