THE FUTURE ‘WARM LIA’ SCENARIO ACROSS THE AMERICAN SOUTHWEST
Given past non-stationarity, a ‘warm LIA’ climate scenario for the coming century that combines high precipitation variability (similar to LIA conditions) with warm and dry conditions (similar to MCA conditions) represents a plausible situation that is supported by recent climate simulations. Our comparison of tree ring-based drought analysis and records from the tropical Pacific Ocean suggests that changing variability in El Niño Southern Oscillation (ENSO) explains much of the contrasting variances between the MCA and LIA conditions across the American Southwest. Our proposed “warm LIA” scenario with high ENSO variability for the 21st century could be induced by a decrease in meridional sea surface temperature gradient caused by increased greenhouse gas concentration, as shown by several recent climate modeling experiments. Overall, these results coupled with the paleo-record suggests that the ‘warm LIA’ concept provides a useful scenario for development of future water-resource management and drought and flood hazard mitigation strategies in the Southwest.