Carbon dioxide emissions are killing off coral reefs and kelp forests as heat waves and ocean acidification damage marine ecosystems, scientists have warned.
Writing in Scientific Reports, researchers say that three centuries of industrial development have already had a marked effect on our seas.
But if CO2 levels continue to rise as predicted, the coming decades and lowering seawater pH levels will have an even greater and potentially catastrophic impact.
Their predictions follow a comprehensive study of the effects of recently discovered volcanic CO2 seeps off Shikine Island, Japan, which is on the border of temperate and tropical climates.
Ocean currents in the area mean there are naturally low levels of surface water CO2, similar to those that would have been present before the global Industrial Revolution. However, the volcanic seeps indicate how rising CO2 levels will affect future ecology, both in the northwest Pacific Ocean and across the world.