January 05, 2006

Hiding Carbon

Dave of Seeing The Forest pointed me to this plan for complying with Kyoto on the cheap. It's a longer piece by Gregory Benford with an excellent point about reducing urban heat profiles and a suggestion regarding cloud seeding that I'm not well-versed enough to say yea or nay to. But there's this:

... Imagine you are standing in a ripe Kansas cornfield, staring up into a blue summer sky. A transparent acre-area square around you extends upwards in an air-filled tunnel, soaring all the way to space. That long tunnel holds carbon in the form of invisible gas, carbon dioxide — widely implicated in global climate change. But how much?

Very little, compared with how much we worry about it. The corn standing as high as an elephant's eye all around you holds four hundred times as much carbon as there is in man-made carbon dioxide — our villain — in the entire column reaching to the top of the atmosphere. (We have added a few hundred parts per million to our air by burning.) Inevitably, we must understand and control the atmosphere, as part of a grand imperative of directing the entire global ecology. Yearly, we manage through agriculture far more carbon than is causing our greenhouse dilemma.

Take advantage of that. The leftover corn cobs and stalks from our fields can be gathered up, floated down the Mississippi, and dropped into the ocean, sequestering it. Below about a kilometer depth, beneath a layer called the thermocline, nothing gets mixed back into the air for a thousand years or more. It's not a forever solution, but it would buy us and our descendents time to find such answers. And it is inexpensive; cost matters.

The US has large crop residues. It has also ignored the Kyoto Accord, saying it would cost too much. It would, if we relied purely on traditional methods, policing energy use and carbon dioxide emissions. Clinton-era estimates of such costs were around $100 billion a year — a politically unacceptable sum, which led Congress to reject the very notion by a unanimous vote.

But if the US simply used its farm waste to "hide" carbon dioxide from our air, complying with Kyoto's standard would cost about $10 billion a year, with no change whatsoever in energy use. The whole planet could do the same. Sequestering crop leftovers could offset about a third of the carbon we put into our air. ...

This is a challenging suggestion, particularly because of its ostensibly reasonable character. Of course it does represent a great deal of carbon and currently much crop waste is simply burned, which is unhelpful to say the least. Unfortunately, if implemented, it would help one environmental problem by drastically worsening another. It's almost the equivalent of suggesting that in order to ensure our air supply, we should give up eating. Let me explain.

Consider a wild prairie. It has covered the land for tens of thousands of years with a flat blanket of greenery. The sun beats down and the rain falls, allowing the genetic information in seeds to turn water, carbon dioxide and soil nutrients into plants. Imagine further that there are herds of grazing ruminants that periodically wander around nibbling off the tasty bits of the grasses and other plants, sometimes birds come to hunt for the insects that live on seeds, leaves, each other and the rich soil biota. The ruminants and the birds eat their fill and leave behind excrement that adds to the soil humus. Add to your picture, though you wouldn't notice them at all if you were standing on an actual prairie, a deep mat of mushroom mycelium intertwined deeply through the rich soil with multitudes of insects and hosts of bacteria. Every year, the plants seed and die. Their bodies become food for mycelium and when their husks are unidentifiably ancient and buried beneath their descendents, their remains will hold water and air in the soil below to sustain life far into the future.

When you stand on good soil, you stand on the remains of ancient living things that have mixed into a matrix of rock dust and clay, helping dead matter to support life. You walk on a former sand desert or bare rock face that has been transformed utterly by long cyclings of the life and death of plants. You stand on a graveyard that has become a vibrant community. The community must be fed. It needs the bodies of those who have lived out their lives in its rich environs or it will perish.

As you might imagine, this cycle is not well served by our current practice of carting off the majority of the plant material grown on a piece of ground and returning virtually nothing. Robbed of the decaying root structure of previous growth and the security of consistent ground cover, agricultural land is blowing and washing away at an alarming rate. The soil organic content (the amount of carbon containing compounds left over from decay and excretion) of agricultural soil goes down with every round of plant removal and pesticide application. This means that getting productivity out of that soil in the future is even more likely to require petrochemical fertilizer, shipped in on a gas guzzling truck and produced using energy generated by burning gas or coal. After that, the resulting agricultural product will be shipped an average of 1500 miles to the eventual consumer by plane, truck, train or boat.

Is it just me, or does it look like there are a lot of other carbon leaks that could be plugged before we decide to ship a basic ingredient of future topsoil straight to the bottom of the ocean? An enormous amount of carbon could be kept out of the air by eating more local food, let alone food that meets organic standards.

Preserving healthy soil can also be its own reward in the carbon exchange stakes. Consider this tidbit from a primer on Amazonian dark soils, or Terra Preta:

... The global carbon cycle has been brought to wide attention due to its importance for the global climate. The Intergovernmental Panel on Global Change (IPCC, 2001) recently confirmed that the anthropogenic greenhouse effect is a reality, which we have to deal with in the future. The atmospheric CO2 has increased from 280 ppm in 1750 to 367 ppm in 1999 and today's CO2 concentrations have not been exceeded during the past 420,000 years (IPCC, 2001). The release or sequestration of carbon in soils is therefore of prime importance.

Soil organic carbon is an important pool of carbon in the global biogeochemical cycle. The total amount of organic carbon in soils is estimated to be 2011 Gt C, which constitutes about 82% of the global organic carbon in terrestrial ecosystems (Watson et al., 2000).

Amazonian dark earths have high carbon contents of up to 150 g C/kg soil in comparison to the surrounding soils with 20-30 g C/kg soil (Sombroek, 1966; Smith, 1980; Kern and Kämpf, 1989; Sombroek et al., 1993; Woods and McCann, 1999; Glaser et al., 2000). Additionally, the horizons which are enriched in organic matter, are not only 10-20cm deep as in surrounding soils, but may be as deep as 1-2m (average values probably around 40-50cm)! Therefore, the total carbon stored in these soils can be one order of magnitude higher than in adjacent soils. ...

The Terra Preta soils are widely and solidly believed to have been spread or originated through the practices of former natives to the region, though there are no written records that can clarify the issue. Point is, right now human interaction with soil is usually formulated around extraction or the mitigation of extraction. Building it, along with its carbon sequestering organic content, generally doesn't enter the picture. Animal wastes that would have added back aren't considered worth carting more than five miles to add to cropland that may have fed their growth. Plant material is carted away and poorly substituted for by petrochemical soil amendments. Composting on a wide scale is considered too costly and time consuming, even though the world certainly doesn't lack for a labor pool.

Our soil's nutrients are eaten and not returned. It blows and washes away to the sea, millions of years worth of work lost to the land.

Another issue is that human beings already persist in eating other life forms out of house and home, as exemplified by this 1986 analysis that calculated human consumption of net primary productivity. Net primary productivity, or NPP, is the technical term for carbon fixation by photosynthesizers. Which in itself is the technical terminology for compounds that plants, algae and cyanobacteria make out of inert gas and sunlight, which is how new chemical energy (yay, sugar!) is introduced into the biosphere and made available for general consumption.

As of 1986, it was estimated that 30-40% of terrestrial (on land, as opposed to in the oceans) NPP was either consumed or pre-empted by humans. That means 30-40% less potential food for other organisms that we share the land with. But hey, animals and trees can't buy real estate, so screw 'em.

Benford then closes with these inflammatory and, imo, ill-informed comments:

... Yet if Kyoto fails to gather momentum, as seems probable to many, what else can we do? Turn ourselves into ineffectual Mommy-cop states, with endless finger-pointing politics, trying to equally regulate both the rich in their SUVs and Chinese peasants who burn coal for warmth? Our present conventional wisdom might be termed The Puritan Solution — Abstain, sinners! — and is making slow, small progress. The Kyoto Accord calls for the industrial nations to reduce their carbon dioxide emissions to 7% below the 1990 level, and globally we are farther from this goal every year.

These steps are early measures to help us assume our eventual 21st Century role, as true stewards of the Earth, working alongside Nature. Recently Billy Graham declared that since the Bible made us stewards of the Earth, we have a holy duty to avert climate change. True stewards use the Garden's own methods.

Yeah, whatever can we do? Apparently, reinforce the right wing talking points that are getting us ever deeper into this mess. Benford doesn't bother to clarify that the big problem with Americans accepting Kyoto was that it didn't regulate Chinese peasants burning coal for warmth, much to the ire of wealthy, Western SUV drivers.

But Lord knows, we wouldn't want to act like mommies, who never did anything for any of us anyhow, and mandate to the various peoples of the world that we quit committing mass suicide. Though it's perfectly alright to do our manly, biblical duty and follow the Original Gardener. One can only presume he wasn't talking about the Earth Mother or the Gaia consciousness.

Whatever gardener he's talking about, it seems to be the fevered imaginary creation of a man who thinks that the whole world should adopt the municipal yard waste bin model. You have a yard, you cut out what you don't want, and it all gets collected for shipment Away, where we don't have to worry about it anymore. It isn't the conclusion of someone who knows much about the natural processes of the biosphere and if there is a deity, I sure the hell hope they know more about that than Gregory Benford.

Lastly, as a committed (No, no, not the straitjacket again!) member of the environmental community, I'd like to suggest that his broad characterization of the movement as a collection of Puritans is ridiculous. And once again, unhelpful. There are those who would like to see people do with less, but the current thrust of the effort is to find less harmful ways to provide the services that people expect and enjoy today.

People need food; great. Let's grow it without using harmful and valuable petrochemicals, then try to eat it closer to where it was grown. People need transportation; fine. Let's increase the mileage of their cars, give them more fuel efficient public transport, or look for fuels that don't contribute to the global warming problem. People need electricity; we get it. Let's invest in renewables and keep working at it until we find cost-effective solutions that can be widely deployed before we run out of the fossil fuel energy needed to kick-start the process. People need housing; okay. Why not try to use more local materials and build with an eye towards energy efficiency.

Benford's model for thinking about this problem is fundamentally flawed. He may know his physics, but his concept of biological processes and 1970's ideas about the environmental movement suggest perhaps that he considers a deeper study of these issues beneath him and believes that his expertise is directly transferable. How unfortunate.

Posted by natasha at January 5, 2006 07:16 PM | Environment | Technorati links |

Modern combine tractors spew out chopped up stalks, husks and all. Assuming the author's $10 billion is going towards new combines for all farmers, there is the added energy input in producing that many more machines and the enormous energy sink that is the necessary hauling of materials, not to mention just how the new breed of combine could collect both seed and plant, the latter being perhaps 50 times the former's mass.

Glad to read a solid rebutal based on a learned appreciation of good old black gold!

Posted by: Jared Scarborough at January 7, 2006 07:08 PM