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Geoengineering accidentally for decades? Looks like it

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August 4, 2023

Have we been accidentally geoengineering for decades?

Science broadcaster extraordinaire Hank Green wrote on X, the platform formerly known as Twitter, on Friday, August 4, 2022, on the subject of a major source of sulfur dioxide in Earth’s atmosphere … international shipping. He said:

Big ships use dirty fuels, dumping a ton of sulfur dioxide into the atmosphere, thus seeding clouds. You can actually see them from space …they’re called ship tracks.

Why should we care? Because, as Green explains in the video above, sulfur dioxide molecules in the air can cause cooling (yes, cooling) in the atmosphere over a specific area. The cloud seeding is what causes it. He also was careful to mention that the cooling effect doesn’t last very long, nowhere near as long as the effect of global warming by carbon dioxide.

But, here’s the thing. In 2020, the U.N.’s International Maritime Organization ordered the world of international shipping to clean up its fuels. And so they have. Ships have burned cleaner fuels as they’ve crossed Earth’s oceans over the past several years.

Accidentally geoengineering? Moving image of Pacific Ocean with blue colors turning to red near the coast of western South America. — Here’s another way to look at sea surface cooling in 2023. This visualization shows sea surface temperatures in the tropical Pacific Ocean from early January through early March 2023, compared with the long-term average. East of the international date line, waters remained cooler than average, a sign of the 2023 La Niña. Image via climate.gov/ Environmental Visualization Lab/ NOAA.

Could we, should we … will we?

Now, Hank Green believes, there’s evidence that the semi-unintentional pumping of sulfur dioxide into Earth’s atmosphere was indeed causing cooling. It has now ended due to the new requirement for shipping to clean up its fuels.

He also seems to think, as many are beginning to think (even me, and I hate this idea) that some form of geoengineering – some form of the intentional changing of Earth’s atmosphere, in order to cool Earth or at least keep it from warming further – is going to become necessary in the years and decades ahead.

So will sulfur dioxide be used in the decades ahead to promote global cooling? For the full story, check out Hank’s video above, and/or his … what do we call these things now? Xs? at the bottom of this post.

Line in the clouds. — Ship tracks. Read more about them from NASA Earth Observatory here. Image via NASA Earth Observatory.

Accidentally geoengineering

To see Hank Green’s clear explanation in printed form, be sure to click into the discussion below.

Massively under-reported science story because there's so much going on right now but…it turns out that we might have figured out what's causing this very scary spike.

Quick thread, on how WE'VE BEEN ACCIDENTALLY GEOENGINEERING FOR DECADES…but then we stopped: pic.twitter.com/pLWzgOr8C7

— Hank Green (@hankgreen) August 4, 2023

Bottom line: Have we been geoengineering accidentally for decades? Hank Green thinks so. Now he points to sulfur dioxide as a possible road to (temporary) cooling. Btw, in case you’re wondering, Hank has been undergoing chemotherapy for cancer. Hence the beanie. Love you, Hank!

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August 4, 2023

Earth

Deborah Byrd

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About the Author:

Our Editor-in-Chief Deborah Byrd works to keep all the astronomy balls in the air between EarthSky's website, YouTube page and social media platforms. She's the primary editor of our popular daily newsletter and a frequent host of EarthSky livestreams. Deborah created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Prior to that, she had worked for the University of Texas McDonald Observatory since 1976, and created and produced their Star Date radio series. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. In 2020, she won the Education Prize from the American Astronomical Society, the largest organization of professional astronomers in North America. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.

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