(CNN) If you like to take a walk in the woods in the United States or you prefer to decorate a Douglas fir at Christmas, you should know that climate change is making both of those activities a lot harder. Some forests in four regions in California, Colorado, the Northern Rockies and the southwestern part of the United States have crossed "a critical climate threshold for postfire tree generation," the study says. Climate conditions over the past 20 years have accelerated changes that would have otherwise taken decades or even centuries to play out across broad regions of the country. This is leading to the abrupt decline of trees and making these lands increasingly unsuitable for tree regeneration. Climate change is endangering our forests now, not just in some distant future.

Source: CNN March 11, 2019 20:03 UTC