Acidification of the western Arctic Ocean is occurring three to four times faster than in other ocean basins, new research shows.
The ocean, which absorbs a third of all carbon dioxide in the atmosphere, has become more acidic due to the use of fossil fuels. The rapid loss of sea ice in the Arctic region over the past three decades has accelerated the rate of long-term acidification, according to a study published in the journal Science on Thursday.
Researchers from the Institute of Polar and Marine Research at Jimei University, China, and the School of Marine Science and Policy at the University of Delaware in the US, say the rapid loss of sea ice exposes seawater to the atmosphere, promoting the absorption of atmospheric carbon dioxide. faster than in the Atlantic, Pacific, Indian, Antarctic and Subantarctic basins.
“In other ocean systems, acidification is driven by increases in atmospheric carbon dioxide, which is increasing at a rate of about 2 ppm [parts per million] per year,” said Wei-Jun Tsai, an expert in marine chemistry at the University of Delaware and one of the authors of the paper.
Acidification trends tend to follow those predicted from increasing carbon dioxide over time, he said. But when scientists compared data collected from the Arctic between 1994 and 2020 with ocean basins elsewhere, they found that acidification is happening much faster in the Arctic.
“We were shocked to see that acidification was happening three to four times faster,” Tsai said.
If sea ice continues to disappear in the western Arctic, the process could continue and intensify over the next few decades, scientists predict.
The research follows a separate study in August, which found the Arctic has warmed about four times the global average over the past 43 years. The faster warming, known as Arctic amplification, is a feedback process driven by melting sea ice, which also leads to faster acidification, researchers say.
“Melting ice dilutes or reduces the alkalinity of seawater.” This dilutes the water’s buffering capacity, its ability to resist acidification,” Tsai said.
The effect of altered seawater chemistry will have “huge implications” for marine life, Cai predicted. As an example, he cited studies showing that ocean acidification poses a threat to coral reefs.
“In lower latitudes you have coral reefs and if you add carbon dioxide to the water, the carbon saturation rate will increase and the corals will not grow,” he said. Acidification reduces the carbonate ions needed to build coral skeletons.
The lower pH, or acidity, of seawater can affect many systems and even make some metals more toxic, he added.
“We are far from knowing the cost of biological systems.” We do not know which organisms might be affected. It’s something the biological community needs to consider.”