What would happen if we decided to completely ignore the Paris climate change agreement, dig up all the known fossil fuel reserves in the world, and burn them all? How bad could the resulting temperature change possibly be? A new study, published in the journal Nature Climate Change, decided to investigate, and the answer is terrifying: The world would be nothing less than scorched.

Burning all known oil, gas and coal reserves could raise average temperatures by 9.5°C (17°F), five times that of the temperature cap set in Paris. Not only would this make equatorial desert regions nearly impossible to live in, but the Arctic, which is already warming twice as fast as the rest of the planet, would be up to 20°C (36°F) hotter, which would obliterate its ice and snow cover.

Although some global action on climate change is appearing to occur, it cannot be ruled out that the world will continue along its “business-as-usual” path and burn fossil fuels with reckless abandon. “It is relevant to know what would happen if we do not take actions to mitigate climate change,” Kasia Tokarska, a doctoral student at the University of Victoria in British Columbia, Canada and lead author of the study, told AFP.

^{Temperature (a) and precipitation changes as a percentage of pre-industrial levels (b) under the 5 trillion tonnes emissions model. Tokarska et al./Nature Climate Change}

This self-destructive conflagration of fossil fuels would release 5 trillion tonnes (5.5 trillion tons) of carbon into the atmosphere, mainly as carbon dioxide, a long-lasting and powerful greenhouse gas. At the current rates of energy generation, this would be achieved by the year 2300.

Using four separate cutting-edge climate change simulation models, it was clear that the oceans – which are huge carbon absorbers, or “sinks” – would not be able to efficiently remove much of this carbon being unleashed into the atmosphere. Consequently, the oceans will not be able to reduce the scale of global warming, as other studies have suggested.

At the very least, the global temperature under this worst-case scenario would increase by 6.4°C (11.5°F). This degree of warming would unleash an untold pandemonium of severe heatwaves, droughts, floods, prolonged wildfires, potent hurricanes, sea level rises, and ecological destruction on the world.

In addition to all known fossil fuel reserves, there are plenty of natural accelerant mechanisms relating to climate change that also need to be considered, as the study notes.

Right now, we are pumping greenhouse gas emissions into the atmosphere at a rate roughly 10 times that observed during a catastrophic 56-million-year-old event called the Paleocene-Eocene Thermal Maximum (PETM). This was a natural climatic warming event which many think may have been down to a destabilization of frozen methane reservoirs deep beneath the ocean.

^{The world’s permafrost is experiencing unprecedented melting, in terms of both degree and extent. Stockdonkey/Shutterstock}

This type of event could very well happen again today, particularly when the methane and carbon dioxide reservoirs beneath the world’s terrestrial permafrost is taken into account. There’s a real chance that if warming reaches a certain point – the temperature of which is currently unknown – it could begin to unleash these gasses, which would in turn rapidly heat the climate and release even more trapped gasses in a dangerous positive feedback cycle.

Once such a greenhouse gas time bomb is set off, it cannot be stopped, and climate change mitigation will become essentially impossible. Worryingly, even if we don’t use up all our fossil fuel reserves, the level of warming showcased in this study will likely be approached if the current rate of warming destabilizes enough of the world’s permafrost.