 continues it could still reduce the region’s ability to take up carbon. Dutkiewicz also said the study’s findings have applications beyond the Arctic’s borders.
"The processes we’re looking at are happening everywhere,” Dutkiewicz said. “We need to be studying it (in the Arctic) and understanding the changes. That will help us understand what will happen in 20 or 50 years in other parts of other oceans.”
The other study, a review published in Nature, found that coastal oceans are also helping store carbon. Coastals oceans account for only 7 percent of the overall area of oceans, but the new study finds they play an outsize role when it comes to carbon storage.
Coastal zones weren’t always carbon sinks. Prior to the Industrial Revolution, oceans acted as net emitters of carbon. However, in the ensuing 50-100 years, a shift occurred and these areas now take up more carbon than they emit.
The new research estimates that in pre-industrial times, coastal areas emitted about 150 million metric tons of carbon a year. Presently they take up 250 million metric tons annually. That’s about equivalent to Turkey’s carbon emissions in 2008.
An algae bloom off the coast of Bordeaux, France in May 2013.
Credit: NASA Goddard Photo and Video/Flickr
“Traditionally, most thinking has been that there’s a shift in biological production in recent decades, that the ocean has become more productive,” said Wei-Jun Cai, an oceanographer at the University of Delaware and author of the report. The reason, he said, is because increased runoff from agriculture finds it way down rivers and into the coastal zone, which in turn increases plant life.
However, Cai believes there’s another mechanism at play. Measurements in the open ocean of carbon dioxide in the water and the atmosphere tend to show the two stay pretty close to equilibrium. In other words, if there’s 400 parts per million of carbon dioxide in the atmosphere, a similar ratio is likely to exist in the ocean waters.
That relationship doesn’t exist in coastal areas, though. Cai recalled a trip to measure carbon dioxide in the water off the Georgia coast in 2005.
“It was very similar to what someone else measured in 1995,” he said about his measurements. “I was shocked as there was very little increase. The reason is the water doesn’t stay there for a long enough time so it doesn’t really accumulate the anthropogenic signal.”
Instead, water in coastal zones is constantly on the move thanks to the conveyor belt of ocean currents. Those currents eventually dive to the depth of the ocean, and could be storing the carbon down there according to Cai’s theory.
Both studies point to the need for better monitoring in both those regions. They offer tantalizing results that suggest revisiting our understanding of the globe’s carbon budget, but more data is needed to reinforce their results.
That data would not only inform a better understanding of the planet’s carbon budget, but also paint a clearer picture of how regions that have great economic and environmental importance are changing.
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