Things are about to get hotter than we expected.
New research suggests that the greenhouse gases we’re putting into the atmosphere by burning fossil fuels will heat the planet more quickly than we assumed. By 2100 mean temperatures could rise 6.5 to 7.0 degrees Celsius above pre-industrial levels if carbon emissions continue unabated, according to two separate models from leading research centers in France.
"With our two models, we see that the scenario known as SSP1 2.6 -- which normally allows us to stay under 2°C -- doesn't quite get us [the intended results]," Olivier Boucher, head of the Institute Pierre Simon Laplace Climate Modelling Centre in Paris, told AFP.
The 6.5 to 7.0 degrees Celsius mark is two degrees higher than the equivalent scenario (SSP5) set out in the Intergovernmental Panel for Climate Change's (IPCC) 2014 benchmark 5th Assessment Report. This difference in temperatures comes from refined predictions based on more complex and reliable climate scenarios, the team explains. They also suggest that the Paris Agreement goals of capping global warming at "well below" 2°C, and 1.5°C if possible, will be harder to reach, the scientists said.
It may not seem like a lot, but you have to keep in mind that the recent uptick in deadly heat waves, droughts, floods, and the intensity of tropical cyclones we’ve been seeing lately are happening with barely one degree Celsius of warming.
The two new models are part of a generation of around 30 new climate models collectively known as CMIP6; these will be used as a base for the IPCC's next major report, scheduled for 2021. While they're definitely not perfect, the models in CMIP6 are the best and most refined of their kind that we have. Their advantages include increased supercomputing power and sharper representations of weather systems, natural and man-made particles, and how clouds evolve in a warming world.
"We have better models now," said Boucher. "They have better resolution, and they represent current climate trends more accurately."
One of the core findings of these models is that increased CO2 levels in the atmosphere will warm Earth's surface more easily than earlier calculations had suggested. The higher "equilibrium climate sensitivity" (or ECS) predicted by the models means that humanity's carbon budget -- how much we can emit before we see negative effects -- is smaller than we previously assumed. Boiled down, a higher ECS means a greater likelihood of reaching higher levels of global warming, even with deeper emissions cuts.
Needless to say, this is bad news for global efforts to curb climate change.
The two French climate models, including one from France's National Centre for Meteorological Research (CNRM), are to be unveiled at a press conference in Paris.