We’ve been accidentally geoengineering the Earth for decades

For the past few decades, the entire planet has been running an experiment that could save us from the disaster of climate change. It’s the kind of experiment that would never be allowed under normal circumstances, because of how dangerous it is and how catastrophic the results could be.

In fact, we didn’t even realize we were running it until recently. In 2020, the United Nations International Maritime Organization (IMO) imposed a regulation requiring ships to reduce sulfur pollution emitted from the fuel they burn by more than 80 percent to improve air quality. A few years later, scientists began to study the clouds formed by the exhaust gases from these ships known as ship tracks.

What they found was a double-edged sword. While the number of ship tracks dropped considerably (indicating that the IMO regulation was working), this also resulted in something else: global warming. It turned out that the sulfur dioxide emitted by the ships was not only making the air quality worse; it was also seeding low ocean clouds, lighting them up and causing them to reflect sunlight away from the planet and cool things down.

“You had a reflection effect that reflected sunlight back into space and caused cooling,” Michael Diamond, an assistant professor of meteorology and environmental science at Florida State University, told The Daily Beast. “If we look before and after the entry into force of the regulation, we can already see the clouds have changed. They’re not shining as bright as before.”

Diamond wrote a article published on July 25 in the magazine Chemistry and Atmospheric Physics examining changes in clouds over major shipping corridors in the Atlantic Ocean. He found evidence suggesting that the loss of cloud brightness resulted in a 50 percent increase in sunlight hitting the ocean surface, causing temperatures to rise as a result.

These findings, along with a number of other studies conducted to examine the loss of high-sulfur ship tracks over the ocean, may help bolster the case for geoengineering, a term to describe technologies that can be used to alter artificially the Earth’s climate. While it’s a controversial and potentially dangerous strategy, advocates say it’s fast becoming one of the few options we have to avoid the worst impacts of climate change.

“It’s really natural to wonder if we should be doing this deliberately to buy time for decarbonization or to scale up carbon renewal technologies,” Diamond said.

While it sounds like an idea ripped from the pages of a science fiction novel, the idea of blocking out the sun to cool the planet is rapidly gaining favor. He The White House has announced funding for a five-year research plan to geoengineering in response to a congressional mandate developed with the National Oceanic and Atmospheric Administration.

These initiatives typically come in a variety of different forms. The most common include some form of solar radiation management (SRM), which are systems for reflecting sunlight away from Earth. We’ve seen this happen before in nature during large volcanic eruptions that spew massive clouds of debris and gases like sulfur dioxide into the air, blocking sunlight and can cause global temperatures to drop.

Similarly, the ship’s tracks had previously been cooling the Earth, all while poisoning the air. Shrinking ship tracks resulted in a drop in sulfur dioxide emissions, but also caused temperatures to rise.

Of course, this raises a strange and uncomfortable question: if reducing greenhouse gases actually warms the planet, why would we want to? Diamond is quick to point out that the deleterious effects of greenhouse gas emissions are far more destructive than the rise in temperatures caused by reduced ship tracks. Also, the benefits of getting rid of greenhouse gases like carbon dioxide, sulfur dioxide, and methane will eventually provide a much stronger cooling effect.

“If you reduce (carbon dioxide), methane and other aerosols, you get a short-term acceleration in warming, but that will cancel out in the long term,” he said.

Using this idea, researchers can develop their own artificial marine cloud glow systems to replicate the effects of ship tracks, but without toxic sulfur dioxide or other greenhouse gas emissions. One method would involve the use of specifically designed nozzles to spray specific-sized aerosols of seawater into the atmosphere over ships to mimic ships’ tracks. A few fleets of these ships saturating the skies over our oceans would have an almost immediate effect on cooling our oceans.

However, the ramifications of such a measure could be serious, such as accidentally causing massive rainfall in ecosystems ill-prepared for it, or making the world too cold, resulting in a “little ice age” scenario where crops fail causing worldwide famine.

There’s also the question of whether or not it would actually work, something scientists are already wondering when it comes to the latest research on ship tracks.

This might seem like a clear indicator that solar geoengineering is not only a viable option, but that we’ve already been inadvertently employing it to cool our planet for decades. But experts are actually divided on what the data means. Although Diamond believes the evidence should encourage more scientists and institutions to invest more in geoengineering research efforts, he and other atmospheric scientists say it is a long way from providing conclusive evidence that bright marine clouds could be a panacea. or even an effective tool for our climate problems.

“There has been some dimming, but not as much as we expected,” Duncan Watson-Parris, an atmospheric scientist at the Scripps Institution of Oceanography, told The Daily Beast. He has co-authored several different studies in recent years on the impact of ship tracks on the brightness of marine clouds, and has seen his beliefs evolve over the years.

a 2022 Nature study Watson-Parris helped lead used ship-tracking data to analyze clouds over the locations where these ships traveled to assess their impact on nearby clouds without ship contamination. He and his team found that it resulted in increased cloud volume and brighter sea clouds that caused a cooling effect.

But, in a preprint published on May 16 in Chemistry and Atmospheric Physics, the same researchers looked at the brightness effects before and after 2020 and found that there really wasn’t much of a change between the two. This shows that the clouds are “quite saturated,” according to Watson-Parris.

“Even with 80 percent reduction in emissions, the clouds themselves don’t get much darker because they already have a lot of aerosol in them,” he explained. “This leads me to think that, in reality, the clouds are already quite saturated with aerosols and pollution. And therefore the emissions reductions probably didn’t have a massive effect.”

The effects of decreased sunlight hitting Earth due to IMO regulation are also difficult to quantify, according to Rob Wood, an atmospheric scientist and principal investigator with the University of Washington’s Marine Cloud Illumination Project. He noted that carbon dioxide emissions have increased during this time and have a much longer lifetime in the atmosphere than sulfur dioxide, “so it is difficult to compare the effect of the IMO regulation with the increase (of carbon dioxide carbon),” he told The Daily. Beast.

“In addition, on time scales of a decade or less, the natural variability of the climate system tends to control temperature fluctuations,” he added. “In summary, we are going to have to wait a few more years to determine the impact of the IMO 2020 regulation.”

Therefore, it is still quite early after the IMO regulation to draw firm conclusions about its impact. While solar geoengineering experts are hopeful about the new research, they caution that everything should be taken with a grain of salt.

“Our conclusion is that reducing aerosols from ship emissions, and indeed all emissions, is a critical near-term climate risk that we do not understand well enough,” Kelly Wanser, Co-Founder and Senior Advisor at Marine Cloud Brightening. Project at the University of Washington, he told The Daily Beast. “In particular, we have not had sufficient observational coverage to collect the data necessary to understand and quantify these effects.”

Despite this, both Wood and Wanser believe this should encourage stakeholders such as world governments and academic institutions to invest in geoengineering research. More needs to be understood before implementation, especially when the consequences of doing so could be immense.

“This is controversial,” Diamond said. “There are potential downsides to the technology, such as perhaps changing circulations and rainfall patterns in ways that are potentially harmful to certain communities and ecosystems.”

“We lack enough information about the efficacy and risks of the side effects of marine cloud glow to know whether or how to try using marine cloud glow to maximize efficacy and minimize risk,” Wanser said. “A lot of research is needed.”

Like the clouds over our oceans, we want to look to a brighter future. We just don’t want to do it at the expense of our lives, but then again, we may not have much of a choice soon.