For the past few decades, the entire planet has been carrying out an experiment that could save us from the catastrophe of climate change. This is the kind of experiment that would never be allowed to happen under normal circumstances, due to its dangerousness and catastrophic results.
In fact, we didn’t even realize we were doing it until recently. In 2020, the United Nations’ International Maritime Organization (IMO) imposed regulations requiring ships to reduce sulfur pollution emitted from the fuel they burn 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 tracks was drastically reduced (indicating that the IMO regulations were working), it also led to something else: global warming. It turned out that sulfur dioxide emitted by ships didn’t just worsen air quality; it was also seeding low ocean clouds, thinning them out and causing them to reflect sunlight away from the planet and cool things down.
“You had a reflection effect that sent sunlight back into space and produced a cooling,” Michael Diamond, assistant professor of meteorology and environmental science at Florida State University, told The Daily Beast. . “If we look before the regulations came into force and after, we can already see the clouds changed. They don’t shine as brightly as before.”
Diamond is the author of an article published on July 25 in the journal Chemistry and physics of the atmosphere examining changes in clouds over major shipping lanes in the Atlantic Ocean. He found evidence to suggest that the loss of cloud brightness caused a 50% increase in sunlight hitting the ocean surface, causing temperatures to warm.
These findings, along with a number of other studies conducted on the loss of high sulfur ship tracks over the ocean, may help strengthen the case for geoengineering, a term describing technologies that can be used to artificially alter the Earth’s climate. Although a controversial and potentially dangerous strategy, its proponents say it is fast becoming one of the few options we have to ward off the worst impacts of climate change.
“It’s really natural to ask whether we should do this deliberately to buy time for decarbonization or to develop the carbon renewal technologies,” Diamond said.
Although 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 popularity. The White House announced funding for a five-year geoengineering research plan in response to a congressional mandate developed with the National Oceanic and Atmospheric Administration.
These initiatives usually come in different forms. The most common include some form of solar radiation management (SRM), which are systems to reflect sunlight away from the Earth. We’ve seen this happen in nature before with large volcanic eruptions that shoot huge clouds of debris and gases like sulfur dioxide into the air, which block sunlight and can drop temperatures. world.
Likewise, the tracks of ships previously chilled the Earth, while poisoning the air. Shrinking ship trajectories have led to lower sulfur dioxide emissions, but also caused rising temperatures.
Of course, this raises a strange and uncomfortable question: if reducing greenhouse gases is actually warming the planet, why would we want to do it? Diamond is quick to point out that the deleterious effects of greenhouse gas emissions are far more destructive than the warming temperatures caused by shrinking ship routes. Additionally, the benefits of getting rid of greenhouse gases like carbon dioxide, sulfur dioxide, and methane will ultimately provide a much stronger cooling effect.
“If you reduce [carbon dioxide]methane and other aerosols, you get a warming acceleration in the short term, but it will cancel out in the longer term,” he said.
Using this idea, researchers can develop their own artificial marine cloud brightening systems to replicate the effects of ship trajectories, but without toxic sulfur dioxide or other greenhouse gas emissions. One method would be to use specially designed nozzles to spray specific size seawater aerosols into the atmosphere atop ships to mimic ship trajectories. 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 move could be severe, such as accidentally causing massive rainfall in ecosystems ill-prepared for it, or causing the planet to overcool, resulting in a “little ice age” scenario where crops fail and cause global starvation.
There’s also the question of whether or not it would work, something scientists are already wondering about 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 one we’ve already been inadvertently using to cool our planet for decades. But experts are actually divided on what the data means. Although Diamond thinks the evidence should encourage more scientists and institutions to invest more in geoengineering research efforts, he and other atmospheric scientists say he is a long way from providing evidence. conclusive evidence that marine cloud brightening could be a panacea or even just an effective tool for our climatic woes.
“There has been some attenuation, but not as much as expected,” Duncan Watson-Parris, atmospheric scientist at the Scripps Institution of Oceanography, told The Daily Beast. He has co-authored a number of different studies over the past few years regarding the impact of ship tracks on marine cloud brightening, and has seen his beliefs on this subject evolve over the years.
A 2022 Nature Watson-Parris study helped lead used ship tracking data to analyze the clouds over which these ships moved to assess their impact on nearby clouds without ship pollution. He and his team found that this led to an increase in cloud volume and thinning sea clouds causing a cooling effect.
But, in a preprint published on May 16 in Chemistry and physics of the atmosphere, the same researchers looked at lightening effects before and after 2020 and found that there was actually not much change between the two. This shows that the clouds are “roughly saturated”, according to Watson-Parris.
“Even reducing emissions by 80%, the clouds themselves don’t get much darker because they’ve already had a lot of aerosols,” he explained. “This leads me to think that in fact the clouds are already quite saturated with aerosols and pollution. And therefore, the emission cuts probably haven’t had a massive effect.
The effects of decreased sunlight hitting Earth due to IMO regulations are also difficult to quantify, according to Rob Wood, an atmospheric scientist and principal investigator of the Marine Cloud Brightening project at the University of Washington. He noted that carbon dioxide emissions have increased over this period and have a much longer lifetime in the atmosphere than sulfur dioxide, “thus comparing the effect of the IMO regulations with the increase [carbon dioxide] is hard to do,” he told The Daily Beast.
“Furthermore, 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 IMO 2020 regulations.”
It is therefore still quite early after the IMO regulations to draw definitive conclusions on its impact. While solar geoengineering experts are optimistic about the new research, they caution that all of this 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 don’t understand well enough,” said Kelly Wanser, co-founder and senior adviser of the Marine Cloud Brightening. Project at the University of Washington, told the Daily Beast. “In particular, we did not have sufficient observational coverage to collect the data needed to understand and quantify these effects.”
Despite this, Wood and Wanser believe it should encourage stakeholders such as world governments and academic institutions to invest in geoengineering research. More needs to be known before deployment, especially when the consequences could be immense.
“It’s controversial,” Diamond said. “There are potential downsides to the technology, like perhaps changing circulations and precipitation patterns in a way that is potentially detrimental to certain communities and ecosystems.”
“We lack sufficient information about the effectiveness and risks of side effects of marine cloud brightening to know whether to try using marine cloud brightening, or how it might be used to maximize efficiency and minimize risk,” Wanser said. “A lot of research is needed.”
Like the clouds above our oceans, we want to look towards a brighter future. We just don’t want to do this at the expense of our lives, but then again, we may soon have no real choice.
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