ASHINGTON, Dec. 2 — On Tuesday, the Bush administration convenes a three-day meeting here to set its new agenda for research on climate change. But many climate experts who will attend say talking about more research will simply delay decisions that need to be made now to avert serious harm from global warming.

Climate experts say greenhouse gas concentrations may cause coastal damage as sea levels rise. Countries like the Netherlands, above, are particularly vulnerable.

President Bush has called for a decade of research before anything beyond voluntary measures is used to stem tailpipe and smokestack emissions of heat-trapping gases that scientists say are contributing to global warming.

"When you're speeding down the road in your car, if you've got to turn around and go the other direction, the first thing is to slow down, then stop, then turn," said David K. Garman, the assistant secretary of energy for energy efficiency and renewable energy.

But many climate experts say the perennial need for more study can no longer justify further delays in emission cuts.

"Waiting 10 years to decide is itself a decision which may remove from the table certain options for stabilizing concentrations later," said Dr. Michael Oppenheimer, a professor of geosciences at Princeton.

For example, under today's rate of emissions growth, he and other experts say that certain losses are already probable, including dwindling of snow-dependent water supplies and global die-offs of vulnerable ecosystems like coral reefs, alpine meadows and certain coastal marshes.

Nevertheless, administration officials say further research is still necessary because scientists cannot say exactly what effects human activity will have on global climate and how dangerous they will be. It is worth taking the time to conduct more analysis at least to clarify the balance of environmental and economic risks, they say.

"Science rarely gives enough information to narrow policy choices to a single option, but it can clear away some of the underbrush," said Dr. John H. Marburger III, assistant to the president for science and technology.

Some energy and climate experts have run new kinds of analyses showing that there is still time to avoid the worst effects of climate change while also limiting economic costs involved with an abrupt shift from fossil fuels, the main source of the warming gases.

The meeting, involving hundreds of experts, will be the biggest public airing of arguments in many years.

Most scientists concur on the basics. Atmospheric levels of the heat-trapping gases, mainly carbon dioxide from burning coal and oil, have increased by more than a third since the start of the Industrial Revolution, and there is wide agreement that they will probably double from preindustrial concentrations by the end of the century, driven by energy demands of developing countries.

International and American panels of experts have concluded that these gases have caused most of the warming trend over the last 50 years. But there is still a wide range of projections indicating how much warmer things may get, how storm and drought patterns may respond and what the effects will be on ecosystems, agriculture and health. These uncertainties are unlikely to be dispelled soon. But many climate experts say that some effects can reasonably be predicted and that prudence calls for more action now.

Dr. Warren M. Washington, a senior scientist at the National Center for Atmospheric Research, likened the situation to the debate over smoking's link to cancer.

"Even with smoking, it's still basically a statistical thing," said Dr. Washington, who is chairman of the National Science Board, a panel that advises the White House and Congress. "But vested interests do not want to take action based on early indications, and with climate early indications is what we have."

If greenhouse gas concentrations double, climate experts expect substantial disruptions of ecosystems and water supplies, coastal damage as sea levels rise and intensified drought and downpour cycles. Even more calamitous surprises could lie in store, including disruptions in the Atlantic Ocean currents that help warm Europe.

The experts concede that they cannot say exactly what may happen, or when. Also, changes will probably occur slowly — sea levels rising by millimeters a year, say — so there will be no one event to prompt people to choose a fuel-saving hybrid car over a gas-guzzling S.U.V.

But the warming will have enormous momentum, they say. Unlike soot or sulfur pollution, which falls out of the atmosphere within days or weeks, molecules of carbon dioxide and other greenhouse gases can circulate for a century or more.

As a result, scientists say, allowing things to go on as they are is like making minimum payments on a credit card while still using it: the balance grows and grows.

In the long run, almost all experts agree, stabilizing carbon dioxide concentrations in the atmosphere will be a century-plus process that will necessitate eliminating — or capturing — all releases of carbon dioxide from burning coal, oil and other fossil fuels.

That will require a fundamental shift to energy technologies that do not yet exist. But it also requires emission cuts in the next decade or so, even as trends for such emissions are sharply up.

"We will probably need everything in the tool kit to cut emissions enough to stop the worst things from happening," said David D. Doniger, the director of climate policy for the Natural Resources Defense Council, a private group. "A long-term technology program is definitely in order, but we also need to be acting now with the technology available now."

But the Bush administration is resisting calls for quick action. Its focus on more research comes straight from the president. In his first speech on climate, in June 2001, Mr. Bush defended the need for more research by saying, "No one can say with any certainty what constitutes a dangerous level of warming, and therefore what level must be avoided."

In February, he reaffirmed the country's commitment to pursue the goal of a climate treaty his father signed in 1992: to stabilize greenhouse gas concentrations at a level that will prevent dangerous interference with the climate.

But he has rejected the instrument chosen by almost all other industrialized countries to start on a path toward that goal, the 1997 agreement called the Kyoto Protocol. It requires industrialized countries that submit to its terms to reduce greenhouse-gas emissions by 2012 to levels below those measured in 1990.

Instead, Mr. Bush calls for voluntary actions.

Ten years from now, if scientists still think climate change is worrisome, other strategies may follow, he said.

Although many climate experts say delays are risky, others, including Dr. James A. Edmonds of the Energy Department's Pacific Northwest National Laboratory, have calculated that Mr. Bush's timetable and prompter actions like the Kyoto treaty do not lead to significantly different outcomes in the long run. The most critical challenge by far, he said, is the sharp decline in emissions in midcentury.

Other scientists whose views are embraced by industry say there still isn't enough evidence for quicker action.

"We are still struggling with the `what will be' question, especially at regional scales, which makes answering the `what will be dangerous' question too difficult to handle," said one of these researchers, Dr. John R. Christy, the director of the Earth System Science Center at the University of Alabama in Huntsville.

As a result, he said, any emissions plan should be "economically benign."

The meeting this week is likely to see many clashes between the two camps, with more than 1,000 scientists, industry lobbyists, environmental campaigners and others planning to weigh in.

Sam Thernstrom, a spokesman for the White House Council on Environmental Quality, says the goal is to hear all views before the research plan is finished next spring and a series of two- to five-year projects is begun.

"Anyone who has quibbled with how this plan is put together," he said, "they and the rest of the world are invited to come on down and make suggestions. All ideas will be considered."

Those eager for more aggressive actions say they doubt the meeting will lead to significant policy shifts, particularly now that relevant Congressional committees are controlled by Republicans pushing for more, not less, exploitation of fossil fuels.

They also say that the administration's 170-page research plan (available on the Web at www.climatescience.gov) includes no commitments that adequate money will flow to support new science.

To build a more convincing case for faster action, a growing group of researchers is trying new ways of conveying the risks of certain emissions paths, including pinpointing when actions have to start to stabilize greenhouse gases at particular levels.

The current concentration of carbon dioxide in the atmosphere is 370 parts per million, and the level before industrialization began was about 280 parts per million.

Under what is considered a best-case model, global annual emissions of carbon dioxide will have to start declining by 2020 to stabilize atmospheric carbon dioxide at 450 parts per million. Even at that level, there would probably be substantial losses, Dr. Oppenheimer and others say, including a global die-off of coral reefs.

Societies have probably already missed that turning point, scientists say, and the longer societies wait to act, the higher the eventual greenhouse plateau and the greater the consequences.

If emissions do not start declining until 2033, carbon dioxide concentrations will plateau at 550 parts per million — more than double preindustrial concentrations. That level raises the likelihood of more calamitous consequences, including intensified storm and drought cycles, wider extinction of species and perhaps the eventual freeing of the West Antarctic Ice Sheet, which could raise sea levels a century or two from now 15 feet or more, inundating coasts where most human settlements are concentrated.

In between these extremes, some climate experts and economists see a path that could avoid the worst environmental and economic risks. The problem is that this would depend on a fairly prompt start on emission reductions and aggressive research on finding new sources of nonpolluting energy.

There are other reasons for prompt action, experts say. One is that energy providers like power plant owners plan their investments in new equipment a decade or two ahead of time, said Dr. David G. Victor, the director of the energy and sustainable development program at Stanford.

Another problem with relying on more research, many climate experts say, is the presumption that the extra effort will reveal a "safe" level of greenhouse gases.

Better computer models and observations are likely to refine the menu of impacts, but reducing uncertainty still "doesn't necessarily provide what is needed by decision makers," said Dr. Roger A. Pielke Jr., an expert on environmental risk at the University of Colorado. Society as a whole must answer those questions, he and other scientists say.

"To avoid danger implies a threshold," said Dr. Henry D. Jacoby, an economist at the Massachusetts Institute of Technology and co-director of its program on the science and policy of global change. "But with climate, I don't believe there is one."

"There are so many different effects, in so many different countries, in so many different sectors, affecting so many different processes, affecting so many different people in so many different situations that there's not going to be a clearly defined break point," Dr. Jacoby said.

Dr. Jacoby likened the situation to a doctor-patient conference, when the patient learns that his high cholesterol puts him at risk for a heart attack.

"Is your next question `Tell me exactly when my heart attack is coming and how serious it will be?' " Dr. Jacoby said. "No. You want to know what you can do about it now."

AN FRANCISCO, Dec. 7 — The melting of Greenland glaciers and Arctic Ocean sea ice this past summer reached levels not seen in decades, scientists reported today.

This year's summertime melt, which provides more evidence of recent quick warming in the Arctic, is in part driven by natural climate oscillations, the researchers said. But they added that human-driven changes to the environment like the destruction of ozone and the emission of carbon dioxide could well have accelerated and enlarged the effect.

In September, the end of summer, ice coverage of the Arctic Ocean dipped to two million square miles before it started to grow again. Since 1978, when direct satellite measurements of sea ice started, the average summertime minimum has been 2.4 million square miles. Of the sea ice that survived, most was thinner than usual.

"That was probably the craziest summer I've ever seen up there," said Dr. Mark Serreze, a researcher at the National Snow and Ice Data Center in Boulder, Colo., and one of the scientists who presented the findings at a news conference at a meeting of the American Geophysical Union here.

Weather in the Arctic was unusually warm and stormy this year, which broke up ice and melted it more readily. The shrinking fits in with the trend since the late 1970's and general predictions of global warming. "It's the kind of change we'd expect to see," said Dr. James Morrison of the University of Washington in Seattle.

Other data, including some gathered from airplane flights, indicate that the Arctic has not been this ice-free at least since the 1950's. If the shrinking continues at current rates, year-round average sea ice coverage may drop by 20 percent by 2050, and the Arctic may be almost ice-free during summer months, Dr. Serreze said. "I believe we will continue to see reductions in sea ice cover, because I think we are having an effect on the climate," he said. "The rate of that change is debatable."

Other evidence, like melting permafrost and the northward spread of trees, has also suggested that the recent warming is quick and unusual.

The reduction of sea ice is expected to affect global ocean currents. Fresh water from melting ice is less dense than salty sea water and could prevent water from the deep ocean from rising. Open water should also be warmer than ice-covered ocean, because it absorbs more than 80 percent of sunlight that hits it, while ice reflects about 80 percent.

Satellite instruments also observed melting ice over 265,000 square miles of the Greenland ice sheet, exceeding the previous maximum melt area by 9 percent. Ice was melting in areas up to 6,560 feet in altitude that had never shown melting before.

Melted water flows to the base of glaciers, acting as a lubricant that speeds the sliding of the glaciers into the ocean.

In an article in the current issue of the journal Science, scientists at NASA's Jet Propulsion Laboratory in Pasadena, Calif., and the Royal Observatory of Belgium reported that melting glaciers have even changed the shape of the planet. Since 1997, the Earth has become slightly more oblate, like a pumpkin. That reverses a trend since the end of the last Ice Age when, relieved of the crushing ice sheets at the poles, the Earth had been bouncing back into a more spherical shape.

The authors of the Science article wrote that the addition of water melting from glaciers, which then shifted toward the equator, accounted for the squashing of the planet.

ELYSTAD, the Netherlands — When the telephone rings in this Dutchman's car, chances are that it is a windmill calling. A windmill?

"It's telling me there's a problem, maybe it has stopped," said Herre van der Meulen, a technician at Nuon, a Dutch utility.

He searches through his laptop, checks the disturbance and sends a telephone signal back to the computer aboard the windmill. Moments later, the blades are spinning again, yielding electricity. "Usually I can fix most problems from a distance," he said.

That he can do his job from afar is a good thing — soon technicians may have little choice. Across wind-swept Northern Europe, hundreds of high-powered turbines are being planned or are under construction offshore, beyond the easy reach of engineers.

"Going offshore is the new trend, and it's huge," said Bruce Douglas of the European Wind Energy Association, an industry group based in Brussels. "The demonstration projects out at sea have been a success. Now people are going for full-scale marine wind parks. Some are close to land, some are so far you can't see them."

Denmark uses wind turbines like these off the coast near Copenhagen to produce 18 percent of its electricity.

In the business, the talk is of a veritable rush offshore. Power companies are staking out suitable tracts of sandbanks, reefs and shallow open waters from the shores of Ireland to the Baltic Sea. They are joining with traditional offshore oil and gas companies, including giants like Shell, that have the capability to drill and rig up the 100-ton towers at sea.

Engineers say that wind parks at sea have two main advantages: the wind blows harder and more steadily than on land and there are no residents protesting against great wind parks marring the landscape.

On the Dutch coast near Lelystad, 28 windmills stand in a perfect lineup near the shore, anchored in about 20 feet of water. The swoosh of the wind going over the blades is barely audible, even drowned out by the squawking of the sea gulls.

"It's new, it's clean, it's high tech," said Henk Kouwenhoven, a manager of Nuon, who watched the towers go up in 1996. "The offshore potential is enormous. Here we never run out of wind. It blows 90 percent of the time. The main issue is making it cost-efficient."

Europe's wind-driven energy has been growing at 40 percent a year. With a capacity of more than 20,000 megawatts installed on land, it now represents three-fourths of the world's total wind-power output. Europe hopes to raise this to 60,000 megawatts in the next six years. Much of that growth is expected to come from sea-based turbines.

"It's going so fast now because there is a race to go offshore, with manufacturers and utilities competing for the jobs," said Corin Millais of the European Wind Energy Association. "Companies are now talking of wind fields, like oil reserves or coal reserves, waiting to be tapped. The beauty of it is that it is inexhaustible."

Advocates see the move offshore as an impressive rite of passage in the history of an ancient technology. For centuries, tapping the wind was the domain of the miller, his family and his hand-set sails. Even modern wind energy had humble beginnings in Europe. In the 1970's, it was started by grass-roots groups of often politically motivated investors putting up one or two private windmills. There are still thousands of private owners in Denmark, Germany and the Netherlands.

But wind power is no longer a cottage industry, and the windmills of today are not the charming, stubby kind that once pumped much of this country dry and became a national emblem. These are the modern variety, called turbines, that are becoming sleeker, taller and more powerful by the year.

"The largest turbines now produce 250 times more electricity than the ones built 20 years ago," Mr. Millais said. Today wind provides some 28 million Europeans with electricity, he said, about half of them in Germany, Europe's largest producer.

The European Union has been pushing to develop alternatives to fossil fuels, which are widely believed to contribute to global warming. It wants 22 percent of its electricity — and 12 percent of all energy — to come from renewable sources by 2010, to meet its commitment under the Kyoto treaty to reduce greenhouse gases. In the United States, wind energy has stalled at about one-fifth of Europe's capacity.

Here, wind projects have been encouraged with incentives like tax credits and guaranteed rates, and the emphasis is now shifting offshore. About 100 sea-based turbines are already operating. This year, Britain, Denmark, Germany, Ireland and the Netherlands have all earmarked large offshore sites and issued licenses. Some of the projects are scheduled to be ready next year.

The new endeavors are not without problems or critics. Environmental groups are divided. Some defend the wind turbines as a renewable source of pollution-free energy, while others fear the offshore turbines will disturb fishing and spawning grounds and endanger flocks of birds that migrate at night.

In Britain and Norway, the military has objected to some designated coastal sites, saying that wind parks can produce false radar echoes and disturb telecommunications.

There are other hurdles as well. Offshore turbines may be more productive, but building costs are 50 percent higher than on land and maintenance is difficult in a region where winters bring Atlantic gales. "When waves are up and your boat sways back and forth, it's unsafe to try and get onto the landing platform," said Mr. van der Meulen, the technician who monitors about 200 windmills scattered over a large area, including some at sea. "You can do maintenance work really only in the summer."

Then there is the issue of price. Industry spokesmen contend that, strictly speaking, the price of wind-driven energy is close to being competitive with other sources. They argue that traditional fossil fuels and nuclear energy get enormous hidden or indirect subsidies, to the tune of billions of dollars a year. For example, in some European countries, governments pay for the insurance of nuclear power plants.

While no one expects wind to become more important than traditional power sources, enthusiasts are undeterred, and the growth of wind-powered turbines is likely to continue. Denmark already uses wind to produce 18 percent of its electricity, the world's highest per capita consumption. Britain intends to catch up.

The British have designated 12 offshore turbine sites. Brian Wilson, the energy minister, said studies had shown there is enough wind to provide electricity for the whole country. He said he expected the global market for offshore energy to be worth $12 billion by 2007. Most of that, he said, will be in Europe.

"I don't see anything stopping offshore electricity now," said Mr. Kouwenhoven, of Nuon, which has teamed up with Royal Dutch Shell in a joint venture. "Shell knows the offshore business, we know the wind business. It's just a matter of moving ahead."

December 31, 2002