The Eastern Caribbean Might Possibly Experience A Severe Water Deficit In Early 2016…Maybe?

This year’s Climate and Society class is out in the field (or lab or office) completing a summer internship or thesis. They’ll be documenting their experiences one blog post at a time. Read on to see what they’re up to.

Discolored vegetation due to water deficit in Saint Lucia. Credit: teleSUR

By Shem Willie, C+S ’15

Flying into the eastern Caribbean region at the end of May, the lush green vegetation that would normally greet visitors from the skies above was visibly brown. This was the first indication that precipitation over the islands was below normal, a fact confirmed by the climatological reports from the various islands.

The precipitation data from the Saint Lucia Meteorological Office indicated that Saint Lucia has been experiencing below normal precipitation for the months of April to June, with the precipitation for May being the lowest since 1989. For the island of the Antigua, Dale Destin (C+S ‘14) said in a drought statement that their drought level in Antigua was raised to severe and this was the fourth lowest precipitation they’ve experienced since 1928.

In addition to reduced precipitation amounts, the temperatures over the eastern Caribbean have been above normal, which increases the loss of water by evaporation, making the situation more alarming. Climatologically, the Eastern Caribbean is classified as having a Tropical Savannah climate. There is a dry season which runs from December to May and a wet season (which is also the hurricane season) from June to November. Since the rainfall deficit thus far has occurred in the drier season, the hope is that the subsurface and groundwater could be recharged during the wet season. But will this really happen?

The answer to this was given at the 2015 Caribbean Climate Forum (CARICOF), held in in Saint Lucia at the beginning of June. The CARICOF is a meeting where meteorologists and climatologists in the region meet with persons in climate-sensitive sectors to discuss the climatological forecast and the implications it could have on the activities in their respective sectors. The forum is coordinated by the Caribbean Institute for Meteorology and Hydrology in collaboration with international partners such as the International Research Institute for Climate and Society.

The seasonal precipitation forecast for Eastern Caribbean for the period June to August call for a 50 percent chance that it will be below normal, 30 percent chance of it being normal and 20 percent above normal. For the months of September to November, the precipitation forecast is about the same, with a 50 percent chance of below normal precipitation, 35 percent chance of being normal and 15 percent chance of above normal. As for the temperature forecast, the probability of it being above normal is 40 percent for June to August and this probability increases to 50 percent for the period September to November.

Precipitation outlook for the Caribbean. Credit: CIMH

Such a forecast for the rainy season is indeed concerning since the underlying message here is that the deficit in the amount precipitation is expected to continue throughout the period where the region experiences most of its precipitation.

As a result of this, the water supply in the region will not be replenished to its normal levels before moving into the dry season, hence the possibility of a water deficit is relatively high looking ahead for early 2016.

At least some of the reason for the elevated chance of below normal precipitation is due to the warmer than usual sea surface temperatures in the Pacific Ocean as result of El Niño. On a positive note, the El Niño phenomena results in fewer tropical cyclones in the Atlantic Ocean, which is always a major concern for this region at this time of year. But this comes at the expense of reduced precipitation since convective activity is suppressed as a result of unfavorable upper level conditions.

In response to the drier than normal conditions, there have been some adjustments in some of the sectors to help conserve water. Saint Lucia’s highly anticipated H20 wet fête — an annual event where patrons emerge themselves in water in festive celebration — was cancelled by the water authorities, since the country was placed under a water emergency and this would activity would not be in keeping with goal of saving water.

Water for some communities is now supplied on a schedule and residence are being reminded of Water Emergencies Act, which enforces water conservation restrictions which limits lawn sprinkling, vehicle washing, golf course and park irrigation and other nonessential uses. While these water restrictions should help in conserving water, given the possibility of an extended period of below normal precipitation, there might be a need for adjustments based on how the severity of the water deficit at the end of 2015 and early 2016.