We have accidentally geoengineered the Earth for decades using ship tracks

Over the past few decades, the entire planet has conducted an experiment that could save us from the catastrophe of climate change. It’s the kind of experiment that would never be allowed to happen under normal circumstances, given how dangerous it can be and how disastrous the results can be.

In fact, we didn’t even realize we were having it until recently. In 2020, the UN’s International Maritime Organization (IMO) imposed a regulation requiring ships to cut sulfur pollution from the fuel they burned by more than 80% to improve air quality. A few years later, scientists began studying the clouds formed from the exhaust of these ships known as ship tracks.

What they found was a double-edged sword. While the number of ship itineraries has been significantly reduced (suggesting an IMO regulation was at work), this has also led to something else: a warming planet. It turns out that the sulfur dioxide emitted by the ships wasn’t simply making the air quality worse; It was also seeding low-lying ocean clouds – brightening them and making them reflect sunlight away from the planet and cool things down.

“You had a reflection effect that reflects sunlight back into space and creates a cooling,” Michael Diamond, assistant professor of meteorology and environmental sciences at Florida State University, told The Daily Beast. “If we look before the regulation goes into effect and afterward, we can already see the clouds changing. They are not as bright as they used to be.”

Al-Mass A Paper published July 25 in the journal Atmospheric chemistry and physics A study of changes in clouds over major shipping lanes in the Atlantic Ocean. He found evidence suggesting that the loss of cloud brightness led to a 50 percent increase in sunlight hitting the ocean’s surface – causing warming as a result.

These findings—along with a number of other studies conducted examining the loss of high-sulfur ship tracks over the ocean—may help bolster the case for geoengineering, which is a term to describe techniques that can be used to artificially alter Earth’s climate. While it’s a controversial and potentially dangerous strategy, its proponents say it’s fast becoming one of the few options we have for staving off the worst effects of climate change.

“It’s really natural that we ask the question whether we should be doing this deliberately to buy us time to decarbonize or to scale up carbon regeneration 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 quickly gaining popularity. The White House announced funding for a five-year geoengineering research plan in response to a congressional authorization developed with the National Oceanic and Atmospheric Administration.

These initiatives usually come in different forms. The most common is a form of solar radiation management (SRM), which are systems that reflect sunlight away from the Earth. We’ve seen this happen before in nature during large volcanic eruptions that throw huge clouds of debris and gases like sulfur dioxide into the air, which block sunlight and can cause global temperatures to plummet.

Likewise, ship tracks once served to cool the Earth, all while poisoning the air. Decreased ship routes led to lower sulfur dioxide emissions, but also caused higher temperatures.

Of course, this raises a strange and uncomfortable question: If reducing greenhouse gases does indeed warm the planet, why would we want to do it? Diamond was quick to point out that the harmful effects of greenhouse gas emissions are far more devastating than the high temperatures caused by the dwindling of ship lanes. Moreover, the benefits of eliminating greenhouse gases such as carbon dioxide, sulfur dioxide and methane will ultimately provide a much stronger cooling effect.

“If you reduce [carbon dioxide]And methane and other aerosols, you’ll get a short-term acceleration in warming, but that will negate in the long term.”

Using this idea, researchers could develop their own artificial marine cloud brightening systems to replicate the effects of ship tracks — but without toxic sulfur dioxide or other greenhouse gas emissions. One method involves using specially designed nozzles to spray seawater mist of a specific size into the atmosphere above ships to mimic ship tracks. Some of these fleets of ships dousing the skies over our oceans will have an almost immediate effect in cooling our oceans.

However, the repercussions of such an action could be as severe as accidentally causing torrential rains in ecosystems unprepared for them, or causing the world to cool down so much that it “Little Ice AgeThe scenario where crops fail causing worldwide famine.

There’s also the question of whether or not it will actually work — something scientists are already asking when it comes to the latest ship trajectory research.

This would seem like a clear indication that solar geoengineering is not only a viable option, but one we’ve already inadvertently used to cool our planet for decades. But experts are actually divided on the meaning of the data. Although Diamond believes the evidence should encourage more scientists and institutions to invest more in geoengineering research efforts, he and other atmospheric scientists say he provides no conclusive evidence that marine cloud brightness can be a panacea or a cure. Even just a powerful tool for our climate problems.

“There was some darkening — 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 a number of different studies in the past few years regarding the influence of ship tracks on the luminosity of marine clouds, and has witnessed the evolution of his beliefs on the matter over the years.

2022 nature Stady Watson-Paris helped drive Vessel tracking data were used to analyze clouds above where these vessels traveled to assess their impact on nearby clouds without polluting the vessels. He and his team found that this led to an increase in cloud size and the appearance of bright marine clouds, which caused a cooling effect.

But in Preprint published May 16 in Atmospheric chemistry and physicsAnd The same researchers looked at the effects of radiance before and after 2020 — and discovered that there wasn’t much change between the two. This indicates that the clouds are “largely saturated,” according to Watson-Paris.

“Even by reducing emissions by 80 percent, the clouds themselves don’t get any darker because they already have a lot of aerosols,” he explained. “This leads me to believe that the clouds are already somewhat saturated with aerosols and pollution. Thus, the emission reductions may not have had a massive impact.”

It’s also difficult to gauge the effects of reduced sunlight hitting the Earth due to the IMO regulation, according to Rob Wood, an atmospheric scientist and principal investigator of the University of Washington’s Marine Cloud Lightening Project. He noted that carbon dioxide emissions have increased during this time and it has a much longer lifetime in the atmosphere than sulfur dioxide, “so comparing the impact of the IMO regulation with increasing [carbon dioxide] He told The Daily Beast: “It’s hard to do.

“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 short, we will have to wait a few more years to determine the impact of the 2020 IMO regulation.”

So it is still too early after the IMO regulation to draw any strong conclusions about its impact. While solar geoengineering experts are hopeful about the new research, they caution that everything must be taken into account.

Kelly Wanser, co-founder and senior advisor for the Marine Cloud Brightening project at the University of Washington, told The Daily Beast. “In particular, we did not have sufficient monitoring coverage to collect the data needed 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 publishing – especially when the consequences of doing so can be enormous.

“It’s controversial,” Diamond said. “There are potential downsides to the technology such as altering flows and precipitation patterns in ways that are potentially harmful to specific communities and ecosystems.”

“We lack sufficient information about both the efficacy and side effect risks of marine cloud brightening to know whether marine cloud brightening should be attempted, or how to use it to increase efficacy and decrease risk,” Wanser said. “A great deal of research is needed.”

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