The U.S. Geological Survey released a report presenting a worrying trend in western U.S. where the death rate of trees in the area’s forests doubled over the past two to three decades. The phenomenon is caused by warmer temperatures and water scarcity, which are both linked to the climate change.

The study is presented in the online journal Science Express. It involved the careful study of the forest plots in three main regions across the West, taking notes on the fire history, the tree sizes and dominant species. This represents the largest research project ever based on old-growth forests in North America.

"It's very likely that mortality rates will continue to rise," said Nathan L. Stephenson, a scientist at the Geological Survey's Western Ecological Research Center and also one of the lead authors. He added that the reason why this is a certainty is because the summers in the West are getting longer and hotter and the death of older trees already exceeds the growth of new ones. The droughts and insect infestations are also important factors.

The report was coordinated and presented by a team of 11 researchers brought from several institutions including the University of Colorado at Boulder; the USGS and the Forest Service; Northern Arizona University; the University of British Columbia in Vancouver; the University of Washington at Seattle; Oregon State University; and Pennsylvania State University.

Now that the problem has been identified, the next step is to find a way to address the matter and turn it around. Still, such a strategy will need time to be put together so it might take a while before anything will be tried.