Global warming will disrupt four-fifths of the world's oceans by 2050 if greenhouse gas emissions keep rising, threatening fish that are the main source of food for a billion people, scientists say.
Curbs on man-made emissions, however, would give marine life more time to adapt to warming conditions or shift to cooler waters nearer the poles.
"By 2050 around four-fifths of the ocean surface will be affected by ocean acidification and ocean warming," lead author Stephanie Henson, of the British National Oceanography Centre in Southampton said on Tuesday.
Carbon dioxide, the main greenhouse gas, forms a weak acid in water. Currently, only about 10 per cent of the oceans are under stress from the twin impacts of high temperatures and acidification, she said.
Cuts in greenhouse gas emissions, in line with goals set by almost 200 nations under a Paris Agreement on climate change in 2015, could limit the impact to two-thirds of the ocean by 2050, giving marine life more time to adapt.
However declines in the amount of oxygen in the waters and a reduction in nutrients, both linked to climate change, would add to stresses on the oceans this century.
The effects on individual species of seafood - such as lobsters, herring, sharks or whales - and on the ocean life as a whole were "poorly understood", the scientists wrote in the journal Nature Communications.
Many fish species, such as cod or haddock, are already moving north in the Atlantic to cooler waters.
