Of all the various experts gathered to speak about global warming and sea level rise at last Friday’s Living on the Edge conference on Nantucket, Franklin W. Nutter, president of the Reinsurance Association of America, delivered perhaps the most disturbing message.

His insight was not related to the phenomenon itself so much as to the chances of a meaningful and concerted response. It was about politics and psychology more than environmental science.

Mr. Nutter spoke about the relationship between disaster preparedness, disaster relief and electoral results. The record showed that people reward politicians for disaster relief, but not disaster preparedness, he said.

It is far more politically advantageous to wait for the worst to happen — and then offer help — than to offer means by which the disaster might be averted in the first place, he said. People were grateful for money spent cleaning up a catastrophe, but resentful of expenditure aimed at averting catastrophe.

He suggested that explained a lot. Like the fact that between 1985 and 2004, natural disasters cost America some $16.5 billion in damage to property and crops, resulting in the expenditure of some $3 billion in federal disaster relief money. But the amount spent on disaster preparedness was just $195 million.

And that reality in turn, was just a political expression of human psychology: people underestimate risk, particularly when the risk does not seem immediate.

But the risk is very real, he said, and he cited some very big numbers to press home the point. Between 1960 and 2008, the percentage of the population in Massachusetts living in coastal counties increased from 16 to 23 per cent. The number of housing units jumped from 900,000 to 1.5 million. The total insured value of coastal properties climbed to $773 billion.

He spoke about the disconnect between community planners and disaster planners, and about the difficulty of getting across the message about the value of mitigation measures taken in advance.

But there was a great deal that could be done, he said. For example, in the aftermath of Hurricane Charlie — which caused about $13 billion in damage in Florida in 2004, that state had adopted new building codes, considered the best in the country.

The result was a subsequent decline in the frequency of insurance claims on properties built under the new code, compared with ones built before it, of 60 per cent. The size of individual claims was down 42 per cent.

Mr. Nutter also offered some advice to the 100 or so experts and concerned members of the public in the room: press for better local data and better codes, and do it strategically. The chances of implementation were best straight after an event, he said, when people were more likely to focus on the problem.

The Living on the Edge Conference was not a forum designed to debate whether global warming and sea level rise were real and human induced. The people gathered were way beyond that debate. They were discussing how it might better be measured and mitigated, and to convince the skeptics of the urgency of the problem.

Ben Strauss, interim executive director of a group called Climate Central, an expert in mapping, spoke about the shortcomings of online maps, accessible through Google, which purport to show the effects of rising water levels.

He said the maps are vague and based on topographical maps taken from satellite data which often had a margin of error of as much as 30 feet. Furthermore, the projections of sea level rise are very much “one size fits all,” Mr. Strauss said.

The generally accepted notion of sea level was “based on [measurement] at one rock in Quebec,” he said.

“But the sea is not flat. Sea level is not the same everywhere. And tides are not the same everywhere,” Mr. Strauss said.

Nor is the impact of storm surges.

His mission is to collate more localized data, based on more precise measurement of topography sea levels and tidal movements, such that people could get a realistic understanding of the effects of sea level rise at the addresses where they lived.

The three keys to persuading people of the risk are to “make it local, make it as close in time to the present as possible and make it personal,” he said.

The fact is that sea level rise is one of the more predictable effects of global warming, even though the rates of rise are different in different places.

The problem is not one of the far-distant future, he said. In the decade to 2008, sea level rose 10 centimeters in this area. The probability of serious flooding also is far more imminent than people realized. The probability of the type of flood which now occurs once in a century will increase to once in a decade by 2030.

He ended his presentation by showing a picture of a young girl, standing more than waist deep in water, representing the midrange rise in sea level she could expect in her lifetime.

Sarah Newkirk, director of coastal conservation at The Nature Conservancy, told the conference that even if the people of the world did “all the right things now” making an essentially carbon-neutral civilization, we still could assume a metre of rise in the oceans because of what she called “the residence time” of past carbon emissions in the atmosphere.

The world will have to deal with its historical emissions for the foreseeable future, she said. Apart from sea level rise, we will experience a variety of climate changes — temperature changes, precipitation changes and others, which she categorized as “global weirding.”

She too relied on a high-impact picture — a dummied-up front page of the New York Post, with a banner headline: “We’re Screwed.”

And so the conference went, expert after expert hammering home the message. Julia Knisel of the Massachusetts Office of Coastal Zone Management localized it by noting that the tide gauge at Nantucket had shown a one-foot rise in sea level over the past century.

She came with a slide presentation showing seven critical facilities in Hull including the high school, senior center, wastewater treatment plant, post office and light plant, all inundated by various depths of water, in accordance with various models of the water’s rise.

She also had a real picture, of the veranda of a home in Falmouth, inundated during Hurricane Bob.

“I would say this is pretty compelling,” she said.

Ben Gutierrez, a geolgist with the U.S. Geological Survey, talked about effects other than outright inundation of property. Like the damage to wetlands, which often, because of coastal settlement, cannot retreat to accommodate higher sea levels. That will likely have a major impact on migratory birds and fish stocks, he said.

Inland waterways would become saline, as would some groundwater people now use for drinking, he warned. The water table would rise. Coastal erosion, already a major problem in this part of the world, would accelerate.

Stan Riggs, a coastal marine expert at Eastern Carolina University, spoke of his work studying the barrier islands of North Carolina. Where they had not been modified by development, he said, the natural movement of sand had allowed them to change shape, but remain.

“But all the islands that have been modified are hardly there anymore,” he said.

“The bottom line is we’ve got to adapt and move with these dynamic islands. There will always be a shoreline, it just won’t be where you want it.”