Ocean Acidification: The Other CO2 Problem

The Chemistry

Carbon dioxide pollution is transforming the chemistry of the ocean, rapidly making the water more acidic.

Caldeira, K. and M. E. Wickett. 2003. Anthropogenic carbon and ocean pH. Nature 425:365-365 Link to article

RoyalSociety. 2005. Ocean acidification due to increasing atmospheric carbon dioxide. The Royal Society: the science policy section, London. Link to article

Recent Changes in Ocean Chemistry

Since the industrial revolution, the ocean has absorbed roughly one-quarter of the carbon dioxide produced by burning fuels.

Sabine, C. L., R. A. Feely, N. Gruber, R. M. Key, K. Lee, J. L. Bullister, R. Wanninkhof, C. S. Wong, D. W. R. Wallace, B. Tilbrook, F. J. Millero, T. H. Peng, A. Kozyr, T. Ono, and A. F. Rios. 2004. The oceanic sink for anthropogenic CO2. Science 305:367-371 Link to article

Orr, J. C., V. J. Fabry, O. Aumont, L. Bopp, S. C. Doney, R. A. Feely, A. Gnanadesikan, N. Gruber, A. Ishida, F. Joos, R. M. Key, K. Lindsay, E. Maier-Reimer, R. Matear, P. Monfray, A. Mouchet, R. G. Najjar, G. K. Plattner, K. B. Rodgers, C. L. Sabine, J. L. Sarmiento, R. Schlitzer, R. D. Slater, I. J. Totterdell, M. F. Weirig, Y. Yamanaka, and A. Yool. 2005. Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature 437:681-686. Link to article

Since the industrial revolution, the ocean acidity has increased by 30 percent.

Caldeira, K. and M. E. Wickett. 2003. Anthropogenic carbon and ocean pH. Nature 425:365-365 Link to article

RoyalSociety. 2005. Ocean acidification due to increasing atmospheric carbon dioxide. The Royal Society: the science policy section, London. Link to article

Already we've seen water showing up off the coast of northern California that's acidic enough to actually start dissolving seashells. It's thought that this kind of corrosive water showing up will become more and more common.

Feely, R. A., C. L. Sabine, J. M. Hernandez-Ayon, D. Ianson, and B. Hales. 2008. Evidence for upwelling of corrosive "acidified" water onto the continental shelf. Science 320:1490-1492. Link to article

Projected Changes in Ocean Chemistry

With mathematical models scientists have demonstrated that if we continue to pollute as we are now, the ocean acidity will double by the end of the century, compared to pre-industrial times.

Caldeira, K. and M. E. Wickett. 2005. Ocean model predictions of chemistry changes from carbon dioxide emissions to the atmosphere and ocean. Journal of Geophysical Research-Oceans 110. Link to article

Orr, J. C., V. J. Fabry, O. Aumont, L. Bopp, S. C. Doney, R. A. Feely, A. Gnanadesikan, N. Gruber, A. Ishida, F. Joos, R. M. Key, K. Lindsay, E. Maier-Reimer, R. Matear, P. Monfray, A. Mouchet, R. G. Najjar, G. K. Plattner, K. B. Rodgers, C. L. Sabine, J. L. Sarmiento, R. Schlitzer, R. D. Slater, I. J. Totterdell, M. F. Weirig, Y. Yamanaka, and A. Yool. 2005. Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature 437:681-686. Link to article

By mid-century if we continue emitting carbon dioxide the way we have been, entire vast areas of both the Southern Ocean and the Arctic Ocean will be so corrosive that it will cause seashells to dissolve.

Orr, J. C., V. J. Fabry, O. Aumont, L. Bopp, S. C. Doney, R. A. Feely, A. Gnanadesikan, N. Gruber, A. Ishida, F. Joos, R. M. Key, K. Lindsay, E. Maier-Reimer, R. Matear, P. Monfray, A. Mouchet, R. G. Najjar, G. K. Plattner, K. B. Rodgers, C. L. Sabine, J. L. Sarmiento, R. Schlitzer, R. D. Slater, I. J. Totterdell, M. F. Weirig, Y. Yamanaka, and A. Yool. 2005. Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature 437:681-686. Link to article

Steinacher, M., F. Joos, T. L. Frolicher, G. K. Plattner, and S. C. Doney. 2009. Imminent ocean acidification in the Arctic projected with the NCAR global coupled carbon cycle-climate model. Biogeosciences 6:515-533. Link to article

In decades, rising ocean acidity may challenge life on a scale that has not occurred for tens of millions of years.

Pearson, P. N., and M. R. Palmer. 2000. Atmospheric carbon dioxide concentrations over the past 60 million years, Nature, 406, 695-699, doi:10.1038/35021000. Link to articlel

Caldeira, K. and M. E. Wickett. 2003. Anthropogenic carbon and ocean pH. Nature 425:365-365. Link to article

F.T. Mackenzie, R.S. Arvidson, M. Guidry. 2008. Chemostatic modes of the ocean-atmosphere-sediment system through Phanerozoic time. Mineralogical Magazine, 72, 329-332. Link to article

Impacts to Shelled Organisms

So by removing the essential building block for shell formation, it's making the organisms work a lot harder to build their shells, and that means they have less energy to get food, they have less energy to reproduce, and eventually the organism can no longer compete ecologically. The surprise is how sensitive some marine organisms are to this increased acidity from carbon dioxide. And when acidity gets too high, shells dissolve.

Feely, R. A., C. L. Sabine, K. Lee, W. Berelson, J. Kleypas, V. J. Fabry, and F. J. Millero. 2004. Impact of anthropogenic CO2 on the CaCO3 system in the oceans. Science 305:362-366. Link to article

Fabry, V. J. 2008. Ocean science - Marine calcifiers in a high-CO2 ocean. Science 320:1020-1022. Link to article

Sensitivity of Pteropods

Pteropods are a kind of plankton that live all around the world and in great abundance in polar waters. Pteropods are especially vulnerable.

Orr, J. C., V. J. Fabry, O. Aumont, L. Bopp, S. C. Doney, R. A. Feely, A. Gnanadesikan, N. Gruber, A. Ishida, F. Joos, R. M. Key, K. Lindsay, E. Maier-Reimer, R. Matear, P. Monfray, A. Mouchet, R. G. Najjar, G. K. Plattner, K. B. Rodgers, C. L. Sabine, J. L. Sarmiento, R. Schlitzer, R. D. Slater, I. J. Totterdell, M. F. Weirig, Y. Yamanaka, and A. Yool. 2005. Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature 437:681-686. Link to article

Fabry, V. J. 2008. Ocean science - Marine calcifiers in a high-CO2 ocean. Science 320:1020-1022. Link to article

Sensitivity of Corals

We know that coral reefs are particularly sensitive to ocean acidification and the reason for that is that corals are unable to form their skeletons as quickly as they used to

Kleypas, J. A., R. W. Buddemeier, D. Archer, J. Gattuso, C. Landon, and B. N. Opdyke. 1999. Geochemical Consequences of Increased Atmospheric Carbon Dioxide on Coral Reefs. Science 284:118-120. Link to article

Gattuso, J. P., M. Frankignoulle, I. Bourge, S. Romaine, and R. W. Buddemeier. 1998. Effect of calcium carbonate saturation of seawater on coral calcification. Global and Planetary Change 18:37-46. Link to article

Langdon, C., T. Takahashi, C. Sweeney, D. Chipman, J. Goddard, F. Marubini, H. Aceves, H. Barnett, and M. J. Atkinson. 2000. Effect of calcium carbonate saturation state on the calcification rate of an experimental coral reef. Global Biogeochemical Cycles 14:639-654. Link to article

Marubini, F., C. Ferrier-Pages, and J. P. Cuif. 2003. Suppression of skeletal growth in scleractinian corals by decreasing ambient carbonate-ion concentration: a cross-family comparison. Proceedings of the Royal Society of London Series B-Biological Sciences 270:179-184. Link to article

Kleypas JA, Feely RA, Fabry VJ, Langdon C, Sabine CL, Robbins LL. 2006. Impacts of ocean acidification on coral reefs and other marine calcifiers: a guide for future research. 88 pp. Report of a workshop sponsored by NSF, NOAA, and the U.S. Geological Survey. St. Petersburg, Florida Link to article

Hoegh-Guldberg, O., P. J. Mumby, A. J. Hooten, R. S. Steneck, and E. G. P. Greenfield, C. D. Harvell, P. F. Sale, A. J. Edwards, K. Caldeira, N. Knowlton, C. M. Eakin, R. Iglesias-Prieto, N. Muthiga, R. H. Bradbury, A. Dubi, M. E. Hatziolos. 2007. Coral reefs under rapid climate change and ocean acidification. Science 318:1737-1742. Link to article

Marine life that might withstand warming temperatures or rising acidity may succumb when confronted by both. Coral reefs already struggle to survive in warming waters. Rising ocean acidity puts them in double jeopardy.

Smith, S. V. and R. W. Buddemeier. 1992. GLOBAL CHANGE AND CORAL-REEF ECOSYSTEMS. Annual Review of Ecology and Systematics 23:89-118. Link to article

Reynaud, S., N. Leclercq, S. Romaine-Lioud, C. Ferrier-Pages, J. Jaubert, and J. P. Gattuso. 2003. Interacting effects of CO2 partial pressure and temperature on photosynthesis and calcification in a scleractinian coral. Global Change Biology 9:1660-1668. Link to article

Anthony, K. R. N., D. I. Kline, G. Diaz-Pulido, S. Dove, and O. Hoegh-Guldberg. 2008. Ocean acidification causes bleaching and productivity loss in coral reef builders. Proceedings of the National Academy of Sciences of the United States of America 105:17443-17446. Link to article

. . . one in every four species in the ocean lives on a coral reef.

Spalding M, Ravilious C, Green EP (2001) World Atlas of Coral Reefs. Univ. of California Press

We may lose those ecosystems within 20 or 30 years.

Hoegh-Guldberg, O., P. J. Mumby, A. J. Hooten, R. S. Steneck, and E. G. P. Greenfield, C. D. Harvell, P. F. Sale, A. J. Edwards, K. Caldeira, N. Knowlton, C. M. Eakin, R. Iglesias-Prieto, N. Muthiga, R. H. Bradbury, A. Dubi, M. E. Hatziolos. 2007. Coral reefs under rapid climate change and ocean acidification. Science 318:1737-1742. Link to article

Silverman, J., B. Lazar, L. Cao, K. Caldeira, and J. Erez. 2009. Coral reefs may start dissolving when atmospheric CO2 doubles. Geophysical Research Letters 36. Link to article

Impacts to Fisheries

Ocean acidity will rise most quickly in cold water regions, and areas where deep water wells up to the surface. That is disconcerting because it coincides with the regions of the most productive fisheries in the world.

McKinnell, S. 2008. Salmon pHishing in the northeast Pacific: an archaeological dig in the North Pacific survey data (1956-1964) - abstract at The Ocean in a High-CO2 World, Monaco October 2008.

Benefits of Ecosystem Resilience

To make the oceans more resilient to these changes, we need to do a better job of keeping the oceans healthy. That means restoring depleted fish populations, establishing marine protected areas all around the globe and reducing pollution, particularly nutrient pollution in the coastal zones.

Palubmi, S. R., K. L. McLeod, D. Grünbaum. 2008 Ecosystems in actions: lessons from marine ecology about recovery, resistance, and reversibility. Bioscience 58(1) 33-42. Link to article

Levin, S. E., J. Lubchenco. 2008. Resilience, robustness, marine ecosystem based management. Bioscience. 58(1) 27-32. Link to article

Solution

The only way to stop acidification is to emit less carbon dioxide.

RoyalSociety. 2005. Ocean acidification due to increasing atmospheric carbon dioxide. The Royal Society: the science policy section, London. Link to article

UNESCO. 2009. Monaco Declaration. http://ioc3.unesco.org/oanet/HighCO2World.html

Doney, S. C., V. J. Fabry, R. A. Feely, and J. Kleypas. 2009. Ocean Acidification: The Other CO2 Problem. Annual Review of Marine Sciences 1:169-192. Link to article

For more information, view measurements illustrating the process of ocean acidification.