Excerpt:

July 15, 2013 — Under elevated carbon dioxide levels, wetland plants can absorb up to 32 percent more carbon than they do at current levels, according to a 19-year study published in Global Change Biology from the Smithsonian Environmental Research Center in Edgewater, Md. With atmospheric CO₂ passing the 400 parts-per-million milestone this year, the findings offer hope that wetlands could help soften the blow of climate change.

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Then this, from truthdig, two days ago. P.S. The way “biochar” is defined, I imagine wetlands naturally contain lots of biochar. In other words the two rays of hope are connected?

Photosynthesis Could Be a Climate Change Solution

Researchers say “one of the most common [biological] processes on Earth” is also “one of the most promising means of extracting atmospheric carbon dioxide” on a scale potentially large enough to reduce the risk of catastrophic global warming.

The key substance is called biochar. “Biochar … is basically a fancy scientific name for charcoal [and] is produced when plant matter—tree leaves, branches and roots, cornstalks, rice husks, peanut shells—or other organic material is heated in a low-oxygen environment,” writes Mark Hertsgaard at Mother Jones. “Like compost, all of these materials contain carbon: The plants inhaled it, as carbon dioxide, in the process of photosynthesis. Inserting biochar in soil therefore has the effect of removing carbon dioxide from the atmosphere and storing it underground, where it will not contribute to global warming for hundreds of years.”

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Aha, I just googled the question, “Is wetlands a low oxygen environment?” and the answer is YES.