An intercomparison of three regional climate models (RCMs) (PRECIS‐HadRM3P, RCA4, and RegCM4) was performed over the Coordinated Regional Dynamical Experiment (CORDEX)—Central America, Caribbean, and Mexico (CAM) domain to determine their ability to reproduce observed temperature and precipitation trends during 1980–2010. Particular emphasis was given to the North American monsoon (NAM) and the mid‐summer drought (MSD) regions. The three RCMs show negative (positive) temperature (precipitation) biases over the mountains, where observations have more problems due to poor data coverage. Observations from the Climate Research Unit (CRU) and ERA‐Interim show a generalized warming over the domain. The most significant warming trend (≥0.34°C/decade) is observed in the NAM, which is moderately captured by the three RCMs, but with less intensity; each decade from 1970 to 2016 has become warmer than the previous ones, especially during the summer (mean and extremes); this warming appears partially related to the positive Atlantic Multidecadal Oscillation (+AMO). CRU, GPCP, and CHIRPS show significant decreases of precipitation (less than −15%/decade) in parts of the southwest United States and northwestern Mexico, including the NAM, and a positive trend (5–10%/decade) in June–September in eastern Mexico, the MSD region, and northern South America, but longer trends (1950–2017) are not statistically significant. RCMs are able to moderately simulate some of the recent trends, especially in winter. In spite of their mean biases, the RCMs are able to adequately simulate inter‐annual and seasonal variations. Wet (warm) periods in regions affected by the MSD are significantly correlated with the +AMO and La Niña events (+AMO and El Niño). Summer precipitation trends from GPCP show opposite signs to those of CRU and CHIRPS over the Mexican coasts of the southern Gulf of Mexico, the Yucatan Peninsula, and Cuba, possibly due to data limitations and differences in grid resolutions.

Notwithstanding the tariffication component of the Uruguay Round Agreement on Agriculture, import tariffs on farm products continue to provide an incomplete indication of the extent to which agricultural producer and consumer incentives are distorted in national markets. As well, in developing countries especially, non-agricultural policies indirectly impact on agricultural and food markets. Empirical analysis aimed at monitoring distortions to agricultural incentives thus need to examine both agricultural and non-agricultural policy measures including import or export taxes, subsidies, and quantitative restrictions plus domestic taxes or subsidies on farm outputs or inputs and consumer subsidies for food staples. This paper addresses the practical methodological issues that need to be faced when attempting to undertake such a measurement task in developing countries. The approach is illustrated in two ways: by presenting estimates of nominal and relative rates of assistance to farmers in China for the period 1981–2005; and by summarizing estimates from an economy-wide CGE model of the effects on agricultural versus non-agricultural markets of the project's measured distortions globally as of 2004.

No abstract

Computable General Equilibrium (CGE) models are commonly used for global agricultural market analysis. Concerns are sometimes raised, however, about the quality of their output since key parameters may not be econometrically estimated and little emphasis is generally given to model assessment. This article addresses the latter issue by developing an approach to validating CGE models based on the ability to reproduce observed price volatility in agricultural markets. We show how patterns in the deviations between model predictions and validation criteria can be used to identify the weak points of a model and guide development of improved specifications with firmer empirical foundations. Copyright 2007, Oxford University Press.

No abstract