Climate Change Once Flooded Florida - And It Could Again

Dec 3, 2019
Originally published on December 6, 2019 9:35 am

On a satellite map, the Lake Wales Ridge stands out as a sandy spine running through the middle of Florida. From Clermont in the north, south almost to Lake Okeechobee, rolling hills give the area a very un-Florida-like feel.

Parts of the Ridge -- especially in the rural southern reaches -- have some of the highest concentrations of plants and animals found nowhere else in the world.

That's because about 2 million years ago, the tops of these low-rising peaks were the only parts of Florida above water.

"This is probably, in terms of climate change, the safest place to be in Florida," said biologist Reed Bowman. "It's not been under the ocean for 2 million years. It's not likely to be under the ocean for that long, as well."

For that to happen, the entire ice caps covering Greenland and Antarctica would likely have to melt. But as global warming once again causes sea levels to rise, the history of the Lake Wales Ridge is a cautionary tale of what the state once was and where it could be headed.

"It could certainly happen again, whether it's anthropogenic climate change, or whether it's natural climate change," said Bowman, who conducts research along the Ridge at the Archbold Biological Station. "But of course, the time frame would be millions and millions of years. But you could take that as an analogue. You could see severe consequences of that. We could see similar consequences with just little bits of sea level rise. Not so much that we're going to displace animals, but we are going to displace humans."

Archbold was established in 1941, a gift from the grandson of the man who built the Brooklyn Bridge. The station sits on nearly 9,000 acres of preserved land and is dedicated to long-term ecological research of the natural environment.

As Bowman bumps along the sandy roads that bisect the station, he points out features of the Ridge's topography. It's a rare expanse of Florida scrub, with its sandy soil and evergreen shrubs giving way to endless vistas from atop gentle rises. The closest town is a crossroads called Venus, with 850 people.

The station is about 75 miles from the coast in both directions, so it's hard to imagine the sea once rose to its sandy borders.

But Florida's coastlines have ebbed and flowed over the millennia. A map created by the University of South Florida's Libraries and School of Geosciences (shown above) reveals only parts of the Lake Wales Ridge and the northern extreme of the state bordering Georgia and Alabama as above water during the last extreme event of global warming, about 125,000 years ago.

Petroniu Bogdan Onac is a professor of biology at the University of South Florida, who has been researching historic sea level rise in both Florida and the Mediterranean.

He says with the exception of the Lake Wales Ridge and areas around Ocala and the northern edge of the state, Florida was completely under water between two and three and a half million years ago.

As recently as 20,000 years ago - before the generally-accepted time that humans first arrived in North America - Onac says the seas were about 330 feet below the current level. This would put Florida's west coast from 100 to 150 miles offshore.

"At that time, most of that water was held into the big ice sheets, which entirely covered Canada and most of northern North America," he said. "Each time there was a glaciation and the ice was up, then the sea was going down. Then, when the climate came back to what we call 'interglacial' when it was warmer, the ice melted, and it came back to high levels. Some 125,000, 126,000 years ago, it was 5 to 6 meters (16 to 20 feet) above present day."

Even though this ebb and flow is natural, Onac says human-created record-high carbon emissions are now forcing the hand of nature.

"If it were only nature, then we should expect to see a kind of cycle, where we could predict where it's going," he said of sea level rise. "But the problem here is we are witnessing  -- since the tide gauges came on board since 1850s in some of the countries in Europe -- is we're seeing that it was slowly increasing, and then there is the effect of the big ice sheets melting, and since 1980 on, it's accelerated, and since it's accelerating so much, it's rising and rising.

"This cycling that we're expecting is not entirely natural," Onac said. "Three million, 3 1/2  million years ago, it changed during the earth's evolution. The only change is we're forcing the evolution now."

On top of that, he noted Florida's flat topography means storm surge - as well as hurricane surge - will cause salt water intrusion into the state's underground freshwater aquifer.

Back on the Lake Wales Ridge, researcher Reed Bowman stands on the most ancient part of Florida -- and one of its most threatened.

The endangered Florida scrub jay has made a stand here. It's the only species of bird endemic to Florida -- and one of only 15 species found solely in the continental U.S.

Bowman fears that climate change is already starting to effect the birds.

"We are seeing some directional changes. For example, the birds I study, Florida scrub jays, have begun nesting earlier and earlier every year," he said. "We don't know whether that's driven by climate change, but we suspect so. And we don't yet know what the consequences of that is. Is it hurting the jays, or are they just adapting to the different climate?"

Bowman said he's seeing other impacts of climate change as well.

"I  mean as more and more people suffer the effects of climate change close to the coasts, there's going to be an inward migration of people into high ridges like the Lake Wales Ridge," Bowman said. "And that, I think, is already occuring. And that puts more pressure on all of our natural systems. And I think that's being driven in large part by climate change."

Like in previous epochs of climate change, animals have to shift where they live and where they eat, Bowman said. But because their habitat is now cut up by development and groves, he said the consequences of this climate change are going to be quite different than any other period in the Earth's history.

Copyright 2019 WUSF Public Media - WUSF 89.7. To see more, visit WUSF Public Media - WUSF 89.7.