THIS FIERCELY cold winter now threatens severe fuel shortages in many parts of the country, particularly in the upper Midwest. The threat offers several useful lessons to the new administration. Not the least of them is the unwisdom of following policies that depend upon mild weather. The Carter prople are now talking anxiously about emergency legislation; but the unfortunate fact of the matter is that it's too late for legislation to affect things very much this winter. What happens now depends on the ice in the rivers, the turn of the weather, the success of the industry in delivering fuel and the willingness of its customers to use that fuel sparingly.

In each of the past four years, the Federal power Commission has warned of a possible shortage of natural gas. But the past three winters have been unusually warm and, when the shortage repeatedly failed to develop, most Americans laughed off the warnings. Congress, meanwhile, continued to insist on a wholly irrational system of price controls that keeps gas hardly more than half as expensive as oil. So not many people shifted to oil. But starting last October, it suddenly took a lot more gas to warm houses and shops.Events since have demonstrated how one shortage rapidly leads to many in an overextended supply system.

As thermometers dropped, the gas pipelines began cutting off low-priority customers - factories and utilities. That meant unemployment, first of all. But it also set off a scramble for fuel oil to replace the gas. One company that serves the Midwest, Standard of Indiana, says that its sales of fuel oil are up 60 per cent over last year. The company can get crude oil to its refineries, since they are fed by pipelines unaffected by the cold. But it normally depends heavily on river and lake barges to deliver refined products to its customers, and ports and rivers have been frozen shut. The company is trying to round up trucks to carry the load.

That is only the beginning of the disruption caused by the ice. In 1973, during the last cold winter, this country was importing some 1.3 million barrels of oil a day from Canada. Now, whith Canada pursuing its own Project Independence, the flow is down to less than 400,000 barrels a day. The difference is made up by imports from overseas. But, once again, a lot depends on the way it moves. The oil from Alberta comes down by pipeline. Much oil from Saudi Arabia comes down by pipeline.Much oil from Saudi Arabia comes up the Mississippi by barge, and the river is now closed. In shifting from Canadian to Middle Eastern oil, this country inadvertently moved from a weatherproof transportation system to one that is anything but.

The Canadians, incidentally, will permit increased exports of both gas and oil over the rest of the winter. Since it's the rough edges of the Canadian-U.S. relationship that have attracted most of the attention lately, this welcome assistance deserves a note of gratitude.

From World War II into the 1970s, the fuel supply system in this country worked miraculously. But by the summer of 1973 gasoline consumption was accelerating rapidly, refineries and pipelines were overtaxed, and gasoline shortages appeared in the Rocky Mountain states, the first since the war. Later that year, the massive increases in worldwide use of oil gave OPEC the power, at last, to set prices where it pleased. Now, in the middle of a cold winter, important parts of the country's distribution system are on the edge of breakdown. It is further evidence that any remedy will require Americans to push down the dangerously high rate at which we are still increasing our daily use of oil and energy.