UN Report: World Will Blow Past 1.5°C Climate Limit

The United Nations has conceded that the world has lost its chance to avoid crossing the 1.5 degrees Celsius (2.7 Fahrenheit) warming limit set under the 2015 Paris climate accord, according to a bleak first-of-its-kind report released Wednesday by the U.N. Environment Programme.

Earth is currently about 1.4 degrees Celsius (2.5 Fahrenheit) above pre-industrial levels, based on a 20-year average, and the report says the world will cross the 1.5 threshold "in the next few years" due to continued burning of coal, oil and gas.

"Humanity is speeding past the limit to avoid climate catastrophe," U.N. Secretary-General António Guterres said.

Rather than abandoning the 1.5-degree goal, the report calls for a strategy of "overshoot": limiting the peak temperature, then working to bring warming back down below 1.5 degrees, ideally by the end of the century. Under the most optimistic scenario, warming could peak at 1.8 degrees (3.2 Fahrenheit) around midcentury if countries pursue ambitious climate policies. But current government policies would push temperatures to 2.6 degrees (4.7 Fahrenheit) by 2100.

"Let's be very clear, 1.5 target is still the goal. But now we need to approach it differently from above," said UNEP Executive Director Inger Andersen.

Report co-author Richard Betts, a climate scientist at the University of Exeter, said the findings are "a reality check. We have to live with this warmer world. But there's still a lot we can do to limit warming."

The world is expected to remain in the overshoot period for "many, many decades," Betts said. During that time, the report warns of rising deaths and illness from extreme weather, falling food production, worsening water shortages, and the risk of irreversible "tipping points" — including loss of the West Antarctic and Greenland ice sheets, the Amazon rain forest, and a shutdown of the Atlantic Ocean circulation system that warms Europe.

University of Victoria climate scientist Andrew Weaver, who was not part of the study, called it "among the bleakest U.N. climate reports I have read," though he said it carries urgency rather than resignation. Climate Analytics CEO Bill Hare said the report describes "the hole we've dug ourselves into" but does a poor job showing a way out.

The report says eventually removing carbon dioxide from the atmosphere — through tree planting and newer technologies — will be needed to bring temperatures back down, though it notes trees alone could shave at most a tenth of a degree off global temperatures.