New York, NY —

As part of our series on climate change, we take at a look at the threat of the rising level of the seas. With hundreds of miles of coastline in the tri-state area, our region is particularly vulnerable to coastal erosion and greater and more frequent flooding.

In the next 90 years or so, scientists say climate change will cause the sea level in our area to rise between 7 inches and nearly 2 feet. And those numbers could be a bit higher if the accelerated melting of the ice sheets, particularly the one in Greenland, continues. On Long Island alone, tens of thousands of homes would be at risk of being damaged or destroyed by flooding and storms.

NEWKIRK: Sea level rise is happening. It's accelerating and even if we reduced our carbon emissions to 1990 levels right now, it would still happen.

REPORTER: Sarah Newkirk, who directs the Coastal Program of the Nature Conservancy on Long Island showed me one example of that rise, which can be found on the barrier island beach south of Hampton Bays. This thin strip of sand is kind of an eastward extension of Fire Island, where dozens of multimillion dollar homes on stilts are nestled between undeveloped county parkland. The island's main thoroughfare, Dune Road, at some points has water from the bay right up against it.

NEWKIRK: We're driving along the road here where there is a lot of puddling from basically high tide encroaching on the road itself. And the road has a lot of potholes because it's regularly inundated here at high tide, and flooded entirely during some extreme high tides. You see signs that say look out, high tide floods this road here.

REPORTER: The flooding here has gotten more frequent over the years and the continued rise of the sea level will only make it worse. In fact New York's largest insurance provider, AllState, has stopped writing homeowners' policies in many coastal areas here and elsewhere. And several other companies have raised premiums and/or lowered coverage.

NEWKIRK: You know, in my mind, almost nothing more has to be said than the insurance folks who are experts at calculating risk, have looked at the risk of insuring these properties and have decided it's just not worth it as a matter of an entire region. And that is incredibly telling, I think.

REPORTER: Some might say when it comes to the possible risk they face, local residents and homeowners may be in denial to a degree. After all, who would want to dwell on the possibilities of catastrophic flooding and storm surge, especially when nothing close to that has happened in decades...

GOLDIE: I took the view that the last big hurricane came through here in the late '30s, so at some stage, it may come through again, but I mean if you're going to worry about that kind of thing all the time...

REPORTER: James Goldie and his family are preparing to move into a new home they're having built a little further east on Long Island, near Sag Harbor. They live in London full-time and primarily plan to use it as a summer getaway, drawn by the allure of Long Island's sunny climate and pristine beaches. The house is about about a quarter-mile from the waters of Noyac Bay.

GOLDIE: The water's never that far away from here, so it was on my mind, but I think yeah you wouldn't want the water to come up the road or into the basement. But I did my work, background checks and, you know, everything looks pretty good.

REPORTER: But the Nature Conservancy's Sarah Newkirk says she thinks people in our area will start to feel tangible effects of climate change sooner rather than later.

NEWKIRK: I don't want to sound fatalistic, but it's not a matter of if the big storm is coming, it's a matter of when it's coming. Every year you read the likelyhood of the hundred year flood happening is more and more and more.

REPORTER: So what to do? There is no easy answer. Trying to manipulate nature or gird against its forces can be a difficult balancing act. And there are several stakeholders involved with competing agendas including property owners, who love living on the water, local governments, which like the tax revenues those houses generate and environmentalists, who feel we should move out of harm's way and let nature take its course.

One way to combat flooding and beach erosion has been coastal engineering...

BOCAMAZO: We're trying to help along nature by putting material on shore, on to the beach to keep the integrity of this barrier island.

REPORTER: Lynn Bocamazo is a Senior Coastal Engineer with the Army Corps of Engineers. Back on the barrier island south of Hampton Bays, a 10-year old Army Corps beach renourishment project has added a couple hundred feet to the beach near Cupsogue Beach County Park...

BOCAMAZO: The barrier islands do act as protection to the back bay. If we reduce the possibility of breaching, then we add protection to those homes in the back bay.

REPORTER: She says even a small rise in sea level would have a great impact on areas on the main island behind the barrier islands because those communities are built in low-lying areas. Those areas include parts of Bayport, Lindenhurst and Patchogue, which are between 6 and 12 feet above sea level.

But coastal engineering isn't perfect. Critics say it may save some beachfront homes, but it's expensive, must be maintained, and endangers natural habitats such as salt marshes on the bay side -- marshes that improve water quality and that serve as the source of food for commercially important fisheries.

Instead of trying to engineer a solution, the Nature Conservancy suggests that where possible, people in at-risk areas should consider picking up and moving their homes further inland and to higher ground. But since that's only a realistic possibility for a small fraction of at-risk homes, the group's Sarah Newkirk says communities should be developing post-storm redevelopment plans...

SARAH NEWKIRK: If these houses got wiped away in a hurricane, would we -- are we a kind of community that would take the approach that it would be OK to build them in exactly the same spot, you know with 20/20 hindsight knowing what we know now. Is this a good idea? The barrier island naturally rolls over and should be migrating landward. And so you protect people's existing properties up to a point, but once it's destroyed does it make sense to make the same mistake over and over and over again? And I think we would say no.

REPORTER: So, you're basically envisioning a kind of a coastline right up against the shore that would be public parkland, basically.

SARAH NEWKIRK: Ideally, yes. We've been built out on western Long Island for a really long time and so is that realistic? Probably not. But should we protect it to the extent that we can here on eastern Long Island? Yeah, probably so. And in a post-storm situation, if we could revert to something like that, wouldn't that make sense? I would say yes.

REPORTER: That would be a politically difficult undertaking -- and a very expensive one too, with governments telling homeowners they couldn't rebuild on their land and then compensating them for their property.

One area that most involved parties seem to agree on is the need for regional coordination. Currently, local governments decide what can be built where through their local zoning rules, while county, state and federal agencies have have control over permits for specific concerns such as development near wetlands. Sometimes, the rules don't jibe and there's no one looking at the broader island-wide scenario. Since the effects of climate change transcend political boundaries, proponents of regional coordination say the solutions need to as well.

The Army Corps' Lynn Bocamazo...

BOCAMAZO: It may be changing in zoning laws. It maybe raising elevation of houses. It may be raising elevation of roads in some locations, and again if all levels of government would come together and make a decision on what would be a good policy for the various locations, include the homeowners in that conversation, then solutions could be raised. It's a large problem, but it's not being really addressed.

REPORTER: So, until officials figure out a comprehensive plan to safeguard coastal areas, especially during storms, which are predicted to become stronger and more frequent, what's a water-loving islander to do?

BOCAMAZO: People should be aware first and foremost of their elevation. And if you are aware of what elevation you're at, that if you in the immediate time period, know a storm is coming, get out if you know the storm surge is going to be very large, you need to move. Secondly, you need to be aware that if you're in a low elevation, you may be at more risk in the future. And then there are ways that private property owners can do things to protect their homes, to flood-proof your house, so that you'll have less damages.

REPORTER: As for the Goldie family, building their summer home near the water on Long Island's East End, their builder says they are 20 feet above sea level, and so they should be OK. -- for now. Many people who live near the water say they're willing to deal with some damage occasionally, because the proverbial 99 percent of the time, things are fine. Climate change, though appears to be changing those odds. Some estimates give the tri-state area a good 10 to 15 years before we start seeing more serious adjustments to sea level rise. Experts say officials should be using that "grace period" to come up with ways to prepare. But they also point to Hurricane Katrina to warn that damaging storms could come at any time.

I'm Soterios Johnson. You're listening to Morning Edition on WNYC.