The [US] NOAA has a longish article on its new climate.gov site about ocean acidification that’s worth your time. (The article carries a date of October 30th 2009, but this is the first time I’ve seen it.)
Here’s just a taste of the article, ClimateWatch Magazine: An Upwelling Crisis: Ocean Acidification:
In 1981, Feely’s program began measuring the amount of carbon dioxide in the ocean to complement the records of atmospheric carbon dioxide that had been taken since the late 1950s. Getting started was difficult. There were no existing standards for measuring carbon dioxide in seawater, so Feely and his team had to develop their own.
As part of this investigation, Feely and his colleagues participated in research cruises along coastlines and across ocean basins studying ocean carbon chemistry at a range of locations and depths. During these cruises, the team saw the first indications that seawater was storing excess carbon dioxide – some of water samples had higher-than-expected concentrations of carbon dioxide and lower-than-expected pH values. When carbon dioxide reacts with seawater, carbonic acid forms. The acid mixes and reacts with other constituents of seawater, reducing its pH.
Feely published these findings in the mid-1980s, but few people noticed. The science community wasn’t too concerned about tiny changes in pH in a few areas of the world’s vast ocean. Yet Feely suspected that the problem could be worldwide; if so, even small changes in pH could lead to large changes in the marine ecosystem. “Over the past 20 million years, ocean ecosystems have evolved in a very stable pH environment,” Feely explained. “I’m worried that if concentrations of carbon dioxide continue to rise, the ocean could undergo large and rapid changes in pH.” Feely decided to launch a global investigation. In the early 1990s, he and his team of researchers expanded their observation program from the Atlantic and Pacific Oceans to launch a worldwide effort involving laboratories from several countries. On 99 oceanic cruises over a 10-year period, they collected nearly 72,000 seawater samples from all over the world. Feely invited oceanographer Christopher Sabine to join him at NOAA’s Pacific Marine Environmental Laboratory and, together, they began the arduous task of analyzing the thousands of samples to characterize the global ocean’s carbon dioxide content.
In 2004, they published the results of this colossal effort in two articles in the prestigious journal Science. In the first of the two studies, Sabine and Feely and their colleagues found that the ocean has absorbed about one-third of the carbon dioxide emitted by human activities. This absorption slows the rate of global warming by removing carbon dioxide from the atmosphere, but it also changes the chemistry of seawater. Historically, the average pH of seawater around the globe has been approximately 8.2, a value that is slightly basic. Since the Industrial Revolution, the average pH of surface oceans has decreased to 8.1, which means the seawater is becoming less basic-more acidic. Based on current and projected concentrations of carbon dioxide in the atmosphere, the pH of surface waters is expected to decrease to 7.8 or 7.7 by the end of this century.
Feely led the second of the two Science studies, which was a cross-disciplinary collaboration with biologists and ecologists to assess the potential impact of ocean acidification on marine life forms. The scientists found that in some conditions, acidified water “eats away,” or corrodes, calcium carbonate minerals that many calcifying, or shell-building, organisms rely on to build their shells and skeletons. This study alerted biologists that acidified waters could begin to interfere with marine organisms’ abilities to form their protective armor.
