Everyone knows it: If you shake a bottle with a carbonated beverage, the contents spray out at you when you open it, because the unstable carbonic acid decomposes when you shake it and carbon dioxide is released, which takes up more space than the carbonic acid. In the ocean, the situation is similar – dissolved carbon dioxide absorbed from the atmosphere reacts with water via carbonic acid to form the more stable compound hydrogen carbonate, by far the most abundant carbon compound in the ocean. And if the oceans are churned up by storms, the same thing happens as with the beverage bottle – carbon dioxide is released. An international team of researchers has now discovered that the amount of carbon dioxide released back into the atmosphere through storms is significant for climate change. The new study, which may enable better climate models, was published in the journal Nature Communications.
The world’s oceans absorb about 30% of the carbon dioxide in the atmosphere, and about half of that is stored by the Southern Ocean alone, which is why it plays a significant role in global climate change. The current study examined the complex processes that drive the exchange of gases such as carbon dioxide between the atmosphere and the ocean.
The international team with scientists from South Africa, the US, Sweden and Norway deployed two different autonomous robots in the Southern Ocean south of the Antarctic Polar Front at 54° South on the prime meridian. Over nearly two months, a Wave Glider recorded wind speed above the water’s surface and an underwater robot, the Slocum Glider, collected data down to a depth of 1,000 meters on parameters such as salinity, temperature and currents.
The results of the studies show that storms bring carbon-dioxide-rich water to the surface, once again underlining the important role of this region in climate change: “We show how the intense storms that often occur in the region increase ocean mixing and bring carbon-dioxide-rich waters from the deep to the surface. This drives an outgassing of carbon dioxide from the ocean to the atmosphere. There has been a lack of knowledge about these complex processes, so the study is an important key to understanding the Southern Ocean’s significance for the climate and the global carbon budget,” says Sebastiaan Swart, a professor of oceanography at the University of Gothenburg, and co-author of the study.
Climate scientists expect that there will be stronger storms in the future, making it critical to understand the impact of storms on the outgassing of carbon dioxide into the atmosphere, the researchers point out. “This knowledge is necessary to be able to make more accurate predictions about future climate change. Currently, these environmental processes are not captured by global climate models,” says Marcel du Plessis, from the University of Gothenburg, who was also involved in the study.
Julia Hager, PolarJournal
Link to the study: Sarah-Anne Nicholson, Daniel B. Whitt, Ilker Fer, Marcel D. du Plessis, Alice D. Lebéhot, Sebastiaan Swart, Adrienne J. Sutton, Pedro M. S. Monteiro. Storms drive outgassing of CO2 in the subpolar Southern Ocean. Nature Communications, 2022; 13 (1) DOI: 10.1038/s41467-021-27780-w.
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