Should we dim the sun to help curb climate change?

“The 360” shows you diverse perspectives on the day’s top stories and debates.

What’s happening

Late last month the White House released a report cautiously calling for more research into one of the most hotly debated theories for combating climate change: partially blocking the sun to cool the planet.

While it sounds like something straight out of science fiction, interest in what’s known as solar geoengineering has increased in recent years as scientists have become more pessimistic that humans will not reduce carbon emissions in time to avoid the catastrophic potential impacts of climate change.

Solar geoengineering involves a variety of techniques for reflecting certain amounts of sunlight so that less heat reaches the planet’s surface. The most promising potential approach, according to scientists, would involve using planes to release reflective particles into the upper atmosphere to bounce a small amount of sunlight back into space before it reaches Earth.

Researchers are reasonably confident that solar geoengineering could work. Massive volcano eruptions over the past century or so have served as natural experiments proving that reflective aerosols can meaningfully reduce global temperatures. But concerns about the potential risks of tinkering with the Earth’s natural processes have meant that no known real-world experiments in man-made solar geoengineering have ever been conducted — other than weather balloons released by a startup in Mexico earlier this year, a stunt that inspired the country to ban all research on the topic within its borders.

Why there’s debate

Because solar geoengineering wouldn’t remove any carbon from the atmosphere, no one argues that it could be an alternative to the green energy transition. At best, it’s viewed as a means of temporarily staving off the direst weather effects of climate change while the world carries out the lengthy and expensive effort of decarbonizing the global economy.

A group of leading climate scientists has called for a worldwide ban on solar geoengineering research, arguing that it poses an “unacceptable risk” to the climate. They worry about potentially catastrophic side effects that could occur if humans start tinkering with the climate, the risks of conflict that could arise if nations begin competing to improve their own weather at the expense of their neighbors and the danger that geoengineering could be used as an excuse to slow or abandon the green energy transition.

But supporters say these hypothetical risks pale in comparison to the catastrophe that experts say will come if we don’t intervene to stop the Earth from continuing to get hotter. They argue that simply cutting emissions won’t be enough to stave off the worst, and scientists can’t understand the full risks of geoengineering unless they’re allowed to run experiments on it in the real world.

Perspectives

SUPPORTERS

Going green won’t be enough

“Pretending that climate change can be solved with emissions cuts alone is a dangerous fantasy.” — David Keith, professor of applied physics and of public policy at Harvard, to the Guardian

Scientists can’t understand the dangers of geoengineering unless they’re allowed to research it

“It is so late in the climate fight that some solar geoengineering may well be a good idea. We won’t know, unless scientists are able to do the hard work to find out.” — Gernot Wagner, Washington Post

We need to buy ourselves time to make decarbonizing work

“In the case that man-made warming turns out to be much faster than currently projected, putting up a stratospheric sunscreen would provide humanity extra time in which to develop and deploy low-carbon energy technologies and devise ways to reduce the extra carbon dioxide in the atmosphere.” — Ronald Bailey, Reason

SKEPTICS

Geoengineering won’t save us and could distract us from what actually can

“Even if solar geoengineering can help deflect heat and improve weather conditions on the ground … it’s not a long-term solution to climate change. It sends a message to the world that we can carry on over-consuming and polluting because we will be able to engineer our way out of the problem.” — Chukwumerije Okereke, New York Times

The potential side effects could be worse than anything climate change will do

“There’s no shortage of potential unintentional consequences. For one, some areas of the planet, like the tropics, might overcompensate and cool down too much while other areas, like the polar regions, would cling on to warmth. Messing with the atmosphere could also mess with natural climate systems.” — Mirjam Guesgen, Vice

Any science that gives nations such immense power would inevitably lead to conflict

“Who would be in charge? What country gets to decide when the sun is going to be blocked, to what degree the sun’s rays will be dimmed and for how long? Who gets the God-like power to decide where on Earth the sun would continue to shine and which regions would see their sunlight taken away at any given time?” — Tom Wrobleski, SI Live

The dangers of climate change aren’t an excuse to take dangerous risks

“Just because we’re desperate doesn’t suddenly make solar geoengineering a good idea, because the risks are so immense.” — Lili Fuhr, environmental law expert, to CNN