Paleo-perspectives on ocean acidification

13 pages, 2 figuresThe anthropogenic rise in atmospheric CO2 is driving fundamental and unprecedented changes in the chemistry of the oceans. This has led to changes in the physiology of a wide variety of marine organisms and, consequently, the ecology of the ocean. This review explores recent advances in our understanding of ocean acidification with a particular emphasis on past changes to ocean chemistry and what they can tell us about present and future changes. We argue that ocean conditions are already more extreme than those experienced by marine organisms and ecosystems for millions of years, emphasising the urgent need to adopt policies that drastically reduce CO2 emissionsE.C. and C.P. acknowledge funding from the Spanish Ministerio de Ciencia e Innovación through grants CTM2006-01957/MAR, CTM2008-01614-E/MAR, CTM2009-08849, CSD2008-00077 and a Ramón y Cajal contract to E.C. O.H.G. would like to acknowledge support from the Coral Reef Targeted Research Program of the World Bank and Global Environment Fund (www.gefcoral.org) and the Australian Research Council Centre for Excellence in Coral Reef Studies (www.coralcoe.org.au). This is a contribution from the Marine Biogeochemistry and Global Change research group, funded by Generalitat de Catalunya (Catalan Government) through grant 2009SGR142Peer reviewe