“Animals go where the climate takes them,” says TIME senior science writer Jeffrey Kluger. “What the butterflies are telling us is that we have been in denial for some time: Global warming is not just coming, it is upon us.” Scientists have calculated that Europe is now slightly warmer than it was 100 years ago and they predict that it will continue to get warmer, and at a faster rate, during the next century because of the greenhouse effect of pollution. “Evidently some species are already taking steps to adapt to what we have wrought,” says Kluger. Which raises a big question: If butterflies are wasting no time to vote with their wings, where does that leave us?
Boy, is it getting hot! No, we’re not talking about this week’s heat wave over the eastern half of the country (though that may get some folks thinking). We’re talking about the northward shift in European butterfly populations. A study published in Thursday’s issue of the journal Nature discovered that 22 out of 35 continental species that researchers tracked either had died out at the southern edges of their habitat or had extended their range northward, or both. The push to the north extended sometimes as far as 150 miles; one species abandoned Spain and spread to Estonia. Scientists interpreted the shift as yet another confirmation of global warming.