Cutting pollution from the shipping industry accidentally increased global warming, study suggests

The shipping industry's attempt to reduce air pollution has inadvertently accelerated global warming in the short term and contributed to record-breaking sea temperatures, according to a new climate model.

Recent global shipping regulations slashed the sulfur dioxide emissions from cargo ships by a dramatic 80%. But this rapid reduction in sulfur pollution may have "created an inadvertent geoengineering termination shock with global impact," a new study has suggested. 

"The warming effect is consistent with the recent[ly] observed strong warming in 2023 and [is] expected to make the 2020s anomalously warm," the researchers wrote. The warming is equivalent in magnitude to "80% of the measured increase in planetary heat uptake since 2020."

And this reduction in pollution "could lead to a doubling (or more) of the warming rate in the 2020s compared with the rate since 1980," the researchers suggested in the new study, published May 30 in the journal Communications Earth and Environment.

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The new shipping regulations, which were implemented in 2020 by the International Maritime Organization (IMO) reduced the maximum sulfur content in shipping fuel from 3.5% to 0.5%, with the aim of improving air quality and preventing an estimated 30,000 premature deaths each year. 

But aerosols such as sulfur dioxide particles are highly reflective, and when they are released they settle in the stratosphere and bounce the sun's rays back into space — sometimes acting as a giant planetary sunblock.