The Super La Nina and the Coming Winter
Things might get real cold.
October 25, 2010 - 12:00 am
A super La Nina is developing.
Historically, these strong La Nina events drop the Earth’s average temperature around one degree Fahrenheit, and the drop comes quickly. As a result, some of the same places that had record heat this summer may suffer through record cold this winter.
La Nina is the lesser-known colder sister of El Nino. La Nina chills the waters of the tropical Pacific Ocean, and in turn cools the entire planet for one to two years or more. This chilling has the potential to bring bone-numbing cold to many parts of the world for this and the following winter. As a result, world energy demand may spike in the next one to two years as much colder weather hits many of the major industrial nations.
This La Nina appears to be special, at least so far. It is well on its way to being the strongest of these events since the super La Nina of 1955-1956. During that powerful La Nina that lasted two years, the global average temperature fell nearly one degree Fahrenheit from 1953 to 1956.
The Southern Oscillation Index (SOI) measures the air pressure difference between Darwin, Australia, and Tahiti. The lower the value of the index, the stronger the El Nino typically is. The higher the SOI index, the stronger the La Nina. The September SOI value of +25.0 was the highest of any September going back to 1917, when it was +29.7. During that super La Nina, the global temperature fell 1.2 degrees Fahrenheit from 1915 to 1917. The +25.0 September SOI reading is also the highest for any month dating back to the +31.6 value in November of 1973.
The most recent La Nina developed in the spring of 2007, and persisted until the early summer of 2008. The global average temperature fell one degree Fahrenheit in that period of time, equal to all of the warming of the last 100 years! If the trend of this rapidly developing, potentially super La Nina continues, an equal or larger temperature drop can be anticipated during the next one to two years. This La Nina is coming on very fast and very strong. Already it is colder than the six coldest La Ninas of the last 60 years when they were at a similar stage of development.
What about the recent heat we’ve all heard about?
For the last year, the world has been dealing with the warming effects of a strong El Nino. The El Nino warms the ocean waters of the tropical Pacific Ocean and in turn heats the atmosphere. Western Russia melted under a record heat wave this summer, after freezing from record cold last winter. Many parts of the southern United States had record heat this summer, but also shivered under record cold last winter. The persistence of the jetstream to blow in patterns that changed very little for long periods of time contributed to these extremes of temperature. This locked in jetstream wind pattern enhances temperature anomalies by restricting the exchange of air flow from one place to another. What would be hot becomes very hot, and what would be cold becomes very cold.