Buying us time on global warming

From Anne B. Butterfield

Buying us time on global warming

July 27, 2008 (Daily Camera)

For those who seriously worry about the twin threats of climate change and ocean acidification and pale at the thought of costly geoengineering schemes to save the planet, a powerful and cost effective form of relief is in the works. And like Rolaids, it comes in a simple seven letter word: Biochar.

Now all the buzz in gardening blogs, biochar (aka char or agrichar) is studied in about a dozen institutions around the world as a soil amendment to enhance moisture retention and productivity for our overworked agricultural soils. It's an old practice, dating back to pre-Columbian Indians who charred their trees and organic waste and buried it in the poor soils in the Amazon basin. Now seven-thousand years later, the black "Terra Preta" soils still yield high fertility with a carbon content of 9 weight-percent compared with neighboring soils having only 2 percent or less.

Applied globally and organically, the ramifications of agrichar for our food-stressed, toxified world are immense. The practice may end the use of costly fossil fuel based fertilizers whose run-off has caused a dead zone the size of New Jersey in the Gulf of Mexico. Crop yields could rise by 20 percent. Most tantalizing, but still under study, is the potential for a scaled up agrichar practice to be a carbon sink. With the burial of carbon in this persistently stable form, plus its tendency to attract and bond with carbon dioxide, methane and nitrous oxide, plus the resulting heavier plant growth, agrichar could capture nearly twice our current annual emissions from fossil fuels (5.4 billion tons per year) while creating bio-oil for our projected demand for renewable fuels by 2100. (Source: Scientific American May 2007)

Pragmatically, this agricultural and bio-fuel scheme has challenges. We need to assess what agrichar would do over the long term to our foods. Also, we need policy on how to find large amounts of dead biomass for feedstock, lest we deface our forests to run our cars. Also, the ashy char coming from bio-oil production is not as effective at storing carbon and enhancing soils as char made at low temperature, so are we to choose again between great market approaches or showing loving kindness for the Earth?

Enter stage west, my friend, our local geologist, Alison Burchell. Three years ago she tripped on a rock near a Silverton mine reclamation area and tumbled into a nest of loamy soil topped with ferns, mosses, mushrooms and trees -- a Shangri-la amid the dry grass and barren tailings piles. Digging in and testing her samples Burchell found bits of biochar left over from ancient forest fires. She had landed in a natural biochar lab, and it was sequestering carbon to over 30 weight-percent; that's three times what the agrichar experts are claiming for their niche of this emerging market.

With partners at three federal agencies plus experts such as Cornell's soil scientist Johannes Lehmann, Burchell has been advancing research on her scheme of Natural Terrestrial Sequestration (NTS) for reclaiming mining areas here in the Rockies where certain of our volcanic soils present a "secret recipe" for drawing more carbon into soils than noted anywhere else. The total sequestration that Burchell suspects could be achieved through NTS (applied to mine areas, forests and agriculture) in the American west could be 15-30 weight-percent. That represents one or two of the so-called "wedges" coined by Socolow and Pacala in their seminal work on climate mitigation.

With carbon trading likely in the near future, states like Colorado could make money enriching its climate-stressed soils.

This ministry to help the Earth do what it can is what Burchell calls "geomimicry." It may be labor-intensive, but it's not unsophisticated or unmechanized, and the idea of widespread NTS and agrichar brings images of a revitalized agrarian age that could slowly reverse the legacy of centuries of coal mining. Logically, Burchell is also sketching out plans to help heal the wreckage left by mountaintop removal mining in Appalachia. Not bad for a penitent planet.

Anne Butterfield has known Alison Burchell for a year of watching her give papers and talks on NTS.