Agriculture, food systems, energy, and global change.

In “Greenhouse gases in intensive agriculture: Contributions of individual gases to the radiative forcing of the atmosphere” (Reports, 15 Sept., p. [1922][1]), G. P. Robertson, E. A. Paul, and R. R. Harwood offer an excellent long-term and systems-based analysis of the relative impacts of different cropping systems upon global warming potential (GWP). They find that no-till management has the lowest net GWP, followed by organic and low input management (each with legume cover). These three all have much lower GWP than conventional tillage (Table 2, p. 1924). In concluding, they state that “[a]griculture…plays a minor role in the GWP economy of the U.S., yet net mitigation of agricultural fluxes could offset the current annual increase in fossil fuel CO2 emissions.” This kind of basic research is of great importance in setting intelligent research and policy agendas for agriculture, and it deserves further elaboration. It is also crucial that such research and analysis be placed in the larger context of food systems. Research done in the 1960s and 1970s showed that (i) agriculture represented only about a third of the total energy used in the U.S. food system, (ii) the typical food calorie on a dinner plate required 10 calories of energy input ([1][2]), and (iii) the average food item was shipped some 1300 miles ([2][3]). Internationally, a 1993 estimate indicated that “only about 10% of the fossil fuel energy used in the world's food system is used in production” ([3][4]). We desperately need to update and improve the quality of these data and formulate an analysis of their GWP to determine where the greatest reductions are to be found. Any search for more sustainable ways to structure our food systems will require more than an energy analysis of current long-distance industrial food systems. It will be necessary to review the underlying theories of social change in conventional energy approaches ([4][5]). In addition, the many significant social, health, and environmental externalities of industrial food systems must be included ([5][6]). Global warming studies should examine not only current industrial structures and food systems, but more localized alternatives—both traditional and emerging ([6][7]). Only with such a comprehensive and systematic approach will we be able to assess the full range of the costs and benefits of more global versus more local food systems. 1. [↵][8]1. J. S. Steinhart, 2. C. E. Steinhart , Science 184, 307 (1974). [OpenUrl][9][FREE Full Text][10] 2. [↵][11]1. S. L. Brown, 2. U. F. Pilz , U.S. Agriculture: Potential Vulnerabilities (Stanford Research Institute, Menlo Park, CA, 1969). 3. [↵][12]1. G. Tansey, 2. T. Worsley , The Food System (Earthscan, London, 1995), p. 223. 4. [↵][13]1. S. Rayner, 2. E. L. Malone 1. E. Shove, 2. L. Lutzenhiser, 3. S. Guy, 4. B. Hackett, 5. H. Wilhite , “Energy and Social Systems,” in Human Choice and Climate Change, vol. 2, S. Rayner, E. L. Malone, Eds. (Batelle, Columbus, OH, 1998), pp. 291-325. 5. [↵][14]1. K. A. Dahlberg New Directions for Agriculture and Agricultural Research (Rowman & Allanheld, Totowa, NJ, 1986). 6. [↵][15]United Nations Development Program (UNDP ), Urban Agriculture: Food, Jobs, and Sustainable Cities (UNDP, New York, 1996). [1]: /lookup/doi/10.1126/science.289.5486.1922 [2]: #ref-1 [3]: #ref-2 [4]: #ref-3 [5]: #ref-4 [6]: #ref-5 [7]: #ref-6 [8]: #xref-ref-1-1 "View reference 1 in text" [9]: {openurl}?query=rft.jtitle%253DScience%26rft.stitle%253DScience%26rft.issn%253D0036-8075%26rft.aulast%253DSteinhart%26rft.auinit1%253DJ.%2BS.%26rft.volume%253D184%26rft.issue%253D4134%26rft.spage%253D307%26rft.epage%253D316%26rft.atitle%253DEnergy%2BUse%2Bin%2Bthe%2BU.%2BS.%2BFood%2BSystem%26rft_id%253Dinfo%253Adoi%252F10.1126%252Fscience.184.4134.307%26rft_id%253Dinfo%253Apmid%252F4816130%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [10]: /lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6MzoiUERGIjtzOjExOiJqb3VybmFsQ29kZSI7czozOiJzY2kiO3M6NToicmVzaWQiO3M6MTI6IjE4NC80MTM0LzMwNyI7czo0OiJhdG9tIjtzOjI1OiIvc2NpLzI5MC81NDk1LzEzMDAuMS5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30= [11]: #xref-ref-2-1 "View reference 2 in text" [12]: #xref-ref-3-1 "View reference 3 in text" [13]: #xref-ref-4-1 "View reference 4 in text" [14]: #xref-ref-5-1 "View reference 5 in text" [15]: #xref-ref-6-1 "View reference 6 in text"