A group of scientists just presented updated sea level rise projections to Tampa Bay politicians. Here's what they say.

Beachfront areas like Redington Beach could face sea level rise of anywhere from 2 to 8 feet by the end of the century, according to the latest projections. [Luis Santana | Times]
Beachfront areas like Redington Beach could face sea level rise of anywhere from 2 to 8 feet by the end of the century, according to the latest projections. [Luis Santana | Times]
Published May 14, 2019

PINELLAS PARK — A group of local scientists has been working on and off for months to come up with Tampa Bay-area projections for sea level rise.

Their verdict: the problem is getting worse.

The Tampa Bay Climate Science Advisory Panel, a group of climate scientists that formed in 2014, presented its findings to a Tampa Bay Regional Planning Council committee Monday. They found that the region is likely to face between 1.9 and 8.5 feet of sea level rise by the year 2100.

The projections are the group's second round of local sea level rise predictions. The current forecasts are 12 to 18 inches higher than their 2015 estimates on average.

Maya Burke, who sits on the advisory panel and who presented the findings Monday, said the projections have gotten more dire for two reasons. One, global greenhouse gas emissions have risen since 2015. Two, scientists understand how arctic ice melt contributes to sea level rise better today than they did a half-decade ago.

The lead authors on the group's paper detailing the projections are Burke, the science policy coordinator for the Tampa Bay Estuary Program; Libby Carnahan, a Florida Sea Grant extension agent for Pinellas County; Kelli Hammer-Levy, the Environmental Management Division director for Pinellas County and Gary Mitchum, an associate dean and a professor of marine science at USF.

The range of uncertainty between 2 and 8.5 feet may still seem wide. Burke said the scenarios vary so much because it's difficult to project human activity decades into the future. Will we still be emitting greenhouse gases at today's rates in 2050? Will we have found a way to suck carbon out of the atmosphere by then? There's no way to know.

However the physics of sea level rise are relatively straightforward, Burke said. Increasing global temperatures cause the oceans themselves to expand. On-land arctic ice sheets melt. Both phenomenons causes seas to rise.

Read more: Climate change is here. Will Tampa Bay finally get ready?

"It's really that human element that we don't understand as much right now," Burke told the small gathering of local politicians and civic planners at the Regional Planning Council headquarters.

The scientists' range of outcomes wasn't as broad as it could have been. The panel made its recommendations based on the National Climate Assessment, a federally mandated climate change study that is produced with the help of hundreds of experts every four years.

The fourth installment of the NCA, which came out in November 2018, offered six possibilities for sea level rise, ranging from "low" — about 1.5 feet by 2100 — to "extreme" — a whopping 10.5 feet by century's end. (Local tide gauge readings show that Tampa Bay-area seas have risen almost eight inches on average since 1946, the advisory panel noted in the paper detailing their projections.)

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The Climate Science Advisory Panel recommended that the Tampa Bay region discount the assessment's "low" and "extreme" scenarios. The "low" scenario, the authors explained, does not account for any acceleration of sea level rise — a phenomenon we're already beginning to witness.

The "extreme" projection presents the worst-case scenario for arctic ice melt, which the group said likely won't happen before 2100.

Even the most optimistic scenario recommended by the scientists would present a planning challenge. In 2015, MacDill Air Force Base commissioned a study about encroachment issues that could affect the base's mission. It found that sea level rise was a threat to the base, which sits, at its peak, just 14 feet above sea level.

Even a few feet of sea level rise would threaten the natural areas that the base uses as a buffer between its training grounds and the local environment, Base Community Planner Tony Rodriguez said. Especially come storm surge season.

Read more: Pinellas County announces hiring of new climate change resiliency officer

Sea level rise doesn't happen uniformly across coastlines. The Virginia Institute of Marine Science projects that some areas, like the Gulf coast, are particularly vulnerable to rising oceans. But some parts of Alaska are actually seeing its land mass rise due to melting ice and shifting tectonic plates. Those areas are less threatened by sea level rise.

The local differences in tidal patterns and land movement make regional sea level rise projections all the more important, Burke said. The Climate Science Advisory Panel recommends taking readings from local tide gauges so municipal planners can know the risks associated with approving long term infrastructure projects near the coasts.

Janet Long, who chairs the Regional Planning Council-sponsored Tampa Bay Regional Resiliency Coalition, was in the audience for Burke's presentation Monday. The Pinellas County Commissioner said local officials should heed the scientists' projections.

"Whether you believe in this data or you think it's all a bunch of bunk, you have a responsibility to your citizens to become really educated about this," Long said.

For the sake of clarity, this story was updated Tuesday morning to list the names of the main authors of the Climate Science Advisory Panel sea level rise study.

Contact Kirby Wilson at (727) 893-8793 or Follow @kirbywtweets.