Earth is destined to be destroyed by the Sun billions of years from now. But life on Earth will have been wiped out long before this happens. As the sun expands, CO2 levels on Earth will drop to the point where plants can no longer grow. This will mark the end for most lifeforms, including humans (if we have not already gone extinct).
However, Michael Hahn and Daniel Wolf Savin, astrophysicists from Columbia University, have said the end is not necessarily nigh for mankind. Writing for science magazine Nautilus, they put forward a number of options humans have to try to stop the demise of our species.
Hahn and Wolf Savin note that without intervention, humans will not exist on Earth in 500 million years. "And things get worse from there. After the atmospheric CO2 is gone and no longer able to regulate Earth's surface temperature, things will start to get very hot," they wrote.
As temperatures rise, any remaining animal life will have to migrate to the poles. But eventually even these regions will become too hot: "Not even cockroaches will survive," they said.
However, all is not necessarily lost. They propose three options to "stay our execution". The first involves moving Earth's orbit: "If we fired a 100 km-wide asteroid on an elliptical orbit that passed close to the Earth every 5,000 years, we could slowly gravitationally nudge the planet's orbit farther away from the sun, provided that we don't accidentally hit the Earth."
Another idea is creating a massive solar sail behind Earth that would pull the planet away from the sun and keep it within the Sun's habitable zone. "Such a sail acts like a kite, where the photons from the sun are the wind and the gravity between the solar sail and the Earth acts as the string. The sail would need to have a diameter 20 times that of the Earth but a mass only about 2% that of Mt. Everest, a mere trillion metric tonnes. Strategies like these could, in principle, keep the Earth in the habitable zone until the sun expands into a red giant."
A final method of survival would mean accepting life as we know it cannot exist and allowing non-biological life to take over. The brighter sun would provide increased solar power. Also the solar storms that currently disrupt technology on Earth would become less frequent.
"Given these facts, we humans might simply decide to upload ourselves into machines, which would be relatively comfortable on the dystopic future Earth," Hahn and Wolf Savin wrote. While an advanced understanding of computers and neuroscience would be required, "there is no known fundamental reason why we could not exchange our biological hardware for robotic replacements". And this, they say, humans "could probably figure it out in the next few hundred million years".