UN: World could hit 1.5-degree warming threshold by 2024

The world could see annual global temperatures break 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 1.5 degrees Celsius (2.7 Fahrenheit) higher than the pre-industrial average in at least one year between 2020 and 2024.

The 1.5 C mark is the level countries agreed to cap global warming at in 2015. 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.

Scientists say average temperatures around the world are already at least 1 C higher now than from 1850-1900 because of man-made greenhouse emissions.

The Geneva-based WMO said there's a 70% chance that the 1.5-degree mark will be exceeded in a single month between 2020 and 2024. The five-year period is expected to see annual average temperatures that are 0.91 C to 1.59 C higher than pre-industrial averages, it said.

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

WMO chief Petteri Taalas said the study shows "the enormous challenge" countries face in meeting the goals of the 2015 Paris accord. The agreement sets a goal of keeping global warming well below 2 degrees Celsius (3.6 Fahrenheit), ideally no more than 1.5 C.

The agency noted that the models used for the forecast don't consider the impact that the coronavirus pandemic might have on reducing emissions of planet-warming gases such as carbon dioxide.

"The industrial and economic slowdown from COVID-19 is not a substitute for sustained and coordinated climate action," Taalas said.

"Due to the very long lifetime of CO2 in the atmosphere, the impact of the drop in emissions this year is not expected to lead to a reduction of CO2 atmospheric concentrations which are driving global temperature increases," he said.