The sweltering heat is predicted to occur due to increased carbon dioxide in the atmosphere, largely as a result of tectonic activity triggering volcanic eruptions and the sun producing 2.5 per cent more radiation.
The study, led by Dr Alexander Farnsworth at the University of Bristol’s School of Geographical Sciences, was published in Nature Geoscience.
Mr Farnsworth told MailOnline: “The outlook in the distant future appears very bleak.
“Carbon dioxide levels could be double current levels.
“Humans – along with many other species – would expire due to their inability to shed this heat through sweat, cooling their bodies.”
However, the modelling does not factor in man-made greenhouse gases in the atmosphere, meaning the extinction date could happen even sooner.
The simulation predicts that all the planet’s continents will combine to form a supercontinent called Pangea Ultima within the next 250 million years. Only 8 per cent to 16 per cent of this future continent will be habitable.
Earth’s landmass would then form a doughnut shape with an inland sea in the middle. The Pacific oOcean will make up the majority of the planet’s surface.
Mammals, including humans, are better adapted to living with cold, with many species growing fur or hibernating. They are less able to deal with extreme heat.
“The newly-emerged supercontinent would effectively create a triple whammy, comprising the continentality effect, hotter sun and more CO2 in the atmosphere, of increasing heat for much of the planet,” said Dr Farnsworth.
“The result is a mostly hostile environment devoid of food and water sources for mammals.
“Widespread temperatures of between 40 to 50 degrees Celsius, and even greater daily extremes, compounded by high levels of humidity would ultimately seal our fate.”
“We can’t predict how long humans will exist for, however, should we assume that we do last that long such a future world would be inhospitable for us,” Dr Farnsworth added.