AGRICULTURAL AND FOREST METEOROLOGY
and Forest Meteorology
80 (1996) ix-xi
Adapting North American agriculture to climate change William E. Easterling Depurtment
University of Nebraska-
Lincoln, Lincoln, NE 68583-0728,
Climatologists are in general agreement, with some notable exceptions, that past anthropogenic greenhouse gas emissions may have committed the Earth to an unknown but probably significant amount of future warming accompanied by regionally-differentiated climate changes. Reifsnyder (1989) listed ten ‘fallacies’ that seem unquestioningly accepted by the lay public and scholars alike concerning the possibility of global warming. Among the fallacies listed was the supposition that ‘government imprimatur equals scientific validation’. That is, government interpretation and presentation of the results of scientific studies of climate change has, in some cases, tended to ‘rise above’ scientific uncertainties in proclaiming global warming as a major policy issue. Concern over such a supposition was partly responsible for the establishment of the Intergovemmental Panel on Climate Change by the World Meteorological Organization. Though Reifsnyder’s point here was in connection with the uncertainty of how climate may change, the point is equally valid for the estimation of possible impacts of climate change on vulnerable systems such as agriculture. The possibility that agriculture might fully or partially adapt to climate change was beyond the scope of many key early studies. Hence, those studies quite naturally tended to overstate the magnitudes of impacts and thus got the attention of the policy community and the public. On the other hand, subsequent government-sponsored studies focusing on potential adaptation of agriculture to climate change may have understated magnitudes of impacts. The point here is that a careful comparison of early studies less concerned with adaptation versus more recent adaptation-focused studies is needed to provide insights into the different levels of impacts. In late 1992, the Office of Technology Assessment of the United States Congress commissioned a series of working papers that became the core of a major report entitled ‘Preparing for an Uncertain Climate’ (Office of Technology Assessment, 1993). The report was prompted in part by the then new publication by the National Academy of Sciences National Research Council entitled ‘Policy Implications of Greenhouse Warming’ (National Research Council, 19911, which emphasized adaptation. I prepared a 016%1923/96/$15.00 0 1996 Elsevier Science B.V. All rights reserved SSDI 016% 1923(95)023 14-3
md Forest Meteorology
80 (1996) ix-xl
review of the expected potential of United States agriculture to adapt successfully to climate change without a loss of comparative advantage, which was extensively peer reviewed and then used as a guide in drafting the agriculture component of the OTA report. As I prepared the OTA review, it became quite apparent that a significant amount of research on agricultural adaptation to climate change has accumulated in the literature, especially concerning production agricultural systems. It is now time to take stock of this research, see what can be concluded from the research and to suggest new research directions, especially in the economic assessment of adaptability. The material reported here consists of three papers. The first paper is a broad overview of the adaptation of North American agriculture to climate change based on the literature. The paper analyzes climate-related and nonclimate-related factors that will influence the vulnerability of future North American agriculture to climate change. It then critically reviews past research on agricultural adaptability to climate variation and change. Because of the large number of studies on the subject the review is restricted to those studies most widely disseminated throughout the scientific and policy communities. Doubtless some important studies were overlooked, though we are confident that the major ones are included here. Adaptation strategies considered in the review range from short-term agronomic adjustments at the farm-level to long-term changes in the dynamics of regional trade flows. The policy relevance of existing adaptation assessment methodologies is assayed and, caveats notwithstanding, a plausible scenario of the adaptability of North American agriculture to climate change based on the methodologies is presented. Two streams of modeling methodologies are developed in the review and subsequent papers. The first stream consists of procedures which link in situ process-level models of crop growth with economic models. I refer to these as bottom-up or ‘atomistic’ modeling approaches that attempt to assemble all of the relevant biophysical and economic pieces in a causal chain that culminates through scaling and aggregation in a regional economic impact assessment. The second stream consists of economic models that endeavor to internally represent biophysical response to climate change with carefully specified statistical equations relating spatially aggregated climate and crop yield series with economic proxies such as land values that are argued to reflect gradual climate changes. I refer to these as top-down or ‘reduced-form’ economic models. The second and third papers in this set each represent one of the two streams mentioned above. In the second paper, Mendelsohn and colleagues argue that Ricardian principles and the notion of land rent as a measure of embodied climate can be used empirically to evaluate the regional economic impact of climate change on agriculture, net of adaptation. They use econometric techniques to test their model and evaluate the results. Mendelsohn and colleagues’ paper is an example of reduced-form modeling. In the third paper, Antle examines the question of modeling agricultural adaptability with a farm-level approach that represents land-use and crop-specific management decisions in relation to spatial and temporal variation in the physical environment, technology, prices of outputs and inputs and policy variables. Using this model, he discusses a number of issues that arise in modeling impacts of and adaptation to climate change, including the choice of a modeling ‘scale’ or level of data aggegation, and the effects of changes in
and Forest Meteorology
80 (1996) k-xi
agricultural policies on impact assessments. Antle’s paper is an example of an atomistic modeling approach. This three-paper set provides a comprehensive evaluation of current research on agricultural adaptation to climate change, the policy relevance of such research, and new directions future research should take to improve the robustness of what has been the least well-developed element of adaptation assessments: economic analysis.
References National Research Council, 1991. Policy Implications of Greenhouse Warming. National Academy Press, Washington, DC. Office of Technology Assessment, 1993. Preparing for an Uncertain Climate, Vols. I and 2. US Government Printing Office, Washington, DC. Reifsnyder, W.E., 1989. A tale of ten fallacies: The skeptical enquirer’s view of the carbon dioxide/climate controversy. Agric. For. Meteorol., 47: 349-371.