UF-led team says 30 years of sea level rise creates bleak forecast
Published: Friday, July 24, 2015 at 7:55 a.m.
Last Modified: Friday, July 24, 2015 at 7:55 a.m.
The globe is rapidly approaching conditions that could cause a 20-foot or higher rise in sea levels that would wipe out much of coastal South Florida, a recently published scientific study reported.
The study, with its lead writer University of Florida geology professor Andrea Dutton, was posted online in Science last week. It examined 30 years of climate change field research and archives to improve understanding of how fast sea levels could rise in the future.
Current models are not good enough to project that time, she said.
“So right now what we are trying to do is look at these past records to get a better estimate of the rate of sea level rise,” she said. “We want actual data to say how fast did it rise.”
Dutton and her colleagues in the study belong to an international consortium of scientists called PALSEA2, a working group of Past Global Changes, an “international effort to coordinate and promote past global change research.”
By improving their understanding of past changes, the group hopes to better predict future climate and environment changes and inform public policies and strategies for sustainability.
“The decisions that we’re making right now will strongly influence the pathways we’re committing ourselves to in terms of the long-term sea level rise,” Dutton said.
Two weeks from now, the group will defend its findings at an international summit in Japan.
And at a Paris summit in November, nearly 200 international leaders will discuss creating new global policies on climate change.
The key to projecting future sea level increases is getting a better understanding of how the planet’s largest ice sheets respond to environmental changes, Dutton said.
The researchers focused on periods of time when polar ice sheets responded to warming temperatures and looked at the geological record when rising temperatures coincided with sea level rise.
They looked at two interglacial periods from about 125,000 years ago and 400,000 years ago, when flooded coastlines were common. They also looked at the pliocene epoch, when temperatures were 2-3 degrees centigrade higher than preindustrial levels and sea levels were 25 meters higher than today.
They chose the pliocene epoch because it was the earliest era in which they could find carbon dioxide levels at current levels of around 400 parts per million.
“The main take-home message I’ve had from this review of 30 years of research is that we are very close to the point where in the past warmer climates have caused more than 6 meters (more than 20 feet) of sea level rise from much smaller ice sheets,” said Anders Carlson, a study co-author and associate professor in the College of Earth, Atmospheric and Oceanic Sciences at Oregon State University.
Ben Strauss, vice president for sea level and climate impacts with Climate Central, said a 20-foot sea level rise would probably mean the end for most coastal cities in the world.
“It would certainly mean the end for southern Florida, but neither would it spare Jacksonville, Tampa or St. Petersburg,” he said. “An incredible amount of our heritage and history is at stake.”
Florida is already experiencing sea level rise. Miami, for example, was 2.6 feet above the mean high tide line as of 2012, Climate Central said. It predicts a 3.4-foot rise in sea level by 2100.
Tampa was 4.9 feet above local high tide line for 2012, and Climate Central predicts a 3.2-foot sea level rise by 2100.
A 2C rise in temperature would turn Jacksonville into several islands, widen the St. Johns River, eliminate the barrier islands and submerge Kennedy Space Center. Most of the Florida peninsula south of Lake Okeechobee would be underwater.
“Sea level rise is not a thing of the future,” Dutton said. “It is already happening and it will continue to happen so we can make decisions that affect the rate at which that occurs.”
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