Dr. Henning had a letter posted in USA Today combating myths about beef and global warming.

Here is Dr. Henning’s letter.

Why the shift in scrutiny from our use of fossil fuels to the carbon footprint of our food? USA TODAY’s article, Eating can be Energy Efficient, too, repeated the fashionable claim that switching to a “low-carbon diet” would make a meaningful reduction in a person’s carbon footprint (Life, April 22).

Yet the Environmental Protection Agency reports that all U.S. agriculture, including livestock and crops, accounts for only 6% of U.S. greenhouse gas emissions.  I find the article seriously in conflict with this report.

The experts cited in USA TODAY’s article claim to understand the impact of animal agriculture on carbon emissions, yet they ignore how tightly intertwined our animal and crop production systems are.

For example, how will we replace livestock manure used to fertilize our crops without resorting to fossil fuel-derived fertilizers? What happens to feeds that are unsuitable for humans and the use of byproduct feeds? And, knowing that 85% of U.S. grazing land isn’t suitable for crop production, do we know if we can support ourselves on the cropland that remains? What gasses are produced in the decomposition of the unused plants and in crops such as rice?

Advocating the seemingly easy and convenient solution of low-carbon diets to solve the environment dilemma might be tempting, but have we assessed the nutritional impact for reducing our major sources of balanced proteins in children?

Environmentally conscious consumers should continue to enjoy lean meat with confidence, knowing they are doing the right thing for their bodies and for the environment.

Posted on USA Today at 12:09 AM/ET, April 30, 2009.

The United Nations (UN) Food Summit (High-Level Conference on World Food Security), held in Rome in early June, 2008, was designed to address food security issues in the face of soaring food prices (see Figure below), and the growing challenges associated with rising energy costs, and how this has impacted food prices and food security.

The increase in food prices is astounding! For example, during the early part of 2008, nominal prices of all major food commodities reached their highest levels in the past 50 years. For the first time, the annual global food import bill will surpass $1trillion (FAO, Food Outlook, June 2008)!

Part of the food price “shock” relates to level of current food stocks (reserves) in the World. Since 1995, global cereal stock levels have declined at a rate of about 3.5% per year…which is due to demand growth surpassing supply (FAO, 2008). FAO is estimating that by the end of 2008, global cereal stocks will decrease an additional 5%, reaching their lowest levels in the past 25 years!

Identifying strategies to increase food production (and efficiency) are clearly among the the biggest challenges we confront. I have written about various aspects of this in previous Terry Etherton blogs. It is important to appreciate that developing and implementing solutions to these problem is not easy, cheap…and, certainly doesn’t happen quickly.

Unfortunately, the Declaration published from the UN Food Summit provides little assurance that anything will be done by the UN to solve the problems! It would have been far better to invest the money frittered away supporting the UN Food Summit on research to pursue new ways to improve food production and food production efficiency.

At the core of “research needs” is the need for a much larger investment in biotechnology research for food production. The advances in plant and animal biotechnology and their impact on food production and productive efficiency have been impressive. We, however, must continue to invest in developing new science-based food biotechnologies for application on the farm..to feed a growing World population. This need coincides with a current “funding environment” for agricultural scientific research in the U.S. that is, at best, “modest”. This certainly does not help this situation.

My encouragement is to increase the investment in science. Historically, this has led to the development and application of new discoveries that benefit production agriculture in the World. We should not be “fiddling” away precious time and resources that could be invested in science to help feed the global village.

Unfortunately, many government and inter-government agencies are spending more time fiddling than finding ways to increase food production and productive efficiency. This is unfortunate given the current era of soaring food prices, and the reality we have of needing to find ways to feed a growing World population.

(Published in Science 319:43-44, 2008)

Global warming and escalating petroleum costs are creating an urgent need to find ecologically friendly fuels. Biofuels–such as ethanol from corn (maize) and sugarcane–have been increasingly heralded as a possible savior (1, 2). But others have argued that biofuels will consume vast swaths of farmland and native habitats, drive up food prices, and result in little reduction in greenhouse-gas emissions (3-5). An innovative study by Zah et al. (6), commissioned by the Swiss government, could help to resolve this debate by providing a detailed assessment of the environmental costs and benefits of different transport biofuels.

To date, most efforts to evaluate different biofuel crops have focused on their merits for reducing greenhouse-gas emissions or fossil fuel use. Some studies suggest that corn-derived ethanol in the United States (7) and Europe (8) consumes more energy than it produces; others suggest a modest net benefit (2). Relative to petroleum, nearly all biofuels diminish greenhouse-gas emissions, although crops such as switchgrass easily outperform corn and soy (9). Such comparisons are sensitive to assumptions about local growing conditions and crop by-products, but even more important, their focus on greenhouse gases and energy use is too narrow.

The arguments that support one biofuel crop over another can easily change when one considers their full environmental effects. A key factor affecting biofuel efficacy is whether native ecosystems are destroyed to produce the biofuels. For example, regardless of how effective sugarcane is for producing ethanol, its benefits quickly diminish if carbon-rich tropical forests are being razed to make the sugarcane fields, thereby causing vast greenhouse-gas emission increases (4). Such comparisons become even more lopsided if the full environmental benefits of tropical forests–for example, for biodiversity conservation, hydrological functioning, and soil protection–are included (10, 11).

Another environmental cost that varies among biofuels is trace-gas emissions. For example, crops that require nitrogen fertilizers, such as corn or rapeseed, can be a significant source of nitrous oxide, an important greenhouse gas that also destroys stratospheric ozone. When nitrous oxide emissions are compared among ethanol-producing crops, grasses and woody coppice become more favorable, whereas corn or canola may be worse for global warming than simply burning fossil fuels (3).

In the debate about different biofuels, one can easily be overwhelmed by the “apples and oranges” problem: Each biofuel has certain benefits and potential costs, and there is no common currency for comparing them. This is where Zah et al. have broken new ground by devising a conceptual scheme to evaluate different biofuels using just two criteria: greenhouse-gas emissions and overall environmental impact.

The authors compare gasoline, diesel, and natural gas with 26 different biofuels produced from a wide range of “crops.” They assess the total environmental impact of each fuel by aggregating natural resource depletion and damage to human health and ecosystems into a single indicator, using two different methods (12). The second key criterion for each fuel is its greenhouse-gas emissions relative to gasoline.

The findings of Zah et al. are striking (13) (see Figure 1 below). Most (21 out of 26) biofuels reduce greenhouse- gas emissions by more than 30% relative to gasoline. But nearly half (12 out of 26) of the biofuels–including the economically most important ones, namely U.S. corn ethanol, Brazilian sugarcane ethanol and soy diesel, and Malaysian palm-oil diesel–have greater aggregate environmental costs than do fossil fuels (see Figure 1, top panel). Biofuels that fare best are those produced from residual products, such as biowaste or recycled cooking oil, as well as ethanol from grass or wood. The findings highlight the enormous differences in costs and benefits among different biofuels.

Despite its apparent advantages, the scheme of Zah et al. is not perfect. Collapsing disparate environmental costs into a single number is risky, although it is reassuring that the two different methods used yielded similar results. A bigger worry is that their analyses fail to capture the potentially important indirect effects of different biofuels. For example, U.S. government subsidies to encourage corn-based ethanol production are prompting many American farmers to shift from growing soy to growing corn. This is helping to drive up global soy prices, which in turn amplifies economic incentives to destroy Amazonian forests and Brazilian tropical savannas for soy production (14). Furthermore, Zah et al. rely on relatively old (2004) data sets and fail to consider the social consequences of large-scale biofuel production, especially rising food cost.

Zah et al. excluded from their analysis so-called second-generation biofuels, such as those made from the breakdown of plant cellulose or lignin, because of insufficient data. Such biofuels could be produced from nonfood plants–such as prairie grasses or trees grown on marginal land (15), or algae cultivated in aquaculture (16)–reducing the use of food crops for biofuels (see the figure, bottom panel). Some second- generation biofuels appear particularly promising in terms of their benefits and costs for biofuel production (5).

Not all biofuels are beneficial when their full environmental impacts are assessed; some of the most important, such as those produced from corn, sugarcane, and soy, perform poorly in many contexts. There is a clear need to consider more than just energy and greenhouse-gas emissions when evaluating different biofuels and to pursue new biofuel crops and technologies. Governments should be far more selective about which biofuel crops they support through subsidies and tax benefits. For example, multibillion-dollar subsidies for U.S. corn production appear to be a perverse incentive from a rational cost-benefit perspective.

References and Notes

1. S. Pacala, R. Sokolow, Science 305, 968 (2004).
2. A. E. Farrell et al., Science 311, 506 (2006).
3. P. J. Crutzen, A. R. Moiser, K. A. Smith, W. Winiwarter, Atmos. Chem. Phys. Discuss. 7, 11191 (2007).
4. R. Righelato, D. V. Spracklen, Science 317, 902 (2007).
5. J. Hill, E. Nelson, D. Tilman, S. Polasky, D. Tiffany, Proc. Nat. Acad. Sci. U.S.A. 103, 11206 (2006).
6. R. Zah et al., Ökobilanz von Energieprodukten: Ökologische Bewertung von Biotreibstoffen (Empa, St. Gallen, Switzerland, 2007).
7. D. Pimentel, T. Patzek, G. Cecil, Rev. Environ. Contam. Toxicol. 189, 25 (2007).
8. S. Ulgiati, Crit. Rev. Plant Sci. 20, 71 (2001).
9. P. R. Adler, S. J. Del Grosso, W. J. Parton, Ecol. Appl. 17, 675 (2007).
10. G. Bala et al., Proc. Nat. Acad. Sci. U.S.A. 104, 6550 (2007).
11. W. F. Laurance, Biol. Conserv. 91, 109 (1999).
12. The authors use Swiss environmental impact points, which measure how much the environmental impacts exceed legal limits (see www.esu-services.ch/download/Frischknecht-2006-EcologicalScarcity-Paper.pdf) and the European Eco-indicator, which quantifies damage to human health and ecosystems (see www.pre.nl/eco-indicator99/default.htm).
13. A figure summarizing the findings of (6) is available as supporting material on Science Online.
14. W. F. Laurance, Science 318, 1721 (2007).
15. D. Tilman, J. Hill, C. Lehman, Science 314, 1598 (2006).
16. A. Melis, T. Happe, Plant Physiol. 127, 740 (2001).

Figure 1. Greenhouse emissions are plotted against overall environmental impacts of 29 transport fuels, scaled relative to gasoline. The origin of biofuels produced outside Switzerland is indicated by country code: Brazil (BR), China (CN), European Union (EU), France (FR), and Malaysia (MY). Fuels in the shaded are considered advantageous in both their overall environmental impacts and greenhouse-gas emissions.