Oceanography students voyage to study sea level rise

From the top of a hill on Long Island, Bahamas, Paloma Cartwright looked down into a valley and watched as everything she owned literally got swept away. Her books, school uniforms, even her shoes-the flood waters spawned by powerful Hurricane Joaquin, which had pummeled the island for 24 hours, had taken it all.

Hundreds of other residents living on the small islet, population 3,100, fared no better, losing everything to the Category 4 hurricane, the 10th named storm of the 2015 Atlantic hurricane season.

"I was old enough at 15 to understand the repercussions of what had happened and to realize that this was climate change in action,” said Cartwright, who is now a graduate student at the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science. "I watched as other hurricanes ravaged the Caribbean and hurt the people I love. But it was Joaquin that changed my life. I knew from that experience that I wanted to devote who I was to studying climate change and its consequences.”

For Cartwright, that meant studying one of the biggest influences on climate: the ocean.

As a doctoral candidate in the lab run by oceanographer Lisa Beal, a professor in the Department of Ocean Sciences, Cartwright recently ventured out to sea with a team of scientists to study how potential changes in the Florida Current may lead to rising sea levels and more sunny-day flooding-not only in Miami but also in other East Coast communities and in the Bahamas. "This is research that definitely hits close to home,” she said.

Scientist Lisa Beal coordinates with officers on the bridge of the F.G. Walton Smith for the deployment of an instrument to monitor sea level, heat, and salt content within the Florida Straits.

To get the critical answers she and the other scientists need, Cartwright helped deploy a series of special monitoring devices at nine different locations on a stretch of seafloor between West Palm Beach and Grand Bahama Island, measuring the Florida Current’s speed and taking temperature and salinity readings.

The study, funded by the National Science Foundation, is the first of its kind. Since the early 1980s, researchers relied on an old cable, strung between Florida and the Bahamas to provide internet and phone service, to measure the Florida Current’s velocity. "Scientists were able to use the voltage measured across the cable to determine Florida Current transport,” Cartwright explained. "But that method provided readings only once a day.”

With the Currentand Pressure-recording Inverted Echo Sounders, or CPIES, deployed by Cartwright under Beal’s supervision, the researchers will get measurements of velocity structure, sea level, and water masses across the Straits every 10 minutes over the next five years.

They deployed the special monitoring instruments during a five-day cruise aboard the Rosenstiel School’s F.G. Walton Smith research vessel.

"The CPIES send a ping to the surface of the ocean, allowing us to measure round-trip travel time, or how long it takes for that ping to go to the surface and back to the instrument,” Cartwright said. "That, along with temperature, salinity, depth, and pressure readings, will give us a total look at the entire water column. From the surface to where the instruments sit on the bottom of the seafloor, we’ll learn how strong the current is moving, which could lead to a better understanding of potential impacts on coastlines and ultimately people.”

Having witnessed how Hurricane Joaquin devastated her Long Island, Bahamas, community, Cartwright knows better than anyone how sea level rise can devastate coastlines and people’s lives.

Cartwright and her mother and father had evacuated their neighborhood before Joaquin hit, moving in with relatives for what was supposed to be only a day or so. After Joaquin had passed and the winds were subsiding, Cartwright and her parents stood on a rock on a hillside, looking down into the valley where their home was located. "I could see the water flowing through my bedroom window,” she said. "I could see my old elementary school just down the street from our home, and I could see the school desks from one of its classroom’s floating outside.”

It took months to rebuild their home. "It was truly a community effort-everyone joining forces to fix the roof of one house on one day and to replace the windows of another the next day,” Cartwright recalled. "The women in the neighborhood would prepare meals and bring food around, so that everyone who was working had something to eat.”

Eight years later, Long Island, where Cartwright was born and raised, is finally back to where it used to be before Joaquin devastated the district.

She hopes the research she is conducting as part of the Beal lab will help coastal communities adapt to sea level rise.

Cartwright has gone out to sea with Beal on three different expeditions. First, she took a 26-day cruise in the Cape Cauldron off South Africa to learn more about how the dynamic mixing of Indian Ocean and Atlantic Ocean waters affects weather and climate. Then, Cartwright went on a five-day expedition to study the Florida Current. That trip was followed by another cruise with UK scientists to learn more about how the enormous poleward fluxes of heat, carbon, salt, and nutrients within the Gulf Stream influence the climate of North America and Europe.

Two other Rosenstiel School students joined her on Beal’s Florida Current cruise: ocean sciences doctoral candidate Rachel Sampson and undergraduate Allie Cook.

Cook, an oceanography major from Pittsburgh, Pennsylvania, thought she would simply observe during the cruise. "I didn’t know going into it what to expect. I thought my role was not to get in the way and to just learn,” she admitted. "But everyone, from the science crew to the crewmembers aboard the F.G. Walton, allowed me to get involved, whether it was helping to configure the instruments or deploy them off the ship.”

Like Cartwright, Sampson grew up in a coastal community often affected by rising sea levels. Many of St. Augustine, Florida, residents live in a floodplain, Sampson pointed out. "For me, even though the cruise was not my project, it was special to be able to participate and help deploy the instruments,” she noted. "Our work will help residents of coastal cities to adapt and learn how to protect themselves.”