A new paper from a team of NASA scientists has pushed one of the most controversial topics in climate science into high gear.
According to the research, published in the journal Nature, a major reduction in emissions of sulfur dioxide in 2020, following the introduction of new international shipping fuel regulations, led to a “termination shock” that they say could add 0.16 degrees Celsius (0.29 degrees Fahrenheit) of heat to the world’s oceans over seven years, greatly accelerating global warming.
The researchers say this is possible because sulfur dioxide, produced by the burning of high-sulfur fuels in ships, reacts with water vapor in the atmosphere to produce aerosols that reflect sunlight back into space. It also helps increase cloud coverage, shielding the ocean from the sun. Reducing those sulfur dioxide emissions, the researchers claim, has therefore led to more of the sun’s energy reaching the oceans.
The authors further suggest that their findings support the viability of geoengineering technologies to brighten clouds, which some researchers have suggested could be used to help to cool the Earth.
Writing on social media, study author Tianle Yuan, a research scientist at the Joint Center for Earth Systems Technology, said the effect was akin to an “inadvertent geoengineering event.” Speaking to media of his team’s findings, he suggested: “If our calculation is right, that would suggest this decade will be really warm.”
The research is controversial on two counts: one is that some climate scientists dispute the extent to which global shipping emissions—or a sudden lack of them—have impacted global heating. The second concerns geoengineering, which is controversial chiefly because it is not known what unintended consequences artificially cooling the Earth might cause.
Nevertheless, many researchers responded positively to the “termination shock” paper. Richard Allan, professor of climate science at the University of Reading, said that while the study was “not the last word and there are varying estimates of how potent this marine cleaning influence has been … the new findings do add still more urgency in massively and rapidly cutting greenhouse gas emissions that are the root cause of the ongoing warming of climate.”
Karsten Haustein, a climate scientist at Leipzig University, found much to appreciate about the research, saying: “The paper does contribute to understanding why the global radiative imbalance is increasing at the rate it has been increasing lately.” He went on: “The remainder of 2024 will tell us whether or not recent temperature records are indeed something to be even more worried about than the already worrisome pace of our human-made warming during the last few decades.”
In May, experts announced that Earth had just experienced its 11th hottest consecutive month on record, with April 2024 being the warmest April since records began. Scientists concur that the never-before-seen rate of warming is a consequence of the accumulation of greenhouse gases released by human activities.
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