MIT Joint Program on the Science and Policy of Global Change
Abstract
http://globalchange.mit.edu/research/publications/2264This paper describes the use of the CliCrop model in the context of climate change general assessment
modeling. The MIT Integrated Global System Model (IGSM) framework is a global integrated assessment
modeling framework that uses emission predictions and economic outputs from the MIT Emission Prediction
and Policy Analysis (EPPA) model and earth system modeling predictions from the IGSM to drive a
land system component, a crop model (CliCrop) and a Water Resource System (WRS) model. The global
Agriculture and Water System are dependant upon and interlinked with the global climate system. As irrigated
agriculture provides 60% of grains and 40% of all crop production on 20% of global crop lands and
accounts for 80% of global water consumption, it is crucial that the agricultural-water linkage be properly
modeled. Crop models are used to predict future yields, irrigation demand and to understand the effect of
crop and soil type on food productivity and soil fertility. In the context of an integrated global assessment, a
crop water-stress and irrigation demand model must meet certain specifications that are different for other
crop models; it needs to be global, fast and generic with a minimal set of inputs. This paper describes
how CliCrop models the physical and biological processes of crop growth and yield production and its use
within the MIT Integrated Global System Model (IGSM) framework, including the data inputs. This paper
discusses the global data bases used as input to CliCrop and provides a comparison of the accuracy of
CliCrop with the detailed biological-based crop model DSSAT as well as with measured crop yields over
the U.S. at the country level using reanalyzed weather data. In both cases CliCrop performed well and the
analysis validated its use for climate change impact assessment. We then show why correctly modeling the
soil is important for irrigation demand calculation, especially in temperate areas. Finally, we discuss a
method to estimate actual water withdrawal from modeled physical crop requirements using U.S. historical
data.The initial funding for CliCrop was provided by USAID under a program on climate change
adaptation in Niger. Further funding was provided by UN University World Institute for Development Economics
Research for the Application and Development of CliCrop in Africa, the authors would like to
particularly thank Prof. Finn Tarp, Prof. Channing Arndt and Dr. James Thurlow for their
support. The authors also would like to thank Dr. Jawoo Koo of IFPRI for his review and
contributions to the software development. The authors also gratefully acknowledge additional
financial support for this work provided by the MIT Joint Program on the Science and Policy of
Global Change through a consortium of industrial sponsors and Federal grants. Development of
the IGSM applied in this research was supported by the U.S. Department of Energy, Office of
Science (DE-FG02-94ER61937); the U.S. Environmental Protection Agency, EPRI, and other
U.S. government agencies and a consortium of 40 industrial and foundation sponsors
