Report Outlines U.S. Food System's Vulnerabilities to Climate Change

A new report by the U.S. Department of Agriculture outlines 20 indicators to track changes to the domestic agricultural system driven by global climate change. The report, “Climate Indicators for Agriculture,” is co-authored by Lewis Ziska, PhD, a leading expert on food systems and climate change and professor of environmental health sciences at Columbia University Mailman School of Public Health.

The report provides a new framework for understanding climate change-related impacts to U.S. agriculture with data that farmers and land managers can use to understand how climate change is affecting their operations and guide the development of effective adaptation. The framework also has implications for public health, in terms of nutrition and food insecurity.  

Climate indicators described in the report are arranged in five categories, including physical (extreme precipitation and nighttime air temperature), crop and livestock (animal heat stress and leaf wetness duration), biological (insect infestation in crops, crop pathogens), phenological (timing of budbreak in fruit trees, disease vectors in livestock) and socioeconomic (crop insurance payments, heat-related mortality of agricultural workers). Indicators are based on the strength of their connection to climate change and availability of long-term data, which is needed to identify how impacts are changing over time and whether adaptive actions are having the desired effect.

Ziska contributed to the section on biological indicators, such as the range and infestation intensity of weeds, pests, and disease that affect crop production and animal agriculture—all which are influenced by temperature, precipitation, atmospheric carbon dioxide concentrations, and other climate variables. The section cites research by Ziska on increasing evidence that warmer temperatures and additional CO2 can reduce the efficacy of pesticide management, and that warmer winters may lead to a northward shift in the northern limit of kudzu and increased application of insecticide and fungicide. Ziska’s research is also cited throughout the 40-page report, including six separate papers he led or co-authored.

“Changes in climate are projected to affect the establishment, spread, and impacts of pest species within agricultural systems. For example, the continuous increase in atmospheric CO2 concentration directly stimulates the growth and fecundity of weedy species, but also has implications for host plants, insects, and plant pathogens. In addition, increased temperatures, particularly warmer winters, may represent a removal of thermal constraints that would allow northward migration of crop and livestock pests,” the authors write.