The rate at which Arctic seas absorb carbon dioxide has increased as a result of melting ice, which has accelerated the rate at which these waters are becoming more acidic. The change might throw entire marine ecosystems into disarray.
Icy seas around the shore of Spitsbergen, which is located in Svalbard, in the Arctic Ocean
Photograph by Stuart Melvin/Alamy
Due to the unprecedented rate at which ice is melting, the western Arctic Ocean is acidifying at a rate that is four times quicker than other oceans.
The process that leads to ocean acidification is called “seawater absorption of atmospheric carbon dioxide.” Because of the rise in atmospheric CO2 since the beginning of the industrial revolution, the average acidity of the world's seas has increased by 30 percent, which has had extensive effects on marine ecosystems.
According to research conducted by Wei-Jun Cai of the University of Delaware, the rate of ocean acidification has closely matched the growing levels of CO2 in the atmosphere across the majority of ocean basins. The Arctic Ocean is distinct because of its low temperatures and year-round ice cover.
Cai and his colleagues looked at data collected on 47 separate journeys to the Arctic between the years 1994 and 2020 in order to have a better understanding of just how different things are there. They took into account not only the pH levels but also the saturation of the mineral aragonite, which is what determines whether or not organisms like coral and oysters are able to produce shells. A higher level of acidification is correlated with lower values of both metrics.
They discovered that the pH dropped nearly four times more quickly on average in the western Arctic than it did in any of the other oceans during the same time period. The saturation of aragonite in the ocean declined three times more quickly than in other oceans. The region of the water that had a low pH and low aragonite content was virtually nonexistent in 1990, but it is expected to make up approximately 7 percent of the entire Arctic Ocean by 2020.
According to Hongjie Wang, an associate professor of chemistry at the University of Rhode Island, “so many things can be touched by this shifting chemistry,” ranging from the plankton to the whales that feed on them. It is not yet known how the impacts of acidification compare to those of other changes, such as warming, but she claims that Arctic ecosystems are more vulnerable to the effects.
According to Jens Terhaar, who works at the Woods Hole Oceanographic Institution in Massachusetts, this study did not take into account the eastern Arctic, which is under the jurisdiction of Russia and has a smaller amount of data available.
The research conducted by Cai's group suggests that the acidification process is being accelerated by the melting of glaciers. When first exposed to air, seawater quickly absorbs carbon dioxide. Additionally, meltwater dilutes molecules that serve as a buffer for absorbed CO2 and reduces the amount of mixing that occurs between the surface and the deeper layers of the ocean. Cai asserts that the formation of a floating freshwater lake on the surface of the ocean can be attributed to the melting of sea ice. He forecasts that the increased acidification will persist for as long as there is summer ice to melt in the ocean.
Terhaar is of the opinion that the melting of sea ice is the primary driver of the accelerated pace of acidity; nevertheless, he acknowledges that there may be additional contributors. The rivers that originate in Siberia and empty into the ocean are likely to have a stronger impact on the environment of the eastern Arctic, for example.