Back to the Future- Using Historical Climate Observations for Climate Change Assessment.

Farmers need information about the climate that match their planning horizon (20 to 30 years), without the biases and problems associated with the climate model outputs. One source of climate information for such assessment can be obtained from historic climate record of surface observations. The analysis of the long-term temperature records of the Southeast U.S. provides a justification for using this approach. Average annual temperatures since 1935 show 2 distinct decades of predominantly warmer temperatures and cooler temperatures. The weather data were divided into 3 different periods: Warm Period (1935-1954); Cold Period (1958-1977); Recent Period (1981-2000).  The objectives of this study are to (i) simulate the effects of long-term weather on crop production and (ii) understand the effects of rainfall and temperature on crop growth and yield. Six locations were chosen for this study from the Southeast U.S.. Two crops were chosen, a summer crop (Maize) and a winter crop (Wheat). The same soil was used across the 6 locations (Silty-Clay-Loam). Results of this study show that the simulated yield for the summer crop is 9% higher during the cold period than the other two periods. The number of days above 27^oC between anthesis and maturity is the variable that caused 20% yield reduction. The winter crop showed an opposite behavior, with simulated yield 7% lower in the cold period than in the warm and recent periods.