Earth Will Be Habitable For At Least Another 1.75 Billion Years, Study Finds

Researchers of a new study found evidence, which suggests the Earth will be habitable for at least another 1.75 billion years before it falls into the Sun's "hot zone."

With global warming, increased levels of carbon in the air and the fast depletion of natural resources, researchers have pondered upon whether and how long Earth will be capable of sustaining life as we know it. In a new study, astrobiologists at the University of East Anglia may have found a possible answer to this question.

A team of researchers from the University conducted a study to analyze the habitable lifetime of Earth and based their findings and observations on the distance of the planet from the Sun and temperatures at which Earth can continue to have the liquid form of water. They also looked at other newly discovered planets outside our solar system to see if they had the potential to host life.

"We used the 'habitable zone' concept to make these estimates - this is the distance from a planet's star at which temperatures are conducive to having liquid water on the surface," lead researchers Andrew Rushby, from UEA's school of Environmental Sciences, said in a press release.

To make the observation, researchers used stellar evolution models and found that the planet will cease to be habitable between 1.75 and 3.25 billion years from now. After that, the Earth may not be able to host life as it will fall into the "hot zone" of the sun. The temperatures will be so high that all water on earth in the form of seas and oceans will evaporate.

However, humans may not exist by the end of this period and researchers predict that the end of humans will occur much before the Earth becomes inhabitable. This is because even small rises in temperature effects mankind to a large extend and as temperatures will continue to rise toward the end of this period, only microbes in niche environments would be able to endure the heat.

Researchers also noted that it takes billions of years for intelligent life to develop. Though the Earth had insects 400 million years ago, dinosaurs 300 million years ago and flowering plants 130 million years ago, the first existence of humans has been traced back to only 200,000 years ago.

"The amount of habitable time on a planet is very important because it tells us about the potential for the evolution of complex life - which is likely to require a longer period of habitable conditions," Rushby explained. "Looking at habitability metrics is useful because it allows us to investigate the potential for other planets to host life, and understand the stage that life may be at elsewhere in the galaxy."

Until now, more than 100 new planets have been discovered outside the Earth's solar system. Researchers of this study used these planets to study the evolving nature of planetary habitability over astronomical and geological time.

They compared Earth to eight planets, including Mars, which are currently in their habitable phase. Researchers found that planets, which orbited stars with smaller mass have longer habitable phases. Two of the planets used in the study were Kepler 22b, which has a habitable lifetime of 4.3 to 6.1 billion years and Gliese 581d, which has a massive habitable lifetime of between 42.4 to 54.7 billion years.

Astronomers are yet to detect an Earth-like habitable planet but authors of this study stated that it is possible that such a discovery will be made in the next 10 light years. However, with current technology, the biggest challenge would be getting to the planet as it would take hundreds of years.

In the event that humans would need to move to another planet, Mars is the best bet. It is closest to the Earth and will remain in its habitable zone till the end of the Sun's life which is 6 billion years from now.

Scientists are already preparing to colonize Mars. A Netherland-based company Mars One has asked people to submit applications to be part of a one-way mission to Mars. These people will colonize the Red Planet, though before the mission actually goes underway, researchers need to work on ways to tackle many problems like food supply, oxygen and exposure to harmful radiations. 

The study was published September 19 in the journal Astrobiology.