Global warming could be combatted with asteroid dust acting like a sunshade for earth, scientists say

• Scottish scientists believe an asteroid could be maneuvered into position before a cloud of dust is blasted from the surface
• Because an asteroid has its own gravitational pull, the dust would be anchored in place

Scottish scientists have come up with an intriguing new idea to combat global warming - blasting the surface of asteroids to create giant clouds of dust which would act as sunscreen for the planet.
Researchers at the University of Strathclyde believe a suitably sized asteroid could be moved into a position close to earth before a giant cloud of dust is blasted off its surface.
And because an asteroid creates a gravitational pull, the dust is held in position rather than being gradually dispersed across space.

Solar shield: Scottish scientists believe an asteroid could be moved into position before a giant cloud of dust is blasted from the surface to act as a sunscreen

The idea is the latest in a series of ambitious projects, known as geoengineering, which aim to alter the climate of the planet by reflecting, diverting or absorbing solar radiation. 

 

Research by he United Nations' Intergovernmental Panel on Climate Change suggests average global temperatures will increase by between 1.1C and 6.4C by the end of this century.
Russell Bewick, one of the research team at the University of Strathclyde told Live Science: 'People sometimes get the idea of giant screens blocking the entire sun.
'This is not the case ... as [the device] is constantly between the sun and the earth, it acts merely as a very light shade or filter.'
'I would like to make it clear that I would never suggest geoengineering in place of reducing our carbon emissions.

The asteroid would be moved into position at what is known as Lagrange point L1, a point in space where the gravitational pull of the Sun and the Earth balance each other out

'We can buy time to find a lasting solution to combat Earth’s climate change. 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.'
An earlier proposal to shade Earth from the sun involved placing giant mirrors in space.
However this is seen as impractical due to the massive cost of building the giant mirrors and blasting them into orbit or constructing them in outer-space.
Another idea involved using blankets of dust to blot out the sun in the same way clouds do on earth.
However while this would be considerably cheaper than placing mirrors in space it is believed the dust would be dispersed due to the gravitational pull of the sun, moon and other planets.
So the Scottish team came up with the novel idea of using an asteroid's own gravitational pull to effectively anchor the cloud of dust and stop it drifting away.
The asteroid would be placed at what is known as Lagrange point L1, a point in space where the gravitational pull of the sun and the Earth balance each other out. L1 is about four times the distance from Earth to the moon.
The asteroid would be fitted with a 'mass driver,' powerful electromagnets that, as well as acting as an engine to maneuver the asteroid into position, could also blast a cloud of dust away from its surface.
The researchers have identified the largest near-Earth asteroid, 1036 Ganymed, as a suitable candidate.
They believe Ganymed could generate a dust cloud large enough to block out 6.58 per cent of solar radiation reaching earth, more than enough to combat any current levels of global warming.
The dust cloud generated would be about 5 quadrillion (5,000,000,000,000,000) kilograms in mass and about 1,600 miles wide.

The research team, from the University of Strathclyde, estimate a suitably-sized asteroid could generate a dust cloud large enough to block out 6.58 per cent of solar radiation reaching earth

Mr Bewick said: 'A very large asteroid is a potential threat to Earth, and therefore great care and testing would be required in the implementation of this scenario.
'Due to this, the political challenges would probably match the scale of the engineering challenge. Even for the capture of much smaller asteroids, there will likely be reservations from all areas of society, though the risks would be much less.'
The main challenge for the scientists is finding a way of moving such a large asteroid into place.
Mr Bewick added: 'The company Planetary Resources recently announced their intention to mine asteroids.
'The study that they base their plans on reckons that it will be possible to capture an asteroid with a mass of 500,000 kilograms by 2025.
'Comparing this to the mass of Ganymed makes the task of capturing it seem unfeasible, at least in everything except the very far term.
'However, smaller asteroids could be moved and clustered at the first Lagrange point.'