Global warming is the cause of bumblebee decline: study

Bumblebee populations have been on a steady decline worldwideand, according to a new report in the journal Science, the main culprit isn't loss of habitat or pesticides it's global warming.

"Bumblebee species seem to be having a real hard time expanding their ranges into areas that used to be too cold for them," saysJeremyKerr,professor of biology at the University of Ottawa, and the leadauthor of the study.

"We're kind of thinking of it as a 'climate vise,'" KerrtellsAs It Happens guest host Laura Lynch."Climate change, as it warms up in the south, may be causing [bumblebee]populations to disappear from places where they used to be quite common. But in the north, they're having a really hard time expanding. The net effect is that their geographical ranges are rolling up from the south, kind of like a rug."

Despite habitat loss andpesticides andneonicotinoidsplaying a part inbee population loss, climate change is the key factor, Kerr says.

"We actually measured changes in land use and changes in pesticide use over that time, wherever we could get those data, and what we found was the only factor that appeared to relate to how things were shifting was changing climatic conditions," he says.

"But that by no means is to say that habitat loss is unimportant or that pesticides are unimportant. That's just not true."

However, unlike honey bees, you cannot simplyplace a bumblebee colony in a van and move it to a new location. Currently, it is unknown why bumblebees have been unable to relocate further north.

"Bumblebees are not like tigers or polar bears. They don't need thousands of square kilometres of pristine wilderness to survive. They can make due with quite small areas. So around agricultural margins for example, if we manage those field margins so that wild flowers are abundant and we're not usingneonicotinoidson those field margins,maybe we can maintain populations." JeremyKerr, University of Ottawa professor

In the study, they've offered a few suggestions that could help their migration:

• Preserving natural areas in higher-altitude or cooler "microclimates."
• Planting gardens with bee-friendly plants such as raspberries.
• Ensuring there are places left for wildflowers and bee nesting areas at the edge of farmers' fields.

"Bumblebees enrich our world," Kerr says."They are beautiful animals and I think it would be a sadder planet to live on if we lost species like this ... they are part of our biological inheritance and they are the gift that we could give our children.

"More than that, bumblebees do things that matter for people. They pollinate our crops. They are keystone pollinators that provide this pollination service. They affect our food security, they have economic benefits."

With files from Emily Chung