“What that means is that, as these species shift out of their historic ranges, we’re starting to see biological events happening earlier," Stein says. "We’re starting to see mismatches between things like flowers and their pollinators, and species that actually depend on one another.”

The impact of a warmer world isn’t just felt in more intense heat waves, droughts and storms every summer, but also in winters that are less cold.

“And those cold temperatures are a critical regulator of species outbreaks and also of species distributions," says ecologist Peter Groffman with the Cary Institute of Ecosystem Studies and also a co-author of the report. "And so what we’ve seen is that these pest outbreaks are much worse than they would be because we’ve lost these very cold temperatures.”

Assault on trees

Bug infestations are killing millions of trees in U.S. forests. If that assault continues, the report warns, tree mortality rates in western U.S. forests could double every 17 to 29 years. The loss of trees would lead to earlier melting of mountain snowpack and reduce the amount of water available for spring planting season.

“These changes in the winter affect ecosystems, biodiversity, during the summer period," Groffman says. "There are big changes in the timing of spring and fall, which affects the success for a variety of plant and animal species, and it affects the ability of ecosystems to hold on to improved water quality and air quality.”