It sounds like a science fiction premise: one day, we might use asteroids like giant space parasols, shuffling them around space to create dust clouds which would shelter Earth from the sun’s radiated heat. In fact, it’s a scheme created by scientists at the University of Strathclyde to combat climate change.
The idea is one of the latest and most ambitious examples of the growing field of “”. The scientific community generally agrees that climate change exists as a phenomenon, and more worryingly that it is accelerating much faster than mankind’s efforts to reduce emissions. In the last few years, some researchers have begun to reason that humanity needs to buy itself more time, and they have come up with large-scale plans which aim to directly modify the planet’s systems to counter the effects of increased emissions. These plans comprise the field of Geoengineering.
Plans range from seeding the ocean with iron to promote carbon-sequestering algal blooms, to artificially increasing cloud cover. The Strathclyde scientists’ plan goes far beyond this: a team led by researcher Russell Bewick has suggested that a large asteroid could be manoeuvred to Lagrange Point L1, a point where the gravitational pulls of Earth and the Sun cancel out, where it would thus remain stable. A “mass driver”- a powerful electromagnetic device- would then hurl large amounts of material from the asteroid out into space, creating a massive dust cloud which Bewick estimates could block at least 1.7% of the sun’s radiation- enough to counter a two-degree rise in global temperatures.
Bewick does not want his idea, or Geoengineering in general, to overshadow attempts to cut emissions. Speaking to LiveScience, he said: “I would like to make it clear that I would never suggest Geoengineering in place of reducing our carbon emissions… The dust cloud is not a permanent cure, but it could offset the effects of climate change for a given time to allow slow-acting measures like carbon capture to take effect.”
The idea obviously has drawbacks. Firstly, the best candidate for creating the cloud- a near-earth asteroid named 1036 Ganymed- has a mass of 130 quadrillion kg. That, to say the least, would be a challenge to shift. There is also the question of how safe it would be to move massive, immensely destructive objects around in close proximity to Earth- and then blow parts of them to pieces. “Great care and testing would be required in the implementation of this scenario,” Bewick commented. “Due to this, the political challenges would probably match the scale of the engineering challenge.”