What is Ensemble in the General Circulation Models list (GCM)?
Climate change analysis becomes more complex for the future than the past because there is not one time-series of climate, but rather many future projections from different GCMs run with a range of CO2 emissions scenarios (IPCC 2007b). It is important not to analyze only one GCM for any given emission scenario, but rather to use ensemble analysis to combine the analyses of multiple GCMs and quantify the range of possibilities for future climates under different emissions scenarios. There are many approaches for doing ensemble analysis ranging from simple averaging approaches to more complex and computationally intensive probability estimation approaches (Dettinger 2006, Araujo and New 2007). Here, we used a fairly simple, yet informative non-parametric quantile-rank approach that maps out the 0 (minimum), 20, 40, 50 (median), 60, 80, and 100th (maximum) percentiles (Figures 6 and 7). While all models agree that mean temperatures will increase everywhere in the world (Figure 6), they of
