Oceans are cooling the climate more than thought

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The study expands the climate impact of marine sulfur as it adds a new compound methanethiol which had previously gone unnoticed. The gas was discovered recently because it was difficult to measure and earlier work focused on warmer oceans, while the polar oceans are emission hotspots.

The research was led by a team of scientists from the Institute of Marine Sciences in Spain. Their findings represent a major step forward in one of the most groundbreaking theories proposed forty years ago about the ocean's role in regulating Earth's climate.

Microscopic plankton living on the surface of the seas produce sulfur in the form of a gas, dimethyl sulfide which once it reaches the atmosphere, oxidizes and forms aerosols. These reflect part of the solar radiation back into space and thus reduce the heat retained by the Earth. The cooling effect is amplified when involved in cloud formation with an effect opposite but of the same magnitude as that of well-known warming greenhouse gases such as carbon dioxide or methane.

The study improves understanding of how the planet's climate is regulated by adding a previously overlooked component and illustrates the importance of sulfur aerosols. It also highlights the impact of human activity on the climate and the fact that the planet will continue to warm if no action is taken.

The researchers collected all available measurements of methanethiol in seawater added those taken in the Southern Ocean and the Mediterranean coast and statistically combined them with satellite-derived seawater temperature. As a result methanethiol was found to increase known marine sulfur emissions by 25 percent annually and on a global average.

Methanethiol is more effective in oxidation and aerosol formation than dimethyl sulphide and therefore its impact on the climate increases. The impacts are much more visible in the Southern Hemisphere where there are more oceans and less human activity.

Source:ScienceDaily/Editorial