WHILE there is concern about possible future climate change, we should pay attention to what is happening today. What we believe to be "normal" climate may not be normal at all.
This is especially important in the case of precipitation and water supply. Inhabitants of some parts of the globe may have based their assessment of long-term average water supplies on their experience with weather in this century that really isn't normal at all. They should consider their weather in the perspective of previous centuries.
For example, the drought that has parched western parts of the United States for the past six years may be a normal climatic feature. Studies at the University Of Arizona's laboratory for tree-ring research in Tucson indicate that long-running droughts are a recurring feature. The relatively wet decades of 1937 through 1986 may be abnormal.
Likewise, the long-playing drought that has brought famine to Africa's Sahel region south of the Sahara Desert also might appear to be anomolous. Research by several scientists over the past decade, however, has shown that the drought is not an aberration. This research includes studies of pollen samples that reflect conditions ranging back as far as 18,000 years ago.
Referring to this growing evidence, ecologist Peter D. Moore of Kings College, London, has observed that "climatic fluctuations in the Sahel, which produce such distressing social consequences, have evidently been proceeding for a very long time."
The western United States and African Sahel are two examples of regions where people are feeling stress because their expectations don't conform to climatic reality. Climate hasn't changed. What has changed is the human population density. These places and many other areas of the world have more people than the normal water resources can sustain.
Sandra Postel of the Worldwatch Institute in Washington warns that this problem is especially acute in Africa and the Middle East. In a recent report, she lists 26 countries in which water supplies can't sustain the populations through continuing drought. Nine of these are Middle Eastern nations, and 11 are in Africa. Her study projects that about a third of Africa's population - some 300 million people - are likely to live under drought conditions by the year 2000.
The study notes that the basic problem is not climate change. It is population growth that overburdens expectable water supplies. People have lived for thousands of years in semi-arid lands. Clever use of water has sustained them.
Now survival has become a race between water management and population growth. The study cautions: "No set of technological feats, however imaginative, can win that race," without a curb on population.
The Worldwatch analysis is only the latest study to warn of the political and social dangers that water shortages involve. It notes, specifically, that water wars could break out in Africa and the Middle East. Arun Elhance of the University of Illinois at Urbana-Champaign emphasized the same danger in a press release last month.
But Professor Elhance adds that water conflicts are, potentially, a worldwide problem. He notes that, even in water-rich lands, it will take careful management, based on cooperation by all nations who share a resource, to meet the burgeoning demand. He observes that, while water can cause conflict, "it also has the potential of uniting countries."
Here is a climate-related challenge that is already upon us. The world cannot continue its water-wasting ways. Population control is essential for semi-arid lands - including those in the United States. But it will be difficult to implement wise water management and wise land use if people do not appreciate what their normal climate can provide.