Jul
05
2010

Ocean Acidification Unprecedented in Earth History

Much attention and debate is focused on the role of human releases of carbon dioxide (CO2) in global warming and climate change but there is another facet of CO2 that deserves much more attention. Increasing concentrations of CO2 in the atmosphere lead to more and more CO2 dissolving into the oceans where it turns into carbonic acid. A story in the June 18 issue of Science reports that there is no doubt whatsoever that human releases of CO2 are acidifying the oceans at a scale unprecedented in the geologic record.

The closest analogue to present day appears to be the Paleocene-Eocene Thermal Maximum (PETM) of 55.8 million years ago. Over the course of several thousand years, huge amounts of methane and CO2 entered the atmosphere (where the methane was quickly converted to CO2). Much of this CO2 dissolved into the oceans, causing a drop in ocean pH. The difference between the present and the PETM is that human releases of CO2 are occurring at a rate at least ten times faster. At takes about 1,000 years for CO2 dissolved in surface waters to reach the deep sea where sediments eventually neutralize the acid. Human releases of CO2 currently far exceed the rate at which the oceans are able to remove it and so the result is a rapid drop in the pH of surface waters.

Many ocean organisms make their shells from carbonate. Acidification changes carbonate into bicarbonate and hydrogen ions, making the mineral much less available to tropical corals, echinoderms, mollusks, and foraminifera. The danger if ocean acidification continues unabated is potentially dramatic and unpredictable changes in marine life everywhere.

Some policymakers and scientists increasingly are raising the idea of perhaps mitigating the effects of climate change through large-scale geoengineering projects intended to reduce the amount of solar energy reaching the Earth’s surface as a last ditch effort to counteract the effects of greenhouse gas warming. Such projects would do nothing to mitigate the growing problem of our acidifying oceans. The only way to reduce ocean acidification is to reduce globally the quantities of CO2 that humans release into the atmosphere.

Your Comments, Thoughts, Questions, Ideas

Shana's picture
Shana says:

So once again we see that a quick fix just isn't going to take care of the problem...that's so scary about the shells, coral, etc. It would change the entire character of our oceans.

posted on Tue, 07/06/2010 - 9:33am
bryan kennedy's picture

I'd heard about ocean acidification for a while before I understood how it worked. For some reason I had it set into my mind that acidification happens by runoff from rivers or direct pollution from ships or anything. But, just to be clear, as Pat points about above, I was WRONG. I wonder if other people have that misconception about this problem.

It took me a while to understand that the carbon we place in our atmosphere affects the oceans that the atmosphere sits in contact with every day. Since the ocean has such an enormous surface area for the atmosphere to interact with, even small changes in percentage of carbon in the massive, but thin atmosphere can result in quite the effect in the ocean.

posted on Wed, 07/07/2010 - 10:25am

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