Limiting global warming to 1.5°C is now impossible

Le Monde – Audrey Garric

According to a group of scientists, the target set by the 2015 Paris Agreement can no longer be met due to the inability of countries to reduce greenhouse gas emissions.

In Varanasi, India, on June 9, 2025. NIHARIKA KULKARNI/AFP

In recent months, scientists had already reached this conclusion individually.

On June 19, renowned French researchers, including former IPCC contributors like paleoclimatologist Valérie Masson-Delmotte, asserted collectively and unequivocally: the goal of limiting global warming to 1.5°C above pre-industrial levels, as set by the Paris Agreement, “is no longer attainable.”

Backed by the CNRS and Météo-France, a new study published in Earth System Science Data confirms global warming’s acceleration. Signed by 61 scientists from 17 countries, the study presents a sobering overview of current climate indicators.

For the third year running, these researchers updated key data from the IPCC’s 2021 Working Group 1 report. “Our work helps fill a gap caused by the long publication timeline of IPCC reports,” said Aurélien Ribes of the National Center for Meteorological Research.

Carbon Budget Almost Exhausted

Among the most alarming findings: only 130 billion metric tons of CO₂ emissions remain to retain a 50% chance of staying within 1.5°C. That’s less than three years at current rates. 

“Methane continues to rise, accelerating the budget’s depletion,” noted Sophie Szopa of the French Atomic Energy Commission. Scientists warn we may breach the 1.5°C threshold by decade’s end.

Climatologist Christophe Cassou acknowledged this as a “reality check.” While emissions aren't dropping and the green transition is under attack globally, he insists the Paris Agreement “is not dead” and remains essential for climate negotiations.

The remaining carbon budget for limiting warming to 2°C is 1.05 trillion tons of CO₂, equivalent to about 25 years of emissions. However, carbon capture technologies to reverse overshoots carry major risks and cannot undo some irreversible damages.

Record Emissions, Record Temperatures

Greenhouse gas emissions hit a record 55 billion metric tons in 2023, driven by fossil fuels and deforestation. As air pollution controls reduce aerosols (which reflect sunlight), the warming effect of greenhouse gases becomes even more pronounced. 

CO₂ levels reached 423 ppm in 2024 – 50% above pre-industrial levels and a peak not seen in over 2 million years.

More greenhouse gases mean more heat trapped in the atmosphere. In 2024, global temperatures rose to 1.52°C above pre-industrial levels, with 1.36°C attributable to human activity. The rest was driven by natural variability, such as El Niño and unusually warm oceans.

'Unprecedented Rate'

“It’s not surprising,” said Cassou, “Climate models predicted a 50-50 chance of hitting these levels.” Most of the warming over the last decade—1.24°C—is due to human actions, not natural events like the 2022 Hunga Tonga eruption.

Warming is now rising at an unprecedented rate of 0.27°C per decade. 

The result? More frequent and intense extreme weather events, glacial and ice sheet melt, and accelerating sea-level rise—3.91 mm/year from 2006 to 2024, over double the 20th-century average.

While some consequences are now irreversible, rapid emissions reductions can limit further damage. France’s 1.8% emissions drop in 2024 is not enough. 

Globally, current policies put us on course for a 3°C rise by century’s end. Greater action is needed, as emphasized in the ongoing climate talks in Bonn, Germany, running through June 26.

Links

• IPCC Special Report: Global Warming of 1.5°C
  The landmark 2018 IPCC report outlining pathways to limit global warming to 1.5°C.
• The World Has Already Blown Past the 1.5°C Climate Threshold—Now What?
  Nature explores the latest science behind temperature overshoot and its implications.
• Global Carbon Budget 2024
  An annual scientific assessment of global CO₂ emissions and the remaining carbon budget.
• UNEP: Emissions Gap Report 2023
  A critical look at the gap between current emissions pledges and what's needed to limit warming.
• Why the 1.5°C Target Matters—And Why It’s Still Worth Fighting For
  Carbon Brief breaks down the science, politics, and urgency of the 1.5°C goal.
• WMO State of the Global Climate 2024
  The World Meteorological Organization’s latest update on global climate conditions and trends.