Compounded Climate Accounting Errors

Timothy Searchinger, visiting scholar at Princeton University, Dan Kammen of the University of California Berkeley, David Tilman of the University of Minnesota and other authors from the Environmental Defense Fund published an interesting new proposal in the Policy Forum section of Science magazine today. The argument put forward is that “Replacing fossil fuels with bioenergy does not by itself reduce carbon emissions, because the CO2 released by tailpipes and smokestacks is roughly the same per unit of energy regardless of the source.”

The premise behind this proposal is that the world is facing such a great need to reduce carbon emissions that future sources of energy and biofuels cannot make use of any currently sequestered carbon. Maybe… but there’s a perverse consequence of using this logic. Fossil fuels are a source of sequestered carbon. If you then say that all existing biomass is an untouchable source of sequestered carbon, you are essentially counting that sequestration as a benefit of having used fossil fuels for the past 150 years.

The logic is particularly tortured when a foregone sequestration penalty is attributed to biofuels when none is counted for petroleum.

There is much in the paper to agree with — particularly in recognizing carbon sequestration benefits from improved land management practices and energy crops. And certainly, the challenge of climate change is so great that implementing best practices for carbon sequestration is a necessity.

But a proposal that attributes carbon sequestration in trees as a plus in the accounting of fossil fuel use is counterproductive.