Study: global warming is limiting bumblebee travel

The number of bumblebees in North America and Europe is declining and the biggest cause is thought to be climate change. That's according to a new study that was recently published in Science showing a trend since the 1970s where bumblebees are no longer traveling as far as they used to. Over this period of time, the travels of bumblebees have shrunk by as much as 190 miles from their previous southern limits, likely due to warming temperatures.

There's a strong correlation between the two — warming temperatures and more limited ranges of bumblebee travel — indicating that warming temperatures are the primary cause of this. Some researchers, however, feel that other factors could also be contributing to the problem.

Unfortunately, bumblebees are not traveling farther north to compensate for the shifts in habitat, and the reason is possibly that the northern habitats aren't as hospitable to them.

To reach this conclusion, the researchers looked at 110 years worth of data in the form of museum records. They tracked 67 different North American and European bumblebee species across 420,000 observations including things like where the bees were and when they were spotted. Climate data starting from the year 1900 and stretching to 2010 was also analyzed.

In addition, the researchers looked at bumblebee population changes that took place from 1974 to 2010, a time when global warming became more of an issue. They found that during this period the southern range in which bumblebees travelled decreased; some species that could previously be found as far south as Georgia are now only spotted in the northern states and areas north in Canada.

One of the more startling discoveries, said the study's co-author Paul Galpern, is that the changes are seen as trends that are "indistinguishable" between North America and Europe. The bumblebee reaction to climate change since 1975 is similar across continents. One of the most surprising and troubling aspects of the study, however, is that bees are not expanding to northern regions as expected, meaning their habitats are shrinking rapidly.

VIA: New York Times