Climate Sense

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The Caribbean Drought and

Precipitation Monitoring Network:

the concept and its progress

Adrian Trotman, Anthony Moore and Shontelle Stoute, Caribbean Institute for Meteorology and Hydrology

ainfall in the Caribbean islands is characterized by

a wet and a dry season in each year. The wet season

normally begins during May to June and finishes during

November to December. At least 70 to over 80 per cent of the

rainfall occurs, on average, during the wet season.

In the case

of Guyana, in particular the northern portion, the influence

of the Inter Tropical Convergence Zone is responsible for the

two wet and two dry seasons per year. The seasons show much

variability in commencement, duration and rainfall quantities.

Also, it is not unusual to experience significant dry spells during

the wet season or very wet spells in the dry season.

Cycles of

50 to 60 years

suggest phases of high and low rainfall, with

significant interdecadal variability. During the low phases,

water shortages will be more frequent, whilst flooding will be

more common during the high phases. Droughts and floods

impact heavily on economic sectors, such as agriculture, water

resources and tourism.

Drought can be defined in a variety of ways. Typically, it is viewed

as abnormally low water availability, often due to abnormally

low precipitation. It is a slow, creeping disaster that may only be

recognized when it is already upon us – then it might be too late.

Droughts range in intensity, duration (weeks to years) and spatial

extent, which is normally greater than for other climate hazards.

Drought impacts are normally cumulative and the effects are

magnified when occurring from one season to the next.

There is,

therefore, the need to closely monitor precipitation for such occur-

rences. If we interpret drought as a ‘water shortage’, the distribution

of water during dry seasons in the Caribbean region makes life

extremely difficult for water resources managers, agriculturists and

ecosystem managers. The region’s booming tourist industry is no

less vulnerable as the dry season, which coincides with the boreal

winter season, realizes the heaviest influx of visitors and places a

greater strain on water supplies. Drought severely magnifies this

lack of water during the dry season. Sub-normal precipitation during

wet seasons is commonplace and can have great impacts on agro-

ecosystems and biodiversity.

In 1998, Guyana experienced water rationing, cessation of logging

and river transport in some places and the loss of livestock due

to drought associated with El Niño conditions.

Rice farmers were

forced to leave 35 per cent of their rice fields uncultivated and

more than 1,500 Amerindian families in southern Guyana reliant

on agriculture were affected by this event.

Jamaica experienced

below normal rainfall from December 1996 into 1998

with the greatest damage occurring in the agricul-

tural sector. Losses in the sugar sector prompted the

Jamaican government to offer the sector a USD100

million assistance package late in 1997.

Later, between

October 1999 and March 2000, when rainfall was

less than 25 per cent of the average in some places,

Jamaican authorities reported crop losses of approxi-

mately USD6 million.

One of the islands making up

Grenada, Carriacou, experiences less rainfall than the

main island. It also accounts for 30 per cent of the

nation’s livestock production, and experienced losses

of 20 and 40 per cent due to drought in 1984 and 1992

respectively.

Flooding is the most frequent natural disaster in the

Caribbean. Flooding in Guyana from late December

2004 to February 2005 severely affected 37 per cent of

the population, was blamed for the deaths of 34 people

and caused about USD465 million in total damage.

Of this, approximately USD250 million was lost in

the housing sector and USD55 million in damage to

the agricultural sector, which in 2004 accounted for

35.4 per cent of Guyana’s gross domestic product.

The following year, a similar, but smaller-scale event

resulted in losses to the agriculture sector of USD22.5

million in the major affected regions.

In January

2001, flooding associated with the passage of a cold

front resulted in losses of more than USD3 million in

Jamaica.

It has also been reported that in Trinidad,

estimated damage from flood events in 1993, 2002 and

2006 was USD580,000, USD3.3 million and USD2.5

million respectively.

With limited peer-reviewed information for the

Caribbean, the Intergovernmental Panel on Climate

Change projects in its Fourth Assessment Report

that there is a 90 per cent chance that tempera-

tures will rise across the Caribbean. An average

of 21 models suggests the increase in the annual

temperature could be in the range of 2

C to 2.5

There is, however, greater uncertainty in the rainfall

projections for the region, particularly in the Lesser

Antilles. Nonetheless, it is projected with 66 per

cent certainty that rainfall is likely to decrease in the

bserving

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