Commentary: USDA misleads on farming’s climate future

Originally published in the January 22, 2010, print edition.

The Land — The U.S. Department of Agriculture has issued a new report that attempts to forecast the impact of climate change on American farming in the next 50 years. The 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 1976-98 and cooling from 1940-75.

What does the 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 the 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?)

The 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 to 50 percent, and of trees by 50 to 80 percent, based on hundreds of studies in dozens of countries.

Higher CO2 levels should mean higher crop and livestock yields. Talley ho!

Resources:

B.A. Kimball, 1983, “Carbon Dioxide and Agricultural Yields: An Assemblage and Analysis of 430 Prior Observations,” Agronomy Journals 75, pp 779-788.

K.E. Idso and S. B. Idso, 1994, “Plant Responses to Atmospheric CO2 Enrichment in the Face of Environmental Constraints, A Review of the past 10 years’ Research,” Agriculture and Forest Meteorology 69, pp 153–203.

R.R. Nemani et al., 2003, “Climate-Driven Increases in Global Terrestrial Net Primary Production from 1982 to 1999,” Science 300, pp 1560-1563.

•••

This commentary was submitted by Dennis Avery, a senior fellow for the Hudson Institute in Washington, D.C., and the director for the Center for Global Food Issues. He was formerly a senior analyst for the Department of State. Readers may write him at P.O. Box 202, Churchville, VA 24421 or e-mail to cgfi@hughes.net.

Text Only