V.I. Has a Lot to Lose to Rising Sea Levels

A King Tide has temporarily covered a wide expanse of beach, leaving a refreshment center at Emerald Beach on St. Thomas just steps from the water’s edge. (Photo by Gregory Guannel)

By the time today’s babies start building their own families, they will likely live in a topographically changed island from the one that welcomed them in 2022.

A federal climate report out this week concludes that the world’s sea levels are rising even faster than the dire predictions of a few years ago. In the next 30 years, waters surrounding the continental U.S., Alaska, Hawaii and in the Caribbean will rise as much as they did over the last century, for an average of about a foot.

Exact amounts will vary in different locations because of various factors, notably the condition of the land near the shoreline. For instance, waters on the West Coast of the U.S. are expected to rise anywhere from four inches to eight inches, whereas those lapping the East Coast will rise somewhere between 10 inches and 14 inches.

The difference is attributed to “land subsidence” and the compaction of sediment, which means land at the shoreline is lowered. Gulf states, partly because of the commercial extraction of gas, are especially impacted; Gulf waters are predicted to rise between 14 inches and 18 inches by 2050.

The Virgin Islands, Puerto Rico and other Caribbean islands are expected to see sea level rise between 8 inches and 10 inches by 2050, according to the study, raising the spectrum of shoreline erosion.

A dinghy dock on Coral Bay, St. John is all but submerged by a King Tide in November 2021. (Photo by Gregory Guannel)

Rising sea levels also translate into more frequent, more serious, and more far-reaching flooding.

The report says U.S. coastal areas currently deal with minor, sea-related flooding an average of about three times a year. Minor flooding is described as “nuisance” or disruptive flooding. By 2050, there will be more “moderate” floods per year (an average of four) than the minor floods seen today. A “moderate” occurrence typically causes some damage.

Because the water is higher, it will also reach further inland than it does today, according to the study.

“The 2022 Sea Level Rise Technical Report” is the work of the Interagency Sea Level Rise and Coastal Flood Hazard and Tool Task Force – a group with representatives from eight different departments and agencies: the National Oceanic and Atmospheric Administration, NASA, the Federal Emergency Management Agency, the Environmental Protection Agency, the U.S. Geological Survey, Homeland Security, the Department of Defense and the U.S. Army Corps of Engineers.

The researchers said satellites and other technological advances have improved the ability to monitor ocean levels and the thickness of ice sheets. That, presumably, was a reason for issuing the report, which is basically an update of a 2017 climate report.

The findings were “not a surprise” to Gregory Guannel, the director of the Caribbean Green Technology Center at the University of the Virgin Islands. With all the information coming out on the speed of global ice melts and other climate phenomenon, “Everything was pointing at that.”

In a November 2021 King Tide, water in Charlotte Amalie has risen almost level with the adjacent land. (Photo by Gregory Guannel)

For the last few years, Guannel and a small team have conducted surveys in November, when the highest natural tides, known as King Tides, affect the Virgin Islands. In 2021, they found the water levels were higher than in 2020, with the water encroaching further onto the land.

At Emerald Beach on St. Thomas, for instance, the water line was just a few feet from a restaurant/bar that normally sits well back from the shore. In Coral Bay, St. John, a dinghy dock was almost submerged. In western Charlotte Amalie, water was inches below the land.

The King Tide is just a precursor of what’s to come.

“That’s going to be what the normal water level will be in a few years,” Guannel said.

The federal interagency study comes on the heels of another report that NOAA issued last month on “State Climate Summaries 2022” which looked at both ocean water level and temperature increases.

In Puerto Rico and the U.S. Virgin Islands, according to the Climate Summaries report, average air temperatures as well as water temperatures have risen almost two degrees Fahrenheit since 1950.

The annual typical rainfall in the U.S. Virgin Islands is less than 60 inches across all the islands, the report states. In the wet season, from May to October, much of the rain comes from tropical cyclones moving from east to west, and storms can also be triggered by warm ocean surface temperatures. In the dry season, November-April, what rain there is comes with cold fronts moving west to east.

Higher sea surface temperatures will have several effects. The warmer water will result in more water vapor to churn hurricanes and other tropical cyclones; storm surge heights will increase; and there will be more major storms (Category 3 and above) though not necessarily more storms altogether, according to the report.

At the same time, the periods between rainfalls will lengthen, making the territory lurch between flood and drought.

“Rising sea levels will likely result in increased coastal flooding, coastal erosion, and disruptions to coastal ecosystems and critical infrastructures,” the report states.

On the plus side, the report says that “Most of the U.S. Virgin Islands are well above sea level,” suggesting impacts will be less than in some other U.S. regions.

“(H)owever, waterfront property in the capital, Charlotte Amalie, is generally within a few feet of sea level,” making it more vulnerable.

Guannel said he thinks Charlotte Amalie is well protected from storm surge by a seawall. However, as sea levels continue to rise, “the issue will be drainage.” In rain events, St. Thomas guts carry excess water down from the hillsides and, through outflows, direct it into the harbor. But if those outflows are underwater because of high sea level, it will become a struggle between rainwater pushing to get out and sea water pushing to get in.