From greenhouse gases to sea level rise and the threshold of +1.5°C of warming, key climate indicators are headed “wrong.” This is confirmed by some sixty renowned researchers in a comprehensive annual study published.
Human-caused warming “has increased at a rate unprecedented in the records. It has reached 0.27°C per decade between 2015 and 2024,” conclude the scientists from prestigious institutions.
Greenhouse gas emissions, especially from the use of fossil fuels, hit a record high in 2024. The average was 53 billion tons of CO2 each year over the past decade. Furthermore, particulate pollutants in the air, which have a cooling effect, have decreased.
This finding, published in the journal Earth System Science Data, is the result of the work of researchers from 17 countries. They used the methods of the IPCC, the UN-appointed group of climate experts, to which most belong or have belonged.
The study’s purpose is to provide annually updated indicators based on the IPCC report. This is done without waiting for the next report, which will be published in several years. In 2024, observed warming compared to the pre-industrial era reached 1.52°C, of which 1.36°C is attributable solely to human activity.
A “foreseeable” level
It’s a record level, but “foreseeable” considering human-caused warming. Sometimes these natural phenomena are added, notes expert Christophe Cassou of the French National Center for Scientific Research (CNRS). “It’s not an exceptional or surprising year as such for climatologists,” he says.
This doesn’t mean that the planet has already exceeded the most ambitious threshold of the Paris Agreement. The goal of limiting global warming to 1.5°C is a phenomenon that must be observed over several decades.
But the window is increasingly closing.
The residual carbon budget – the scope for action expressed in the total amount of CO2 that could still be emitted – is shrinking. This budget aims to maintain a 50% probability of limiting global warming to 1.5°C.
This “budget” is now on the order of 130 billion tons by early 2025. This is equivalent to a little more than three years of emissions at the current rate. A year ago, it was around 200 billion.
“Exceeding the 1.5°C threshold is now unavoidable,” says one of the authors, Pierre Friedlingstein of the CNRS. “I tend to be an optimist,” says the study’s lead author, Piers Forster of the University of Leeds. “But if we look at this year’s publication, everything is going in the wrong direction.”
“Reducing emissions”
The authors have included two new indicators this year. They include one on sea level rise, which is expanding due to global warming. This phenomenon receives significant volumes of freshwater due to the accelerated melting of glaciers.
The annual rate has more than doubled, with an increase of about 26 mm between 2019 and 2024. The average was less than 2 mm per year since the beginning of the 20th century.
In total, ocean levels have risen 22.8 cm since the beginning of the last century. This increase is large enough to increase the destructive power of storms and threaten the existence of some island states. This rise, which is due to complex phenomena, is subject to strong inertia and would continue even if emissions ceased immediately.
However, humanity is not helpless
“What can we do to limit the speed and magnitude of sea level rise? Reduce greenhouse gas emissions as quickly as possible,” says climatologist Valérie Masson-Delmotte.
But, with less than six months until COP30 in Brazil, climate policies are being weakened. This is due to the United States’ withdrawal from the Paris Agreement, at the initiative of Donald Trump.
“Any change in trajectory or in terms of public policies that could increase or maintain emissions will have implications. These emissions, which would otherwise have been reduced, will influence the climate and the level of warming in the years to come,” recalls Aurélien Ribes of the French National Center for Meteorological Research.
