The headlines speak of a miners' strike broken in Great Britain, and of Pan American workers' staging a walkout that threatens the future of that American flag carrier. Union writers in Hollywood and New York risked the public's ire by a strike that could have cut off favorite soap operas and situation comedies. The Bureau of Labor Statistics puts out a report saying that union membership in the United States dropped below 20 percent of the labor force -- to 18.8 percent, actually -- in 1984, continuing a steady downward trend.

It is an odd time to talk about a "new day" for the American trade-union movement. But it is possible that future historians may see the winter of 1985 as some kind of a turning point. At the meeting of the AFL-CIO executive council in Bal Harbour, Fla., at the end of February, the labor leaders approved and issued a report titled "The Changing Situation of Workers and Their Unions" that clearly suggests a shift of direction -- and almost of fundamental attitude -- for the labor movement.

The report has significance not only for workers and employers but for anyone interested in the future of American politics. For people my age, at least, it is impossible to imagine a strong current of liberal politics in this country without a strong labor movement. As unions have declined in membership strength and political clout, so has the Democratic Party. If you believe that labor is doomed to inevitable decline as the American economy shifts from the heavily unionized manufacturing industries -- such as autos and steel -- into the much less unionized service and communications and high-tech jobs, then you almost have to conclude that liberal politics and the Democratic Party are on a similar downward path.

For reasons that are clearly argued in an important article by James Fallows in the current Atlantic Monthly, the sweep of American history, to say nothing of common sense, dictates that the changes in our economy -- no matter how disruptive to individuals and communities -- be accepted and welcomed as the real engines of opportunity and progress.

The union movement has been seen by many people, including some of its allies in the Democratic Party and liberal politics, as fighting a rear- guard action against economic and social change -- as being more worried about protecting past gains than it is interested in helping its people prepare for the future.

In the largest sense, the AFL-CIO report is a declaration by labor's top leadership that it is ready to tackle that future. It is a remarkable document.

Starting with the blunt declaration on the first page that "unions find themselves behind the pace of change," it documents the growing gap between the perceived positions of union leaders and the desires of the rapidly changing work force where, as the report says, people "are less likely to see work as a straight economic transaction providing a means of survival and more likely to see it as a means of self-expression and self- development."

Candidly citing survey findings that a majority of non-union workers believe union leaders force members to accept decisions they don't like, including strike decisions and that unions stifle individual initiative, fight change and increase the risk that companies will go out of business, the report says: "It is apparent . . . that the labor movement must demonstrate that union representation is the best available means for working people to express their individuality on the job and their desire to control their own working lives, and that unions are democratic institutions controlled by their members, and that we have not been sufficiently successful on either score."

There are several dozen specific recommendations for experiments in organizing and representation techniques that individual unions have begun to discuss or, in some instances, put into place. But the report is optimistic about the ability of unions to adapt. The reasons may surprise you as much as they did me.

The most important of those reasons is that unions are middle-class institutions and are still a ticket to the middle class. Union workers earn one-third more than their non-union counterparts, the report says. They recruit best among the elements that are growing fastest in the work force, especially the better-educated. Only 26 percent of union members (compared with 28 percent of the general population) lack a high- school diploma. Some 21 percent of union members (compared with 16 percent of the general population) have college degrees. If the future of work is in white-collar jobs, unions are well-positioned. They already represent more white-collar than blue-collar workers -- 41 to 36 percent.

As Thomas R. Donahue, the AFL-CIO secretary-treasurer and head of the committee that prepared the report, pointed out in an interview, how successful the unions will be in organizing the new work force depends critically on the labor laws. Canada and the United States have similar economies but very different labor laws. In Canada, where the laws favor organizing, the percentage of the labor force in unions has grown from 30 to 40 percent in the last 20 years; in the United States, it has gone just the other way.

That is one reason the unions will stay in politics. And that is another reason why everyone has a stake in their effort to adapt to changing times.