MCCIP Ecosystem Linkages Report Card 2009 CO2 and ocean acidification

The oceans are an enormous store of carbon, substantially greater than on land or in the atmosphere and hence play a key role in the global carbon cycle, especially in helping regulate the amount of CO2 in the atmosphere. The oceans are important because they have taken up around 27-34% of the CO2 produced by humankind through the burning of fossil fuels, cement manufacturing and land use changes since the industrial revolution. Whilst this has somewhat limited the historical rise of CO2 in the atmosphere, thereby reducing the extent of greenhouse warming and climate change caused by human activities, this has come at the price of a dramatic change to ocean chemistry. In particular, and of great concern, is the measurable change in ocean pH and carbonate and bicarbonate ion concentration – ‘ocean acidification’. Our understanding of the impact of CO2 on the carbonate chemistry is such that we know with very high certainty that ocean acidification will continue, tracking future CO2 emissions to the atmosphere.