Ships are using cleaner fuels to reduce air pollution, but this is causing clouds to decrease their ability to reflect sunlight back into space.
The shift of ships to low-polluting fuels has accelerated global warming, according to a new study published in the journal Communications Earth and Environment on May 30. The study indicates that the maritime industry’s transition to low-sulfur fuels beginning in 2020 could potentially double (or more) the rate of warming this decade, even contributing to record temperatures observed in the past year.
Ships using cleaner fuels contribute to the acceleration of global warming. (Photo: Pixabay)
The reason is that tiny particles in sulfur pollution help reflect sunlight back into space, making clouds more mirror-like and creating a temporary cooling effect on Earth. Scientists had previously predicted that transitioning to cleaner fuels would reduce this reflective effect and hasten the warming process, although the extent of this impact was unclear.
In this new study, the team of experts combined satellite observations and simulations to estimate the climate impact of reducing sulfur in fuels as per regulations from the International Maritime Organization (IMO) that took effect in January 2020. This regulation, aimed at limiting air pollution, has helped reduce sulfur dioxide emissions from global shipping by 80%, according to Tianle Yuan, the lead author of the study and a scientist at NASA’s Goddard Space Flight Center.
However, Yuan noted that this rapid decline has also created a “shock” effect on Earth, causing clouds to reduce their ability to reflect some of the sun’s energy back into space, leading to planetary warming. “Essentially, the rate of warming is expected to double in the 2020s,” he said.
This effect is not uniform globally, appearing to be stronger in the North Atlantic, resulting in warmer sea surface temperatures. “It contributes to the abnormal warming that the world has experienced in 2023 and 2024. However, we cannot precisely determine the extent,” Yuan explained. The research team also could not conclude that this is the primary cause.
2023 was the hottest year on record, and this trend continues into 2024, with land and sea temperatures reaching new highs monthly. Human activity is the main driver of warming. However, scientists are also considering other factors that may contribute to this abnormal heat, such as El Niño, a natural periodic weather pattern in the Pacific Ocean.
The new study also provides evidence that technology that sprays particulate matter into clouds to enhance their heat-reflecting ability could help slow global warming to some extent. However, this technology remains controversial regarding its long-term impacts on Earth.
