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A malnourished wild horse in Australia's Bago State Forest.

A malnourished wild horse in Australia's Bago State Forest.

Photographer: Matthew Abbott/The New York Times via Redux

Green
Energy & Science

Climate Models Are Running Red Hot, and Scientists Don’t Know Why

The simulators used to forecast warming have suddenly started giving us less time.

There are dozens of climate models, and for decades they’ve agreed on what it would take to heat the planet by about 3° Celsius. It’s an outcome that would be disastrous—flooded cities, agricultural failures, deadly heat—but there’s been a grim steadiness in the consensus among these complicated climate simulations.

Then last year, unnoticed in plain view, some of the models started running very hot. The scientists who hone these systems used the same assumptions about greenhouse-gas emissions as before and came back with far worse outcomes. Some produced projections in excess of 5°C, a nightmare scenario.