by Whit Gibbons

February 13, 2005

Sometimes an environmental column needs to address mundane issues as well as the exciting new findings in ecological research or the latest polarizing issues that the public doesn't agree about. The weather qualifies. I have written about the weather before, indicating my distrust and suspicions about what the local weather forecast has to offer. Things have not changed in the last 16 years, when I first published a version of the following column.

One thing that ecologists and real people have in common is a fascination with weather. How plants and animals respond to rainfall and temperature dominate many environmental studies conducted by research ecologists. Indeed the concern for these particular environmental variables seems to be the most exciting part of the life of many individuals who are not ecologists.

Humans can learn a lot from animals about a variety of subjects, and weather prediction is one area where we can really take a lesson. The lesson is that day to day variation in the weather cannot be predicted by plants and animals. I know of no species of the millions of different kinds of plants and animals that bases its behavior, physiology, or other biological plans on the basis of a five-day weather forecast.

A difference between wild animals and humans is that animals that based their survival on being able to predict the weather eventually left no descendants. That kind of thinking no longer exists in the animal kingdom, except for humans.

One of the impressions we sometimes have of animals is that they are predicting the weather, whereas actually they are only responding to meteorological conditions at the time. For example, frogs sometimes begin calling before a rain, but conditions of high humidity, barometric pressure changes, and dark clouds are detectable. The frogs are merely making a short-range prediction of a few minutes or hours. You can do that just as well. And sometimes both frogs and people are wrong about predicting rain within the next hour.

Birds that migrate north in the spring and south in the fall are not making long-range weather predictions either. Birds, like any of us, can safely predict with 100% assurance that winter will be colder than summer. In the North Temperate Zone, birds, other animals, and even trees have evolved to prepare for the change in the seasons. Predicting seasonal changes is something that all surviving species of plants and animals can and must do. Yet none is able to predict the weather of next week, or even of tomorrow.

Why do we continue to pay any attention to a weather forecast that is more than a few hours away? Meteorological studies have shown that the prediction that the weather tomorrow will be exactly like it was today is more likely to be right than any other predictions that are made. An example of long-range weather reporting being a hazy exercise was the result of a science fair project by my youngest daughter when she was in high school. Each day she kept a record of the five-day weather forecast in regard to whether it would rain or not. Then, on the day itself she recorded what the weather was. I was impressed. The weather forecast was right almost as many times as it was wrong.

In other words, you could flip a coin and your chances would be just as good at predicting whether it would rain or not rain five days later. I am not so naive as to think that each weather station that provides these five-day reports keeps a special coin for such occasions. Instead, I think they probably have a pair of dice so that more possibilities are available. After all, they do like to provide us with the exact high and low temperatures that we can expect five days later.

Despite the weekly confirmation that a long-range weather forecast is absolutely meaningless, we still routinely check to see what the weather prognosticators say is in store for us. After you finish reading this column, I feel confident you will do just what I intend to do, if you have not done so already. That is, check the weather report in the paper so you can plan for the rest of the week.

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