Investigating climate change impacts and thresholds: An application of theCLIMPACTS integrated assessment model for New Zealand agriculture

The determination of `critical thresholds' is an essential task for informe d policy decisions on establishing greenhouse gas emission targets. This pa per presents a framework for determining critical thresholds for New Zealan d agriculture, focusing on three agricultural crops - kiwifruit, grain maiz e, and Paspalum dilatatum - as exemplars for the fruit production, arable c ropping and dairy production industries in New Zealand. The approach is bas ed on the application of a country-scale, integrated assessment model, call ed CLIMPACTS. The CLIMPACTS system contains a climate change scenario gener ator, climate and land data, and sectoral impact models. Importantly, CLIMP ACTS allows time-dependent assessments of climate change and its effects, w hich facilitates the identification and examination of thresholds, which la rgely relate to spatial changes, over time, in regions of economic importan ce for these crops. However, whether such thresholds are `critical' for New Zealand cannot currently be addressed by the CLIMPACTS model. The determin ation of `criticality' requires a fully integrated assessment in which the social, economic, and environmental costs and risks associated with these t hresholds are comprehensively evaluated.