Climate

The Rocky Mountain Biological Laboratory is in the former ghost town of Gothic, abandoned after the closure of its silver mines. Over winter, the landscape lies quietly under a bed of snow. In early spring, the only way for researchers to get to experimental sites – at an altitude of 10,000ft – is by skiing across country.

Electric infrared radiators warmed five experimental plots of 30 sq metres year-round. Head-height heaters were on day and night over a patch of meadow, keeping it 2C above normal temperatures with an annual electricity bill of $6,000 (£4,450). They warmed the top six inches of soil. Animals could come and graze and the natural system was preserved as much as possible.

Over 29 years, researchers found that shrubs increased by 150% in warmed plots compared with those without warming. The surface of the soil was dried by up to 20%, and shallow-rooted plants became stressed. Some wildflowers went extinct in heated plots. "It's a sign of things to come," says lead researcher Lara Souza from the University of Oklahoma.

Scientists also noted big changes in the invisible world of soil fungi and microbes. Shrubs and sage brush don't rely on fungi in the same way as grasses. They found a decline in fungi that help plants acquire nutrients, and an increase in fungi that decompose organic matter. "This highlights that when you have a big change above ground, you've likely got a big change below ground," says Souza. "Turning back is very unlikely."