Two scientists at Britain's University of East Anglia in Norwich said their determination about the habitable lifetime of Earth is based on the planet's distance from the sun and temperatures at which the planet can have liquid water, the university said Thursday in a release.
The research team used recently discovered planets outside the Earth's solar system as examples and investigated the potential for these planets to host life, the university said.
"We used the 'habitable zone' concept to make these estimates," team leader Andrew Rushby, from UEA's school of Environmental Sciences, said. "This is the distance from a planet's star at which temperatures are conducive to having liquid water on the surface."
Rushby said the team used stellar evolution models to estimate the end of a planet's habitable lifetime by determining when it will no longer be in the habitable zone.
"We estimate that Earth will cease to be habitable somewhere between 1.75 and 3.25 billion years from now," Rushby said. "After this point, Earth will be in the 'hot zone' of the sun, with temperatures so high that the seas would evaporate. We would see a catastrophic and terminal extinction event for all life."
While the Earth may be habitable for 1.75 billion years, living conditions for humans and other complex life will become impossible much sooner, Rushby said.
"Humans would be in trouble with even a small increase in temperature," he said, "and near the end only microbes in niche environments would be able to endure the heat."