The October 23rd issue of Science has an interesting study, “Fixing a Critical Climate Accounting Error,” in which the authors contend that across-the-board exemption of carbon dioxide (CO2) emissions from bioenergy — the use of plant materials known as biomass for the production of renewable fuels — is improper in greenhouse gas regulations, if emissions due to land-use changes also are not included.
According to a summary by the Woodrow Wilson School of Public and International Studies at Princeton University:
“[The prior method of calculation] treats all uses of bioenergy as carbon-neutral, renewable energy regardless of the source of the biomass, and could create strong economic incentives for large-scale land conversion as countries around the world tighten carbon caps.
According to the researchers, the greenhouse gas consequences of using bioenergy vary greatly depending on the source of the biomass. For example, if plant growth increases to produce bioenergy, as when fast-growing trees or grasses are grown on degraded land, bioenergy reduces global warming because the plants absorb more carbon from the atmosphere, which offsets the CO2 emitted by burning the bioenergy.
However, if bioenergy use results from burning wood chips from existing forests for electricity, or clearing rain forests to grow palm oil and other crops for biofuels, bioenergy does not reduce greenhouse gas emissions, and instead may increase them. Thus, the accounting rules in these legal measures mistakenly exempt the CO2 emitted by bioenergy regardless of the source, according to the authors.
Neither the Kyoto Protocol, nor the existing or proposed climate legislation in Europe and the United States, currently applies limits to emissions from land use such as deforestation. Because of that, the exemption of the CO2 actually emitted from the burning of biofuels and wood for electricity means all forms of bioenergy are treated as carbon neutral, which creates incentives to clear land.”
According to a number of studies, applying this incentive globally could lead to the loss of most of the world’s natural forests as carbon caps tighten. The Intergovernmental Panel on Climate Change (IPCC) estimates that the cutting down of forests is now contributing close to 20% of the overall greenhouse gases entering the atmosphere. Forest degradation also makes a significant contribution to emissions from forest ecosystems.
Co-author Philip Robertson states: “The promise of cellulosic biofuels is huge for our climate and economy. We don’t want to find out later that we’ve built a new industry on a house of cards.”