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Dangerous Brew

Are you optimistic for the future of the planet and if so why?
Iglesias-Prieto: “I am conservatively optimistic about the future of the planet. Although the challenges that climate change is imposing on us are quite dramatic, we as species can learn from our collective experience.

Read Roberto Iglesias-Prieto
full Q&A

A diver returns to a favorite childhood snorkeling spot to snap some long-awaited underwater photos. Instead of the wonderland she remembers, a place filled with kaleidoscopic corals, anemones and schools of fish, she encounters only an eerie white wasteland. All around her, the corals are bleached and broken; the reefs are empty. Not a fish is in sight.

As our climate changes, this scene is becoming more and more frequent, with increasingly dire consequences for both coral reef and human communities. Coral reefs not only provide recreational playgrounds for millions of people, they offer critical habitat to nearly a quarter of the world’s fish. In addition, they provide vital protein resources to numerous nations and can serve as barriers against storms. Coral reefs have been around for hundreds of millions of years. How could atmospheric carbon dioxide pose such a threat to these vast and seemingly robust underwater habitats?

According to oceanographers, the ocean has absorbed nearly half of our human-generated carbon emissions since industrial times began more than 200 years ago. And while Earth’s average atmospheric temperature has risen 0.6 degrees Fahrenheit (1 degree C), so too has the average temperature of the global ocean. Corals are extremely sensitive to changes in their environment. If surrounding waters get too warm, many coral polyps simply expel their colorful cohabitants called zooxanthellae. These single-celled algae live inside the coral cells and extract energy from the sun to help feed their coral host. Without them, the coral stops growing and becomes vulnerable to further damages and disease.

And that’s not all. Carbon dioxide packs another punch in the form of pH. When CO2 from the air mixes with seawater, it forms carbonic acid, which in large enough portions, lowers the ocean’s pH. This process, called ocean acidification, is already changing the chemistry of the ocean more rapidly than it has during the past 650,000 years.  The pH of surface waters has decreased from 8.25 to 8.14 since the 1800s, and the Intergovernmental Panel on Climate Change reports that if we continue at our current rate, it will drop another 0.4 units by the year 2100. These pH changes may seem slight however at such levels, but coral experts caution that it could be detrimental for corals and other calcifying organisms at the base of the marine food web: they will have difficulty creating and repairing their skeletons, deteriorate and begin to crumble, taking with them the billions of animals that depend upon them.

National Autonomous University of México researcher Roberto Iglesias-Prieto has discovered a tool that could help researchers determine the health of the coral polyps and their symbiotic algae around the world. If one shines a light into a coral’s calcite skeleton and the coral brightens and reflects the light, all is well. If it absorbs the light, the organisms inside may be in trouble. This happens because suffering coral polyps may allow in excess light, which in essence can overload the algae and coral tissues and lead to further damage.

This innovative diagnostic tool can enhance conservation efforts. However, without concerted efforts to reduce carbon emissions worldwide, such work will not suffice to save our coral reefs. Together, we all need to become part of the solution and work to ensure healthy reefs for ourselves and future generations. Here’s how we can help:

  • Reduce your carbon footprint by conserving energy in your home: replace traditional appliances and light bulbs with those that are energy efficient.
  • Reduce your carbon emissions during travel by biking, carpooling or taking public transportation whenever possible.
  • Most importantly, support policies that encourage research and implementation of alternative, clean-energy fuels along with measures to reduce heat-trapping gases in our atmosphere.

For more solutions, see What Can We Do?

» Feely, D.A., Sabine, C.L. and Fabry, V. J. (2006). Carbon dioxide and our ocean legacy,  http://www.thew2o.net/events/oceans/docs/ocean_acidification_4-5-06.pdf Off-site Link

Kolbert, E. (2006). Annuals of Science, The Darkening Sea, The New Yorker, Nov 20, p.66.

» Enríquez, S., Méndez, E. R., Iglesias-Prieto, R. (2005). Multiple scattering on coral skeletons enhances light absorption by symbiotic algae. Limnology and Oceanography, 50: 1025-1032.
http://www.aslo.org/lo/toc/vol_50/issue_4/1025.pdf Off-site Link
» Hoegh-Guldberg, O., Mumby, P. J., Hooten, A. J., Steneck, R. S. Greenfield, P., Gomez, E. Harvell, C. D., Sale, P. F., Edwards, A. J., Caldeira, K., Knowlton, N., Eakin, C. M., Iglesias-Prieto, R., Muthiga, N., Bradbury, R. H., Dubi, A. and Hatziolos, M. E. (2007). Coral Reefs Under Rapid Climate Change and Ocean Acidification, Science, 318 (5857): 1737-1742. www.sciencemag.org/cgi/content/abstract/318/5857/1737 Off-site Link
» Sabine, C. L., Feely, R. A., Gruber, N., Key, R. M., Lee, K., Bullister, J. L., Wanninkhof, R., Wong, C. S., Wallace, D. W. R., Tilbrook, B., Millero, F. J., Peng, T., Kozyr, A. R., Ono, T. and Rios, A. F. (2004). The Oceanic Sink for Anthropogenic CO2. Science, 305 (5682): 367-371.
www.sciencemag.org/cgi/content/abstract/305/5682/367 Off-site Link
www.sciencedaily.com/releases/2004/07/040719092807.htm Off-site Link

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