The oceans have long been known as the Earth’s natural climate regulators, absorbing heat and redistributing it across the planet.
Now, scientists have discovered that the oceans also emit a sulfur gas that cools the climate more than previously thought.
This groundbreaking research, published in Science Advances, reveals how sulfur emissions from marine life play a crucial role in reducing global warming.
For decades, researchers have known that microscopic plankton in the oceans produce a sulfur gas called dimethyl sulfide.
When released into the atmosphere, this gas transforms into tiny particles called aerosols. These aerosols reflect sunlight back into space, cooling the Earth. They also help form clouds, which further enhance this cooling effect.
But this new study adds a twist: another sulfur compound called methanethiol. Methanethiol has been largely overlooked until now because it’s incredibly hard to measure.
However, researchers have now identified it as a major contributor to the ocean’s cooling power, especially in the Southern Ocean around Antarctica.
Dr. Charel Wohl, a lead researcher now based at the University of East Anglia in the UK, explained, “We knew methanethiol was coming from the oceans, but we didn’t know how much or where. This study shows it has a much bigger impact on the climate than we realized.”
Using advanced measurement techniques, the research team collected data on methanethiol emissions from different parts of the ocean, including the Southern Ocean and the Mediterranean. By combining these measurements with seawater temperature data from satellites, they mapped out global emissions of methanethiol.
Their findings showed that methanethiol increases known sulfur emissions from the oceans by 25%. While dimethyl sulfide is more common, methanethiol is better at forming aerosols, making it more effective at cooling the planet.
“This might seem like a small increase, but methanethiol’s efficiency in creating aerosols magnifies its impact,” said Dr. Julián Villamayor, a co-lead of the study.
The study highlights the importance of the Southern Ocean in this cooling process. Unlike other regions, the Southern Ocean has less human activity and fewer emissions from burning fossil fuels. This makes the cooling effect of natural sulfur emissions more noticeable.
“Climate models have struggled to accurately simulate clouds over the Southern Ocean,” said Dr. Wohl. “This new data helps bridge the gap between what we see in models and what we observe in the real world.”
By including methanethiol emissions in climate models, researchers can now make better predictions about global warming and the effects of rising temperatures. These improved models are especially useful for creating strategies to limit warming to 1.5 or 2 degrees Celsius, targets set by international climate agreements.
The research not only improves our understanding of the ocean’s role in regulating the climate but also highlights the importance of sulfur aerosols in cooling the planet. These natural emissions counteract some of the warming effects of greenhouse gases like carbon dioxide and methane.
Dr. Martí Galí, a researcher from Spain’s Institute of Marine Sciences, emphasized, “Thanks to advancements in measurement technology, we now know that plankton emit both dimethyl sulfide and methanethiol. By quantifying these emissions, we can better understand and represent their effects on cloud formation and cooling.”
The findings underline the complexity of Earth’s climate system and the critical role of oceans in maintaining its balance. They also serve as a reminder of the impact human activities have on this delicate system.
As the researchers continue to refine their models and collect more data, they hope to provide even clearer insights into the planet’s natural cooling mechanisms. With better understanding comes the potential for smarter climate policies to address global warming.
“Oceans do so much more than we thought to regulate our climate,” said Dr. Wohl. “Now, we can represent these processes more accurately in climate models and use this knowledge to guide future action.”
