In a Policy Forum article in the 17 August 2007 issue of Science, Righelato and Spracklen (2007) write that the use of biofuels for transport, particularly ethanol from the fermentation of carbohydrate crops as a substitute for petrol, and vegetable oils in place of diesel fuel, "would require very large areas of land in order to make a significant contribution to mitigation of fossil fuel emissions and would, directly or indirectly, put further pressure on natural forests and grasslands."

As an example of this phenomenon, the two UK researchers calculate that a 10% substitution of petrol and diesel fuel would require "43% and 38% of current cropland area in the United States and Europe, respectively," and that "even this low substitution level cannot be met from existing arable land," so that "forests and grasslands would need to be cleared to enable production of the energy crops."

Adding insult to injury, Righelato and Spracklen hasten to add that the required land clearance "results in the rapid oxidation of carbon stores in the vegetation and soil, creating a large up-front emissions cost that would, in all cases examined [our italics], out-weigh the avoided emissions." Furthermore, even without the large up-front carbon emissions, they report that individual life-cycle analyses of the conversion of sugar cane, of sugar beet, and of wheat and corn to ethanol, as well as the conversion of rapeseed and woody biomass to diesel, indicate that "forestation of an equivalent area of land would sequester two to nine times more carbon [our italics and boldface] over a 30-year period than the emissions avoided by the use of the biofuel." As a result, they rightly conclude that "the emissions cost of liquid biofuels exceeds that of fossil fuels."

Coming to much the same conclusion in a News & Views article in the 27 September 2007 issue of Nature was Laurance (2007), who discussed the ability of forests to reduce catastrophic flooding. In addition to this important virtue, he writes that "tropical forests, in particular, are crucial for combating global warming, because of their high capacity to store carbon and their ability to promote sunlight-reflecting clouds via large-scale evapotranspiration," noting that "such features are key reasons why preserving and restoring tropical forests could be a better strategy for mitigating the effects of carbon dioxide than dramatically expanding global biofuel production."

Yet, either knowing these things, or not knowing them -- both of which alternatives are inexcusable -- Houghton invokes religion as a reason for "very large growth" in biofuel production.

The lesson to be learned from this sad state of affairs is that religious principles cannot be properly applied without a correct understanding of the pertinent science. We must know the facts about all aspects of earth's climate system, as well as the many biological effects of atmospheric CO2 enrichment, together with their interactions with the climate system, before we can be truly confident that what we propose about the matter is truly in the best interests of man and nature alike. This essentially self-evident principle should resonate with people of all faiths. Acting too quickly, and without thorough study, may lead even a Saint to promote that which is evil in the name of God, or -- to accommodate atheists -- to promote that which is wrong in the name of reason.

References
Laurance, W.F. 2007. Forests and floods. Nature 449: 409-410.

Righelato, R. and Spracklen, D.V. 2007. Carbon mitigation by biofuels or by saving and restoring forests? Science 317: 902.