Global Warming’s Evil Twin

We may admire the first person ever to eat an oyster, like this one from the Pacific Northwest. We may soon meet the last, because of rapid ocean acidification. (Photo by adactio/Flickr).

To the extent that we talk, think or do anything about the threat of the industrial age’s rampant and accelerating pollution of air, water and land, we focus these days on climate change. It is a serious effect (serious enough to induce blindness and deafness in nine out of ten candidates for the Republican presidential nomination), but far from the only serious effect of industrial pollution. The same stuff that’s making our atmosphere warmer is turning our oceans to acid — and, little noticed outside the shellfish industry, has very nearly removed oysters from the national menu.

Two-thirds of the carbon dioxide belched into the air by factories, coal-burning power stations, cars and, yes, cows, remains airborne and has the effect of trapping heat in the atmosphere. The other one-third — an estimated one million tons per hour — is eventually absorbed by water. First, it’s used by plankton in photosynthesis; when they die and sink to the bottom, they release carbon as they decompose; the carbon combines with water to form carbonic acid.

Sea water can hold 50 times more carbon than air. Cold water can hold more carbon than warm water. Cold water sinks, so at first glance it seems that the carbon and the acid are, as it were, buried at sea, out of sight and out of mind. (Speaking of being out of mind: credentialed people have seriously proposed that we inject carbon into the deep oceans in order to “dispose” of it.) But the carbon, now an acid, will not stay put, because of  a common phenomenon called upwelling.

Water, like air, circulates vertically as well as horizontally, and is stirred by temperature changes, large-scale currents and by wind acting on the surface. There are places, for example off the northwest coast of the United States, where this stirring, or upwelling, occurs frequently. (Another place is off the coast of Peru, where upwelling is an essential part of the chain of weather events that has become infamous as “El Niňo.) For three years, beginning in 2007, upwelling off the Pacific Northwest acidified the surface water so much that it virtually wiped out the farmed oyster larvae that provide American tables with something like 175 million oysters a year.

The oyster growers did not know what hit them in 2007. The entire Northwest oyster industry very nearly crashed before they figured out what was killing their babies and how to fix it. It’s a riveting story that we never heard from the news industry, but that is well told by Eric Scigliano, writing for the magazine onearth, published by the National Resources Defence Council.

But here’s the thing. The fix they put in place, which was to avoid the worst times and places for upwelling and hence acidification, is temporary. There is, it turns out, a 30-50 year lag between the absorption of the carbon by the sea and its regurgitation to the surface in upwelling. So the current threats are the results of the pollution levels of the 1950s-70s. We were amateurs at pollution then. In the 80s, 90s, and 00s, we got really good at it.

So the dire threat to the Pacific oyster industry was only the beginning, and what they did to survive cannot work very long. “We’ve mailed a package to ourselves,” says Oregon State oceanographer Burke Hales, “and it’s hard to call off delivery.”


[For updates on this and other stories, and for short takes on other subjects, check out The Editor’s Log.]

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