Corrosive Oceans and the Aquatic Food Chain

Over at Yale's Environment 360, New York Times science writer Karl Zimmer has an excellent post on what carbon emissions are doing to the chemistry of our oceans. Increasingly acidic oceans have the possibility to undermine much of the marine food chain. I've touched on this before, but a few years ago this wasn't even a topic of conversation. Like the melting of the permafrost, it's another frightening example of the unexpected changes that can occur when you start tinkering with the dynamics of complex systems. I've included a few excerpts below, but the piece is well worth reading.

"The acidification of the ocean today is bigger and faster than anything geologists can find in the fossil record over the past 65 million years. Indeed, its speed and strength — Ridgwell estimate that current ocean acidification is taking place at ten times the rate that preceded the mass extinction 55 million years ago — may spell doom for many marine species, particularly ones that live in the deep ocean."

"When we humans burn fossil fuels, we pump carbon dioxide into the atmosphere, where the gas traps heat. But much of that carbon dioxide does not stay in the air. Instead, it gets sucked into the oceans. If not for the oceans, climate scientists believe that the planet would be much warmer than it is today. Even with the oceans’ massive uptake of CO2, the past decade was still the warmest since modern record-keeping began. But storing carbon dioxide in the oceans may come at a steep cost: It changes the chemistry of seawater."

"To see how ocean acidification is going to affect life in the ocean, scientists have run laboratory experiments in which they rear organisms at different pH levels. The results have been worrying — particularly for species that build skeletons out of calcium carbonate, such as corals and amoeba-like organisms called foraminifera. The extra hydrogen in low-pH seawater reacts with calcium carbonate, turning it into other compounds that animals can’t use to build their shells."

"These results are worrisome, not just for the particular species the scientists study, but for the ecosystems in which they live. Some of these vulnerable species are crucial for entire ecosystems in the ocean. Small shell-building organisms are food for invertebrates, such as mollusks and small fish, which in turn are food for larger predators. Coral reefs create an underwater rain forest, cradling a quarter of the ocean’s biodiversity."


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