Arctic Ocean food chain disrupted as key tipping point passed

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An irreversible shift in the chemical make-up of the Arctic Ocean driven by climate change is disrupting the region’s food chain, a study suggests.

Widespread loss of Arctic sea ice has led to a sharp fall in levels of a key nutrient, affecting populations of plankton, fish, seabirds and marine mammals, researchers say.

Their analysis reveals that exposure to sunlight of vast shallow regions of the ocean previously covered by ice fuels a process that breaks down the nutrient – nitrate – and removes it from seawater.

Nitrate is vital for the growth of plankton at the base of the Arctic food chain, and reduced levels of the nutrient limit the amount of life the ecosystem can support, the team says.