LOS ALAMOS, N.M. — Combine the tree-ring growth record with historical information, climate records, and computer-model projections of future climate trends, and you get a grim picture for the future of trees in the southwestern United States. That’s the word from a team of scientists from Los Alamos National Laboratory, the U.S. Geological Survey, University of Arizona, and other partner organizations.

The research, published in Nature Climate Change this week, concluded that if the Southwest is warmer and drier in the near future, widespread tree mortality likely will cause substantial changes in forest and species distributions.

The researchers aligned some 13,000 tree core samples with known temperature and moisture data, further blending in historical events such as documented megadroughts that drove the ancient Pueblo Indians out of longtime settlements such as those at Mesa Verde, Colorado.

"The strength of this study is the integration of scientific tools to understand the future of an important regional ecosystem under stress from climate change," said USGS Director Marcia McNutt. "By combining historical records extending back one thousand years to understand the relationship between climate and forest health, statistical and ecological studies to tease out which climatological variables matter most to forest growth, and computer models of regional climate, the result is a prediction of declining prospects for southwestern forests."