Will it rain in Spain when tropical forests are plains?

LESTER BROWN and his Worldwatch Institute team may well be right. In their latest State of the World report, they suggest that we are entering ``a new era, one in which [international] attention shifts away from East-West ideological conflicts and toward the reestablishment of an earth with stable, healthy vital signs.'' Indeed, as this annual ecological review documents, those signs now point toward possible - and avoidable - environmental disaster of global proportions that ``no one can afford to ignore.''

This echoes the observation of climatologist Alan Hecht of the US National Oceanic and Atmospheric Administration that environmental concerns will be at the top of the international political agenda within a decade. He explains, as an example, that the squeeze a combination of climate change and environmental mismanagement could put on Egypt's food and water supply could become a greater source of political tension there than Arab-Israel hostility.

Degradation of land and water resources through deforestation and other mismanagement is one of the signs of increasing environmental decay. Worldwatch notes that ``an estimated 26 billion tons'' of topsoil are lost each year. Meanwhile, some 15 million acres of new desert form and 27 million acres of tropical forest disappear.

India's plight illustrates what such abstract statistics mean to an afflicted country. Some 39 percent of its land now is degraded. Although that country currently is self-sufficient in food, Prime Minister Rajiv Gandhi has declared that ``continuing deforestation has brought us face to face with a major ecological and economic crisis.''

While there are many different kinds of environmental assault and many different causes, Worldwatch rightly fingers two as being ``disproportionately important'' - energy use and population growth.

It notes that runaway population ``in many countries is overwhelming local life-support systems.'' This connects, through energy use, with land degradation. In India and many other countries where villagers depend on firewood, excessive fuel harvesting is a leading cause of deforestation.

Such countries are turning more and more toward coal and oil, whenever they can. And that, in turn, accelerates the world's use of fossil fuels. Burning fossil fuels releases sulfur, contributing to forest-destroying acid rain on a global scale and carbon dioxide, whose heat absorbing effect may already be starting to warm Earth and change climate in ways only dimly foreseen.

In short, national environmental problems can have global consequences and global environmenal change can exacerbate local degradation. ``The health of the earth's inhabitants cannot be separated from that of the planet itself,'' the report observes. Rehabilitating Earth is everybody's business.

Worldwatch wisely points out that the main obstacles to doing this are outmoded attitudes and chauvinistic preoccupations rather than any insurmountable physical situation or lack of global resources. It estimates that about $150 billion per year for the next decade would be needed to restore a healthy planetary environment. That level of investment could be obtained by redirecting 17 percent of the $900 billion the world now spends annually for military purposes.

Last year's agreement by 24 nations to restrict the use of chemicals that destroy Earth's protective ozone layer and the World Bank's new emphasis on environmentally safe development may reflect the beginning of a new sense of priority. Thus Worldwatch is cautiously hopeful for the future.

We need to love our planet. It's the only home we've got. And all the good we try to achieve in developing its resources will come to naught if we destroy its habitability in the process.

A Tuesday column. Robert C. Cowen is the Monitor's natural science editor.