Sunshade in space could stop earth warming up

A professor from the US National Academy of Sciences suggests a 600km in diameter shield be built to reflect light back at the sun.

Dr Istvan Szapudi, of the University of Hawaii, who wrote the study, said it could be possible to reduce the solar energy reaching us by 1.7 per cent using a space shield.

With net zero a distant goal and temperature records tumbling, researchers are exploring a radical solution to global warming: a giant parasol a million miles away in space.

A study published in Proceedings of the National Academy of Sciences has looked at whether a shield could be built to block some of the sun’s energy.

The professor behind the research believes it could grow into a fully-fledged construction scheme when engineering techniques catch up with his ideas. Other experts agreed that his findings were valuable, but mostly because they highlighted how difficult it would be to put them into action.

The plan calls for a shield at least 600km in diameter to be built from an ultra-lightweight material. The researchers envisage that such a shield would reflect light back at the sun to prevent Earth from heating up.

The preferred location would be close to a region in space known as the first Lagrange point (L1), where the gravitational forces of the Earth and the sun are in balance.

This is not a new idea. However, the shield would have to be enormously heavy to prevent it being blown towards the Earth, like a sail, by pressure exerted by solar radiation.

One solution would be to anchor the shield, which would weigh 3.5 million tonnes, to a collection of asteroids using tethers a million kilometres long.

Dr Istvan Szapudi, of the University of Hawaii, who wrote the study, said it could be possible to reduce the solar energy reaching us by 1.7 per cent. “You would not notice anything on Earth, except heatwaves becoming less frequent,” he said.

“Clearly it would be costly. This is a science paper. This is planting the seeds. It would take a lot of R&D to turn it into engineering.”

Professor Stuart Haszeldine, of the University of Edinburgh, who was not involved in the work, said: “I think it is worthwhile doing this kind of intellectual research, because we need a spectrum of options.”

The Times