Islands. Water. World.
How Might Sea-Level Rise Affect Caribbean Islands and What Might We Do About It?

by Sally Erdle

Due to thermal expansion of the oceans and the melting of ice sheets and glaciers in the Earth’s far latitudes, the global sea level mean is rising. How fast and how much is a matter of debate, with such [US] federal agencies as the US Army Corps of Engineers, NASA and the National Oceanographic and Atmospheric Administration projecting, on the low end, eight inches of sea-level rise by the year 2100, and, on the high end, as much as six feet.
— David Kamp, Vanity Fair magazine, December 2015

This quote is from an article describing the effect of sea-level rise on Miami Beach, Florida, a low-lying city that is already experiencing this phenomenon’s effects. When tides are at their highest, the sea now flows into Miami Beach’s sewer system, bringing water into the city rather than out of it. To combat flooding, electric pumps have been installed in key locations to pump water off the streets during a storm surge or high tide.
Sea-level rise is happening — studies show that the global sea level has already risen around ten to 20 centimeters (four to eight inches) over the past 100 years — and although its impacts haven’t yet begun to be felt as strongly in the Caribbean as in Miami, how might it affect this region, a region heavily dependent on coastal enterprises such as commercial port operations, local recreation, “sun, sand and surf” tourism, and yes, the regional yachting industry?

Six Feet Under
Sea-level rise in the Caribbean is predicted to be more than three feet by the year 2100, according to the CARICOM Climate Change Center in Belize. Other sources predict six feet or more. This is not unprecedented: in the Caribbean region, examination of fossilized coral reefs from the last time the world was warmer than today (approximately 125,000 years ago) found evidence that a sea-level rise of two metres took place in less than a century.

A study prepared for CARICOM Member States by the CARIBSAVE Partnership for UNDP Barbados and the OECS notes the following key points:
• With our proximity to the equator, sea-level rise will be relatively more pronounced in the Caribbean.
• On many of the islands of the Caribbean, all the population live within ten kilometres (about six miles) of the coast. This is important for two reasons: first, that they are disproportionately vulnerable to sea-level rise, but also they are dependent on economic sectors that are more likely to be reliant on coastal activities.
• Large areas of the Caribbean coast are highly susceptible to erosion, and beaches have experienced accelerated erosion in recent decades. Higher sea levels and stronger storm surges will accelerate coastal erosion in these areas.
• Low-lying small islands and cays, largely comprised of coral reefs… are highly vulnerable to sea-level rise and hurricane storm surge. Mainly volcanic islands with only narrow coastal areas are vulnerable to erosion of more limited beach areas and local coastal landslides.
• Also of importance to tourism, but also the wider economy in each nation, is the vulnerability of key transportation infrastructure. Sea-level rise of two metres would inundate 31 out of 64 airports within CARICOM (basically all of the Lesser Antilles, plus Guyana, Suriname, Jamaica, Haiti, Belize and The Bahamas) wholly or partially inundated.

Will Yachts Float?
So, what will be the effect on Caribbean yachting? Would marinas, beach bars and boatyards retreat inland, while anchorages deepen and expand? Will your favorite beaches exist at the end of the century — a mere 84 years from now? Well, most of us reading this won’t exist then either, so why should we care? Let’s call it leaving a clean wake. And curiosity.

Fortunately, we’re not the only ones thinking about this.
Six years ago, Peter A. Murray, Programme Officer in the OECS Secretariat, wrote in a study called Adaptation for Climate Change in the Coastal Sector of Saint Lucia:
“With the yachting sub-sector seen as having potential for further development within the region’s tourism plant, the impacts of climate change on navigation have got to be a consideration. If sea level rises faster than growth of reefs, those hitherto easily identified through clear waters may become more difficult to detect, especially where visibility is reduced due to either human activities or natural hazards. Sediment deposition associated with increased incidence of cyclonic weather events can result in reduced depths for channels and anchorages, with a concomitant increase in the associated costs of dredging, undertaking of bathymetric surveys or updating of navigation charts. (It must be noted that a potential beneficial effect may be the deepening of shallow anchorages.)

“Climate change impacts on marina development should also be considered, for example sediment deposited in marina basins may require maintenance dredging, and particularly where upland uses and higher rainfall alternating with drought lead to accelerated erosion and sediment.”
As reported by Jim Flannery in the January 29th, 2016 issue of Trade Only Today (www.tradeonlytoday.com), marina owners were urged to prepare for higher tides at the International Marina & Boatyard Conference, held that month in Florida, on ways to reduce the effects of storms and sea-level rise on waterfronts. Pam Rubinoff, a coastal management extension specialist for Rhode Island Sea Grant, said the evidence of more and higher storm and “king” tides — tides associated with the gravitational effects of particular alignments of the sun and moon — is pretty clear. And in addition, she noted that the sea level has risen a foot off Newport during the past 100 years. It is expected to rise another foot by 2035, two feet by 2050 and perhaps as much as seven feet by 2100, she said. Jim Flannery wrote, “For marinas and boatyards, this means higher costs of maintenance, retrofits and upgrades; more costly investments in the property in years ahead; rising insurance costs; challenges to the business continuity; and effects on the rest of the community.”

What Can We Do?
As Devi Sharp wrote in “Submerging San Blas” in last month’s issue of Compass (www.caribbeancompass.com/online/february16compass_online.pdf) for some coastal communities, businesses and infrastructure, the answer is simply to move to higher ground. 
“Retreat is a serious but typically unappealing option,” says Emma Doyle of the Gulf & Caribbean Fisheries Institute. “In Port Honduras Marine Reserve in southern Belize, the ranger station is on a cay that is also subsiding due to earth movement, and coupled with sea-level rise it gives a dramatic early look into the future, with desperate efforts to protect existing facilities, big potential costs and serious review of alternatives. Nearby Monkey River is one of the communities most affected by sea-level rise, and a relatively poor community, and they've just been through an adaptation planning exercise with the Toledo Institute for Development and Environment, which helped identify small concrete steps that NOAA is now helping to fund.

“Six Caribbean Marine Protected Areas are working with us to share information about local impacts of climate change and helping local communities with early adaptation planning — do we retreat? build a seawall? better protect reefs and mangroves? change how we earn a living? Concrete actions include providing micro-grants for small adaptation measures such as the installation of water tanks, helping communities develop alternative sustainable livelihoods to fishing (both to take pressure off reefs and for alternative sources of protein), monitoring impacts of coral bleaching, using coral nurseries to reinforce protection of key reefs and mangrove restoration. It’s hard for small islands states to mitigate climate change, so a focus on action we can take to adapt to the forecasts is essential.”

Earth movements including earthquakes, and other natural phenomena common to the Caribbean, add to the sea-level rise problem. Various sources have studied the response of hurricanes to global warming, but the conclusion remains similar to that given by the Intergovernmental Panel on Climate Change in 2007: “Based on a range of models, it is likely that future tropical cyclones (typhoons and hurricanes) will become more intense, with larger peak wind speeds and more heavy precipitation associated with ongoing increases of tropical sea surface temperatures.”
With more severe storm surges expected in addition to sea-level rise, building codes will be looking at flood risk. The Hotel Acuario at Marina Hemingway in Cuba was built decades ago with “washout floors” — open ground levels designed with flooding expected.

At January’s International Marina & Boatyard Conference, Pam Rubinoff said that marinas and boatyards should have floating docks that ride up and down on pilings; lengthen their pilings commensurate with the amount of sea level rise at the facility; elevate utilities and fuel tanks, and secure the tanks; move hazardous materials out of flood zones; move files, computers and electrical breakers to upper floors; secure boats on boat stands by tying them to anchors embedded in the ground; strengthen the roofs of buildings; and put a business continuity plan on paper.
Protecting coastal environments will help, too. Intact mangroves and healthy coral reefs can help protect islands from hurricanes by dissipating the energy of storms before landfall. While both of these protective ecosystems can adapt somewhat to sea–level rise (corals are more negatively affected by increasing sea-surface temperatures and associated coral bleaching), environmental stresses may hinder that adaptation. For example, as reported by the Union of Concerned Scientists at www.climatehotmap.org, from 1980 to 1990 coastal development destroyed 83 percent of Antigua & Barbuda’s mangroves. And that development also obstructs migration paths for the remaining mangroves.

As Esteban Biondi of Applied Technology & Management, Inc (www.appliedtm.com) pointed out in his presentation on sustainable marina design at the 2015 Cartagena Boat Show in Colombia, adaptation to climate change is crucial. “Neglecting the negative impacts of marina construction increases the risk of damage to the project during extreme weather conditions,” he said. However, “Designers can add elements of environmentally friendly design as an attribute of the project.” As an example, he cited the protection, restoration or creation of mangroves by incorporating them into marina designs. Esteban emphasized that marinas and other nautical-recreation infrastructure — structures that must, by definition, occupy our shorelines — can have a net positive effect if proactive consideration is given to environmental issues including climate change.”

Esteban adds a caveat. He tells Compass, “Sea-level rise is an issue that will have impacts on marinas in the next 20 years. However, few developers in the Caribbean ask for studies on future sea-level rise impacts on new projects. And the actual impacts will depend a lot on the particulars of the specific locations — an area with very small tidal range and very protected by natural coral reefs with little hurricane history may have very different impacts than a marina that is now well designed for hurricanes and where sea-level rise a small fraction of the tidal range — so customized analyses are usually required.”

And right now? “The main problem for the Caribbean,” he notes, “is that most places are not really prepared or designed for the hurricanes that can be expected, given the historical record. So we are trying to solve sea-level rise adaptation when we are not really ready for the hurricane that we may get next summer — and next summer we will likely get stronger ones.”

To see sea-level rise risk maps for your area, visit https://coast.noaa.gov/slr (for US Territories) and http://ss2.climatecentral.org
(for the entire world).