The forests of aspen (Populus tremuloides) growing on mountainsides of the American West could be North America are likely to disappear, if emissions of greenhouse gases continue at a high level, scientists warned on Monday. A study recently published in the journal Nature Geoscience, analyzed of drought and heat waves that have killed millions of aspens in Colorado and nearby states over the past decade. Such conditions could become routine across much of the West by the 2050s unless global emissions are brought under control, the study found.

 “I think of aspens as a good canary-in-the-coal-mine tree,” said William R. L. Anderegg, the Princeton University researcher who led the new study, released online Monday by the journal Nature Geoscience. “They’re a wet-loving tree in a dry landscape. They may be showing us how these forests are going to change pretty massively as that landscape gets drier still.”

The study concludes that large aspen die-offs were a near-certainty only if greenhouse emissions were to continue at the runaway pace that has characterized the last decade. If global emissions are brought under control, the chances will improve that large stands of aspens could be preserved, the paper found.

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