Discover how geoengineering solutions—from techniques as natural as planting trees, to vacuuming CO2 out of the air, to science-fiction alternatives like blocking sunlight—can help humanity turn the tide on climate change, and why these approaches are controversial.
Can Geoengineering “Undo” Climate Change?
Published: June 24, 2020
Narrator: What if we could “undo” climate change? We’re already feeling the effects of a warming planet. To prevent further damage from human-induced climate change, we’d need to cut global emissions to zero—something that may take decades. And even then, it could be too late to avoid catastrophic damage.
So, is there another way?
Onscreen: Can We "Undo" Climate Change?
Narrator: Climate change is driven primarily by an excess of carbon dioxide in the atmosphere from human emissions. This CO2 acts like a blanket, trapping heat on the planet. So if we want to reverse the problem, is there a way to just take some of that CO2 out of the atmosphere?
Actually -- yes!
Lola Fatoyinbo-Agueh: There’s carbon all around us. If you think of trees as a machine, then trees would be a carbon capture machine. When we’re looking at trees, about half of that weight is carbon.
Greg Asner: Forests soak up carbon dioxide, and they put it into wood, leaves, roots, you know, the basic building blocks of a tree. And that carbon is held in that tree.
Narrator: According to one recent paper, planting permanent forests—on the order of a trillion trees—could erase nearly a third of all human carbon emissions since human industrial activity began! The potential of trees is HUGE. That paper has met some skepticism regarding how realistic it is. There’s uncertainty in some of the measurements, and a lot of the land where those trees could grow is spoken for. People need land to, for example, produce food for a growing population.
Some agricultural practices have been developed to enhance the ability of farmland to store CO2 in the soil. But still, what if our natural solutions just aren’t enough? Can we engineer an alternative?
Several companies are trying to vacuum CO2 straight out of the air. The carbon dioxide that these so-called direct air capture units collect can then be recycled into useful products, or sequestered underground. The challenge here is: direct air capture takes a lot of energy. And even if it were run on renewables, that clean energy might be better spent powering things that would otherwise rely on fossil fuels. And, it would take a lot of direct air capture to make a dent; one company estimates that it would require about 750,000 of their shipping-container-sized units to offset just 1% of annual global emissions.
There is another approach—and it’s quite controversial. It’s called solar radiation management. And here’s the idea. If we can’t solve the carbon problem fast enough, maybe we can just make the planet a bit cooler in a different way until we can solve the problem: by reflecting some of the heat from the Sun away from Earth. Sulfate aerosols resulting from major volcanic eruptions—like Mt. Pinatubo in 1991—have done this naturally in the past. We could do this artificially, too, by releasing aerosols into the air. Compared to other solutions, it could be relatively cheap and easy. But, it only treats one of the symptoms of climate change, not the cause. For example, it does nothing to fix ocean acidification. And it might lead to unintended consequences, like disrupted weather patterns or worse.
Sheila Jasanoff: This is a manipulation of the Earth’s atmosphere on a huge scale. What happens if things go wrong? Nothing in our scientific capability actually enables us to understand the complexity of the interactions that would be set loose.
Jane Long: It’s not just that it lowers the temperature, but what are some of the effects on the hydrologic cycle or on heat waves and droughts.
David Keith: The root of the concern is that solar geoengineering research, however well-intentioned will be used as an excuse for big fossil fuels to fight emissions cuts. Solar geoengineering does not get us out of the ethical and physical requirement to cut emissions.
Narrator: Ultimately, there are no quick fixes to climate change. And we can’t undo the damage we’ve already caused to some communities and ecosystems. So many scientists agree that we must reduce greenhouse gas emissions as fast as we can, to limit further damage. And, adapt to changes that are already here.
Follow us on social to watch our other episodes that dive into those climate solution strategies.
Narrated by: Caitlin Saks
Produced by: Ana Aceves
Research & Production: Haley Apicella, Sukee Bennett, Ari Daniel, Robin Kazmier, Christina Monnen, and Caitlin Saks
Science Advisor: Scott Denning
Footage: Storyblocks, NASA, Earth Science and Remote Sensing Unit, NASA Johnson Space Center, NASA's Goddard Space Flight Center, USGS, NOAA Fisheries, Flikr/Internet Archive Book Images
Animation: Mitch Butler, Unit TV & Film
Sound Effects: Freesound/zerolagtime, Freesound/LloydEvans09
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