Radical temperatures experienced since April pose unprecedented threats especially to the oceans. The Atlantic Ocean, home to the world’s largest reefs, is warming like never before. As a result, some reefs have bleached, seabirds have died out, and at the same time, warming waters have increased global warming.

The temperatures haven’t even peaked.

The North Atlantic has been warming more slowly than other parts of the world for years. But now it has increased the rate of warming. Last month, the sea surface reached a record 25°C – almost 1°C warmer than the previous highest recorded in 2020 – and temperatures have yet to peak. “This has been a crazy year,” says Tianle Yuan, an atmospheric physicist at NASA’s Goddard Space Flight Center.

The clear and primary driver of this trend is greenhouse gases, which trap the heat that the oceans are constantly absorbing. Another effect is recent weather, particularly stagnant high-pressure systems that suppress cloud formation and allow the oceans to cook in the Sun.

But researchers are now realizing another factor that could fall into the category of unintended consequences: clouds known as ship trails. These clouds do not exist nowadays.

We unintentionally geoengineered

Regulations introduced by the United Nations’ International Maritime Organization (IMO) in 2020 have reduced sulfur pollution from ships by more than 80 percent and improved air quality by 10 percent worldwide. This reduction also reduced the effect of sulfate particles seeding and brightening the distinctive low, reflective clouds that follow the ships and help cool the planet. Duncan Watson-Parris, an atmospheric physicist at the Scripps Institution of Oceanography, described the 2020 IMO rule as “One big natural experiment” and said, “We’re changing the clouds.” used the phrases.

Several new studies have revealed that the planet is warming faster as the number of ship tracks has decreased significantly. This trend is exacerbated in the Atlantic, where maritime traffic is particularly heavy. Michael Diamond, an atmospheric scientist at Florida State University, says it’s like the world suddenly losing the cooling effect of a sizable volcanic eruption each year.

The natural experiment created by the IMO rules offers climate scientists a rare opportunity to examine a geoengineering scheme that has gone wrong. Indeed, one such strategy, called buffing sea clouds to slow global warming, envisions ships injecting salt particles into the air to make clouds more reflective.

Sulfate or salt particles seed clouds by forming nuclei so that the vapor condenses into droplets. The seeds also form smaller, more numerous droplets, making existing clouds whiter and brighter. This creates a reflective effect of the sun’s rays.

The changes didn’t stop there, says Robert Wood, an atmospheric scientist at the University of Washington. He notes that smaller droplets are less likely to coalesce with others, potentially suppressing precipitation. This will increase the size of the clouds and add to the glow effect. But modeling also shows that larger clouds are more likely to mix with dry air, which will reduce reflectivity.

In short, the sulphurous fossil fuels found in shipping have actually temporarily masked much of the warming, convincing the world that global warming does not exist. It might come to mind that “let’s keep spraying sulfur to prevent warming,” but spraying sulfur into the atmosphere can not only lower temperatures, but also turn the skies white, change weather patterns, increase the spread of malaria, deplete the ozone layer and block the light plants need to grow. And, there is a limit to bleaching clouds, and there is a risk of an atmosphere collapse.

Due to the limited time elapsed since the IMO 2020 regulation came into force, the long-term impact of this significant reduction in sulfur emissions is still unclear.