In an October 30, 2007 letter to Intergovernmental Panel on Climate Change Chairman Dr. Rajendra Pachauri, five scientists detail their concerns about the discussion of biofuels in the IPCC’s Fourth Assessment Report (AR4) on Mitigation of Climate Change. In a nutshell, the scientists argue that AR4 downplays the “adverse consequences” of “unbridled biofuel expansion” for “emissions, humanity, and biodiversity.”

Some of their key concerns:

• Even small-scale cultivation of energy crops for biofuels “will take fertile land away from agricultural use”
• The rush to biofuels is “already leading variously to major damage to biodiversity, irregularities in land acquisition and other human rights abuses, water pollution and stress on water resources…”
• “The growing world bioenergy-related market for palm oil is a major part of the speculative incentive for deforestation for new plantations around the tropics,” implicated in “human displacement, the slaughter of orangutans and other losses of very considerable biodiversity.”
• “The emissions associated with palm oil plantations on thick tropical peat are particularly colossal. A major study estimated that producing 1 tonne of palm oil on peatland emitted between 10 and 30 tonnes of CO2 from drainage and decomposition, excluding fires associated with land clearance.”
• “In the United States, increased maize [corn] plantings and their use for ethanol have contributed to price rises for many food commodities…”
• The IPCC cites an estimate of expected emissions savings from biofuel substitutes that “does not make allowance for land-use change emissions,” which may have “cumulative radiative forcing effects far exceeding the hypothetical mitigation from biofuels by 2030…”
• Non-transport land uses (afforestation or growing biomass for electric generation) yield emissions savings 10 to 15 times greater than biofuels per acre of land. Even second generation ethanol (from wood cellulose) yields only 1/5 the emissions mitigation of using wood for stationary energy.
• The IPCC does not adequately warn that expanding arable land into forested areas to grow energy crops “would be likely to release large amounts of carbon from the soil, negating any benefit of the energy crops for decades to come.”
• The IPCC says cellulosic crops “do not compete with food.” This is incorrect, because “such land is often used as pasture for livestock.”

The scientists co-authoring the letter are Prof. David Pimentel (Cornell University), Prof. Tad Patzek (UC Berkeley), Prof. Florian Siegert (RSS GmbH, Munich office), Dr. Mario Giampietro (ICREA Research Prof., Universitat Autonoma de Barcelona), and Prof. Helmut Haberl (Alpen-Adria-Universtat Klagenfurt).