A startling new national report that uses computer imaging to flag the effects of global warming on the Massachusetts coast shows that the south shore of the Vineyard will be washed away and downtown Edgartown will be a swamp in 50 years — even if the most conservative projections about rising sea levels are correct.

The report was issued yesterday by the National Environmental Trust (NET), a nonprofit, nonpartisan group based in Washington, D.C.

Titled The Massachusetts Coast: On The Front Lines of Global Warming, the report uses computer-simulated animations to show the actual effect of the rising seas from global warming. The three models used for the computer animations are downtown Edgartown, South Beach on the Vineyard and Nauset Beach in the town of Orleans on lower Cape Cod.

The animations show the effects of rising sea levels in starkly visual terms.

Two show major losses of shorefront at Nauset Beach and South Beach. A third shows almost all of Edgartown under water in a northeaster following a sea level rise of one meter.

Most scientists agree on one meter, or three feet, as a reasonable estimate for the sea level to rise over the next 50 to 100 years. Some prefer to use two feet, but Dr. Wesley Tiffney, director of the University of Massachusetts field station on Nantucket, said he is comfortable with the one-meter projection because the report and computer animations do not factor in erosion or subsidence — a phenomenon that causes the land to sink from the pressure of encroaching ocean water.

“I do not consider this extremist,” Dr. Tiffney said from his office on Nantucket yesterday. Dr. Tiffney worked as an unpaid consultant on the report.

“I think the report says global warming, sea level rise and coastal retreat are real — they are happening and they are being affected by human activity, namely burning fossil fuel and to some extent deforestation,” he said. “This is a long-term problem and it is going to need a long-term solution in terms of how we use fossil fuels.”

“Our beaches are in trouble,” declared George Abar, who is vice president of the NET. “The more we cut our pollution, the more of our beaches and coastline we can save,” he added in announcing the report.

The computer animations were commissioned by the NET and are the first-ever simulations of broadcast quality. The animations were generated from a computer using government data, including maps from the U.S. Geological Survey, storm surge data from the National Oceanographic and Atmospheric Administration and projections from the United Nations’ Intergovernmental Panel on Climate Change (IPCC).

Dr. Tiffney said the computer imaging was an important adjunct for the report. “It’s very important as an educational tool — getting the message across, that is their value,” he said.

A press conference was set for yesterday in Boston to release the report but, ironically, the briefing was canceled because of the possible weather impacts from Hurricane Bonnie.

The report begins with a fictional account that describes a scene in January of the year 2100. A northeast storm is blowing, and officials are working to keep Logan Airport from flooding. In the city of Gloucester the fishing fleet is tied up at new moorings that were once the site of a shopping center. On Cape Cod, land once valued at millions of dollars sells for next to nothing.

Today, world scientists who study issues related to climate believe overwhelmingly that pollution — primarily from the burning of fossil fuels — is collecting in the atmosphere and warming the earth. The IPCC issued warnings about the effects of these climate changes, and in response, spokesmen for more than 130 nations met in December 1997. They drafted the Kyoto Protocol, a set of binding targets for reducing pollution.

In the United States, the debate over the protocol has focused mainly on its economic impacts.

The NET report takes another view. “Almost completely ignored in this debate has been the cost of doing nothing to stop global warming,” the report states in its introduction.

It later continues:

“This is not an economic study. It does not calculate the cost to Massachusetts in dollars or jobs.

“Instead, this report seeks to remind the Massachusetts reader of the obvious but often overlooked truth in the global warming debate: the state’s coastal economy is its lifeblood. Anti-environmental rhetoric is filled with assertions about how much it will cost to stop global warming. This report speculates on what it will cost — even beyond the possible inundation of 10,273 acres of coastal upland and literally millions of acres of beaches and wetlands — to lose our natural resources.”

The report details the scientific principles behind global warming and the rise in sea level, and it relates the key findings of the IPCC.

But the heart of the report is its graphic depiction of what’s at risk along the Massachusetts coast.

“No state is more historically linked to its shore than Massachusetts. From the landing of the Pilgrims, to 19th-century whaling, to today’s redevelopment and recreation, the Massachusetts we know would not exist without healthy coastal waters and ample shoreline for easy access,” the report states.

The report sketches a detailed profile of the Vineyard, among other things chronicling growth, real estate sales and the efforts by the Island historical society to raise money to refurbish the Edgartown Lighthouse.

“Unfortunately, the money spent to preserve the beloved building and its surroundings will most likely get washed out,” the report declares.

The report relied on extensive data from an array of sources, including regional planning reports, census data and interviews with local officials. It is replete with provocative facts, including:

• Development on the nation’s 300 barrier islands increased more than 150 per cent between 1955 and 1975.

• 180 million Americans visit ocean and bay beaches each year, spending more than $74 billion.

• Commercial fishing generates $65 billion each year and involves 95,000 vessels. Recreation fishing pumps another $15 billion into the economy each year.

Other experts who contributed to the report include Eric A. Davidson, a scientist with the Woods Hole Research Center and an expert in climate change research; Matthew Patrick, a Falmouth selectman and executive director of the Cape and Islands Self Reliance Corporation, and Dr. Steven Leatherman, professor and director of the International Hurricane Center at the Florida International University in Miami and a foremost authority on beach quality and coastal erosion studies.

About the Vineyard, the report concludes: “The natural and human history of the Island is defined by its struggle with the sea. But now there is another chapter, one written by cars choking a Los Angeles freeway and coal plants in Pennsylvania spewing pollution into the air. While it may not be the Island’s final chapter, it threatens to spell the end of all that we know the Vineyard has to offer, washing it away by rising seas and destroying for the future the Island’s carefully preserved past.”