Weather is making news but a group of scientists is trying to call attention to the likelihood that once again it is also going to be making history.

Climatologists have been telling the government and public for several years that the northern hemisphere was entering a new period of climatic uncertainty.

The scientists don't agree among themselves. Some believe the northern hemisphere is turning colder, while others, probably a majority, by Dr. Stephen Schneider's estimate, would argue it's getting warmer.

Whichever is happening, the scientists believe, there is a good chance of serious disruption of global food supplies.

Schneider, of the U.S. National Center for Atmospheric Research in Boulder, Colo., wants to call attention to how clouded the climatologists' crystal balls are because, he says, "We haven't prepared."

"This is a game of values, not so much a game of science," Schneider said. When people realize that science cannot give them certain answers about the future, he hopes they will turn to the political process and build the food stockpiles that would see the world through two or three years of bad weaather.

Former Secretary of Agriculture Earl L. Butz disagreed, and Schneider describes in his book "The Genesis Strategy" how he and Dr. Reid Bryson of the University of Wisconsin tried without success to tell Washington why they believed conditions would worsen. That was 1974.

Brysaid in an interview that the best estimate of the coming decade can always be made from the decade just ended. In the last five years there were two serious Soviet crop failures, drought in the African Sahel, drought in the U.S. corn belt, the freeze that wrecked the Brazilian coffee crop and rain shortfalls in India and China.

"If you are a prudent man, you will plan for difficulties," Bryson added dryly, noting that there will be about 85 million more people on earth next year.

"We have to build resiliency into the system," Schneider said, "to sustain the flucuation [in climate] that are clearly precendented." This winter's weather has clear precedent, Schneider said, but our food and energy situations are so tight that we run into shortages.

Schneider was one of those who predicted that this winter would be unusually cold. But Schneider said he believes that there is very little ability among scientists to predict climatic events in sequence over a period of years.

Climatology is complex and relies on masses of data. Airplanes and ships carry thermometers that measure the air and water they pass through. The readings have to be matched with latitudes, times, dates.

Thus while the trends of the last 100 years are generally well-known, the last five years' reading are still being compiled and what happened that recently is less clear.

From 1915 through 1950 there was a significant warming of the northern hemisphere. Then, about half that gain was lost during the years up to 1972. What Schneider called "a pretty strong reversal" apparently took place from 1972 through 1975, once again raising the hemisphere's temperature.

Some climatologists, including the Soviet Mikhail Budyko, conjecture that the cold of this winter is part of the general warming trend. There is very warm circulation of air over the North Pole now and every newspaper reader knows that Alaska has been warmer than Florida on some recent days. The average temperature for the hemisphere could be warmer even with Eastern and Central states suffering record cold.

In hazarding guesses on future climate changes, scientists consider the amount of carbon dioxide in the atmospheric, volcanic activity, manmade pollution and the thickness of clouds.

Volcanos and pollution increase the quantity of dust in the atmosphere, Bryson based his early warnings of a cooling trend on the observation that dust screens out heat from the sun.

Volcanic activity was almost nonexistent during the warming years up to 1950, but "whole pit fulls of volcanos are active right now," Bryson said. Levels of manmade dust can be predicted, but no one knows what the volcanos will do in the future.

Schneider, however, said it is not automatic that increased dust brings cooler temperatures. It may depend on the dust's color and the brightness of the part of the earth it shields.

White or ligth-colored objects have more reflective power than dark ones. Therefore, light dust would screen much of the sun's radiation, but dark particles over a bright land mass could increase warmth. Dust is not evenly spread over the world, but concentrated over land areas, which are brighter than the seas.

A second major factor influencing the world's climate is the buildup of carbon dioxide in the atmosphere as a result of burning fossil fuels on earth.

Everyone agrees that the carbon dioxide has a greenhouse effect, keeping in much of the long-wave (heat) radiation emitted by the earth.

But nobody knows how fast the gas will build up. It has increased 10 to 15 per cent since the industrial revolution. The entire warming effect of carbon dioxide could be wiped out or, conversely, doubled by a difference of 100 meters in the thickness of the clouds - another unpredictable factor.

As a result of the uncertainly, scientists with a belief usually take the data that supports their belief, Schneider said.

The problems from significant warming it is agreed, could be as great as from major cooling.

Melting of a large portion of the polar ice pack would raise sea levels, flooding coastal areas, for example.

On the other hand, a drop of 6 degrees centigrade in annual average temperature over a sustained period would bring on an ice age.

But short of disasters of that magnitude, fluctuations of climate can render presently arable land arid and could touch off widespread food shortages.

In the rich countries, food would still be available, but at higher prices. For some poor nations, the shortage could bring famine. In 1974 a Central Intelligence Agency report said. "Climate is now a critical factor. The politics of food will become the central issue of every government."

The United States and Canada now export almost 70 per cent of the grain in world trade. If climate fluctuations reduced the grain crops in those two countries, or if there were major failures elsewhere it quickly could become impossible to meet the world's expanding needs.

Bryson and Schneider say they believe the time is long overdue for government leaders to prepare for such possibilities.