ON THE OPPOSITE PAGE TODAY, Jonathan Power discusses the rapid and potentially disastrous rate at which humankind has been creating deserts in its "scramble for survival." It is an awesome problem, only now starting to receive the technological and political priority it deserves. About 43 per cent of the earth's land surface is desert or semi-desert. Experts estimate than 14 million more acres of once-fertile land annually become arid. Some part of over 100 nations is either undergoing desertification or being threatened.

Deserts, by a natural process, are constantly moving. But the more urgent part of their spread is now caused by human exploitation of the land beyond its natural ability to recover. The process can occur in industrialized countries as a result of overintensive farming or mining, but it occurs more often and more painfully in underdeveloped countries, generally as a result of efforts to modernize rapidly or to keep up with galloping population growth. people who are, politically and geographically, on the margins of their societies are particularly vulnerable.

The grim prospect of widespread desertification was conspicuously foreshadowed in the drought that devastated the six-nation Sahel region of Africa in the early 1970s. That tragedy did have one benerficial effect, however. It inspired the U.N. Conference on Desertification in Kenya, which ends its two-week session today.

By the standards of such necessarily diffuse and technical gatherings, the Nairobi conference seems to have been a success. Attention was focused on past efforts to retard desertification or reclaim arid land and on possible ways to draw together the political, economic and scientific resources to make further progress. After some initial political posturing, especially by Arab delegates unhappy over Israel's presence, the delegates settled down to work on a world-wide approach. If their governments and citizens and scientists and the international development agencies follow up in a serious way, then the conference will have been a critical event in the lives of hundreds of millions of people around the world.