摘要：Greenhouse gas induced climate change is expected to lead to negative hydrological impacts for southwestern North America; including California (CA). This includes a decrease in the amount and frequency of precipitation; reductions in Sierra snow pack; and an increase in evapotranspiration; all of which imply a decline in surface water availability; and an increase in drought and stress on water resources. However; a recent study showed the importance of tropical Pacific sea surface temperature (SST) warming and an El Niño Southern Oscillation (ENSO)-like teleconnection in driving an increase in CA precipitation through the 21st century; particularly during winter (DJF). Here; we extend this prior work and show wetter (drier) CA conditions; based on several drought metrics; are associated with an El Niño (La Niña)-like SST pattern. Models that better simulate the observed ENSO-CA precipitation teleconnection also better simulate the ENSO-CA drought relationships; and yield negligible change in the risk of 21st century CA drought; primarily due to wetting during winter. Seasonally; however; CA drought risk is projected to increase during the non-winter months; particularly in the models that poorly simulate the observed teleconnection. Thus; future projections of CA drought are dependent on model fidelity of the El Niño teleconnection. As opposed to focusing on adapting to less water; models that better simulate the teleconnection imply adaptation measures focused on smoothing seasonal differences for affected agricultural; terrestrial; and aquatic systems; as well as effectively capturing enhanced winter runoff.
