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Arctic permafrost thawing faster than ever

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lunedì 30 novembre 2015

Dissolving Shells

Top a pteropod with a healthy shell. Bottom: A pteropod shell showing dissolved ridges, abrasions and cloudiness. Credit National Oceanic and Atmospheric Administration

Search the phrase “climate change” and you’ll find a lot of images of melting glaciers and polar bears standing precariously on little bits of ice. This week, we’ll be featuring less familiar examples of what climate change looks like, such as the dissolving shells of pteropods, tiny creatures with an important place in the ocean’s food chain. 
Pteropods are sometimes called sea butterflies, and salmon, whales and other marine life eat these little snails. And scientists have found that their shells, which contain calcium carbonate, are sensitive to changes in the ocean’s pH levels.
That’s where climate change comes in. Carbon dioxide from human activities ends up in the ocean, increasing the acidity of seawater. As the pH level falls and water becomes more corrosive, calcium carbonate in pteropod shells dissolves.
While the potential for this problem had been demonstrated in labs, last year National Oceanic and Atmospheric Administration scientists were surprised to discover that damage to pteropod shells in the Pacific Ocean had already started. The ocean acidification that damages pteropods could have manifestations in other marine species, too, creating distress on the ocean’s food web 

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