The acidity of the Arctic Ocean currently peaks in winter. A modelling study suggests that this peak could shift to the summer in the future — this is bad news for ecosystem functions, food webs and Indigenous communities.
The global ocean is gradually acidifying on multidecadal timescales. This acidification occurs when carbon dioxide generated by human activities is absorbed by the ocean, and produces conditions in which many marine organisms cannot thrive. Writing in Nature, Orr et al.1 present global simulations suggesting that future warming in the Arctic Ocean will cause CO2 levels to peak seasonally in surface waters in the summer, implying that climate change will further accelerate ocean acidification. The resulting increase in acidification would double down on the already heat-stressed ecosystem, with effects that could creep up the food web — further challenging the food security, culture and well-being of Indigenous peoples.