It will take more than 700 years to reverse ocean acidification to the point of pre-industrial conditions, even with the most aggressive carbon dioxide removal techniques, scientists have said.
Scientists from the Potsdam Institute for Climate Impact Research in Germany say that if we were to remove CO2 from the atmosphere at a rate of 2.5 times that of the current annual emissions, oceans would not recover to a low-emission state by 2700.
Publishing their findings in the journal Nature Climate Change, the scientists used computer models to stimulate the effects of CO2 removal on the marine environment.
They imagined two scenarios – one where five gigatonnes of carbon is removed every year, which is equivalent to around half of our total annual emissions, and another where 25 gigatonnes of carbon is removed. In both scenarios, CO2 emission rates were under "business as usual" conditions.
Carbon dioxide removal (CDR) has been proposed as a means to mitigate global warming and ocean acidification. To work out how effective this would be, the team looked at the pH, temperature and dissolved oxygen: "we find that even after several centuries of CDR deployment, past CO2 emissions would leave a substantial legacy in the marine environment".