03/18/2010 05:12 am ET | Updated May 25, 2011

Below the Radar: Rising Oceanic CO2 Levels Threaten Sea Life

As the time between sunup and sundown gets shorter and shorter, do you find yourself dreaming of white, sandy beaches and crystal blue water? Maybe grabbing a snorkel and some fins and exploring the cove for coral and sea life? Or is your idea of a great seaside holiday sinking your teeth into a fresh crab or lobster, steamed just right, as the sun sets on the horizon?

As perfect as this picture seems, an invisible chemical is threatening it -- CO2, the heat-trapping pollutant emitted by the burning of fossil fuels. You see, oceans like forests are a natural carbon sink, and have absorbed about a quarter of all CO2 emissions, or about 530 billion tons over the last 250 years. But as it turns out, oceans' capacity to absorb CO2 is not a ready solution to the problems created by our fossil fuel addiction. In fact, as any 11th grader will tell you, add enough CO2 to a solution and you lower the pH, creating a less hospitable environment for many forms of sea life.

How Acidity Affects Sea Life

Increased acidity reduces carbonate -- a chemical used to form the shells and skeletons of many shellfish and corals. The effect is similar to osteoporosis, slowing growth and making shells weaker. If pH levels drop enough, the shells will literally dissolve.

This process will not only harm some of our favorite seafood, such as lobster and mussels, but may also injure some species of smaller marine organisms -- including pteropods and coccolithophores --which are a vital part of the food web. If those smaller organisms are wiped out, the larger animals that feed on them will suffer, as well.

Coral Reef Habitat Faces Greatest Risk

Delicate corals may face an even greater risk than shellfish because they require very high levels of carbonate to build their skeletons. Acidity slows reef-building, which could lower the resiliency of corals and lead to their erosion and eventual extinction. A study published in Geophysical Research Letters warns that if carbon dioxide reaches double pre-industrial levels, coral reefs can be expected to not just stop growing, but also begin to dissolve all over the world.

Coral reefs serve as the home for many other forms of ocean life. Their disappearance would be akin to wiping out the trees of a rainforest, with serious consequences to the reef associated animals, and in turn the fishing and tourism industries which it sustains.

The loss of coral reefs would also reduce the protection that they offer coastal communities against storms surges and hurricanes -- which might become more severe with warmer air and sea surface temperatures due to global warming.

Take Action

Stopping the acidification of our oceans and improving their health will require reducing CO2 emissions, and doing so quickly. Of course, reducing CO2 emissions involves changing the way we fuel our world.

* Use NRDC's Action Center to tell your senators to help save our oceans by passing strong energy and climate legislation.

* Use Simple Steps Household Savings Calculators to see "how low you can go" and how much you can save--in $, CO2 and H2O--when you implement some very basic home improvements and changes to your everyday habits and behaviors.

* Support the creation of marine protected areas. Evidence suggests that coral reefs in protected ocean reserves are less affected by global threats such as global warming and ocean acidification.

And if you are planning a seaside vacation, you can help protect coral reefs by:
* Purchasing coral jewelry,
* Not standing on reefs,
* Avoiding use of sun tan lotions that harm reefs (those that contain chemical UV barriers such as benzophenone and cinnamate and also parabens). These trigger viral infections in coral that can kill them.

Want to learn more? Watch Acid Test: The Movie.