The clock is ticking

The end of the world is coming -- but not for a while yet. That's according to a new study indicating that we have 1.75 billion years left until Mother Earth gives up the ghost.
Researchers from the University of East Anglia's School of Environmental Sciences analysed other planets outside our galaxy in an attempt to work out how long it will be before our planet becomes uninhabitable.
The study, published yesterday in the journal Astrobiology, examined seven planets, including Earth, to determine how their "habitable zones" will change as their stars get hotter and brighter over time.
"Within around 1.75 billion years conditions for human life will become impossible as the sun grows in size, temperatures soar and the world's oceans evaporate," Andrew Rushby, who led the study, told The Independent.
The research didn't specifically account for man-made climate change or the "possibility that we'll all be wiped out by an asteroid or a nuclear war", he said.
Climate change may well decimate humanity before the concept of habitable zones become relevant.
"Of course, conditions for humans and other complex life will become impossible much sooner -- and this is being accelerated by anthropogenic climate change," he said.
Even if some humans did manage to survive for another 1.75 billion years, the end would not come instantly.
"Life isn't going to be extinguished at the flick of a switch," Rushby said.
Instead, as the sun gets older, it will get hotter and temperatures on Earth will soar over the course of "perhaps one million years" as we enter a "hot zone".
The study has also allowed Rushby and his team to make predictions about what stage life might be at in other parts of the galaxy.
In particular, the report points to the examples of Kepler-22b and Gliese-581d which have been habitable for up to 6 and 54.7 billion years respectively.