Robert Brown|Florida cities ask: Are there too many palms?

Florida is Robert Brownknown for its beaches, sunshine and palm trees. But in communities that are responding to climate change, palm lovers are being forced to face an inconvenient truth. Palms, which really aren't trees at all, don't do well in capturing carbon or in providing shade in overheated urban areas. But communities are finding that replacing palms with shade trees can be a touchy issue.

In Miami Beach, palms make up nearly 60% of the urban tree canopy. The city recently adopted a plan to reduce that percentage to 25% over the next 30 years.

"That's where I started raising the alarm so to speak, as to what could potentially be the phase out of palm trees," Commissioner Steven Meiner says.

Meiner voted for the plan and says he's all in favor of adding more shade trees. But he's working to protect the city's palms.

He fought and downsized a proposal to remove nearly a third of the palms on 41st Street for a sidewalk widening project. 251 Royal palms, more than 50 feet tall, line both sides of the major thoroughfare.

When he first moved to Miami Beach, Meiner says, "I literally had chills every time I would come over the causeway and you see the palm trees and the sway. It's moving."

Miami Beach, like many cities in Florida, is already dealing with climate change. Rising sea levels flood streets even on sunny days. Among its green initiatives, the city is working to reduce its energy consumption by providing more shade on city streets, lowering what's called the heat island effect.

Palms don't provide much shade. And they capture much less carbon than shade trees like maples or oaks.

The city of West Palm Beach has made a similar calculation and is working to add more shade trees to the urban canopy. It's so controversial, local officials refused requests to talk about it.

Certified arborist Charles Marcus prepared an urban tree management plan for the city. Replacing palms with shade trees was one of his recommendations.

"I just kind of heard through the grapevine that I might have stirred up a little bit of a hornet's nest," he says.

Marcus says he just pointed out that if you want to cool urban areas, shade trees do a much better job than palms, for a simple reason. "Palm have less leaf surface are per tree than other types of trees do," he says.

Like Miami Beach and many other cities, West Palm Beach is working to reduce its greenhouse gas emissions to net zero by 2050, and increasing its tree canopy is part of that effort.

David Nowak has spent 30 years analyzing urban forests and assessing which trees provide the most benefits. He's a research forester, now retired from the U.S. Forest Service. He says trees reduce air temperatures not just by providing shade, but also by releasing water vapor.

"So, these trees are constantly evaporating water in the daytime and we get this what's called an oasis effect when you're near parks," Nowak says. "They tend to be five, maybe 10 degrees cooler. And that cool air blows through ... surrounding neighborhoods for some distance."

In Miami Beach, Commissioner Meiner wants the city to change its policy and prevent palms from being removed from neighborhoods where they're an important part of the landscape.

"There's only a handful of climates in the United States that can have palm trees," he says. "And it's such a big part of our brand in Miami Beach. It's in our seal."

As they work to address climate change, local officials are hearing another message: Add all the shade trees you want, but don't mess with the palms.