Climate Change Has Been “Greatly Overestimated”

When it comes to climate change, a new study finds that our fear over the planet’s health may be “greatly overestimated.”

For the first time, researchers have found oceans help cool global temperatures more than anyone previously thought.

Specifically, sulfur gas produced by marine life emits a second compound that significantly cools the planet. The discovery will help create more accurate climate models and provide another tool to slow global warming.

With almost three-fourths of Earth covered by oceans, the waters capture and redistribute the Sun’s heat. The latest study in Science Advances shows the process goes much deeper than that.

The oceans also create sulfur gases that create particles to cool the Earth, such as brightening clouds that reflect heat.

The new compound released from sulfur gas is known as methanethiol. It has not been detected before because it is extremely hard to measure.

Microscopic plankton living on the seas’ surfaces emit a type of sulfur gas known as dimethyl sulfide. This gas is the one responsible for the stinky smell in shellfish.

Once sulfur gas reaches the atmosphere, it oxidizes and produces small particles called aerosols. These aerosols reflect solar radiation into space, lowering the heat on Earth.

Plankton also releases methanethiol.

The authors quantified the amount of methanethiol released into clouds over the Southern Ocean and observed an even greater cooling effect.

The cooling impact on the climate is bigger than expected and works the opposite of greenhouse gases such as carbon dioxide and methane, which absorb heat.

“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,” says Dr. Charel Wohl, a researcher at the University of East Anglia’s Centre for Ocean and Atmospheric Sciences, in a media release.

“Climate models have greatly overestimated the solar radiation actually reaching the Southern Ocean, largely because they are not capable of correctly simulating clouds. The work done here partially closes the longstanding knowledge gap between models and observations.”

The authors note that the new research helps create more accurate climate models, refining their understanding of the ocean’s role in cooling the planet.

These models include those that predict what would happen to the Earth when the global temperature rises by 1.5 ºC or 2 ºC, with results influencing current climate change policies.

The researchers grouped up all measurements of methanethiol in seawater and added them to measurements made in the Southern Ocean and the Mediterranean coast.

Using seawater temperature collected from satellite data, they then used statistics to calculate their results. [Each year] methanethiol increases marine sulfur emissions by 25%.

“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,” says Dr. Julián Villamayor, a researcher at the Blas Cabrera Institute of Physical Chemistry in Spain.

The team also added marine methanethiol emissions to a climate model to measure their effects on the planet’s radiation.

The impact is more visible in the Southern Hemisphere, where there are more oceans, and fewer humans burning fossil fuels.

While sulfur aerosols are important in cooling the planet, the authors note that human behavior will determine whether the Earth continues to warm.