Humans will go extinct on Earth in 250 million years – but that's if we were to stop burning fossil fuels right now, a bleak new study reveals.
Computer simulations suggest our planet will face a mass extinction that wipes out all mammals, University of Bristol experts report.
Any lifeforms still alive on Earth by this time would have to cope with temperatures of between 104°F to 158°F (40°C to 70°C), they say. 
But their calculations don't account for greenhouse gases emitted by the burning of fossil fuels and other human-caused sources – so the date of our demise will likely be even sooner.
It would be the first mass extinction since the dinosaurs died out, around 66 million years ago, when the Earth was catastrophically hit by a massive space rock.
The new study was led by Dr Alexander Farnsworth, senior research associate at the University of Bristol's School of Geographical Sciences.
'The outlook in the distant future appears very bleak,' Dr Farnsworth said.
'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.'
In 250 million years' time, all of Earth’s continents will have moved together to form a supercontinent known as Pangea Ultima, according to the researchers.
Earth's land would form a doughnut-shape with an inland sea in the middle – all that's left of the once-mighty Atlantic Ocean.
The surrounding Pacific Ocean, meanwhile, would take up the majority of Earth's surface.
Pangea Ultima is just one possible projection of what Earth's supercontinent could look like once the plate tectonics come together.
Whatever the exact alignment, scientists are sure Earth's continents will slowly merge to form one hot, dry and largely uninhabitable mass.