Q: I was horrified to read recently that our oceans are actually becoming acidic, that the continued burning of fossil fuels is changing the chemistry of our seas. What’s going on?
It’s a known fact that our oceans are becoming more acidic as a result of the increasingly large load of human-generated carbon dioxide (CO2) entering our atmosphere. About 25 percent of all the CO2 we send skyward out of our tailpipes and smokestacks ends up in the world’s oceans, where it triggers chemical reactions in the water column that lead to increased acidification. Researchers estimate that the acidity of our seas has increased 29 percent since the dawn of the Industrial Revolution. If we do not slow down the pace of greenhouse gas emissions, our oceans could be two to three times as acidic in 2100 as they already are today, which could prove disastrous to marine ecosystems and the world’s food chain.
“When carbon dioxide is absorbed by seawater, chemical reactions occur that reduce seawater pH, carbonate ion concentration and saturation states of biologically important calcium carbonate minerals,” reports the National Oceanic and Atmospheric Administration (NOAA). These calcium carbonate minerals, typically abundant in areas where most marine life congregates, are the building blocks for the skeletons and shells of many marine organisms, from oysters to coral. “However, continued ocean acidification is causing many parts of the ocean to become undersaturated with these minerals, which is likely to affect the ability of some organisms to produce and maintain their shells,” adds NOAA. The process will not only wreak havoc on the shellfish we eat, but also on smaller marine organisms that are key components on the lower end of the marine food chain.
According to the Natural Resources Defense Council (NRDC), a leading green group, coral reefs around the world 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,” they write. This would be an unmitigated environmental disaster, given that an estimated one million marine species depend on healthy coral reefs for survival.
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