Oceans cool the climate more than previously realized

Our oceans do more than just serve as massive bodies of water. These vast, briny expanses actively participate in regulating our planet’s climate. But, how do they do it?

The answer lies in a small, sulphur-based compound produced by ocean creatures called “methanethiol.”

Ocean’s secret weapon: Methanethiol

In a recent study led by the Institute of Marine Sciences (ICM-CSIC) and the Blas Cabrera Institute of Physical Chemistry (IQF-CSIC) in Spain, a new understanding of marine life’s role in climate regulation came into light.

The sea creatures we share our planet with are inadvertently helping to combat global warming through a gas of their own – methanethiol.

Despite its substantial climatic impact, methanethiol remained off the radar for a long time. This was because it was incredibly difficult to measure and was only recently detected.

Most previous research was biased towards warmer oceans, but it turns out that the polar oceans are the real emission powerhouses. This discovery truly challenges traditional thinking.

Small ocean element with a big climate effect

The research team included Dr. Charel Wohl, formerly of ICM-CSIC and now at the University of East Anglia (UEA).

“This is the climatic element with the greatest cooling capacity, but also the least understood. We knew methanethiol was coming out of the ocean, but we had no idea about how much and where. We also did not know it had such an impact on climate,” said Dr. Wohl.

So, what is methanethiol exactly and why is it so significant for the oceans? Methanethiol is a sulfur-based gas emitted by marine organisms, particularly plankton. Its significance lies in its role in regulating Earth’s climate.

The role of methanethiol in climate regulation

Methanethiol contributes to the formation of aerosols, tiny particles suspended in the atmosphere. These aerosols reflect solar radiation back into space, reducing the amount of heat that reaches and stays on Earth’s surface. This process helps cool the planet.

Additionally, methanethiol-derived aerosols play a crucial role in cloud formation. Clouds enhance the cooling effect by reflecting even more sunlight and moderating Earth’s temperature.

Together, these mechanisms make methanethiol an important natural contributor to the mitigation of global warming.

Climate cooling effects of the ocean

Previously, it was thought that the oceans only emitted sulfur in the form of dimethyl sulfide, a byproduct of plankton. This compound is primarily responsible for the signature smell of shellfish.

However, with the evolution of measurement techniques, it was discovered that plankton also emit methanethiol.

This knowledge helps to more accurately represent clouds over the Southern Ocean in climate models and calculate their cooling effect more realistically.

Methanethiol and ocean sulfur emissions

Thanks to methanethiol, marine sulfur emissions increase by 25% annually on a global average.

“It may not seem like much, but methanethiol is more efficient at oxidizing and forming aerosols than dimethyl sulfide and, therefore, its climate impact is magnified,” noted Dr. Julián Villamayor, a researcher at IQF-CSIC.

Identifying methanethiol as a key component of ocean sulfur emissions represents a big step toward closing the knowledge gap between climate models and observations.

The effects were particularly noticeable in the Southern Hemisphere, where vast oceans and limited human activity make sulfur emissions from fossil fuel burning less prevalent.

New frontier in climate research

The discovery of methanethiol as a critical player in climate regulation marks a new frontier for scientific inquiry linked with oceans.

Researchers now aim to explore its interactions with other atmospheric elements and its role in the broader biogeochemical cycles.

This path could reveal even more about the Earth’s natural mechanisms for balancing its climate. With this knowledge, climate models can be further refined, enabling more precise predictions about global warming and the effects of sulfur emissions.

Importantly, studying methanethiol sheds light on how interconnected ecosystems are, from microscopic plankton to the global atmospheric systems.

Implications for policy and conservation

Understanding the critical role of methanethiol has significant implications for environmental policy and marine conservation efforts.

Protecting polar and Southern Ocean ecosystems becomes even more vital, as these regions produce some of the highest levels of this cooling compound.

Policymakers might see these findings as a call to double down on preserving marine biodiversity and combating threats such as ocean acidification and overfishing.

Furthermore, this research highlights the need for international collaboration to create climate policies that regard the oceans as vital climate regulators, ensuring their role in mitigating global warming is sustained for future generations.

The study is published in the journal Science Advances.

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