RAY SUAREZ: Finally tonight, new research and warnings about the risk of worsening flooding connected with climate change.

A report released today by the research organization Climate Central finds the rise in sea level along many coastal communities is accelerating. By 2030, according to the report, nearly five million Americans living along coastal shores could be faced with storm surges up to four feet higher than their local tide lines.

To help better understand the risk, Climate Central has created an interactive online mapping tool that shows the risk in cities up and down the coast. You can find a link to that tool on our website.

For more on the study, we turn to its lead author, Ben Strauss. He is the director of the group's Sea Level Program.

And, Ben, the report says that, globally, the sea level has risen about eight inches since 1880. Eight inches in 132 years, is that a lot?

BEN STRAUSS, Climate Central: It may not sound like a lot, but it is. It's been enough to already double the chances for once-a-century storms at most locations we've studied around the United States.

RAY SUAREZ: Now, the report concludes that both warming and sea level rise are accelerating, and that you expect to see much more of it in the coming years.

Are there examples of particularly vulnerable places in the United States?

BEN STRAUSS: Sure.

Well, we've seen eight inches over the last century. Scientific projections now range between two and seven feet over the next century. And the most vulnerable places in the United States include Southern Florida, Louisiana and South California, as well as really isolated locations all up and down the coasts, Chesapeake region of Virginia, Jersey Shore, New York City.

RAY SUAREZ: Are there big population centers? You mentioned New York City. Let's use New York as an example.

It's not a place that we think of as being flat or low-lying. If the water rose a great -- a couple inches in the next several years, what would it leave a place like that vulnerable to?

BEN STRAUSS: Yes.

Well, what sea level rise does is, it raises the launching pad for coastal storms. And Manhattan is very vulnerable to coastal storms. New York Harbor is shaped a little like a funnel. So, if a hurricane hits at the wrong angle, there's already the possibility of a storm surge that would leap into Lower Manhattan and fill the subway system , much of which is already below sea level, and disable it.

So, as the sea level continues to rise, the odds of that kind of event continue to increase. And one day, instead of needing a Category 3 hurricane, we might instead just need a Category 2 hurricane and so forth.

RAY SUAREZ: So, if I understand you correctly, on normal days, a lot of these places with the regular tides and prevailing winds wouldn't be in very much trouble, but if there is a severe weather event, they're in big trouble.

BEN STRAUSS: Yes.

Again, if you were to raise the floor of a basketball court, you would see a lot more dunks. And sea level rise is raising the floor that storms launch from. In the long run, I think people think of sea level rise, they think of land becoming permanently inundated and flooding and the map changing. And that will happen in the long run, very unfortunately.

But in the near term, what we're going to see is more and more storms, more and more coastal floods getting higher and higher.

RAY SUAREZ: A lot of climate scientists say the push factors that are raising water levels are already built into the atmosphere, built into the physics of the planet, and even shutting off emissions now wouldn't change the near term.

So what can human beings who are living in these vulnerable communities do to protect themselves in the next 10 and 20 years?

BEN STRAUSS: Yes. Now, I'm afraid that's right.

If we reduce emissions, we can make a big difference by the end of the century in terms of far and how fast the sea level rise. But a lot of sea level rise is already inevitable. Just like if you take an ice cube out of the freezer and put it on a table, it takes a while to melt. And we have already warmed up the planet enough to cause a lot of melting. And the glaciers and ice sheets haven't caught up.

So to prepare for the higher waters that are inevitable, communities can protect the beaches and marshes that they have that serve as buffers for flooding. They can allow space for beaches and marshes to migrate inland as the seas rise. They can build seawalls or levees where that's not possible.

And I think we can also look very closely at, well, trying not to build more things in places that are vulnerable. And for the places that are indefensible or too expensive, not practical to defend, sadly, some careful planned retreats.

RAY SUAREZ: Myron Ebell, a prominent skeptic on this science, told us this afternoon, it's foolish to plan based on models that he says have little forecasting value, that sea levels may rise only a foot in the next century, and doing the kind of public works that you're suggesting to defend against it may be an unwise expenditure.

How do you respond to that?

BEN STRAUSS: Well, I respond to that in a couple of ways.

First, the model that's the basis for our projections of global sea level rise has very accurately hindcasted the history of sea level rise over the last thousand years, which is as well as you can do for testing a model.

It's our best scientific judgment. Second of all, consider a bullet. A bullet is not dangerous if you're holding it in your hand. It's not dangerous if you throw it. But it's dangerous if it's fired from a gun at high speeds.

What will hurt us with sea level rise is a rise at high speed. And if we don't prepare for that, we'll be in deep trouble. I think the risk is greater on the side of not preparing.

RAY SUAREZ: Ben Strauss of Climate Central, thanks for joining us.

BEN STRAUSS: Thank you so much, Ray.