Agricultural impact assessment, vulnerability, and the scope for adaptation

Climate change assessments which have considered climate impacts of a 2xCO( 2) climate, using models of the global agricultural system, have found smal l impacts on overall production, but larger regional changes. Production sh ifts among regions can be considered one mechanism for adaptation. Adaptati on at the farm level, through changes in crops, cultivars, and production p ractices, is another adaptation mechanism. Existing studies differ in how i mportant these mechanisms will be. Studies that have considered yield effec ts at specific sites have found very wide ranges of impacts. A useful way t o evaluate the impacts of climate change, given the uncertainty about futur e impacts, is to consider vulnerability. Studies have defined vulnerability in terms of yield, farm profitability, regional economy, and hunger. Vulne rability and climate impacts, particularly in terms of higher order effects on profitability and sustainability, will depend on how society and the ec onomy develop. Lower income populations and marginal agricultural regions, particularly arid or flood prone areas, are most vulnerable to climate chan ge.