Further climate change-driven declines of bumblebee species across much of North America are likely in the future, according to a study in Scientific Reports.
Over the past century bumblebee species have been declining in range and number. Climate change is one factor contributing to this loss as bumblebees are vulnerable to frequent extreme temperature events. In response to rapid temperature changes, some pollinator species move to higher latitudes. However, the majority of bumblebee species have failed to move beyond their northern range limits and have been decreasing in numbers at their southern range limits.
Catherine Sirois-Delisle and Jeremy Kerr used previous patterns of bumblebee range changes (the geographical area within which a species can be found) and bumblebee queen dispersal rates to model potential changes in their ranges under different future climate scenarios (greenhouse gas emissions peaking by approximately 2020, 2040, 2080, or continuing to rise throughout the century). All model results, including when using the least severe climate change scenario (emissions peaking by 2020), suggest that significant further declines of bumblebee species across much of North America are likely in the future. When using a realistic bee dispersal rate (10 km/year), some modelled species are predicted to experience range losses of over 25% by 2070. The models also show that the potential range expansions of many bumblebee species may overlap with each other, suggesting the presence of ‘hotspots’ (mostly in Ontario, Quebec and northern parts of Michigan) for range expansion, where management activities could benefit many species at once.