One option for slowing climate change? Block out the sun

A once unthinkable solution to human caused climate change is gaining traction, and it's not more renewable energy sources or some bigger battery. Some scientists are considering going right to the source, and blocking out a portion of the sun's rays.

As we stare down rising sea levels, erratic weather, and the world’s hottest year on record, some are asking: Why not block a little of that free light and heat?

Last year an astronomer with the University of Hawaii published a paper considering the possibility of using a giant solar shield to block out some of the sun’s rays.

Now, The New York Times reports that scientists at the Asher Space Research Institute in Israel are ready to test that theory out.

They say they could build a prototype shade to prove if the idea would actually work in practice.

But is a space parasol actually a good idea? The answer is "maybe," according to Jim Hermanson, professor of Aeronautics and Astronautics at the University of Washington.

"The basic concept is reduce the intensity of the solar illumination of the earth by shading some of it," Hermanson said.

"The calculations they've done suggest that if you can block maybe 1% of the sun's light from hitting the Earth, that would be enough to have a beneficial impact on the climate."

Hermanson said that there are stable points in the earth sun system, called Lagrange Points, where you can place a satellite and it won't move. One of those points, around four times the distance of the moon, could work for a potential sunshade.

But just blocking 1% of the sun's rays would be a major effort. According to Hermanson's calculations, the shield would need be big. Really big. Like the size of the country of Peru big.

But Hermanson says that doesn't mean getting the shield into space is impossible.

"Space structures are getting very light, very collapsible, there's a lot of interest in self assembly," Hermanson said. "So having something that could go out and fold out and give you this nice surface — it's technically feasible."

This sun parasol wouldn't be visible from Earth, and the amount of light it blocks likely wouldn't be noticeable.

But the idea of building a giant sun shield leads to other questions for the scientific community. We don’t have a very effective way to build consensus and make decisions as a planet. So who gets to decide to launch a giant sun shield?

Hermanson says it's a question that's being debated about other space regulations right now, like who owns the moon, or who has the right to colonize and explore lunar resources. As of now, there are no clear answers.

Hermanson also notes that, personally, he believes there are better ways to fight climate change.

"I think the actual key to reducing greenhouse emissions is reduced greenhouse emissions ... reducing emissions any way we can on Earth is probably the most viable path forward."