On Climatic Cycles

Weather and climate link closely together since climate is nothing more than the longtime average of the weather. By weather, we mean the air temperature, air humidity, wind, cloudiness, storminess and any other condition of the atmosphere.

If the weather is unusual a few years in a row, one wonders if a long-term climatic change is being signaled. Usually that seems not to be the case because there are cyclic or quasi-cyclic variations of atmospheric conditions. Short cycles--measured in tens or hundreds of days--might be thought of as weather cycles. Cycles lasting years obviously can be thought of as climatic.

Searches through old ships' logs and other historical documents dating back to 1700 have allowed identification of a climatic cycle near 30 to 40 years long. Changes of patterns of wind strength over the Pacific Ocean and ocean temperature show this cycle, according to Dr. Joseph Fletcher, discoverer of Fletcher's Ice Island (Ice Island T-3). He received an honorary doctoral degree from the University of Alaska in 1979 in recognition of his contributions to arctic science.

The 30- to 40-year cycle also shows up in the amount of water discharged from the Nile River over the years and perhaps in the extent of the arctic ice pack. It may be the chief cause of the 1930's dust bowl in the United States. Perhaps it is the reason why northern lakes, such as Harding Lake near Fairbanks, show changing levels.

Dr. Fletcher suggests that the 30- to 40-year climatic cycle is created by interaction between the atmosphere and the ocean. The coupled ocean-atmosphere system transports energy from the hot equatorial regions towards the poles in a not-quite steady fashion. The ability of the ocean water to store heat for a long time may be the chief cause of the 30- to 40-year cycle.