INTERESTING and -- at last -- hopeful changes have begun to transform the ways in which the world uses energy. You wouldn't necessarily learn of it in government pronouncements, since governments tend to think in terms of laws passed and programs adopted. Sometimes governments seem to fall a bit behind reality, even in subjects like energy to which they devote enormous attention. There was a curious example a week ago in the declaration with which the leaders of the seven big industrial democracies ended their meeting in Venice on economic strategy.

"We must break the existing link," the seven bravely stated "between economic growth and consumption of oil, and we mean to do so in this decade." But the link is alreay broken. It was broken in the last decade, visibly and dramatically.

Until the first oil crisis, seven years ago, most people took it for granted that energy and economic growth marched together in lock step -- that each percentage point of growth required one percent more energy.That's the "existing link" that Mr. Carter and his six colleagues were talking about. Until the latter 1970s, a lot of economists feared that any sustained attempt to hold down oil consumption would pitch the world's economy into stagnation or worse. Some of them thought that any attempt to break the link would be a risky and uncertain venture. The seven statesmen in Venice were talking as though they still thought so.

But the International Energy Agency has been tracking the change with detailed statistics -- the most recent of which appeared a month before the Venice meeting. In the five years from 1973 to 1978, the total energy consumption in the industrial world rose, in fact, only one-third as fast as economic output. That's a remarkable departure from the pattern of the 1960s.

The reasons for it are obvious. People, here and abroad, are protecting themselves from rising fuel prices and the threat of shortages. Industry is installing more efficient equipment. Most countries -- if not, unfortunately, this one -- have jacked up their taxes on oil and gasoline. It's true that this process did not proceed fast enough, in the 1970s, for consumers' own protection. Demand for oil climbed too high, setting off last year's wild price increases and this year's recession. The IEA points out, incidentally, that further dangerous oil shortages are in prospect for the years immediately ahead.

The industrial countries are going to have to do a lot more, quickly, to cut their need for oil. But they have already shown, perhaps to their own surprise, that they can do it without paralyzing economic growth. The process of adjustment is already well along -- further and more effectively than, apparently, the seven men at Venice realized.