Rising sea level poses peril for city

USFSP Student Reporter

ST. PETERSBURG – The public official who oversees St. Petersburg’s infrastructure and a professor who specializes in climate change have a warning for the residents of St. Petersburg.

The years ahead will bring serious, expensive problems.

“The air is warming, the sea level is rising, and our climate is changing in many ways that stress the city’s infrastructure. We need to be discussing this,” said Gary Mitchum, an associate professor of physical oceanography at USF’s College of Marine Science.

Mitchum and Claude Tankersley, St. Petersburg’s public works director, shared a microphone on Nov. 20 when the St. Petersburg Downtown Partnership and the Kate Tiedemann College of Business hosted a breakfast-time speaker series called Sunny Side Up.

Tankersley, Bradenton’s public works director from 2008 to 2016, has worked for St. Petersvburg since January 2016.

Mitchum holds a doctorate in oceanography at Florida State University in 1984. He spent 11 years researching short-term climate changes, decadal processes, and long-term sea level rise problems with the Department of Oceanography at the University of Hawaii.

Mitchum is now associate dean for research at the College of Marine Science.

The two tapped their work experience and knowledge to give a presentation dubbed “Reimagine Rising Oceans.”

“What I used to call nuisance flooding is now a serious problem and we need to prepare for future changes,” said Mitchum.

Nuisance flooding is minor flooding that occurs at high tide. It is often associated with minor impacts such as old sea walls overtopped due to an increase in rainfall intensity, climate conditions, and degrading water systems flooding low-lying areas.

Mitchum used a decadal graph chart to predict the elevation of the sea level over the next eight decades.

“Over the past few years the intensity of this city’s rainfall has increased, and the nature of Florida’s climate is impacting sea level rise,” said Mitchum.

Florida’s climate is classified as a monsoon. That means the state experiences heavy rainfall for several months followed by several dry months.

“The combination of our climate and the increasing intensity of rainfall is a burden to our city’s infrastructure, and it will cost us billions of dollars to invest in a solution,” said Mitchum.

How does the rising sea level affect the city’s water system infrastructure? What are other problems must we face because of it?

Mitchum passed the mic to Tankersley to answer those questions.

Tankersley connected how the sea level rise impacts the city’s wastewater management systems, infrastructure and people.

“We rely on wastewater systems to remove any contaminants from our water so it can be returned with little impact on the environment,” said Tankersley

“The effects of intense rainfall and our climate conditions have increased the sea level, endangering the wastewater system and our citizens,” said Tankersley.

Another issue that worsens is flooding.

In 2016, Tankersley said, he received phone calls from residents complaining about flooding they had never experienced.

“People think they are not affected by sea level rise because their home is not close to the sea wall,” he said.

They do not understand that the combination of climate change and the increase in rainfall intensity is breaking down the infrastructure.

Water moves through the infrastructure system to filter out sewage and other contaminants. However, excess water surrounds the exterior of the pipes, which causes them to rust.

Most of the city’s wastewater systems are only 10 feet above the current sea level.

“What if a hurricane cuts off power supply for months and we get stuck with poor wastewater systems? This is a problem I worry about and am working on solving,” said Tankersley.

The impact of rising sea level is expected to change the city drastically over the years, and the only thing the city can do is plan, Tankersley said.

“As of now we are focused on moving forward with the research and knowledge we have and forming an effective solution we can use immediately,” he said.

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