Fish Are Great at Fighting Climate Change. Too Bad We’re Eating Them All

Climate change may be screwing with your seafood, but it turns out your seafood has been fighting back.

June 10, 2014 | Source: Grist | by Amelia Urry

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Climate change may be screwing with your seafood, but it turns out your seafood has been fighting back.

Fish, like Aquaman, might not seem to have a lot of relevance in the world-saving department. Never mind that the world is 99 percent ocean by habitable volume: We’re up here in the 1 percent of living space we care about the most, and they’re stuck breathing through gills and riding around on sea-ponies.

But in a DC Comics-worthy plot twist, a new study shows that fish have been doing a lot more world-saving than we thought, by way of sequestering carbon to stave off climate change – which on the danger scale is up there with supervillain plots like blocking out the sun or moving the moon. The catch (har) is that we can’t eat all our fish and have them save the world, too.

The sea absorbs about half of the billions of tons of CO2 humans emit; if it didn’t, it would already be absorbing quite a few of us. But it’s not like the oceans are just a giant sponge passively sopping up our atmospheric mess. They’re more like a forest – a really, really big one in which plants and animals grow and photosynthesize and eat each other and die, intaking carbon as they go. And a forest is made up of trees, or in this increasingly literal metaphor, phytoplankton and fish and other organisms. You can’t cut down all the fishtrees and expect your oceanforest to keep sucking up carbon.

Though we used to think that phytoplankton near the surface of the ocean did all the work of sequestration on their own, by taking their carbon with them when they died, it it now clear that the process is a little more vigorous than that. Instead of just waiting for carbon-laden plankton to get on their level, certain deep-dwelling, nightmare-inducing predators actually hunt down the tasty upper-level nibbles before swimming back into the extreme depths where all that carbon is effectively trapped for good.