Will dumping cornstalks into the ocean sequester carbon?

There a new ocean carbon sequestration scheme in town – dumping crop waste. A study published in Environmental Science and Technology last month proposes baling up corn husks and wheat stalks, weighting them with rocks, and tossing them into the deep sea. (Here’s the NYT blurb.)

ResearchBlogging.org

The authors claim that marine creatures will be unable to digest chewy terrestrial plants chock-full of lignin and cellulose, so the sea will keep that carbon down for thousands of years. If this worked, they calculate it would reduce carbon accumulation in the atmosphere by 15%.

Unfortunately, their entire premise might be wrong. The deep sea is not a lifeless cold dark empty place – it is filled with animals that are evolved to take advantage of whatever food drifts down from above, terrestrial or not. For example, wood that falls into the deep sea gets eaten. There’s even a deep-sea bivalve that specializes in drilling into wood.

Since wood is a lot harder on the digestion than grass stems, I doubt that all that crop waste would just sit there bereft and alone for thousands of years. It’s going to get munched upon and decomposed, and the carbon will go back into global circulation. I wish that controlling climate change were as simple as dumping some stuff nobody wants anyway into the ocean, but I just don’t think it’s going to be that easy.

Stuart E. Strand, Gregory Benford (2009). Ocean Sequestration of Crop Residue Carbon: Recycling Fossil Fuel Carbon Back to Deep Sediments. Environmental Science & Technology, 43 (4), 1000-1007.

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6 Responses to Will dumping cornstalks into the ocean sequester carbon?

  1. Katkinkate says:

    All that carbon ‘waste’ needs to go back into the soil.

  2. MarkSense says:

    Did the researchers calculate how much carbon would have to be burned to move all that stuff to the ocean? It might be better to burn the corn stalks in the field, and let the biochar sequester the carbon right there.

  3. Katkinkate – They claim that removing 70% of crop waste does not adversely affect the soil. But that’s probably in an industrial farming with intensive fertilization context.

    MarkSense – They do calculate transportation and claim that it would only emit 75.3 kg carbon for every ton carbon sequestered. Of course this is irrelevant if the carbon is not actually sequestered.

  4. [...] and Miriam have beat me to the punch but both of been goading me to comment.  The plan is to dump crop waste [...]

  5. Petrov says:

    There have also been reports of the amounts of dissolved carbon dioxide in sea water causing the death of both plant and wildlife. If carbon dioxide is allowed to keep building up in the depth of the ocean, it is quite possible that we’ll be killing off the number one supply of the oxygen we breath.

  6. Mima says:

    What is the effect of the Great Pacific Garbage Dump on carbon sequestration?

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