That’s one of the worst-case scenarios in the National Climate Assessment released late last week. But even the report’s most moderate predictions are gripping and perhaps most dramatic of all is the documentation of what has already happened.
The report immediately touched off political debate across the country, with President Trump’s critics charging his administration tried to downplay it by releasing it over the Thanksgiving holiday weekend when people aren’t focused on the news.
What may be more important to V.I. residents than the timing is their inclusion in the report findings.
The U.S. Global Change Research Program has been producing a climate change assessment every four years since 2006. This is the first time the report has contained a chapter devoted specifically to what it calls the “U.S. Caribbean.”
The report describes the area as consisting of seven inhabited islands – Puerto Rico and its adjunct islands of Mona to its west and Culebra and Vieques to its east, as well as the three main U.S. Virgin Islands of St. Thomas, St. John and St. Croix, and including almost 800 tiny islands and cays, most of them inhabited only by birds, donkeys and rodents. The human population for the region is listed as 3.4 million, with just 104,000 of that in the U.S. Virgin Islands. The area is marked by open ocean and nearshore marine areas, coastal wetlands, hills, plains, limestone, or karst hills and interior mountains.
As residents know, historically the area has enjoyed a rather stable climate in which even extreme weather events such as hurricanes are restricted to known seasons.
“However, these patterns are changing and are predicted to be increasingly variable as atmospheric greenhouse gas concentrations increase,” the report authors warn.
Both the air and the ocean temperatures are rising and so is the water level.
Since 1950, average temperatures recorded for Puerto Rico have risen by1.5 degrees Farehneit. Global Climate models project an increase of another 1.5 degrees to four degrees by 2050 (little more than 30 years from now) and as high as nine degrees by the end of the century.
Meanwhile, from 2000 to 2017 scientists have measured a sea level rise for the U.S. Caribbean of 0.24 inches.
They expect the water to continue to rise at an accelerating rate, based on a variety of factors, including the rate of greenhouse emissions and the loss of glaciers and ice sheets. With many factors fluctuating, it’s impossible to be precise about exactly how much the water will rise. Some observers think the rise could be higher in the Caribbean region than the global average due to changes in the Earth’s gravitational field, rotation caused by melting land ice and ocean circulation. End-of-the-century projections range anywhere from one to two feet on the low end, to as much as nine to 11 feet on the high side.
But even under the intermediate projections of a 6.5-foot sea level rise, that means a drastic change to the landscape we know today.
Existing power plants for St. Croix and St. Thomas, pipelines for water and sewage, a number of schools and housing communities and the territory’s three largest towns all sit in the potential “inundation zone.” Already, two prehistoric archeological sites are threatened by the rising waters, at Sandy Point and at Great Pond on St. Croix.
In fact, if the 6.5-foot projection for sea level rise is correct, the Virgin Islands will lose 4.6 percent of its land base, all on the coast.
Erosion is not the only problem. Sea-level rise is likely to cause contamination of island fresh water sources and underground acquirers with salt water.
As the water is rising, it’s also warming on the surface. From 1955 to 2016, the waters of the northeast Caribbean warmed at an average rate of 0.23 degrees Fahrenheit per decade. That trend is also accelerating. Over the past two decades, the rate per decade was 0.43 degrees F.
As oceans absorb heat and CO2 from the atmosphere, they become more acidic, which can adversely affect all sorts of marine life.
In 2005 the ocean in the Caribbean region experienced 12 weeks of above normal temperatures, which resulted in a massive coral bleaching event and the loss of 40 percent to 80 percent of corals throughout the region. Recovery is still not complete 13 years later.
The worse case scenario in the Climate Change Assessment is that coral bleaching events will begin occurring twice a year within a decade and that by 2090, Puerto Rico could lose 95 percent of its coral.
Coral reefs are not only important as habitat and food for the fish that live in and around them; so-called fringing reefs, those near a shoreline, also provide wave action needed to sustain mangroves and seagrass beds, both of which act as nurseries for a host of marine life including spiny lobster, queen conch, snappers and groupers.
That has economic consequences. The report cites the following figures for the relatively small, but not insignificant, fishing industries in Puerto Rico and the Virgin Islands: an annual income of $9 million for Puerto Rico, $3 million for St. Croix and $2.4 million for St. Thomas-St. John (in 2014dollars.)
The report warns of larger potential losses, citing the income from “reef-related tourism” in the Virgin Islands as $108 million per year.
In the wider scope, the territory could suffer even greater losses, as its overall tourism industry grapples with the disappearance of its beaches to sea level rise. The report skirts dollar predictions, but it does note that 60 percent of the territory’s economy is devoted to service-related industries and that annually, in 2013 dollars, overnight visitors drop $851 million into the islands and cruise passengers add another $381 million. So any reduction is significant.
Rainfall in the region is highly variable and that complicates the analysis of trends, the report states. Nevertheless, its authors predict that in the near future the Caribbean will experience longer dry seasons and shorter, but wetter rainy seasons.
They also predict an increase in severe weather events. That trend seems to have started already. Since the mid-1990s, Puerto Rico has suffered more than 50 extreme events and since 2001, it has seen at least one disaster declaration per year.
The report makes note of the 2017 hurricane season in which two category five storms visited the Virgin Islands, 22 of the 29 SIDS (Small Island Developing States) of the Caribbean were impacted by at least one named storm and Puerto Rico was devastated by Hurricane Maria and the economic cost was upwards of $48 billion. The report does not directly attribute the storms to climate change, but it does suggest global warming contributes to the formation of disastrous storms.
And it says that the Caribbean is more susceptible to them than are coastal areas on the mainland U.S. Warm waters in both regions encourage the formation of hurricanes, but in the continental U.S. that same warm water discourages other factors needed for the development of cyclones. In the Caribbean, that effect is missing.
The report is not all gloom. It devotes considerable attention to mitigation efforts.
To address problems with drought, for instance, it recommends applying new technologies to manage sedimentation in reservoirs (a particular problem for Puerto Rico) and to limit water loss in distribution systems. It notes that the Puerto Rico Technical Scientific Drought Committee suggests the widespread use of cisterns and that the Virgin Islands already relies heavily on home cisterns. To protect agricultural concerns, it recommends reducing erosion, improving soil fertility and plant breeding to develop drought-resistant crops.
To protect corals and other sea life, the report notes that efforts are already underway to create and maintain protected watersheds, build the resilience of coral colonies by propagating strong organisms, and engage in partnerships with other Caribbean islands to promote international monitoring of marine species.