Quick Guide: El Nino or La Nina
If you want to elicit a strong emotional response from a water manager in California today just mention how El Nino is going to solve the California drought.
A few months ago most people didn’t know the difference between an El Nino and La Nina, but now many people can be heard proclaiming El Nino is going to save California this year.
El Nino, which means Christ child in Spanish, is now used to describe a whole complex of Pacific Ocean sea-surface temperature changes and global weather events. It’s complicated! Most people associate El Nino with the warming of the Pacific Ocean off the coast of South America, but it involves lots more than just water temperature. Typically trade winds blow in a westerly direction (think Peru to Asia) across the equator. These winds push water in a westerly direction and as a result water temperatures in the western Pacific Ocean can be as much as 18 degrees higher than the East. In an El Nino year these winds diminish and warm water is not pushed west. The result is the waters along the coast of South America are warmer than usual. The peak temperatures typically occur in December close to Christmas hence the name El Nino.
Weather and Climate
Weather is a state of conditions, hot or cold, rain or shine over a relatively short period of time. Climate refers to weather patterns over much longer time periods, like months, seasons or decades. If our climate is too cold, water will freeze and not be available for humans to easily use. If the climate is too hot, water will vaporize and not be available either. El Nino affects climate and is associated with flooding rains and warm weather in Peru, drought in Indonesia, Africa, and Australia, torrential downpours and mudslides in southern California, a warm and dry fall in the Pacific Northwest, a mild winter in the northeast, and fewer hurricanes in the southeast. As of September 10, 2015 the Climate Prediction Center and the International Research Institute for Climate and Society issued an El Nino advisory with a 95% chance of an El Nino will continue through the 2015 – 2016 winter.
La Niña is the result of ocean water that is cooler than normal in the tropical Pacific Ocean. When winds across the equator are unusually strong they bring cold water to the surface (this is call upwelling) and ocean temperatures stay cooler than normal. La Nina typically causes drier than normal climate conditions in the Southwestern United States as well as drier than normal conditions in the Central Plains. The Pacific Northwest will be wetter than normal while the southeast is drier.
Will El Nino really solve the California drought?
California is in the grip of a historic drought. The perfect storm would have to occur (and is very unlikely) for just one heavy rainy season to end the drought. Typically what we experience during an El Nino is heavy rains that do not provide much usable water. California does not have the infrastructure to catch and use heavy rainfall. What we could see this winter is California experiencing floods while at the same time experiencing a drought. Fortunately the voters of California passed a Water Bond earlier this year and are taking steps to create additional ways to capture and store water. This will help California in future El Nino years but for the next few years Californians should continue to plan for drought and stick to what they have been doing to reduce water use in the state. So far California residents have slashed water use, exceeding all expectations. Through June 40 percent of urban water suppliers cut their water use dramatically, by 30 percent or more. If you enjoyed this blog please subscribe or consider following me on twitter @H2oTrends