A caustic shift is coming for the Arctic Ocean


Imagine, for a moment, that you are standing on a pier by the sea, grasping, somewhat inexplicably, a bowling ball. Suddenly you lose your grip and it tumbles down into the waves below with a decisive plonk. Now imagine that the bowling ball is made of gas—carbon dioxide, to be specific, compressed down into that familiar size and weight. That’s approximately your share, on a rough per capita basis, of the human-caused carbon emissions that are absorbed by the sea every day: Your bowling ball’s worth of extra CO2, plus the 8 billion or so from everyone else. Since the Industrial Revolution, the oceans have sucked up 30 percent of that extra gas.

The reason so much CO2 ends up in the oceans is because that molecule is extremely hydrophilic. It loves to react with water—much more than other atmospheric gasses, like oxygen. The first product of that reaction is a compound called carbonic acid, which soon gives up its hydrogen ion. That’s a recipe for a caustic solution. The more hydrogen ions a solution has, the more acidic it is, which is why as the CO2 in Earth’s atmosphere has increased, its water has gotten more acidic too. By the end of the century, models predict the oceans will reach a level of acidity that hasn’t been seen in millions of years. Prior periods of acidification and warming have been linked with mass die-offs of some aquatic species, and caused others to go extinct. Scientists believe this round of acidification is happening much faster.

That change is striking hardest and fastest in the planet’s northernmost waters, where the effects of acidification are already acute, says Nina Bednaršek, a researcher at Slovenia’s National Institute of Biology. She studies pteropods, tiny sea snails that are also known as “sea butterflies” due to their translucent, shimmering shells that look uncannily like wings. But scoop those snails from Arctic waters, and a close look at their exoskeletons reveals a duller reality. In more corrosive water, the once-pristine shells become flaked and pock-marked—a harbinger of an early death. Those critters are “the canary in the coal mine,” as Bednaršek puts it—a critical part of the food chain that supports bigger fish, crabs, and mammals, and a sign of coming distress for more species as the oceans become more caustic.

Gregory Barber, Wired, 2 November 2022. Full article.

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