A new NASA-funded study published last month in the journal 'Science' seemingly confirms that the Southern Ocean is soaking up more carbon dioxide (CO2) from the atmosphere than it is releasing. The study results are in direct contrast to some recent reports that suggested the region might not be soaking up as much atmospheric CO2 as previously thought. However, the new study now reestablishes conventional beliefs that the area is, indeed, a significant carbon sink and plays an integral part in maintaining the global carbon cycle.
The increase in carbon levels in the atmosphere directly results from human activity, including burning fossil fuels, such as petroleum and coal. It is also understood that CO2 levels in the air are generally higher over the northern hemisphere, where there are more people and hence, more emissions than in the southern hemisphere. While the Southern Ocean and the Amazon rainforest have long served as important carbon sinks, the role of the latter has steadily dwindled over the past few decades because of rapid deforestation.
The latest report about the Southern Ocean's role in maintaining atmospheric carbon dioxide comes from a study published last month in Science. The study includes observations from research aircraft and shows that the waters in the region absorbed roughly 530 million metric tons more carbon than they released each year. Overall, the Southern Ocean is said to absorb about 550 million tonnes of carbon from the atmosphere every year, which is about 18-percent of all carbon absorbed by the world's oceans combined. The study was funded by NASA, National Oceanic and Atmospheric Administration (NOAA), and the National Science Foundation.
Measuring Atmospheric CO2 Levels Was Important
The research was based on the levels of atmospheric carbon measured by the Global Monitoring Laboratory of the NOAA. According to NOAA, two sets of CO2 levels were measured to get to the conclusion. While the first set of data came from measuring samples collected by NOAA during airborne missions, the second set of data was derived from the surface monitoring stations of NOAA's Global Greenhouse Gas Reference Network.
Explaining the value of atmospheric CO2 levels and why the researchers went about collecting samples from the air instead of relying on the carbon dioxide levels in the water, Colm Sweeney, a co-author of the study and a scientist with NOAA's Global Monitoring Laboratory, said that studying airborne samples offers a better understanding of the carbon absorption as the samples are collected from a vast area, often stretching up to thousands of kilometers. "These measurements allow us to see the strong summer uptake and near-neutral winter outgassing over the Southern Ocean," he said.