CLIMATE CHANGING OCEANS

Oceans Acidifying Faster Today Than in Past 300 Million Years; Few parallels for today's rapid ocean changes in geologic record
March 1, 2012 (National Science Foundation)

"The oceans may be acidifying faster today than they did in the last 300 million years… The oceans act like a sponge to draw down excess carbon dioxide from the air…The gas reacts with seawater to form carbonic acid, which over time is neutralized by fossil carbonate shells on the seafloor…If too much carbon dioxide enters the ocean too quickly, it can deplete the carbonate ions that corals, mollusks and some plankton need for reef and shell-building."

[Bärbel Hönisch, paleoceanographer, Columbia University's Lamont-Doherty Earth Observatory:] “What we're doing today really stands out in the geologic record…We know that life during past ocean acidification events was not wiped out--new species evolved to replace those that died off. But if industrial carbon emissions continue at the current pace, we may lose organisms we care about--coral reefs, oysters, salmon."

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"In a review of hundreds of paleoceanographic studies, [Hönisch and co-researchers] found evidence for only one period in the last 300 million years when the oceans changed as fast as today: the Paleocene-Eocene Thermal Maximum, or PETM…About 56 million years ago, a mysterious surge of carbon into the atmosphere warmed the planet and turned the oceans corrosive…In about 5,000 years, atmospheric carbon doubled to 1,800 parts per million (ppm), and average global temperatures rose by about 6 degrees Celsius…

"As many as half of all species of benthic foraminifera, a group of one-celled organisms that live at the ocean bottom, went extinct, suggesting that deep-sea organisms higher on the food chain may have also disappeared…In the last hundred years, rising carbon dioxide from human activities has lowered ocean pH by 0.1 unit, an acidification rate at least 10 times faster than 56 million years ago…"