Climate models suddenly predict much faster warming, stumping scientists

Several climate models from top institutions around the globe are suddenly predicting the world will warm by 5°C (9°F) by 2100, a possible "nightmare scenario," and scientists aren't sure why, Bloomberg reports.

Why it matters: The 2015 Paris climate agreement set an agreed threshold to attempt to limit warming below 1.5°C (2.7°F). Should these newest projections turn out to be accurate, the Paris agreement's goals would already be well out of reach.

The state of play: These models have projected global warming with relative accuracy for the last half-century, and there has long been a general consensus that warming of 3°C (5.4°F) would produce catastrophic change.

• Yes, but: Researchers don't yet agree on how to interpret the hotter results — based on supercomputer simulations of climate models — and some believe they may have "overshot."

The bottom line: These models inform how policymakers and politicians can plan for the future effects of climate change, so any unexpected and extreme change in their output would radically lessen the time that humanity would have to prepare.

Go deeper: Dissecting Trump's State of the Union energy claims