The U.S. Department of Agriculture has issued new report that attempts to forecast the impact of climate change on American farming in the next 50 years. USDA seems to expect serious climate-related farming problems ahead, but the recent changes in global climate have been tiny—and in the “wrong” direction! The earth’s temperatures are now slightly cooler than when NASA’s James Hansen first warned the U.S. Senate about “runaway global warming” in 1988.
Senior climate researcher Kevin Trenberth of the National Center for Atmospheric Research recently admitted to colleagues “we have no idea why the earth isn’t warming, and it’s a travesty that we don’t know.” That’s a quote from one of those e-mails leaked at Britain’s University of East Anglia.
That pretty much tells us how much faith we dare to put in the new USDA climate-change forecasts.
The USDA report’s timing couldn’t have been worse. Since 2007, the earth seems to have passed a “tipping point” into global cooling—at least temporarily. NASA told us in 2008 that the Pacific Ocean had shifted into a cool cycle, after strong warming both globally and in the Pacific from 1976-1998 and cooling from 1940-1975.
What does USDA predict from its new computer-generated look into the future?
- Grain and oilseed crops will mature more rapidly, because of shorter, warmer winters—although rainfall may be more variable, perhaps even with more drought. (Seems reasonable and generally beneficial—but hardly earth-shaking.)
- Horticultural crops may be more vulnerable to climate change than field crops, since climate factors impact appearance and quality of the produce. (How much did this big report cost)
- Livestock mortality will decrease with warmer winters, but USDA claims this will be more than offset by greater death losses during hotter summers. (More cattle die in blizzards than in summer pastures equipped with shade opportunities)
- Weeds may grow more rapidly with elevated levels of atmospheric CO2. (But so do crop plants. It’s a wash.)
- Disease and insect prevalence will escalate as a result of shorter, warmer winters. (Vaccines and medications have been more important than modest temperature changes—for both human and livestock diseases.)
- The trends toward reduced mountain snowpack and earlier spring snowmelt runoff in the western U.S. imply changes in the availability of irrigation water. (We’ve had lots of snowpack since 2007. Can the USDA tell us when that will change back again, and why?)
USDA left out the most important information about CO2 and farming’s future: More CO2 in the atmosphere raises crop yields substantially, acting like fertilizer for the plants and increasing their water use efficiency. Doubling CO2 in the air raises the yields of herbaceous plants 30–50 percent, and of trees by 50–80 percent, based on hundreds of studies in dozens of countries.
Higher CO2 levels should mean higher crop and livestock yields! Talley ho!