What kind of effects can warming sea temperatures in the Pacific bring to California? The answer: a lot.... First the warming of ocean water in the Pacific leads to a climatic event know as El Niño. El Niño is caused by the warming of ocean water near the South American coast which limits upwelling of cold water further increasing the ocean temperature. The warm water then evaporates and causes warmer climatic conditions throughout North American. Winters in California, during El Niño events, are significantly wetter and warmer. Essentially, El Niño brings a greater amount of precipitation to all regions of North America.
Can the increase in precipitation caused by El Niño be observed by different methods? This study was completed to answer that very question.
Methodology
We analyzed the runoff amounts measured by stream gauges in California to find an increase in runoff during El Niño events. Data for surface runoff was downloaded from the USGS Water Watch data archive for 1991-1998. The data is given in millimeters of runoff per watershed. The watersheds for California were extracted. Known El Niño years runoff amounts were subtracted by the previous year to show the change in runoff amount.
Results
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Conclusions
Overall, for all of the El Niño years, there has been an increase in observed surface runoff amounts. This in large part is due to the higher precipitation amounts, but when you start factoring in the change in air temperature El Niño brings, there are more players in the game of runoff. California has glaciers in the Sierra Nevada, Cascade, and Trinity Alps mountain ranges. The warmer weather during the winter may not allow for the correct accumulation of snow and melts the ice contributing the further surface runoff.
