A Rising Tide

A UM scientist and global warming pioneer warns the muckety-mucks

Twenty-seven years before the greenhouse effect began making daily headlines across the United States, University of Miami geology professor Harold Wanless returned home from an Environmental Protection Agency-sponsored conference with a hypothesis.

To check it, he started looking up tide-gauge records for Miami and Key West. The Magic City's records dated back to 1930; Key West's began in 1913.

Eureka.

The sea level around South Florida, he learned, had risen more than nine inches since 1930, a rate of about one foot per century. That was approximately eight or nine times the rate of the last two or three thousand years.

Wanless jumped to no conclusions — it might have been part of a cycle rather than a new trend. Soon he published his first article on the subject, "Sea Level Rise: So What?" (The title came from a mentor at UM's Rosenstiel School of Marine Science who ended every lecture with that question.) He made no mention of global warming but delineated his findings, which included photos of oysters attached to concrete pilings in Coral Gables six inches higher than where they used to be. An article on his research was published in the Miami Herald. He remembers the reporter asking him, "Doesn't that mean the ocean is just six inches deeper?"

"People didn't really grasp it at first," he says, chuckling.

As satellite technology advanced, scientists definitively proved that the oceans were not only rising, but warming. There was no longer any doubt: The rising sea level was a result of the warming of the North Atlantic and the subsequent expansion of ocean water as it heated. The water was heating because the ocean absorbs approximately 40 percent of the carbon dioxide the industrial age has pumped into the atmosphere. But policy makers refused to believe what was in front of them.

"If you go to the doctor, and he says there's a 60 percent chance you're going to die, it scares the crap out of you," said Wanless during a recent interview at UM's geology department, where rock formations are hung in picture frames like family photos. "But if climate scientists say there's a 99 percent chance this is going to happen, Congress says, öWell what about that one percent?'"

Indeed the numbers are disturbing. Since 1980 Florida's coastal population — among America's most vulnerable to effects of global warming — has grown by almost 75 percent, to more than seventeen million people. The population density in those areas averages 346 people per square mile. Carbon dioxide emissions have increased about 36.5 percent during the last seventeen years in Miami-Dade County alone.

Last week Wanless gave a presentation to the the newly inaugurated Miami-Dade County Task Force on Climate Change. The group includes some of the area's most prominent environmental activists — Nancy Liebman of the Urban Environmental League's , Cynthia Guerra of the Tropical Audubon Society, Alan Farago of the Sierra Club — as well as staff representatives from several county departments. In a conference room at the county courthouse in downtown Miami, lights dimmed for a slide show presentation, and they watched with rapt attention as Wanless delineated his decades of research on sea level rise.

His is a geologist's perspective. He began his lecture scoffing at anyone's notion that something like a coastline might be considered a permanent fixture. "People seem to think of a coast being where it is, of towns and cities being where they are," he says. "Somehow it's been ingrained in us that there's a permanance to Earth."

Instead, he explained, the coastline is one of the most ephemeral parts of the planet's landscape. At the height of the last Ice Age, about 18,000 years ago, the coast near Naples was approximately 100 miles west of where it is today, and Biscayne Bay was dry land. Five thousand years ago, around the time the Sumerians invented the wheel, shorelines were twenty feet farther out than they are today. And, Wanless added, the sea level has never risen in a slow, linear fashion, but has experienced rapid jumps that resemble steps when charted on a diagram.

Sea level may presently be rising at a rate of a foot per century, but as archaeological sites of quickly abandoned cities now under water have proven, coastlines can flood quickly and unexpectedly.

And although the rise in sea lavel hasn't affected anyone's mortgage yet, it has destroyed habitats in the most low-lying coastal areas of Florida — around Florida Bay and Cape Sable.

Brigitte Vlaswinkel is a recent Ph.D. graduate of UM, and a former student of Wanless, now working for Shell International in the Netherlands. For her doctoral dissertation completed last year, she partnered with the UM professor on a study of Cape Sable. Located at the southwest tip of Florida, the cape was for centuries a freshwater marsh protected from the saline water of Florida Bay by a physical barrier (an ancient coastline from about 3000 years ago.)

After World War I it was touted as fertile land ("the finest agricultural soil" reads an old advertisement), and enterprising farmers built roads and houses. But as Vlaswinkel and Wanless discovered, saline waters now flow over the barrier at least 80 times a year. The aquatic life that lives in the freshwater habitat — frogs, snakes, alligators — has all but vanished. Stands of sawgrass have died. Mangroves have started to grow in some areas, but most of the former marsh is now open water.

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