Scientists in the US are looking at the idea that warming may be decreased if dust were used to block some of the Sun’s rays as the globe fights to restrict greenhouse gas emissions.
According to a study published in the journal PLOS Climate, moon dust is the most practical material for the technique, which is intended to block between 1% and 2% of the Sun’s energy.
Because it would be extremely expensive and labor-intensive, researchers from the Centre for Astrophysics at Harvard, the Smithsonian, and the University of Utah believe that launching dust from Earth would not be the preferred method.
Using moon dust would be less expensive and would still be able to shield against enough of the Sun’s rays for the technique to work.
Dr. Scott Kenyon of the Centre for Astrophysics remarked, “It is astonishing to think of how moon dust, which took over four billion years to develop, may assist reduce the rise in Earth’s temperature, a problem that took us less than 300 years to manufacture.”
The scientists’ methods for analyzing how dust that forms rings around stars during planet formation intercepts and reradiates light from the star were used to their research.
Their idea is that a small amount of material in an orbit between the Earth and the Sun could, when broken up, block out a relatively large quantity of sunlight.
Finding orbits that could keep the dust in place for long enough for it to give enough shade was a top goal.
“We can easily utilize the laws of gravity to track the location of a simulated sunshield over time for multiple different orbits since we know the positions and masses of the primary celestial bodies in our solar system,” said Sameer Khan, a University of Utah undergraduate and co-author of the work.
Key to this are Lagrange points, defined by Nasa as “positions in space where objects sent there tend to stay put” because gravitational forces are balanced.
A new space station platform?
The L1 Lagrange point was one potential location for a platform for a space station, from which dust might be launched.
The dust would need to be released every few days, according to simulations, since even while it would temporarily offer shade, it would be readily blown off course by solar winds, radiation, and gravity.
It was challenging to keep the shield at L1 for long enough to generate a significant shadow, “explained Mr. Khan.
“Though L1 is an unstable equilibrium point, this shouldn’t be a surprise.
“Even the slightest deviation in the sunshield’s orbit can cause it to rapidly drift out of place, so our simulations had to be extremely precise.”
The researchers found that if moon dust were aimed at L1, there would be effective shielding of sunlight.
Large amounts of lunar dust would be required, but less energy would be needed to launch it, compared to sending dust from Earth.
“It is astounding that the Sun, Earth and Moon are in just the right configuration to enable this kind of climate mitigation strategy,” Dr Kenyon said.
There is no danger of our planet becoming chronically frigid, the scientists claim, because dust particles are disseminated around the solar system by solar radiation, any sunshield would be transitory, and dust particles would not fall to Earth.
Although the researchers admitted they were not experts in either climate change or the kinds of rockets that could be required to employ the methodologies, they believed it was still worthwhile to examine any possibly effective ways.
Solar radiation control “may be something we will have to explore,” according to Bob Ward of the Grantham Research Institute on Climate Change and the Environment, a division of the London School of Economics.
Particularly given that it is become less probable that we will keep temperature increases below 1.5°C relative to pre-industrial levels, said Mr. Ward, who is unrelated to the current study.
He asserted that employing dust would probably have side consequences, such as possible changes in plant development since less solar energy would reach Earth.
He cautioned that blocking part of the Sun’s rays would not address other effects of elevated carbon dioxide levels in the atmosphere, such as ocean acidification, even if it did change temperatures.
But the problems of using dust may not necessarily be insurmountable, with Mr Ward saying that the approach could be considered a “Plan B” to the “more straightforward solution of stopping greenhouse gases in the first place”.