Researchers used a computer model to assess our planet's fate billions of years from now.

 

They found that as the Sun becomes hotter and brighter, only microbes would be able cope with the extreme conditions that the solar changes would bring.

 

The research is being presented at the National Astronomy Meeting.

 

Jack¹ O'Malley James, from the University of St Andrews in Scotland, said: "There won't be very much oxygen present, so they need to be able to survive in low or zero-oxygen environments, high pressures, and high salinities because of evaporating oceans."

 

 

The future of life on Earth is tied to that of the Sun, and over time, our star will become more and more luminous³（明亮的）.

 

Scientists from the universities of St Andrews, Dundee and Edinburgh used this fact to create a forecast for our planet's future environment.

 

In a billion years' time, the heat from the Sun will become so intense, that the oceans start to evaporate.

 

"Once you get to this tipping point, you get a lot more water in the atmosphere and because water vapour is a greenhouse gas, that sets this runaway⁴ greenhouse effect... and you end up with the Earth heating up to 100C or more plus what we experience today," explained Mr O'Malley James, a PhD student.

 

This, he said, combined with falling levels of oxygen, would lead to the rapid loss of plants and larger animals.

 

Soon after, a group of microbes called extremophiles（极端微生物） would be the only life forms left.

 

These tiny organisms are found on Earth today, and can cope with hostile environments.

 

These, the scientists said, would be the only creatures that could withstand the heat, aridity⁵ and poisonous atmosphere of this future Earth. They believe that they would probably be clustered around the last drops of water deep underground.

 

Eventually as conditions worsen they too will vanish, and in about 2.8 billion years, Earth will be devoid⁶ of all life.

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