Warming from human activities is now increasing at more than 0.2°C per decade, with greenhouse gas emissions reaching unprecedented levels, according to a major international study released on Thursday.
“During the period 2013-2022, human-caused warming increased to an unprecedented rate of more than 0.2°C per decade,” write around fifty renowned researchers in the journal Earth System Science Data, based on the methods of the IPCC , from the UN commissioned climate experts.
The interest of the study is to provide updated indicators from the IPCC report 2021 without having to wait for the next cycle in several years. Scientists aim to provide up-to-date open data each year to feed into the COP negotiations and policy debate, as the current decade is seen as critical to salvaging the 2015 Paris Agreement target.
“It’s a clear reality check on the urgency of reducing global CO2 and methane emissions to limit global warming and the consequent rise in risk,” said French paleoclimatologist Valérie Masson-Delmotte, who was involved in the study. in front of journalists.
“Critical” Decade
Representatives from all countries are currently meeting in Bonn for a technical exchange in preparation for COP28, the major UN climate conference that will take place in Dubai at the end of the year and will focus on the problem of using fossil fuels.
These new estimates, released on Thursday, also come in the middle of a pivotal year for climate policy, as September is expected to release the first “global assessment” of countries’ commitments to implement the Paris Agreement, which effectively limits climate change of warming below 2°C and preferably 1.5°C compared to the pre-industrial period.
However, the warming caused by human activities, mainly through the use of fossil fuels (coal, oil, gas), has already reached 1.14 °C in the period 2013-2022 and 1.26 °C in 2022, according to the calculations of the Study.
Scientists warn that humanity is facing a ‘critical’ decade where the 1.5°C threshold could be reached or exceeded within the next 10 years.
The remaining carbon budget – the room for maneuver, expressed as the total amount of CO2 that could still be emitted while there is a 50 percent chance of keeping global warming below 1.5°C – has been halved compared to the IPCC. That “budget” is only around 250 billion tons, which at the current rate is equivalent to a few years’ emissions.
“The carbon budget decreases every year as we emit CO2 that accumulates in the atmosphere: we are inexorably approaching this limit of 1.5 °C,” stresses Pierre Friedlingstein, researcher at CNRS and co-author of the study.
Not to scale
“The latest available evidence shows that actions taken at the global level are not yet of the magnitude needed to bring about a significant reversal in the direction of human influence on the planet’s energy imbalances and resulting warming,” the scientists write.
That rate of warming is being driven by record levels of greenhouse gas emissions, at about 54 billion tonnes of carbon dioxide equivalent per year over the period 2012-2021, they calculated. In 2021 alone, they reached 55 billion tons.
“It is mainly related to the emissions of methane, N2O (nitrous oxide associated with fertilizers, ed.) and other greenhouse gases”, specifies Pierre Friedlingstein, while the CO2 emissions related to the use of fossil fuels more or less are stable.
The warming has also been caused by a reduction in pollutant particles in the air, which have a cooling effect. This is a paradoxical and short-term effect of reduced coal consumption.