Oceanographers from MIT and Woods Hole Oceanographic Institution report that the northeast Pacific Ocean has absorbed an increasing amount of anthropogenic carbon dioxide over the last decade, at a rate that mirrors the increase of carbon dioxide emissions pumped into the atmosphere. The scientists, led by graduate student Sophie Chu, in MIT’s Department of Earth, Atmospheric, and Planetary Sciences, found that most of the anthropogenic carbon (carbon arising from human activity) in the northeast Pacific has lingered in the upper layers, changing the chemistry of the ocean as a result. In the past 10 years, the region’s average pH has dropped by 0.002 pH units per year, leading to more acidic waters. The increased uptake in carbon dioxide has also decreased the availability of aragonite — an essential mineral for many marine species’ shells. Overall, the researchers found that the northeast Pacific has a similar capacity to store carbon, compared to the rest of the Pacific. However, this carbon capacity is significantly lower than at similar latitudes in the Atlantic. “The ocean has been the only true sink for anthropogenic emissions since the industrial revolution,” Chu says. “Right now, it stores about 1/4 to 1/3 of the anthropogenic emissions from the atmosphere. We’re expecting at some point the storage will slow down. When it does, more carbon dioxide will stay in the atmosphere, which means more warming. So it’s really important that we continue to monitor this.” Chu and her colleagues have published their results in the Journal of Geophysical Research: Oceans.
From MIT Photo Credit John Vlahakis