Climate change a key driver of bumblebee decline

Increasingly hot temperatures appear to be driving declines in bumblebee populations across Europe and North America, according to a UCL and University of Ottawa study. The study, published in Science , found that in the course of a single human generation, the likelihood of a bumblebee population surviving in a given place has declined by an average of over 30%. "We were surprised by how much climate change has already caused bumblebee declines," said study co-author Dr Tim Newbold (UCL Centre for Biodiversity & Environment Research). "Our findings suggest that much larger declines are likely if climate change accelerates in the coming years, showing that we need substantial efforts to reduce climate change if we are to preserve bumblebee diversity." The researchers looked at how climate change increases the frequency of extreme events such as heatwaves and droughts, creating a sort of 'climate chaos' which can be dangerous for animals. Knowing that species all have different tolerances for temperature (what's too hot for some might not be for others), they developed a new measurement of temperature. "We have created a new way to predict local extinctions that tells us, for each species individually, whether climate change is creating temperatures that exceed what the bumblebees can handle," Dr Newbold explained. Using data on 66 different bumblebee species across North America and Europe that have been collected over a 115-year period (1900-2015) to test their hypothesis and new technique, the researchers were able to see how bumblebee populations have changed by comparing where bees are now to where they used to be historically.