(Paris) Dozens of renowned researchers warn in a new study that human-induced global warming has reached an “unprecedented rate” and that the window to limit temperature rises to 1.5 degrees Celsius is already almost closed.
These scientists point out that “human-caused global warming has increased at a rate unprecedented in instrumental measurements, reaching 0.26 degrees Celsius in the period 2014-2023.”
This note was published in the magazine Earth system science datais the result of the work of nearly sixty renowned researchers drawing on the methods of the Intergovernmental Panel on Climate Change and UN-commissioned climate experts.
The interest of the study is to provide updated indicators based on the latest report, without waiting for the next session several years from now.
Compared to the pre-industrial era, this human-caused warming has reached 1.19°C during this decade, which shows a clear increase compared to the numbers contained in the last report published a year ago (+1.14°C during the period 2013-2022).
In 2023 alone, human-induced warming will reach 1.31 degrees Celsius. The total observed warming was 1.43°C – because natural climate variability also played a role, starting with El Niño.
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Scientists intend to provide updated data every year, to feed into COP negotiations and political debate, while the current decade is considered crucial to saving the goals of the 2015 Paris Agreement, which aims to contain global warming to below 2 degrees Celsius and if possible at 1.5 degrees Celsius.
The publication comes as representatives from around the world gather in Bonn to advance climate negotiations ahead of COP29, scheduled to be held in Baku at the end of the year (11-22 November).
The warming comes as a result of greenhouse gas emissions – mainly caused by the intensive use of fossil fuels (oil, gas and coal) – which have reached record levels: about 53 billion tons of carbon dioxide equivalent.2 Annually during the period 2013-2022. They were 55 billion for 2022 alone.
Scientists point out that another effect also played a role: reduced cooling caused by pollutant particles in the air, which reflect the sun and allow certain clouds to form.
“The main reason is to control air pollution, first in Europe and the United States, and more recently in Asia, especially China,” explained Glenn Peters of the Center for International Climate Research in Oslo.
Some researchers highlight the role of recent stricter regulations for maritime transport. But reducing sulfur dioxide emissions, especially in the coal sector, began in the 1980s, confirms Glenn Peters.
“A little optimism”
Remaining carbon budget – room for maneuver, expressed in the total amount of carbon dioxide2 Which can still be emitted while maintaining a 50% chance of limiting global warming to 1.5°C – melt.
This “budget” amounts to only about 200 billion tons, equivalent to about five years of emissions at the current rate, compared to another 250 billion in the last edition of the study a year ago.
“This is a crucial decade,” the authors write. “It is expected that global warming of 1.5°C will be reached or exceeded in the next 10 years,” in the absence of cooling from a major volcanic eruption.
“This is also the decade in which we expect global emissions to peak and begin to decline significantly,” they point out.
Despite the record levels reached, the rate of increase in carbon dioxide emissions2 In fact, the pace has slowed this decade compared to the 2000s. The report contains “a little optimism,” says referees Piers Forster, of the University of Leeds, lead author of the study.
“Greenhouse gas emissions are increasing less rapidly than in 2000, but they are still increasing,” explains Pierre Friedlingstein, of the University of Exeter, so “their concentrations continue to increase and so does the temperature.”
“They must reduce net emissions to zero,” he stressed.
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