The silver lining of the pre-war Gulf crisis was that multitudes realized, as a united Security Council worked around the clock, that whatever else the end of the Cold War may bring, it made possible the rebirth of the United Nations.

It comes not a moment too soon. The times have outgrown many of the U.N.'s founding purposes, but the new challenges that only a United Nations can deal with have never been as weighty. The selection of the U.N.'s next secretary general at the end of this year captures the institution and the world at a moment of tremendous opportunity.

Governments have been ambivalent about the secretary general from the beginning. Often, they talk as though they would welcome a strong leader. Studies and official memorandums spell out lists of qualifications that would eliminate anybody this side of Alexander the Great. In practice, governments have generally opted for someone thought to be passive, a competent administrator, and unlikely to cause trouble.

The sequence of events by which the secretary general is chosen is less a process than a series of haphazard, last-minute, often accidental choices. There is no search for qualified candidates. By the U.N.'s rules, the General Assembly makes the decision on the recommendation of the Security Council. Since this means that the five permanent members of the council can exercise their veto, other governments have had little reason to get involved. The surprise is how little the great powers have cared. A recent study by former U.N. insiders, attributes Kurt Waldheim's selection to "lack of top-level governmental interest, inadequate high-level consultation, opportunism, gossip, rumor, intrigue and a complete absence of record-checking." The fact that such a process once produced a Dag Hammarskjold is small consolation.

So long as the U.N. was hamstrung by East-West polarization, the choice of secretary general mattered little. Indeed, it was a job few individuals of intellectual stature, energy and ambition would want. But now that the political landscape is being transformed and as one global issue after another demands attention, the job could become -- not immediately, but eventually -- one of the most important and rewarding in the world.

The next secretary general could start the process of reshaping the United Nations from an institution designed to manage the status quo to one that catalyzes international problem-solving. He or she will have three great tasks. First, to lead the institution in its enhanced role in actively maintaining international peace. If collective security is ever to be realized, the U.N. must do more than react in crises, though it must do that swiftly and effectively. Second, to manage, motivate, root out ineptitude and cronyism and reorganize an institution in which the proliferation of jealous, independent agencies has created managerial chaos. And third, to define a leading role for the U.N. in the intertwined economic and environmental concerns, from debt and development to global warming, that can only be dealt with at the global level and that will increasingly determine nations' security and well-being.

Optimally, the next secretary general would therefore be a woman or man who is a skillful diplomat, someone to whom governments would readily give a leading role in a crisis (as the United States did not feel it could do in the present crisis) and in mediating disputes before they mature into crises. He or she would be a tough, proven executive, able to initiate sweeping internal change and recapture the post's eroded authority. He or she would be knowledgeable on the issues that make up the new international agenda, issues that are largely multilateral rather than bilateral, defined more by a North-South divide than an East-West one and which are -- to an unprecedented degree -- economic, social and environmental. To make all of these qualities felt, this would be an individual whose intellect and experience command international respect.

Candidates of this caliber must be looked for. In the U.N. system few run for office. The U.N. should create a formal search process, though there is probably not time enough this year. This leaves individual governments, citizens' groups and the media with the task of suggesting and sifting names. No nationality should be ruled out, even the great powers that have traditionally been excluded. Even if the selection of an American or a Russian is politically unrealistic right now, consideration of names like Elliot L. Richardson, Eduard Shevardnadze or Britain's former Permanent Representative Sir Crispin Tickell will help set the standard by which others should be judged. By U.N. tradition it is Africa's "turn" for the post. African candidates should be scrutinized, like all the rest, but the goal should be to find the best individual of whatever nationality.

Most secretaries-general have served for a decade. In this decade, issues such as poverty, population growth, greenhouse warming, international debt and others whose momentum builds on itself are waiting to be dealt with. All of which means that the consequences of this year's choice could be felt well into the middle of the next century. The writer, a vice president of the World Resources Institute, writes this column independently for The Post.