A question to ponder: Why would the temperature of the ocean water off the coast of South America cause a woman in Chicago to re-consider her purchase of soybeans?
For this month’s episode of Big Word of the Month, I want to discuss my favorite oceanic/atmoshpheric phenomenon (you have one too, right!) . Climate scientists use the term El Niño , Southern Oscillation to describe the complex relationship between the patterns of atmospheric pressure over the Pacific Ocean and the ocean circulation patterns off the western coast of South America. Because that phrase is such a mouthful, people use the abbreviation ENSO to save time.
The short and simple version of ENSO is that in most years weather patterns over the Pacific lead the coastal waters of South America to relatively cool. This common situation is referred to as a La Niña condition. Every few years though, the Southern Oscillation shifts back towards the western Pacific and the coastal water of South America warm slightly. If the warming exceeds about 1 degree Farhenheit, the event is described as a El Niño event.
This small change has very large global impacts. The map below shows you how moisture and temperature patterns change around the globe during an El Niño period.
Fig. 1 Winter Impacts from El Niño conditions(image from Wikicommons)
As you can see, an El Niño event leads to wetter and cooler winter in the Southeastern United States and warmer conditions in the Northwest US and Canada. So based on the extra snow here at the Museum and the poor ski conditions at the Olympics in Vancouver, you might not be surprised to learn that this year is a strong El Niño year. Ocean temperatures off South America have been above normal since last fall and are expected to stay that way through early spring.
Back to our question: Why would a woman in Chicago, interested in buying soybeans, be influenced by the temperature of the sea water off the coast of South America? Put your guess in the comments section below. I’ll post the answer in a few days if no one gets it right.
Read more about ENSO at NOAA’s Climate Prediction Center