Could asteroid dust counter climate change on Earth?

Scientists have proposed creating a dust cloud made of asteroid material that could help to cool Earth. Here, an artist's depiction shows what a spacecraft spewing asteroid dust might look like.

NBC news/ By Charles Choi Contributor

To combat global warming, scientists in Scotland now suggest an out-of-this-world solution — a giant dust cloud in space, blasted off an asteroid, which would act like a sunshade for Earth.

The world is warming and the climate is changing. Although many want to prevent these shifts by reducing emissions of greenhouse gases that trap heat from the sun, some controversially suggest deliberating manipulating the planet's climate with large-scale engineering projects, commonly called geoengineering.

Instead of altering the climate by targeting either the oceans or the atmosphere, some researchers have suggested geoengineering projects that would affect the entire planet from space. For instance, projects that reduced the amount of solar radiation Earth receives by 1.7 percent could offset the effects of a global increase in temperature of 3.6 degrees Fahrenheit (2 degrees Celsius).

The United Nations' Intergovernmental Panel on Climate Change has noted that climate models suggest average global temperatures will rise by 2 to 11.5 degrees F (1.1 to 6.4 degrees C) by the end of this century.

"A 1.7 percent reduction is very small and will hardly be noticeable on Earth," said researcher Russell Bewick, a space scientist at the University of Strathclyde in Scotland. "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."

Shading Earth One proposal to shade Earth from the sun would place giant mirrors in space. The main problem with this concept is the immense cost and effort needed either to build and launch such reflectors or to construct them in outer space — the current cost to launch an object into low Earth orbit runs into thousands of dollars per pound. Another would use blankets of dust to blot out the sun, just as clouds do for Earth. These offer the virtue of simplicity compared with mirrors, but run the risk of getting dispersed over time by solar radiation and the gravitational pull of the sun, moon and planets. [Top 10 Craziest Environmental Ideas]

Now, instead of having a dust cloud floating by itself in space, researchers suggest that an asteroid could essentially gravitationally anchor a dust cloud in space to block sunlight and cool the planet.   More >>