Everglades mangroves might hold billion-dollar fix for climate change

Scientists say mangroves, like this one in Hell’s Bay in Everglades National Park, can help combat climate change by storing carbon. They put the value of that storage in the park alone at between $2 billion to $3.4 billion.
Scientists say mangroves, like this one in Hell’s Bay in Everglades National Park, can help combat climate change by storing carbon. They put the value of that storage in the park alone at between $2 billion to $3.4 billion. Miami Herald Staff

The price of fighting climate change in South Florida has so far focused largely on the billions needed to install pumps, raise roads and retrofit the sprawling infrastructure that keeps the region above sea level. But South Florida might already have a valuable weapon that for ages has been sucking up carbon and keeping the planet cool: mangrove wetlands in the Everglades.

To figure out just how valuable, scientists crunched some numbers to assign a price tag to Everglades National Park’s mangroves. It turned out way bigger than anyone thought.

“It was kind of an alarming thing, like oh my gosh, who knew?” said Evelyn Gaiser, a wetland ecologist who has overseen Everglades research at Florida International University for nearly a decade.

For about 360,000 acres of mangrove wetlands, the cash value totaled between $2 billion and $3.4 billion, or nearly seven times the amount Miami Beach plans to spend on new pumps to keep its streets dry.

In the study published in the journal Environmental Science & Policy, FIU economists worked with biologists to perform a kind of cost-benefit analysis, building on earlier calculations that looked at storage capacity but failed to include carbon already trapped in the wetlands. They say they wanted to provide a benchmark in dollars so that a larger audience could understand that the value of the Everglades extends beyond providing drinking water and wildlife habitat.

They had another, equally important objective: to show the cost of inaction. Nearly 16 years into a massive, restoration plan, the Everglades continue to suffer, hammered by decades of flood control and rising sea level that, if left unfixed, could alter the system. Instead of absorbing carbon dioxide, the gas emitted by burning fossil fuels that has sped up climate change since the industrial revolution by trapping more and more heat in the atmosphere, unrestored and eroding wetlands could begin emitting carbon.

“This is an extremely important service they’re providing for society’s well-being,” said lead author Meenakshi Jerath, a risk analyst at FIU’s Extreme Events Institute. “We’re not asking for any payments by putting a dollar value on it. It’s only to understand this is the value and the worth and if we lose it, this is going to cost us.”

Reducing carbon dioxide in the atmosphere is considered one of the key fixes to climate change. It’s also one of the most politically divisive. Last year, President Barack Obama committed to reducing the nation’s carbon emissions by up to 28 percent over the next decade when he signed the Paris agreement. He also enacted a Clean Power Plan requiring power plants nationally to reduce emissions by 32 percent by 2030. Many utilities, including Florida Power & Light, have already met the new limits.

Both initiatives are now under attack.

States, most led by Republicans and including Florida, have sued over the power plant plan. On the campaign trail, President-elect Donald Trump vowed to pull out of the Paris deal. In his first 100 days in office, he also has promised to cancel billions in payments to U.N. climate change programs, although last week in an interview with New York Times staffers he back-pedaled, saying he now believes there is a human connection to climate change, a position he took before his presidential bid. In the Times interview, he says he’ll now have an “open mind” about the Paris agreement.

That’s just the kind of opening researchers are counting on.

Mangrove wetlands, along with the world’s oceans, are a major sponge for carbon. Wetland forests photosynthesize faster and trap more carbon than their terrestrial cousins. They make up just seven-tenths of the planet’s tropical forests, yet mangrove deforestation contribute 10 percent of the carbon from global deforestation because they store so much.

Thanks to Everglades National Park, large swaths of South Florida’s mangrove forests have been saved. But decades of flood control and steadily rising seas over the past century are starting to take their toll. Scientists are particularly worried about the zone between the mangrove forests and the sawgrass marshes where for thousands of year peat has built up, a boggy soil incredibly effective at storing carbon and more sensitive to the mix of fresh and saltwater.

“In layman’s terms, it’s a lockbox,” said the study’s co-author, FIU natural resources economist Mahadev Bhat.

With saltwater increasing in these areas, the peat is collapsing. If it continues, the collapse will release carbon that for thousands of years have been stored in the soil back into the atmosphere, not to mention transforming one of the planet’s most unique ecosystems.

“It appears to be turning the ecosystem from a [consumer] of greenhouse gases to one that is adding to it,” Gaiser said.

Putting a price on the wetlands’ value could also add to the argument for speeding up Everglades restoration. Florida and the U.S. have been struggling to fix the marshes for 16 years under the Comprehensive Everglades Restoration Plan, originally expected to cost about $8 billion and now double that. The work stalled after Congress failed to pass regular waterworks bills between 2007 and 2014. This fall, the two houses finally passed bills that included a suite of projects aimed at the central Everglades, but they still need to reconcile differences in the bills when a new Congress reconvenes in January.

“It gives you a number that you can use in a trade-off model,” Gaiser said. “It helps people deal … [when they’re] being asked to spend billions of dollars to save an ecosystem and they don’t understand why.”

The new study also significantly raises the dollar value over previous studies, revealing the difficulty in calculating carbon storage costs in a complex mix of ecosystems and a still-emerging market.

In 2014, the National Park Service took a look at carbon sequestration in park lands across the nation, including Everglades National Park. The study used a 2013 government estimate that calculated the “social cost of carbon,” including damages from increased flooding, changes in farming and human health and included only annual amounts of carbon stored. They gave all of Everglades National Park a carbon sequestration value of $50.5 million.

But the FIU team wanted to look deeper and include legacy carbon, believing the capacity of old-growth forests added value, Bhat said. They focused on mangrove wetlands, a fraction of the vast ecosystem, as a starting point because previous research has shown their efficiency at trapping and holding carbon.

“This is just a first estimate,” Jerath said. “It is by no means a perfect one, but it is one we want to propose and we hope will encourage the same kind of calculation for the Everglades marshes and other surrounding communities.”

For their appraisal, they considered the storage capacities of different elements in the wetlands, including soils, roots and above-ground branches based on the fieldwork of co-author Victor Rivera-Monroy, a Louisiana State University wetlands ecologist who specializes in soil chemistry. In addition to “social costs” the team also included abatement costs — they used a more conservative $8 billion dollar Everglades restoration price rather than new estimates — and looked at market prices for carbon storage from a nine-state exchange set up in New England in 2005 to cap and trade carbon emissions. They believe what they arrived at is a more realistic price that provides a more reasonable comparison to real infrastructure costs.

“If you let it escape, it’s like a genie in a bottle. It’s going to cause more damage,” Bhat said.

“That’s why we have to keep it trapped,” he added. “Carbon in the Everglades should not be for sale. It’s the opposite. Because it is so valuable, we do not want to sell it.”

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