Climate change could push bumblebees to extinction

Bumblebees are vanishing at a rate consistent with widespread extinction, and climate change is playing a big role. The dire analysis comes from a new study published in the journal Science today. The authors found that the likelihood of a bumblebee population surviving in any given place within North America and Europe has dropped by an average of 30 percent as temperatures have risen.

Pesticides, habitat loss, and pathogens have already hit bumblebee populations hard. The new study, however, is able to isolate the effect that hotter temperatures are having on bumblebees. Sadly, bees are having a hard time adapting to a warming world.

“If things continue along the path without any change, then we can really quickly start to see a lot of these species being lost forever,” lead author of the study Peter Soroye tells The Verge. That’s not just a tragedy for the bees. It’s also bad news for all the plants that they pollinate and for humans who eat the fruits (and vegetables) of their labor. “We also lose out on a lot of color on our plates,” Soroye says. Tomatoes, squash, and berries are just some of the crops we can thank bees for pollinating. Animal pollinators like bees, birds, and butterflies could be responsible for up to 1 out of every 3 bites of food we eat, the US Department of Agriculture says.

For this study, Soroye and colleagues examined data from 1900 to 2015 on 66 species of bumblebees across North America and Europe. They mapped the places bees called home and how their distribution changed over time. They found that bees were vanishing in the areas that had heated up beyond the limit in which the bumblebees had historically been able to survive. Some bee populations are colonizing new territories that were previously too cold. But those gains are overshadowed by losses in areas where the bees once thrived but are now too hot.

These are just the latest findings pointing to an uncertain future for bees since climate change is only piling on top of other stressors. The relative abundance of four different species of bumblebees in the United States dropped by up to 96 percent, while their geographic range shrank by up to 87 percent in as little as 20 years, according to a 2011 study. The rusty-patched bumblebee, which is found across the Midwest and East Coast of the US, was classified as an endangered species in 2017. Seven other species of Hawaiian yellow-faced bees became the first bees on the US Fish and Wildlife Service’s endangered species list in 2016. And the American bumblebee ought to be considered critically endangered in Canada, a study by York University found last year. (Canada has ranked it as having a lower level of risk of extinction.)

“It’s really hard sometimes in that these papers are very devastating and depressing to read,” says Rebecca Irwin, director of the Biology graduate program at North Carolina State University, who was not involved in the study. “This seems to be a strong pattern that’s been observed across a number of studies now, and so it is very worrying,” Irwin says. She and the report authors hope that this research can spur conservation efforts.

“Basically what we study is the end of the world, extinction being the end of a species’ world,” says Jeremy Kerr, a biologist at the University of Ottawa and co-author of the study. “We need some good news too.”

He hopes that by figuring out why species of bumblebees are in decline, researchers will be able to pinpoint ways to help bring bee numbers back up and potentially avert extinction. One small measure that home gardeners can take, the study says, is to also include trees or shady areas where bees can cool down. Sometimes, even the bees need a break.