'Let's turn the red planet green'

Mars can be made to sustain human life - for the same cost as that quoted for mitigating climate change on Earth, according to a top British economist.

Terraforming involves modifying atmosphere, temperature and ecology to make another planet similar to Earth.

"One study of the global costs of mitigating climate change put them at about $3-trillion by 2100, with benefits being felt between 2100 and 2200," said Andrew Lilico, an economist with Europe Economics, writing in The Daily Telegraph.

"A standard estimate is that, for about $2-trillion to $3-trillion, in between 100 and 200 years, we can change Mars from being the red planet to being a blue planet - with a dense enough atmosphere and high enough temperature for Martian water at the poles and in the soil to melt, creating seas," said Lilico.

"From there to microbes and algae, getting us to green planet status, would take 200 to 600 years."

Objections to terraforming are that it is too costly and takes too long - but not when set beside global energy policy, Lilico contends.

"To 2035, investment in energy and energy efficiency - with a decades payback period - would be about$40-trillion," he said.

"But in a century that red dot in the night sky could be a blue dot, and a couple of centuries later a green dot. We know how. We just need to decide to do it. Some of you reading this article could be alive to see that blue dot.

"Choose between spending $3-trillion on preventing the Earth heating up by 3C over the next 150 years and spending it on making Mars a blue planet, and who is going to choose the former?"