Posted on SFGate: 15 Aug 2014 — By Ken Caldeira
The sun sets over the Pacific as powerful waves crash on the rocky shore. We are witnessing a scene that could have been seen billions of years ago. Except now, emissions from our tailpipes and smokestacks are making it more and more likely that those waves crashing against the rocks will be corrosive, dissolving seashells. This process is known as “ocean acidification.”
Dick Feely and his colleagues at Pacific Marine Environmental Laboratory in Seattle have been observing waters along the West Coast, and have seen corrosive water along the shore in Northern California. My friend Tessa Hill, working at the Bodega Marine Laboratory of UC Davis, has been looking into the effects ocean acidification might have on the oyster farms in Tomales Bay – and the news is not good. It looks as if ocean acidification can harm oysters, especially in their larval stages.
My research group has been looking into effects of ocean acidification in Australia’s Great Barrier Reef. One reef we studied is growing 40 percent more slowly than it was just a few decades ago. We project that all of the coral reefs of the world may be dissolving within several decades, if current patterns of carbon dioxide emissions continue.
Carbon dioxide in the atmosphere acts as a greenhouse gas, causing the Earth to warm. But most of the carbon dioxide we emit to the atmosphere eventually will be absorbed by the ocean. And once in the oceans, that carbon dioxide becomes carbonic acid, where it can attack the shells and skeletons of marine organisms. Even if this carbonic acid is not in high enough concentrations to dissolve a seashell, it can make it harder for that clam or sea urchin or oyster to build its shell. And if it is working harder to build its shell, it will have less energy left over to look for food, reproduce or defend itself from predators.
The rate of calcium carbonate shell production has been closely tied to carbon dioxide supply for hundreds of millions of years. The greenhouse gas carbon dioxide comes out of volcanoes. Meanwhile, mountains erode and partially dissolve, and these dissolved minerals flow down streams and rivers to the sea. In the sea, organisms, including oysters and sea urchins and corals, take those dissolved minerals and combine them with dissolved carbon dioxide to form calcium carbonate shells or skeletons. This natural cycle has been highly balanced over most of Earth’s history, with the rate of shell production almost exactly balancing volcanic emissions of carbon dioxide.
Unfortunately, today, about 100 times more carbon dioxide comes out of smokestacks and tailpipes than comes out of all of the volcanoes of the world. A 100 times increase is just too much for Earth’s natural cycles to take care of without expecting some kind of reaction.
When we are overwhelming natural cycles by a factor of 100, small changes will make little difference. If we want to protect our oceans, we need to stop building things with smokestacks and tailpipes. The days when it was OK to use the sky as a sewer and the sea as a cesspool are long over – modern civilization has become too large to consider the sea and sky as infinite.
Yes, there are things we can do to help. Establishing and protecting marine reserves, avoiding unsustainable fishing, and decreasing coastal pollution can all help marine ecosystems be more resilient. Buying hybrid cars, using compact fluorescent light bulbs, and eating less meat all can help, but there is a limit to what individual action can do.
Solving the ocean acidification problem will take societal resolve – our politicians must understand that they cannot ignore the health of the planet and expect to get re-elected. But the main solution to the ocean acidification problem is building an energy system that does not dump its waste into the air and ocean. We need power plants and transportation systems that do not depend on having smokestacks and tailpipes.
When the dinosaurs became extinct, most of the marine species that created calcium carbonate shells became extinct at the same time – likely due to a brief ocean acidification event. It took hundreds of thousands of years for marine ecosystems to recover, and what eventually developed was not the same as what was lost.
If we want our children’s children to be able to go down to the sea, and watch the sunset over crashing waves that are not corrosive, and want our children’s children be able to pick up a seashell and wonder where it came from – It came from volcanoes and dissolving mountains! – we should start building energy and transportation systems that respect the sea and sky.
To learn more
The West Coast Ocean Acidification and Hypoxia Science Panel has been formed to help inform decision makers about these threats to our ocean waters.
Go to www.westcoastoah.org.
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