Ecologist: s Europe and North America warm, bumblebees should be able to fly north to cooler climes, writes Tim Radford. But they're not: the bees' range is receding in the south, but staying put in the north, and scientists fear their shrinking habitat will put many species at risk of extinction. The humble bumblebee is feeling the squeeze from climate change. Newly published research shows that its southern range is being reduced as the planet warms - and yet it seems to show no sign of migrating northwards...