San Francisco Chronicle

U.N. forecasts 2.7degree spike in temperatur­es

- By Nadine AchouiLesa­ge and Frank Jordans Nadine AchouiLesa­ge and Frank Jordans are Associated Press writers.

GENEVA — The world could see annual global temperatur­es pass a key threshold for the first time in the coming five years, the U.N. weather agency said Thursday.

The World Meteorolog­ical Organizati­on said forecasts suggest there’s a 20% chance that global temperatur­es will be 2.7 Fahrenheit higher than the preindustr­ial average in at least one year between 2020 and 2024.

The 2.7 Fahrenheit mark is the level countries agreed to cap global warming at in the 2015 Paris accord. While a new annual high might be followed by several years with lower average temperatur­es, breaking that threshold would be seen as further evidence that internatio­nal efforts to curb climate change aren’t working.

“It shows how close we’re getting to what the Paris Agreement is trying to prevent,” said Maxx Dilley, director of climate services at the World Meteorolog­ical Organizati­on.

Dilley said it’s not impossible that countries will manage to achieve the target set in Paris, of keeping global warming well below 3.6 F, ideally no more than 2.7 F, by the end of the century.

“But any delay just diminishes the window within which there will still be time to reverse these trends and to bring the temperatur­e back down into those limits,” he said.

The forecast is contained in an annual climate outlook based on several longterm computer models compiled under the leadership of the United Kingdom’s Met Office.

Climate models have proven accurate in the past because they are based on wellunders­tood physical equations about the effect of greenhouse gases in the atmosphere, said Anders Levermann, a scientist at the Potsdam Institute for Climate Impact Research near Berlin who was not involved in the report.

“We can make more accurate prediction­s about the climate than about the weather,“he said. “The physics behind it is solid as a rock.”

Leverman said that while hitting the 2.7 F threshold was “a screaming warning signal” it should not become a distractio­n from efforts to reduce manmade greenhouse gas emissions to zero by 2050.

Dilley, the WMO official, said record temperatur­es such as those currently seen in the Arctic are the effect of emissions pumped into the atmosphere decades ago, so attempts to alter the future course of the climate need to happen soon.

 ?? Michael Probst / Associated Press 2019 ?? A man jogs in Frankfurt. The world could see temperatur­es pass a key threshold for the first time.
Michael Probst / Associated Press 2019 A man jogs in Frankfurt. The world could see temperatur­es pass a key threshold for the first time.

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