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Biofuels: Going from Useless to Harmful
Revell, L.E., Bodeker, G.E., Huck, P.E. and Williamson, B.E. 2012. Impacts of the production and consumption of biofuels on stratospheric ozone. Geophysical Research Letters 39: 10.1029/2012GL051546.

Enough serious work has been conducted on the growing, harvesting and processing of the raw materials that can be transformed into biofuels to indicate that they are essentially useless when it comes to doing what they are supposed to do, which is to lead to less anthropogenic-induced CO2 emissions to the atmosphere (see Biofuels in our Subject Index); and now a paper comes along that suggests that biofuels actually have a net negative impact on earth's biosphere.

What was done
Revell et al. first note that the nitrogen-based fertilizers used in growing the crops from which biofuels are produced lead to excessive N2O emissions, citing Crutzen et al. (2008) and Smeets et al. (2009), after which they point out that "N2O is a greenhouse gas with a 100-year global warming potential of ~298, and a lifetime of ~114 years," citing Forster et al. (2007). And on top of these gloomy assessments, they go on to analyze the potential negative consequences of the fact that "N2O leads to stratospheric ozone destruction," as noted over four decades ago by Crutzen (1970).

What was learned
In analyzing "the potential effects on the ozone layer of a large-scale shift away from fossil fuel use to biofuels consumption over the 21st century," the four New Zealand researchers find that "global-mean column ozone decreases by 2.6 DU between 2010 and 2100," due to the fact that "1) large N2O emissions lead to faster rates of the ozone-depleting NOx cycles and; 2) reduced CO2 emissions (due to less fossil fuel burning) lead to relatively less stratospheric cooling over the 21st century, which decreases ozone abundances."

What it means
In light of their findings, as Revell et al. state in the concluding sentence of their report, "increased biofuels production and consumption could therefore be damaging to the ozone layer," which would be detrimental to the biosphere due to the fact that the stratospheric ozone layer filters out much of the harmful UV-B radiation coming from the sun, which otherwise could do much damage to earth's terrestrial plants.

Crutzen, P.J. 1970. The influence of nitrogen oxides on the atmospheric ozone content. Quarterly Journal of the Royal Meteorological Society 96: 320-325.

Crutzen, P.J., Mosier, A.R., Smith, K.A. and Winiwarter, W. 2008. N2O release from agro-biofuel production negates global warming reduction by replacing fossil fuels. Atmospheric Chemistry and Physics 8: 389-396.

Forster, P., Ramaswamy, V., Artaxo, P. et al. 2007. Changes in atmospheric constituents and in radiative forcing. In: Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K.B., Tignor, M. and Miller, H.L. (Eds.). Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom, pp. 129-234.

Smeets, E.M.W., Bouwmanw, L.F., Stehfest, E., van Vuuren, D.P. and Posthuma, A. 2009. Contribution of N2O to the greenhouse gas balance of first-generation biofuels. Global Change Biology 15: 1-23.

Reviewed 10 October 2012