Grenada - Climate

Grenada experiences tropical storms and hurricanes during the hurricane season, from June through November. Sea surges occasionally flood low lying areas, including parts of downtown St. George’s and Hillsborough on the island of Carriacou. Heavy winds periodically close local beaches to swimming.

Yearly precipitation, largely generated by the warm and moisture-laden northeasterly trade winds, varies from more than 350 centimeters on the windward mountainsides to less than 150 centimeters in the lowlands. The greatest monthly totals are recorded throughout Grenada from June through November, the months when tropical storms and hurricanes are most likely to occur. Rainfall is less pronounced from December through May, when the equatorial low-pressure system moves south. Similarly, the highest humidities, usually close to 80 percent, are recorded during the rainy months, and values from 68 to 78 percent are registered during the drier period. Temperatures averaging 29°C are constant throughout the year, however, with slightly higher readings in the lowlands. Nevertheless, diurnal ranges within a 24-hour period are appreciable: between 26°C and 32°C during the day and between 19°C and 24°C at night.

Grenada is already experiencing some of the effects of climate variability and change through damages from severe weather systems and other extreme events (such as Hurricane Ivan in 2004), as well as more subtle changes in temperatures and rainfall patterns. Detailed climate modelling projections for Grenada predict:

• an increase in average atmospheric temperature;
• reduced average annual rainfall;
• increased Sea Surface Temperatures (SST);
• the potential for an increase in the intensity of tropical storms.

And the extent of such changes is expected to be worse than what is being experienced now.

Regional Climate Model (RCM) projections indicate an increase ranging from 2.4°C to 3.2°C in mean annual temperatures by the 2080s in the higher emissions scenario.

General Circulation Model (GCM) projections of rainfall span both overall increases and decreases, ranging from -40 to +7 mm per month by 2080 across three scenarios. Most projections tend toward decreases. The RCM projections, driven by HadCM3 boundary conditions, indicate decreases in annual rainfall (-29%), while simulations based on ECHAM4 also project significant decreases (-22%).

GCM projections indicate increases in Sea Surface Temperatures (SST) throughout the year. Projected increases range from +0.9°C and +3.1°C by the 2080s across all three emissions scenarios.

North Atlantic hurricanes and tropical storms appear to have increased in intensity over the 30 years since the 1980s. Observed and projected increases in SSTs indicate potential for continuing increases in hurricane activity and model projections indicate that this may occur through increases in intensity of events but not necessarily through increases in frequency of storms.

The majority of infrastructure and settlements in small islands, like Grenada, are located on or near the coast, including government, health, commercial and transportation facilities. These areas already face pressure from natural forces (wind, waves, tides and currents) and human activities, (beach sand removal and inappropriate construction of shoreline structures).

It is important to note that the critical beach assets would be affected much earlier than the SLR induced erosion damages to tourism infrastructure. Such changes in the coastal profile would transform coastal tourism in Grenada, with implications for property values, insurance costs, destination competitiveness, marketing and wider issues of local employment and economic well-being of thousands of employees. Moreover, the beaches themselves are critical assets for tourism in Grenada, with a large proportion of beaches being lost to inundation and accelerated erosion even before resort infrastructure is damaged.

Grenada is highly dependent on international tourism and the country will be particularly affected with annual costs as a direct result of SLR. Hard engineering structures such as dikes, levees, revetments and sea walls can be used to protect the land and related infrastructure from the sea to ensure that existing land uses, such as tourism, continue to operate despite changes in the surface level of the sea. Unfortunately, the effectiveness of this approach may not withstand the test of time nor withstand against extreme events.

Protection could also be implemented through the use of soft engineering methods, which require naturally formed materials to control and redirect erosion processes. For example, beaches, wetlands and dunes have a natural buffering capacity that can help reduce the adverse impacts of climate changei. Although less expensive and less environmentally damaging, soft engineering protection is only temporary and a variety of implications need to be considered.