Burning all the world's known fossil fuels would result in the release of the equivalent of 5 trillion tonnes of carbon dioxide and drive global temperatures 8 degrees warmer than pre-industrial levels by 2300, a report by Canadian researchers has found.

The study, published on Tuesday in Nature Climate Change, extended models used for the Intergovernmental Panel on Climate Change and found impacts that were "considerably larger" than previously indicated.

For instance, by 2300, global temperatures would range from 6.4-9.5 degrees warmer than pre-industrial times with a mean warming of 8.2 degrees. Arctic regions warm by as much as 19.5 degrees.

Rainfall changes would include increases of as much as fourfold in tropical areas, while more-temperate areas – such as parts of Australia, the Mediterranean and the Amazon – could have rainfall halved, the researchers led by Katarzyna Tokarska, at University of Victoria, found.