According to recent forecasts from the British Met Office, in 2024, the global average surface temperature may be 1.5 degrees Celsius higher than pre-industrial levels for the first time.
Nick Dunstone from the Met Office said: "For the first time we have reasonably predicted the likelihood of temperatures temporarily exceeding 1.5C in a year."
In 2015, officials from various countries met in Paris, France, and agreed to work to prevent global temperatures from rising 1.5 degrees Celsius above pre-industrial levels.
"Temporarily exceeding 1.5 degrees Celsius does not mean a violation of the Paris Agreement. But the first year above 1.5 degrees Celsius is certainly a landmark event in climate history." Dunstone said.
According to forecasts, there is a 27% chance that the average temperature in 2024 will be 1.5 degrees Celsius higher than the temperature between 1850 and 1900. "But I wouldn't take that number too seriously because it could actually be higher," Dunstone said. Temperatures in 2023 are much higher than the Met Office predicts, but the reasons are not entirely clear.
In the 10 years to 2023, global average surface temperatures have been within the range predicted by the Met Office at the beginning of the year. But 2023 broke the historical record, with an average temperature increase of 1.4 degrees Celsius from January to October, higher than the 1.1 to 1.3 degrees Celsius forecast for the end of 2022.
Dunstone said this may be partly due to the current El Niño becoming stronger than predicted. During El Niño, changes in wind direction spread warm water across the Pacific Ocean, causing temperatures to temporarily rise.
In addition, in 2022, the eruption of a submarine volcano in Tonga injected a large amount of water vapor into the stratosphere, which had a warming effect. What's more, temperatures in the Southern Hemisphere are warmer than expected, for reasons that are not yet known.
Dunstone said projections for 2024 start with the warming observed so far, but could be an underestimate if the factors that led to warmer-than-expected temperatures in 2023 are still at play. However, the team cannot make corrections until they determine what these factors are.
What is clear is that the long-term warming trend is caused by increasing greenhouse gas emissions. Although the climate may become cooler after 2024 due to factors such as the end of the El Niño phenomenon, it is expected that the long-term average temperature will still exceed 1.5 degrees Celsius in 2030 as the long-term average temperature increases. It is widely agreed that this violates the Paris Agreement.
Looking at months rather than years, the first month on record where warming exceeded 1.5 degrees Celsius was January 2016, the last time a strong El Niño occurred. The following month warmed even more, reaching an unseasonable 1.64 degrees Celsius, making it the hottest month to date. This November may surpass it, though.
According to preliminary data, November 17 this year was the first day when the abnormal temperature rise exceeded 2 degrees Celsius. Based on current trends, long-term average warming is expected to exceed 2 degrees Celsius by around the 2040s.
