Greenhouse gases thrust into the atmosphere mainly by burning fossil fuels are warming Earth’s surface more quickly than previously understood, according to new climate models set to replace those used in current U.N. projections, scientists said.
By 2100, average temperatures could rise 7.0 degrees Celsius above pre-industrial levels if carbon emissions continue unabated, separate models from two leading research centers in France showed.
That is up to 2 degrees higher than the equivalent scenario in the Intergovernmental Panel for Climate Change’s (IPCC) 2014 benchmark 5th Assessment Report. With only 1 degree Celsius of warming so far, the world is coping with increasingly deadly heat waves, droughts, floods and tropical cyclones made more destructive by rising seas.
A new generation of 30-odd climate models known collectively as CMIP6 — including the two unveiled earlier this year— will underpin the IPCC’s next major report in 2021.
A core finding of the new models is that increased levels of CO2 in the atmosphere will warm Earth’s surface more — and more easily — than earlier calculations had suggested.
If confirmed, this higher “equilibrium climate sensitivity,” or ECS, means humanity’s carbon budget — our total emissions allowance — is likely to shrink.