Can Moon Dust Keep Earth Cool?

Whether it’s out-of-the-box thinking or a sign of desperation, scientists on Wednesday proposed regularly transporting lunar dust to a point of gravity between the Earth and the sun to temper the ravages of global warming.

Ideas for filtering solar radiation to keep Earth from overheating have been kicking around for decades, ranging from giant space-based screens to reflective white clouds.

But the continued failure to reduce planet-warming greenhouse gas emissions has pushed once-imaginative geoengineering programs to the center of climate policy, investment and research.

Blocking one to two percent of the sun’s rays is all it takes to lower the Earth’s surface by a degree or two degrees Celsius — about the amount it has warmed in the past century.

The solar radiation technique with the most traction to date is the 24/7 injection of billions of shiny sulfur particles into the upper atmosphere.

So-called stratospheric aerosol injection is said to be cheap, and scientists know it works because large volcanic eruptions essentially do the same thing. When Mount Pinatubo in the Philippines peaked in 1991, temperatures in the Northern Hemisphere fell by about 0.5°C for nearly a year.

But there are serious potential side effects, including the disruption of rainfall patterns on which millions depend to grow food.

However, a new study in the peer-reviewed journal PLOS Climate explores the possibility of using lunar dust as a sun shield.

A team of astronomers applied methods used to track planet formation around distant stars — a messy process that stirs up massive amounts of space dust — to Earth’s moon.

Computer simulations showed that placing lunar dust on a gravitational sweet spot between Earth and the sun “blocked a lot of sunlight with a small amount of mass,” said lead author Ben Bromley, a professor of physics at the University of Utah.

– ‘Balancing marbles’ –

The scientists tested different scenarios with different particle properties and quantities in different orbits, looking for the one that would cast the most shadow.

Moondust worked best. The quantities needed, they said, would require the equivalent of a major mining operation on Earth.

The authors emphasized that their study was designed to calculate potential impact, not logistical feasibility.

“We’re not experts in climate change or rocket science,” said study co-author Benjamin Bromley, a professor at the Harvard-Smithsonian Center for Astrophysics.

“We were just researching different types of dust in different lanes to see how effective this approach could be,” he added. “We don’t want to miss a game changer for such a critical issue.”

Experts not involved in the study praised the methodology, but doubted it would actually work.

“Positioning lunar dust at the center of gravity between the Earth and the sun can indeed reflect heat,” said Professor Stuart Haszeldine of the University of Edinburgh.

“But this is like trying to balance marbles on a soccer ball — within a week most of the dust will have spun out of a stable web.”

For Joanna Haigh, emeritus professor of atmosphere at Imperial College London, the study is distracting.

The main problem, she said, “is the suggestion that the implementation of such schemes will solve the climate crisis, while all it gives polluters is an excuse not to act.”


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