Vietnam is likely to be among the countries hardest hit by climate change, threatening its legacy as a champion in leveraging agriculture for development. This paper examines how a changing climate may affect rice production and how Vietnamese farmers are likely to adapt to various climatic conditions using an innovative yield function approach, taking into account sample selection bias and endogeneity of inputs. Model results suggest that although climate change can potentially reduce rice production, farmers will respond mainly by adjusting the production portfolio and levels of input use. However, investments in rural infrastructure and human capital will have to support farmers in the adaptation process if production levels and farm incomes are to be sustained in the future.

The International Food Policy Research Institute's International Model for Policy Analysis of Agricultural Commodities and Trade (IMPACT) supports analysis of long-term challenges and opportunities for food, agriculture, and natural resources at global and regional scales. IMPACT is continually being updated and improved to better inform the choices that decisionmakers face today. This document describes the latest version of the model. IMPACT version 3 expands the geographic and commodity scope of the model in response to desires expressed by researchers and policymakers to address more complex questions involving climate change, food security, and economic development into the future. IMPACT 3 is an integrated modeling system that links information from climate models (Earth System Models), crop simulation models (for example, Decision Support System for Agrotechnology Transfer), and water models linked to a core global, partial equilibrium, multimarket model focused on the agriculture sector. This model system supports longer-term scenario analysis through the integration of these multidisciplinary modules to provide researchers and policymakers with a flexible tool to assess and compare the potential effects of changes in biophysical systems, socioeconomic trends, technologies, and policies.

Approximately 80 percent of poor people in Sub-Saharan Africa continue to depend on the agricultural sector for their livelihoods, but--unlike in other regions of the world--agriculture in Sub-Saharan Africa is characterized by very low yields due to agroecological features, poor access to services, lack of knowledge and inputs, and low levels of investment in infrastructure and irrigation. In addition, high population growth rates, especially in rural areas, intensify pressure on agricultural production and natural resources and further complicate the challenge of reducing poverty. Against this background, potential climate change poses a significant additional challenge to the future of agriculture in the region. Climate change could cause serious deterioration of rural livelihoods and increase food insecurity in Sub-Saharan Africa. Given these multiple challenges, the region's smallholders and pastoralists must adapt, in particular by adopting technologies to increase productivity and the stability and resilience of their production systems.

This article develops an economic model to analyze how the risk of water shortages affects farmers' land irrigation decision and how the priority-based water sharing arrangement redistributes such a risk among farms with different water rights priorities. The analysis brings together an array of comprehensive data files on irrigation rights, water supplies, and agricultural land use from eastern Idaho. Results indicate that a more left-skewed distribution of streamflow significantly discourages land irrigation among farmers except the most senior rights holders. The priority-based water sharing arrangement redistributes the macroscale risk of water shortages and thus exposes farmers of different water rights priorities to heterogeneous levels of risk: senior water rights holders are affected the least and such a risk is instead passed mostly on to junior water rights holders. The role of water rights in risk redistribution is more significant when the probability distribution of water shortage risk is asymmetric rather than symmetric. The historical development pattern of water rights influences how the priority of water rights takes effect on land irrigation decision.

Vietnam is likely to be among the countries hardest hit by climate change, threatening its legacy as a champion in leveraging agriculture for development. This paper examines how a changing climate may affect rice production and how Vietnamese farmers are likely to adapt to various climatic conditions using an innovative yield function approach, taking into account sample selection bias and endogeneity of inputs. Model results suggest that although climate change can potentially reduce rice production, farmers will respond mainly by adjusting the production portfolio and levels of input use. However, investments in rural infrastructure and human capital will have to support farmers in the adaptation process if production levels and farm incomes are to be sustained in the future.