Have we been accidentally geoengineering for decades?

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, sulphur dioxide in the air can cause cooling (yes, cooling) in the atmosphere over a specific area. They do this by seeding clouds. He also was sure to mention that the 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.

But now look at this crazy-looking upward trend in sea surface warming in 2023.

A graph showing a sharp spike in ocean warming in 2023. — See the scary-looking spike in sea surface warming in 2023? What caused it? Could the cause be related to the fact that ships have cleaned up their fuels since 2020, effectively pumping less sulphur dioxide into the atmosphere? If so, yikes. It’s hotter than it would have been if we weren’t inadvertently causing cooling over Earth’s oceans, via international shipping fuels. On the other hand, it’s food for thought. Image via Hank Green.

Moving image of blue colors turning to red near the coast of western South America. — Here’s another way to look at the 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 Dateline, waters remained cooler than average, a sign of the 2023 La Niña. Graphic by Climate.gov, based on data from NOAA’s Environmental Visualization Lab. Description of historical baseline period. Image via NOAA.

Could we, should we … will we?

Now Hank Green believes, there’s evidence that the semi-unintentional pumping of sulphur dioxide into Earth’s atmosphere was indeed causing cooling – which has now ended due to the new requiring 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 sulphur 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, via NASA Earth Observatory. Read more about them from NASA Earth Observatory here.

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 accidentally geoengineering for decades? Hank Green says yes. And he thinks sulphur dioxide might be 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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