Canadian summers have warmed in this century due to pine beetle outbreaks, reports a study published online this week in Nature Geoscience. The beetle-induced warming is comparable to that induced by forest fires, and could modify cloud cover and rainfall in the region.

The current mountain pine beetle infestation in forests in British Columbia ranks among the largest ecological disturbances recorded so far in Canada. Holly Maness and colleagues used satellite data to examine the impact of this infestation on summertime climate in the region. They show that evaporation and plant transpiration have declined as a result of the infestation and accompanying forest dieback, leading to a rise in summertime surface temperatures of around one degree Celsius.