Human-caused global warming has increased at an “unprecedented rate” since the last major climate assessment published two years ago.
According to a study of 50 experts published in the journal Earth System Science Data, this warming is increasing at a rate of more than 0.2 degrees per decade.. Greenhouse gas emissions are at 'an all-time high', scientists say, and are causing an unprecedented rate of global warming.
One of the researchers said that the results are a “wake-up call” that efforts to reduce this warming have been insufficient, and are made public just as climate experts meet in Bonn to prepare for the great COP28 climate conference that will take place. will be held in Dubai in December, where progress will be made to keep global warming at 1.5 degrees by 2050.
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However, according to the latest calculations, the warming caused by human activities, mainly with the use of fossil fuels (coal, oil, gas), has already reached 1.14 degrees in the period 2013-2022, and 1.26 degrees in 2022.
Scientists warn that humanity is facing a “critical” decade in which the 1.5 degree threshold could be reached or exceeded in the next 10 years.
“If we don't want the 1.5 degree target to disappear from our rear view mirror, the world needs to work much harder and with more urgency to reduce emissions,” said Professor Piers Forster, director of the Priestley Center for Climate Futures. in Leeds.
The authoritative source of scientific information on the state of the climate is the UN's Intergovernmental Panel on Climate Change (IPCC), but the turnaround time for its main assessments is five to 10 years, and that creates an “information gap.” “, particularly when climate indicators are changing rapidly, say the scientists.
“The carbon budget is reduced every year since we emit CO2 that accumulates in the atmosphere: we are inexorably approaching this limit of 1.5 degrees,” underlines Pierre Friedlingstein, a researcher at the French National Center for Scientific Research, co-author of the study. .
The residual carbon budget, i.e. the headroom, expressed as the total amount of CO2 that could still be emitted while maintaining a 50% chance of limiting global warming to below 1.5 degrees, has been halved compared to IPCC. This “budget” is only about 250 billion tons, the equivalent of a few years of emissions at current rates.
This warming “is mainly related to emissions of methane, N2O (nitrous oxide, related to fertilizers) and other greenhouse gases”, specifies Pierre Friedlingstein, while CO2 emissions related to the use of fossil fuels are more or less stable.
The warming has also been caused by a reduction in polluting particles in the air, which have a cooling effect.. A paradoxical and short-term effect caused by a lower use of coal.
“This is the critical decade for climate change. We need to be agile, change policy and approaches. Time is no longer on our side,” says Piers Forster.