Oceans becoming more acidic at unprecedented rate

The acidity of Earth’s oceans is increasing at an unprecedented rate, according to an 2010 Earth Day (April 22) announcement today by the National Research Council. They recently completed a study on this subject, at the request of the U.S. Congress.

Some of you reading this post don’t believe we humans can affect nature, especially aspects of nature so vast as Earth’s oceans or air.  But here is more evidence we can affect nature. The National Research Council – scientists who studied for years and then worked for decades to understand Earth’s intricacies – are saying that, unless man-made carbon dioxide (CO2) emissions are substantially curbed, or atmospheric CO2 is controlled by some other means, the ocean will continue to become more acidic.

They say that long-term consequences of ocean acidification on marine life are unknown, but that many ecosystem changes are expected to result.

Here’s how it works. CO2 is a natural substance, a gas needed by earthly plants to thrive. But now that we humans number 6.8 billion and counting, some of our everyday activities – the fossil-fuels we burn to drive our cars and run our machines, deforestation, and (says the National Research Council) cement production, causes us to emit more CO2 than would naturally be in Earth’s air. This excess has to go somewhere, and, as it turns out, our world’s vast ocean absorbs approximately a third of man-made CO2 emissions.

The CO2 taken up by the ocean decreases the pH of the water. This process – excess CO2 absorbed by ocean waters – leads to a combination of chemical changes collectively known as ocean acidification.

Since the beginning of the Industrial Revolution, the average pH of ocean surface waters has decreased approximately 0.1 unit – from about 8.2 to 8.1 – making them more acidic.  Models project an additional 0.2 to 0.3 drop – meaning a still more acid ocean – by the end of the 21st century.  This rate of change exceeds any known to have occurred in hundreds of thousands of years, according to the National Research Council.

Studies on a number of marine organisms have shown that lowering seawater pH affects biological processes. Photosynthesis, nutrient acquisition, growth, reproduction, and individual survival all may be affected. The affect varies with how much acidification is present, and by species.  Reef-building corals are suffering severely, as well as several types of plankton at the base of marine food webs. Can these organisms adapt to a more acid ocean? No one knows.

On EarthSky’s Facebook page the other day, someone was remarking on the introduction of alien species – carried by humans from one part of Earth to another – in Hawaii. That’s another way we humans affect Earth, but her comment holds true for this situation as well.

She said, “It makes the same feeling as when somebody near you dies, and you say ‘I didn’t show her/him enough interest, or love, or…'”

Happy Earth Day, y’all.

April 22, 2010

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