Volume 10, Number 43: 24 October 2007
In two prior Editorials, those of 26 September 2007 and 10 October 2007, we describe two important scientific findings that refute the "creation care" contention of England's Sir John Houghton that "very large growth" in the biofuels industry will be required in taking the moral high-road to help slow CO2-induced global warming. Those findings are that: (1) in order to produce enough biofuels to offset a significant amount of fossil fuel usage, humanity would have to employ a large portion of earth's remaining arable land and freshwater resources, which would result in the driving of innumerable species of plants and animals to extinction due to massive habitat loss, and (2) forestation of the land area needed for biofuel production would likely remove much more carbon from the atmosphere than what would not be put into the air by using biofuels in the place of fossil fuels. Here, we describe yet a third way in which replacing fossil fuels with biofuels may be detrimental to earth's climate and the biosphere.
In an important new paper published on 1 August 2007 in Atmospheric Chemistry and Physics Discussions, Crutzen et al. (2007) calculate the amount of nitrous oxide (N2O) that would be released to the atmosphere as a result of using nitrogen fertilizer to produce the crops used for biofuels, which analysis, in their words, "only considers the conversion of biomass to biofuel" and "does not take into account the use of fossil fuel on ... farms and for fertilizer and pesticide production." As they describe it, this work revealed that "all past studies have severely underestimated the release rates of N2O to the atmosphere, with great potential impact on climate warming." And why would greater N2O emission rates have a tendency to cause the climate to warm? Because, in their vernacular, N2O "is a 'greenhouse gas' with a 100-year average global warming potential 296 times larger than an equal mass of CO2."
The ultimate consequence of this phenomenon, as best the four researchers could evaluate it, is that "when the extra N2O emission from biofuel production is calculated in 'CO2-equivalent' global warming terms, and compared with the quasi-cooling effect of 'saving' emissions of fossil fuel derived CO2, the outcome is that the production of commonly used biofuels, such as biodiesel from rapeseed and bioethanol from corn (maize), can contribute as much or more to global warming by N2O emissions than cooling by fossil fuel savings."
As a result of these observations, Crutzen et al. conclude that "on a globally averaged basis the use of agricultural crops for energy production can readily be detrimental for climate due to the accompanying N2O emissions." In addition, they note that "increased emissions of N2O will also lead to enhanced NOX concentrations and ozone loss in the stratosphere." Taken together, they thus conclude that the relatively large emission of N2O associated with biofuel production "exacerbates the already huge challenge of getting global warming under control."
Clearly, Houghton's call for "very large growth" in biofuel production to combat global warming not only does not do any good in this regard, it is actually counterproductive. Hence, it behooves everyone to carefully sift through the religious rhetoric he employs in his "creation care" campaign to get to the real facts of the matter. Appeals to morality based on faulty premises can have most unfortunate consequences, leaving people feeling not only misled but betrayed.
Sherwood, Keith and Craig IdsoReference
Crutzen, P.J., Mosier, A.R., Smith, K.A. and Winiwarter, W. 2007. N2O release from agro-biofuel production negates global warming reduction by replacing fossil fuels. Atmospheric Chemistry and Physics Discussions 7: 11,191-11,205.