U.N.: Likelihood of hitting warming limit is growing

There’s a two- out- of-three chance that the world will hit a key warming limit temporarily within five years, the United Nations weather agency said Wednesday.

But it likely would be only a fleeting and less worrisome flirtation with the internationally agreed-upon temperature threshold. Scientists expect a temporary burst of heat from El Niño — a naturally occurring weather phenomenon — to supercharge human-caused warming from the burning of coal, oil and gas to new heights. Temperatures then are expected to slip down a bit.

The World Meteorological Organization forecasts a 66% likelihood that before 2027 the globe will have a year that averages 1.5 degrees Celsius (2.7 degrees Fahrenheit) warmer than the mid-19th century.

That number is critical because the 2015 Paris climate agreement set 1.5 degrees Celsius as a global guardrail in atmospheric warming, with countries pledging to try to prevent that much long-term warming if possible.

Scientists in a special 2018 United Nations report said going past that point would be dangerously different with more death, destruction and damage to global ecosystems.

“It won’t be this year probably. Maybe it’ll be next year or the year after” that a year averages 1.5 degrees Celsius, said report lead author Leon Hermanson, a climate scientist at the United Kingdom’s Met Office.

But climate scientists said what’s likely to happen in the next five years isn’t the same as failing the global goal.

“This report does not mean that we will permanently exceed the 1.5 C level specified in the Paris Agreement, which refers to long-term warming over many years. However, WMO is sounding the alarm that we will breach the 1.5 C level on a temporary basis with increasing frequency,” WMO Secretary- General Petteri Taalas said.

“We haven’t been able to limit the warming so far, and we are still moving in the wrong, wrong direction,” Taalas said at a news conference Wednesday.

Hermanson cautioned that “a single year doesn’t really mean anything.” Scientists usually use 30-year averages.

Those 66% odds of a year hitting that threshold in five years have increased from 48% last year, 40% the year before, 20% in 2020 and 10% about a decade ago. The WMO report is based on calculations by 11 climate science centers across the globe.

The world has been inching closer to the 1.5- degree threshold for years. The warming of this year’s expected El Niño makes it “possible for us to see a single year exceeding 1.5 C a full decade before the long-term average,” said climate scientist Zeke Hausfather.