Due to climate change, the Arctic Ocean could in future be more acidic in summer than in winter. The authors of a study published in the journal "Nature" came to this conclusion. Naturally, acidification in the Arctic Ocean is greatest in winter. But with increasing global warming, it could increase in the summer in the future.

"These results worsen the prospects for some Arctic fish, such as polar cod, which are already threatened by climate change," said co-author Hans-Otto Pörtner, from the Alfred Wegener Institute (AWI), the Helmholtz Center for Polar and Marine Research , in Bremerhaven.

According to the AWI, over the past 200 years the oceans have absorbed more than a quarter of the man-made carbon dioxide (CO2) from the atmosphere. They have therefore become almost 30 percent more acidic since the beginning of the industrial revolution. However, the acidity of the water varies depending on the season and region.

According to the AWI, air temperatures in the Arctic will rise more sharply in summer than before, more sea ice will melt and the water will warm up more quickly than before, also due to increased solar radiation. According to researchers, there are complex reasons why the Arctic Ocean will become more acidic in the summer as a result. Acidification is not only influenced by one factor, but by a sensitive interaction of physicochemical and biological processes. Ultimately, it can no longer be compensated - for example by algae that carry out photosynthesis and thus absorb CO2.

In their study, the researchers analyzed simulations of several models and developed future climate scenarios. The changes in acidification were larger for medium and high greenhouse gas emissions - and significantly smaller for low emissions. "For the researchers, a glimmer of hope that key elements of the Arctic Ocean ecosystem can be preserved if average global warming can be kept below two degrees Celsius," the statement said.