Description

This research presents a synthesis of the first phase of regionalizing climate projections for the Altiplano, the elevated central Andean plateau in Bolivia and Peru. A prerequisite to any downscaling process is the analysis of the large scale forcing provided by the global, multi model dataset. The global climate models in the Coupled Model Intercomparison Project (CMIP3) archive are evaluated against observations for the recent period followed by analysis of the CMIP3 models 21st century projections including changes in the annual cycle, extremes, and soil moisture. Our analysis indicates that the observed warming in the region will continue and accelerate in the coming decades with increases greater than 5% by the 2080s under the high emission scenario, and commensurate increases in temperature related extremes. Precipitation projections show less agreement among the models and larger uncertainty, but suggest an evolution toward a shorter, more intense rainy season with weakened early season (Sep Nov) precipitation and increases in peak season (Jan Mar). These results are consistent with projections for the large scale South American Monsoon and observations indicate trends (not significant) similar to the projections. Extremes analysis suggests that precipitation will likely be experienced more often as intense storms and with more consecutive dry days. These results are consistent with soil moisture projections, which indicate dryer conditions during the rainy season, despite the projected increases in precipitation. This synthesis of observations and current global model projections suggests the changes in the Altiplano are likely to have serious consequences for water management and indigenous agriculture.