A warming planet is pushing bumblebees to extinction in North America and Europe, claims study

'Bumblebees are the best pollinators we have in wild landscapes and the most effective pollinators for crops like tomato, squash, and berries'


                            A warming planet is pushing bumblebees to extinction in North America and Europe, claims study
(Antoine Morin)

It was the dinosaurs over 66 billion years ago. It could soon be bumblebees, as a new study finds that their population is sinking at levels consistent with mass extinction events.

Driving extinction of bumblebees are humans, who have sparked off "climate chaos", say authors of the study. The study found that the warming planet has reduced the likelihood of bumblebee populations surviving in North America and Europe by about 46% and 17%, respectively, compared to 1901-1974. 

"We have now entered the world's sixth mass extinction event, the biggest and most rapid global biodiversity crisis since a meteor ended the age of the dinosaurs," says Peter Soroye, a Ph.D. student at the University of Ottawa and one of the authors of the study.

This connection between ''climate chaos'' and extinctions is not new. According to Soroye, these extinctions began decades ago. "In this paper, we offer an answer to the critical questions of how and why that is. We find that species extinctions across two continents are caused by hotter and more frequent extremes in temperatures."

Bumblebees' pollination services drive global food supply and provide American farmers worth $9 billion per year. "Bumblebees are the best pollinators we have in wild landscapes and the most effective pollinators for crops like tomato, squash, and berries," Peter Soroye says. 

According to the International Union for Conservation of Nature (IUCN), bumblebee populations have been declining in Europe, North America, South America, and Asia. They are also being threatened by habitat loss and degradation, introduced diseases and pesticide use.

A bumblebee species visits a flower on Manitoulin Island (Peter Soroye)

In this study, Soroye and his colleagues predict exactly how changing conditions could affect bumblebee populations, such as their distribution across the two continents, their ability to colonize new areas and vulnerability to local extinction. 

To do this, they gathered data on the distribution of 66 bumblebee species collected over 115 years (1900-2015). This data was then compared with local changes in temperature and precipitation.

"We found that populations were disappearing in areas where the temperatures had gotten hotter," Peter Soroye explains. "Using our new measurement of climate change, we were able to predict changes both for individual species and for whole communities of bumblebees with surprisingly high accuracy," he adds.

Among the countries surveyed, bee populations were declining the most across warming regions such as Spain and Mexico due to more frequent extreme warm years.

Now, the team hopes to track extinction levels for other species like reptiles, birds, and mammals. It could also help conservators to identify areas with the most effective conservation actions.

"Ultimately, we must address climate change itself and every action we take to reduce emissions will help. The sooner the better. It is in all our interests to do so, as well as in the interests of the species with whom we share the world," says Dr Jeremy Kerr, professor at the University of Ottawa, and one of the authors of the study.

"This work also holds out hope by implying ways that might take the sting out of climate change for these and other organisms by maintaining habitats that offer shelter, like trees, shrubs, or slopes, that could let bumblebees get out of the heat," Dr Kerr adds.

The study has been published in Science.

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