Rapid acidification of western Arctic Ocean is driven by sea ice loss

Ocean acidification due to increased uptake of anthropogenic atmospheric carbon dioxide is happening all over the world, but a new study by Di Qi and colleagues shows that acidification in the western Arctic Ocean is happening at a rate three to four times higher than in other ocean basins. They suggest this increase has been driven by the rapid loss of sea ice in the region, which has exposed carbon dioxide-poor waters to the atmosphere where they can absorb more CO₂. Qi et al. analyzed data collected from 47 Arctic research cruises from 1994 to 2020 to estimate changes in seawater pH and the saturation state of the calcium carbonate mineral aragonite, both measures of ocean acidification. Not only did their results reveal a faster pace of acidification for the western Arctic compared to other global oceans, but it showed a surprising correlation of these two features with the regional decrease in sea ice over the past 26 years. If sea ice continues to disappear in the western Arctic, this process could continue and intensify over the next few decades, the researchers write. They also note that the phenomenon of seasonally melting sea ice exposing more water to sea-gas exchange could affect acidification at the Southern Ocean as well.