DAVID GREENE, HOST:
Florida is preparing for the possibility of a major hurricane in coming days. And scientists are saying that mangroves might help lessen the impact of a storm surge. Mangroves are tropical trees with a tangled web of roots that grow along warm coastline. Mangroves are spreading, growing farther north and south as the earth gets warmer. But as it turns out, these trees may actually help slow the effects of climate change.
Here's Brendan Rivers with member station WJCT in Jacksonville, Fla.
BRENDAN RIVERS, BYLINE: Danny Lippi walks down a wooden path in a beachfront park in St. Augustine, Fla. Coastal trees poke up through the shrubbery around him.
DANNY LIPPI: All of these are mangroves right here.
RIVERS: Lippi is a certified master arborist, one of a select few the state allows to trim mangroves.
LIPPI: I've been here since 1981, you know, on and off. And I don't remember the mangroves like this when I was a kid.
RIVERS: Recently, more mangroves have been arriving in northeast Florida and thriving. They're growing taller, blocking waterfront views and boosting demand for his services. The known northern-most limit of mangroves in the U.S. is about 70 miles north of here on Amelia Island.
LIPPI: And the research does indicate they are migrating north. They've been there before, but it's an ebb and flow. They go, they come back. They go, they come back. What seems to be different now is that the mangroves are getting taller and bigger faster. And they're persisting along.
RIVERS: And this isn't just happening in Florida. Researchers say the trees are moving forward globally, a phenomenon that's being driven by climate change - specifically, fewer and less intense freezes and more intense storms. As storms grow in intensity, they're able to carry the trees' seed-like propagules farther. And the last freeze strong enough to wipe mangroves out in northeast Florida was 30 years ago. Since then, researchers say mangrove forests have expanded by 1,700 acres here.
Villanova University biologist Sam Chapman predicts warming could push the uppermost range of mangroves into Georgia within the next decade.
SAM CHAPMAN: As we have mangroves moving into places, which have been saltmarsh for at least a few decades, that can be upsetting to some people. And I understand that. It changes the way your natural environment looks, and I don't think any of us like that.
RIVERS: Chapman says people may need to adapt and embrace these changes, especially as greenhouse gas emissions rise around the world.
CANDY FELLER: Each of these leaves is actually...
RIVERS: Smithsonian insect and plant ecologist Candy Feller has studied mangroves for decades. On a cloudy Sunday morning, with a backpack over her shoulders and a big water bottle at her side, Feller hikes through a heavily-forested trail in the Guana Tolomato Matanzas Research Reserve near St. Augustine. Feller calls the trees protectors of the coast because they act as physical flood barriers during storms. And they actually produce soil, raising the height of the coastline.
FELLER: You know, those mangroves are standing between them and sea level rise, is standing between them and the next hurricane that comes through.
RIVERS: The trees are credited with preventing $13 billion in property damage in the U.S. each year, that's why the federal government and the insurance industry are partnering to fund mangrove conservation and preservation. And Feller says mangroves also help limit the impact of climate change. The trees trap and bury carbon dioxide in the soil below. It's called blue carbon and mangroves bury more of it than any other type of forest on earth.
FELLER: That blue carbon, we're calling it, is considered one of the most valuable assets of mangroves.
RIVERS: In fact, researchers say if mangrove ranges continue to expand at their current rate, the trees could reduce emissions in Florida alone by as much as 25% over the next few decades.
For NPR News, I'm Brendan Rivers in Jacksonville.
GREENE: And we should say, Brendan's story was produced in partnership with the news group Climate Central.
(SOUNDBITE OF YPPAH AND JOSEF PETERS' "WASH IN THE SEA") Transcript provided by NPR, Copyright NPR.