Should We Sequester Carbon?

When people talk about "clean coal" (for example, President Obama) they're really talking about carbon sequestration, a geoengineering approach for the long-term storage of carbon dioxide. Let's see if this is a good or even practical idea.

Here's a simple model taken from Nikiforoff (1959). The dark lines show combustion of fossil fuels and the sequestration of atmospheric CO2. These are industrial, capital intensive activities that work in parallel with natural processes that deal with atmospheric CO2.

QUESTION: Why do we have to rely on carbon sequestration when there is a perfectly good process already in place called the natural carbon cycle? Natural systems already do a better job of carbon fixation. Living matter converts CO2 in the atmosphere into organic compounds (usually sugars) through photosynthesis. Living matter also returns CO2 to the atmosphere through ecosystem respiration. When living matter dies it turns into humus through the process of humification (the stuff you eat with pita bread at a Middle Eastern restaurant is hummus) and then returns to the earth through carbon fixation.

ANSWER: Neoliberal economists have convinced us that capital can always be substituted for natural resources. Here's an example involving natural ecosystem services where it doesn't work. The natural carbon cycle is in equilibrium. Data from the 1990's suggests that we would need to sequester about 6.4 Gt/yr of carbon to bring the systems back into balance--every year for the rest of eternity even if we cap emissions at today's levels (if we don't cap emissions, the 6.4 Gt/yr number will increase exponentially). Does anyone other than a neoliberal economist think this is a practical idea?

A somewhat better response is the UN REDD program (Reducing Emissions from Deforestation and forest Degradation). Unfortunately, reforestation competes with other land uses: food production, livestock grazing and living space for further economic growth (for example, parking lots so that the projected world population of between 5 billion and 14 billion people in 2100 can all have three automobiles and a place to part them).

A better response would be to reduce exponential growth rates and give the environment some time to recover and give us some time to figure out how to live in balance with the biosphere (sometimes called the precautionary principle). The alternative response is to look at sequestration as a marginal part of of a "policy wedge" approach, which would seem to be the way the Obama administration is going. If they play the Stabilization Wedge Game they have until 2056 to get back to 2006 emission levels and then from there get to sustainable emission levels. Do you think they will be successful?