New climate models unveiled by French researchers Tuesday showed Earth's average temperature could rise a "terrifying" 6.5-7.0°C above pre-industrial levels by the end of the century if dramatic action is not immediately taken to slash carbon emissions.

The findings, presented at a press conference in Paris, suggest the planet may be warming significantly faster than scientists previously believed as the world's major economies continue to burn fossil fuels at unsustainable rates.

"Unfortunately, our global failure to implement meaningful action on climate change over recent decades has put us in a situation where what we need to do to keep warming to safe levels is extremely simple," Joeri Rogelj, an associate professor at Imperial College London, told AFP. "Global greenhouse gas emissions need to decline today rather than tomorrow, and global CO2 emissions should be brought to net zero."

The new models are expected to form part of the U.N. Intergovernmental Panel on Climate Change's Sixth Assessment Report, which is set to be published in 2021. The IPCC's Fifth Assessment Report, published in 2014, presented a worst-case scenario of five degrees Celsius of warming by the end of the century.

Olivier Boucher, head of the Institute Pierre Simon Laplace Climate Modeling Center in Paris, which developed one of the new models, said the latest data provide a better look at where the climate is heading without drastic changes to global energy production.

"We have better models now," Boucher told AFP on Tuesday. "They have better resolution, and they represent current climate trends more accurately."

Bloomberg reported that just "one of the updated climate models used by the researchers allowed for the global temperature increase to remain below 2°C by the end of the century." That model assumed global carbon neutrality by 2060.

The worst-case scenario of 6.5-7.0°C of warming assumed continued economic expansion driven by growth of fossil fuel production.

That 2.5 degree global temperature increase that was predicted to happen this century has been revised to 6.5-7 degrees. This is not good. https://t.co/DDZFSRAmSj — Megara9 (@Meg9Time) September 17, 2019

The IPCC warned last year that even limiting planetary warming to 1.5°C by the end of the century, the goal of the Paris Climate Agreement, would not prevent many of the disastrous effects of the climate crisis. Warming of 6.5-7.0°C would be catastrophic.

"Higher warming would allow less time to adapt and mean a greater likelihood of passing climate 'tipping points' such as thawing of permafrost, which would further accelerate warming," said Boucher.

In an email to Common Dreams, Penn State University climate scientist Michael E. Mann sounded a note of caution about the dire scenarios predicted by the new models.

"Some earlier versions of the models appeared to underestimate climate sensitivity somewhat," said Mann, "and I suspect that some of these more recent versions are actually over-estimating it a bit."

"I suspect, when all is said and done, we're probably looking at something in the range of 3-4°C and no higher, at least for near-term warming," Mann added. "If we allow the warm[ing] to persist for centuries, then other long-term positive feedbacks (vicious cycles) could kick in, giving us substantially more warming."