Near-term Climate Predictions and Their Impacts on the Physiology of Temperate Crops

Prediction of climate change over the next decade or two presents challenges both shared with and distinct from climate predictions for mid-century and later.  We review general aspects of predicting future climate change, including distinctions between forecasts and projections, and the specific challenges of near-term predictions.  From the perspective of impacts, adaptation and vulnerability in the agricultural sector, we discuss approaches that might be most appropriate to climate predictions for the next two decades, and how these approaches compare with widely discussed projections of climate change such as those found in the Intergovernmental Program on Climate Change (IPCC) assessment reports. The uncertainties in future climate change associated with uncertainty in the future use of fossil fuels and the implementation of strategies to mitigate those emissions are, for example, of little concern over the next decade or two because alternative future energy scenarios diverge very little in the near term. Differences in the simulated response of the climate system to these small scenario differences are even smaller, or at least well within the uncertainties and internal variability of the climate models.  With this understanding of near-term climate prediction, we then consider how near-term changes in climate might impact the physiology of temperate-latitude crops as represented by process-based, biophysical crop growth models such as the Decision Support System for Agrotechnology Transfer cropping system model (DSSAT), the Environmental Policy Integrated Climate crop growth model (EPIC), and the crop module of the land-surface scheme (CLM-Crop) of the Community Earth System Model (CESM).  With a brief review of the treatment, or more nearly non-treatment, of horticultural crops in these widely utilized types of agricultural models, we present results for cotton (Gossypium hirsutum) in the Blackland Prairie region of Texas from simulations with DSSAT and EPIC.   We illustrate how model results vary with the source of climate change prediction, and conclude with discussions of the modeled response of plants to elevated future atmospheric CO₂ concentrations (CO₂ fertilization) and physiological acclimation to higher temperatures and other changes in the environment.