The oceans hide secrets that go far beyond their blue depths. A little-known gas called methanethiol is emerging as a major player in cooling our planet. New research shows that this sulfur compound, produced by marine life, helps form cooling aerosols that reflect sunlight away from Earth’s surface. The findings are prompting scientists to rethink the oceans’ role in climate regulation.

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Methanethiol is a sulfur gas produced by marine life.

Uncovering a Hidden Climate Agent

Methanethiol (CH₃SH) was once overlooked in favor of its chemical cousin dimethyl sulfide (DMS). Marine biologists long assumed that DMS was solely responsible for producing sulfate aerosols. However, recent studies reveal that methanethiol plays a significant role by increasing the overall sulfur emissions from the ocean.

Researchers have now quantified its global release and found that it adds about 25% to the marine sulfur budget. This extra sulfur boosts the formation of tiny particles that scatter sunlight and promote cloud formation, thereby cooling the Earth’s surface, according to a study published in Science Daily.

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Marine organisms release methanethiol during DMSP breakdown.

How Marine Life Cools the Planet

Plankton and other ocean organisms produce methanethiol as they break down dimethylsulfoniopropionate (DMSP), a compound central to the sulfur cycle. Once released, methanethiol reacts quickly in the atmosphere. Its rapid oxidation leads to the production of sulfur dioxide (SO₂) and subsequently sulfate aerosols. According to a study published in Science Advances, these aerosols reflect incoming solar radiation and encourage cloud formation. Not only do they cool the surface directly by scattering sunlight, but they also indirectly enhance the cooling effect by increasing the brightness of clouds.

Enhanced Cooling over the Southern Ocean

The cooling influence of methanethiol is most pronounced over the Southern Ocean. This vast, relatively pristine region is less affected by human-made pollutants, making natural processes more visible. Climate models that incorporate methanethiol emissions now predict an increase in sulfate aerosol formation by 30–70% in these southern waters, the Science Advances study reports. As a result, the excess sunlight that was once thought to reach the ocean’s surface is more effectively blocked by clouds and aerosols, reducing the overall heat retained by the Earth.

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The gas boosts sulfate aerosol formation.

Revising Climate Models

The discovery of methanethiol’s role comes at a time when scientists are striving to reduce the uncertainties in climate models. Traditional models have focused on DMS emissions and have struggled to explain observed discrepancies over regions like the Southern Ocean. By adding methanethiol into the mix, models now account for a larger fraction of the natural cooling process. According to StudyFinds, this advancement helps bridge the gap between observations and predictions, leading to more accurate estimates of solar radiation reflection and cloud cover dynamics.

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Oceans play a key role in temperature regulation.

Implications for Future Climate Research

The impact of methanethiol on Earth’s climate is not just a matter for academic interest. As the reports University of East Anglia reports, it has real implications for policy and environmental management. As human emissions of sulfur compounds decline due to stricter air quality regulations, natural sources become even more crucial.

Understanding and accurately representing the contributions of methanethiol can lead to better predictions of future warming scenarios and inform strategies to mitigate climate change. Marine conservation may also benefit from this knowledge, as preserving ocean ecosystems becomes key to maintaining the planet’s natural cooling systems.

Marine scientists now face a new frontier. Their task is to refine measurement techniques and further integrate these findings into global climate models. As Spain’s Institut de Ciències del Mar reports, the oceans, it turns out, have been quietly moderating our climate all along through a complex chemical ballet.

As researchers continue to unravel these processes, our understanding of Earth’s natural climate regulation is set to improve, offering hope for more informed environmental policies in the years ahead.