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Geoengineering Schemes Could Block View of the Night Sky, Astronomers Warn

At the American Astronomical Society meeting in Texas, astronomers got together to debate the pros and cons of engineering Earth’s climate to save the planet.

Beyond just reducing our carbon emissions, some people have suggested that to combat climate change, we could pump small particles into the atmosphere to reflect more sunlight away from Earth, thereby cooling the planet. But this could seriously mess with humanity's ability to see the stars, astronomers warned on Wednesday at the 229th American Astronomical Society Meeting in Grapevine, Texas.

They were on a panel discussing some of the possible benefits and drawbacks of geoengineering—schemes to modify the Earth's climate system on a massive scale.

This year's AAS meeting, which runs through this week, is hosting about 2,400 scientists. Between presentations on black holes and alien planets, a panel that included astrobiologist David Grinspoon and Mel Ulmer, director of astrophysics at Northwestern University, discussed the potential planet-wide climate project.

Motherboard caught the chat as it was being livestreamed on Facebook.

There are many ideas floating around about how we could deliberately tinker with Earth's climate, from launching big reflective mirrors into space, to creating algae blooms to photosynthesize the excess CO2. One of the most prominent ideas is to release gases like sulfur dioxide into the stratosphere—the outer edge of the earth's atmosphere—to increase albedo. This would reflect more of the sun's energy back into space. (The same mechanism causes worldwide cooling after major volcanic eruptions.)

The panelists' discussion showed that scientists are taking these ideas seriously. And they agreed there may be some potential to use them in the short–term to protect our overheating world.

Read More: We Can't Count on Geoengineering to Save Us From Climate Change, Scientists Warn

The question that hit closest to home was inspired by a recent poster from Charlie Zender, professor of Earth System Science at the University of California, Irvine. Zender predicts that humanity's ability to see the stars from the ground would be immediately impaired by any plans to increase the albedo of the atmosphere.

According to him, urban skies could get as much as 25 percent brighter, making it harder to see the stars. That's a problem for astronomers, but not only them: animals like bats and turtles are already being negatively affected by our current levels of light pollution, which is thought to be bad for human health, too, as Zender notes.

But panelists said the small cost of fewer stars twinkling in the night sky wouldn't necessarily be a deal breaker if such schemes could actually save the planet. "Fixing global warming is more important than astronomy," said Grinspoon.

Beyond all the unanswered questions about geoengineering—not to mention how technologically far-out many of these ideas still are—such solutions are still only theoretical stop gaps to the larger issue of ceasing CO2 emissions, panelists recognized.

"If we're going to do this," said panelist Tom Ackerman, Professor of Atmospheric Sciences at the University of Washington, "we're going to have an argument about what planet do we want to have, and who gets to decide."

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