Climate change effects on agriculture: Economic responses to biophysical shocks

Abstract

Agricultural production is sensitive to weather and thus directly affected by climate change. Plausible estimates of these climate change impacts require combined use of climate, crop, and economic models. Results from previous studies vary substantially due to differences in models, scenarios, and data. This paper is part of a collective effort to systematically integrate these three types of models. We focus on the economic component of the assessment, investigating how nine global economic models of agriculture represent endogenous responses to seven standardized climate change scenarios produced by two climate and five crop models. These responses include adjustments in yields, area, consumption, and international trade. We apply biophysical shocks derived from the Intergovernmental Panel on Climate Change's representative concentration pathway with end-of-century radiative forcing of 8.5 W/m 2 . The mean biophysical yield effect with no incremental CO 2 fertilization is a 17% reduction globally by 2050 relative to a scenario with unchanging climate. Endogenous economic responses reduce yield loss to 11%, increase area of major crops by 11%, and reduce consumption by 3%. Agricultural production, cropland area, trade, and prices show the greatest degree of variability in response to climate change, and consumption the lowest. The sources of these differences include model structure and specification; in particular, model assumptions about ease of land use conversion, intensification, and trade. This study identifies where models disagree on the relative responses to climate shocks and highlights research activities needed to improve the representation of agricultural adaptation responses to climate change.climate change adaptation | model intercomparison | integrated assessment | agricultural productivity C limate change alters weather conditions and thus has direct, biophysical effects on agricultural production. Assessing the ultimate consequences of these effects after producers and consumers respond requires detailed assessments at every step in the impact chain from climate through to crop and economic modeling.Comparisons of results from global studies that have attempted such model integration in the past show substantial differences in effects on key economic variables. Studies in the early 1990s found that climate change would have limited agricultural impacts globally, but with varying effects across regions (1-3). Adaptation and carbon dioxide (CO 2 ) fertilization effects were the two largest sources of variation in the results. New simulation approaches emerged in the mid-2000s, with gridded representation of yield impacts and more comprehensive coverage of variability in climate model projections (4, 5). However, these studies still relied on a single crop model and a single economic model. The number of economic models used for these types of analysis has remained relatively limited, and there has been no attempt to compare their behavior systematically. The Fourth Assessment Report of the Inte...

Global and regional health effects of future food production under climate change: a modelling study

“…Climate change leads to changes in temperature and precipitation which are expected to reduce global crop productivity, 5,15 lead to changes in food production and consumption, 6 and impact health by altering the composition of diets and, with it, the profile of dietary and weight-related risk factors and associated mortalities. 13 The results of this study indicate that even relative modest reductions in per-capita food availability could lead to changes in the energy content and composition of diets that are associated with significant, negative health implications.…”

“…The current state of global crop modelling allowed us to directly model climate change effects on most major crops, such as groundnuts, maize, potatoes, rice, sorghum, soybeans, and wheat, 5,15 but the impacts on other crops had to be inferred from biophysical similarities. 6,15 Second, the economic responses of agricultural commodity markets to climatic shocks are subject to high uncertainty. A recent comparison of global economic models of agriculture showed a wide range of projections of production and consumption across models.…”

“…33,34 Relative to that, climate change leads to changes in temperature and precipitation, which is expected to reduce global crop productivity, 5,15 and via market responses, lead to changes in management intensity, cropping area, consumption, and international trade. 6 From a health perspective, changes in food availability and consumption affect dietary and weigh-related risk factors associated with an increased incidence of non-communicable diseases and mortality, such as low fruit and vegetable consumption, [16][17][18] high red meat consumption, [18][19][20] and increased body weight. 21,22 In line with the conceptual framework, we devised a multi-step methodology, depicted in Figure 1, which leads from climate-change impacts on agricultural yields, through changes in food production and consumption, to changes in dietary and weight-related risk factors and associated mortalities.…”

“…23,24 We used the IMPACT model to produce global food scenarios for the year 2050. Building on methods developed by the Agricultural Model Intercomparison and Improvement Project (AgMIP), 6 we analysed the range of potential climate impacts by comparing a reference "middle-of-the-road" development scenario without climate-change impacts to scenarios with high climate-change impacts. Panel 1 discusses the socio-economic and emissions pathways adopted, and Appendix A2 provides additional detail on the model inputs used for constructing the model scenarios.…”

“…2 The impacts on the food supply and food security may be one of the most important consequences of climate change due to the large number of people that may be affected. [2][3][4] Climate change impacts are expected to reduce the quantity of food harvested, 5 which could lead to higher food prices and reduced consumption, 6 and to an increase in the number of malnourished people. 7,8 However, the relationship between agriculture and health goes beyond issues of food security and caloric availability.…”