With a new temperature record in March, the last twelve months have been the hottest ever recorded in the world, 1.58°C warmer than in the planet's climate in the 19th century, before the effect was felt from the burning of fossil fuels, deforestation or intensive agriculture.
Continuing an uninterrupted series of ten monthly records, March 2024 constitutes a new signal after a year where anthropogenic global warming, accentuated by the El Niño phenomenon, increased natural disasters, while humanity has not yet reduced its emissions greenhouse gases.
- Limit of 1.5°C -
If July 2023 became the hottest month ever measured in the world, every month since June has also broken its own record. March 2024 continues the series, with an average temperature 1.68°C higher than a normal month of March in the climate of the pre-industrial era (1850-1900), according to the climate change service (C3S) of the European Copernicus Observatory.
Over the last twelve months, the global temperature has been 1.58°C higher than in the pre-industrial era, exceeding the limit of 1.5°C set by the Paris agreement. This anomaly should however be noted on average over
“at least 20 years”
to consider that the climate, and not the annual weather, has reached this threshold, recalls the observatory. But
“we are extraordinarily close to this limit and we are already on borrowed time
,” Samantha Burgess, deputy head of C3S, told AFP.
Absolute record for the oceans
It has now been more than a year since the temperature of the oceans, major climate regulators which cover 70% of the Earth, has been warmer than ever. March 2024 even sets a new absolute record, all months combined, with an average of 21.07°C measured on their surface (excluding areas close to the poles) by Copernicus.
“It’s incredibly unusual
,” notes Samantha Burgess. This overheating threatens marine life and brings more moisture into the atmosphere, meaning more unstable weather conditions, such as high winds and torrential rains. It also reduces the absorption of our greenhouse gas emissions in the seas, carbon sinks which store 90% of the excess energy caused by human activity.
Droughts and floods
“The more the global atmosphere warms, the more extreme events will be numerous, severe, and intense
,” recalls the scientist, citing the threat
of “heat waves, droughts, floods and forest fires
. ”
Among recent illustrations, serious water shortages are hitting Vietnam, Catalonia and even southern Africa: after Malawi and Zambia, 2.7 million people are threatened by famine in Zimbabwe, which declared the state of national disaster. Bogota has just rationed drinking water and the fear of shortages hangs over the electoral campaign in Mexico.
Conversely, Russia, Brazil and France experienced remarkable flooding. The influence of climate change on each event remains to be established through scientific studies. But it is established that global warming, by accentuating evapotranspiration and increasing potential humidity in the air, increases the intensity of certain precipitation episodes.
End of El Niño but no records
Since June, global weather has been affected by the natural climatic phenomenon El Niño, synonymous with higher temperatures. This reached its peak in December but must still result in above-normal continental temperatures until May, according to the World Meteorological Organization (WMO).
According to her, there are chances that the opposite phenomenon - La Niña - will develop
"later this year"
after neutral conditions (neither one nor the other) between April and June. Will other records be broken in the coming months?
“If we continue to see this much heat at the surface of the ocean (...) it is very likely
,” warns Ms. Burgess.
Acceleration?
Do these records exceed forecasts? The question is being debated by climatologists after an extraordinary year 2023, the hottest ever measured. This additional heat,
“we can explain it to a large extent, but not entirely
,” summarizes Ms. Burgess.
“2023 is within the range of climate model predictions, but really at the outer limit
,” far from the average, she adds, worried.
Air concentrations of carbon dioxide (CO2), methane and nitric oxide - the three main human-caused greenhouse gases - will increase further in 2023, according to US agency estimates. Oceanic and Atmospheric Observation (NOAA), published Friday. The CO2 concentration averages 419.3 parts per million (ppm) in 2023, an increase of 2.8 ppm since 2022.
According to the Carbon Monitor project, however, global CO2 emissions in 2023 increased by only 0.1% compared to 2022, reaching 35.8 Gigatons. If these estimates suggest a plateau in human emissions, they nevertheless represent
“10% to 66.7% of the remaining carbon budget to limit warming to 1.5°C”
, note the authors.