January 06, 2004

Decadal Oscillators

Global Cooling

The Iceman Cometh

Last month Barrons ran an article in their commodity section entitled The Iceman Cometh a catchy title that discussed the impact of the Pacific Decadal Oscillators (PDO) on long term worldwide weather patterns.

Using extensive databases and computers to examine historical weather data the PDO was discovered by researchers in 1996. Pacific? refers to the slow fluctuation of water temperatures in the northern Pacific Ocean, Decada? refers to a trend lasting multiple decades, and Oscillator? means that pattern moves back and forth between phases.

PDO is similar to El Nio/Southern Oscillation of the tropical Pacific. While El Nio and La Nia have been recognized for more than a century, the PDO is a recent discovery. Consequently, its effects are not as well known outside the scientific community.

Data indicates that the PDO has a cycle of 20-30 years. One phase produces hot/wet weather in North America and the other cold/dry weather. When the PDO is in a cool phase? it drives frigid Arctic air southward into the United States in the winter season.

According to researchers we have just finished around 20 years of the warm cycle and are in the early stages of a cold cycle. Scientists in the U.S. Geological Survey's Earth Surface Dynamics Program observed a hot/wet regime from 1900 to 1941; cold/drought from 1942 to 1977; hot/wet from 1978 to the late 1990s; and now the phase is trending back to cold/drought