Temperature records keep coming. This January was the hottest on record, with 1.7°C above the pre-industrial average for the month, according to the European Union's Copernicus climate change service.
This means that there was a 12-month period in which the average global surface temperature was more than 1.5°C higher than the average from 1850 to 1900, the period considered a pre-industrial reference point.
“2024 begins with another record month,” Samantha Burgess of the Copernicus Climate Change Service said in a statement. “Rapid reductions in greenhouse gas emissions are the only way to stop rising global temperatures. »
At the 2015 Paris climate meeting, countries committed to trying to prevent global temperatures from rising more than 1.5°C above pre-industrial levels. Climatologists will only consider this limit exceeded when the long-term average global temperature has remained above this level for several years.
Currently, the long-term average is 1.25°C warmer than pre-industrial times, according to Richard Betts at the Met Office, the national weather service of the United Kingdom. But as carbon emissions continue to rise, it seems certain that, by this measure, the 1.5°C limit will soon be exceeded, probably around 2030.
The long-term global average is increasing in line with climate model projections. However, the extremely rapid warming observed over the past two years has far exceeded expectations. Among other records, 2023 was the first day it was more than 2°C warmer than the average from 1850 to 1900.
We still don't know why the warming has been so rapid over the past year or so and how long it will continue. Possible factors that could have increased warming include the 2022 eruption of the Tonga volcano, which injected large amounts of water into the stratosphere, and a reduction in aerosol pollution from ships.
Climatologists have defined pre-industrial temperature as the average from 1850 to 1900 for practical reasons, because few temperature records exist before that date. But using that as a benchmark could mean the level of warming from fossil fuel emissions is underestimated.
A 2017 study suggests we were wrong by about 0.2°C. Another publication this week, based on an analysis of sea sponges, estimates the gap at 0.5°C, meaning the 1.5°C limit has already been exceeded – but other climate scientists are not sure. not convinced.