Selected Papers

Woodill, A. J., Nakamoto, S. T., Kawabata, A. M., & Leung, P. (2017). To Spray or Not to Spray: A Decision Analysis of Coffee Berry Borer in Hawaii.

      Insects, 8(4), 116. [link]

Woodill, A. J., Hemachandra, D., Nakamoto, S. T., & Leung, P. (2014). The Economics of Coffee Production in Hawai’i, (June),1-9. [link]

Richardson, G. M., Bowers, J., Woodill, A. J., Barr, J. R., Gawron, J. M., & Levine, R. a. (2014). Topic Models: A Tutorial with R. International Journal

      of Semantic Computing, 08(01), 85-98. [link]

Working Papers

Adaptation to Climate Change: Disentangling Revenue and Crop Choice Responses

Many suggest that adaptation will mitigate the harmful effects of climate change on agriculture, and offer this as a critique of studies that estimate climate-change impacts by extrapolating from short-run links between crop yield and weather. Theory indicates that weather responses should provide a first-order approximation to the climate response, a point we clarify more generally in this paper. Empirically, some studies focus on cross-sectional associations between agricultural outcomes and prevailing climate, implicitly accounting for adaptation; but the adaptive mechanism is not clear and the relationships may be confounded by unobserved factors. In this paper, we use a long history of crop choice and productivity outcomes to estimate effects of both weather and climate for major field crops in the United States. The approach leverages historical differences in climate trends across U.S. counties, differences that are large enough to span anticipated climate changes over the next 50 years, even after removing state-level trends. Climates are defined by backwardlooking rolling means of the weather measures, with lag length selected via cross-validation. We then estimate the effect of climate change from a base level to uniform increases in temperature from 0-5°C. We find adaptation slightly reduces impacts relative to estimates that consider weather alone.

Nonlinear Temperature Effects and Short-Run Adaptation of the Dust Bowl Region during the 1930s

The Dust Bowl of the 1930s was one of the most significant environmental events in American history. Understanding the short-run adjustments from major weather events on agricultural yield can shed light on the economic impacts of changing weather conditions. Nonlinear temperature effects are examined in the Great Plains region of the US from 1910 - 1960 to identify changes in corn yield and short-run adaptation. Results show the Dust Bowl region had more harmful temperatures than the Northern Great Plains, but the temperature effect on corn yields were similar in each region; however, total corn yields from 1910-1960 were less in the Dust Bowl region. Nonlinear estimation results show slight adaptation in the Dust Bowl region and no adaptation in the Northern region. Adaptation appears to be limited in the short-run even with the introduction of hybrid corn and changing farming practices. Precipitation also appears to play less of a role on crop yields. These results add a historical perspective to the issue of short-run adaptation due to extreme weather events.

Optimal spraying and harvesting strategies to combat CBB in Hawaii: A dynamic approach

This paper considers optimal decisions coffee farmers make to combat damage from the coffee berry borer in Hawaii. We model the decision to spray or not spray a biological insecticide, Beauveria bassiana, based on the expected damage from not spraying versus the cost to spray. If damages are greater than the cost to spray, then it is beneficial to spray in order to mitigate damage to coffee. A time-inhomogenous Markov-chain is used to estimate economic damage in each month based on whether a farm decides to spray or not spray. The Markov-chain is incorporated into a dynamic programming model to optimize the net benefit during a coffee season. Results provide an optimal decision path for a coffee growing season. Next, a simulation of a two-farm scenario is conducted to test the differences between a well-managed and poorly-managed farm to show the initial infestation levels are important factors in reducing economic damage. We also trace out an infestation threshold where a farmer would be indifferent between spray or not spray to allow for better decision making.