Climate-change modeling finds many crop yields are likely to decline

Is an organic tomato grown in Mexico better for the environment than a conventional one grown 150 miles away from your Bay Area home? Is it more sustainable to drive to a big-box store and buy lots of groceries to keep in the freezer, or to purchase ready-made meals or cook individual ingredients at home? These types of questions are at the heart of a UC Agricultural Sustainability Institute (ASI) project that is examining the food system’s role in climate change. “Changes in consumer food choices, as well as in our vast food-production system, could contribute substantially to meeting goals for reducing greenhouse gases,” ASI director Thomas Tomich says. “Individual foods vary tremendously in their carbon footprints.” The low-carbon diet project uses life-cycle assessment methodology to tally the energy used to produce particular foods, then does computer modeling to estimate greenhouse-gas emissions. Researchers identify and collect data on farming practices, pest control, irrigation, harvesting, processing, transportation, refrigeration, storage and even cooking. “We’re looking for all the inputs, from farm to fork,” says Gail Feenstra, ASI food systems analyst. The project has collected data on processing tomatoes, dairy and rice, and Sonja Brodt and Alissa Kendall of UC Davis are currently crunching numbers to find the “break-even” point for the energy usage of rice. A new effort in conjunction with Cornell University, funded by the Kellogg Foundation, will examine the carbon footprints of local foods in California and elsewhere in the United States. ASI is also launching the California Nitrogen Assessment, funded by the Packard Foundation, to further quantify the scope of the state’s greenhouse-gas emissions. An estimated 15% of U.S. energy usage and greenhouse-gas emissions is related to the food system. The major contributors are livestock-related Science briefs