Rising sea levels could contaminate supplies of fresh water and changing climate patterns could result in less rain to supply reservoirs in the coming decades, scientists and officials caution at a recent conference in St. Lucia.

Experts are sounding a new alarm about the effects of climate change for parts of the Caribbean - the depletion of already strained drinking water supplies throughout much of the region.

"Inaction is not an option," said Lystra Fletcher-Paul, Caribbean land and water officer for the U.N. Food and Agriculture Organization. "The water resources will not be available."

Many Caribbean nations rely exclusively on underground water for their needs, a vulnerable source that would be hit hard by climate change effects, local non-profit environmental groups say.

Parts of the Caribbean have been experiencing an unusually dry spell that began last year.

In August 2012, some islands reported extremely dry weather, including Grenada and Anguilla. By July of this year, those conditions had spread to Trinidad, Antigua, St. Vincent and Barbados, according to the Caribbean Institute for Meteorology & Hydrology.

Intense rains have been reported in recent months in some Caribbean areas, but that doesn't mean an increase in fresh water supply, said Bernard Ettinoffe, president of the Caribbean Water and Sewerage Association Inc., a St. Lucia-based group that represents water utilities in the region.

Heavy rains mean there's not enough time for water to soak into the ground as it quickly runs off, he said. In addition, the cost of water treatment increases, and many islands instead shut their systems to prevent contamination.

Some of the possible solutions include limits on development, increased use of desalination plants and better management of existing water supplies, but all face challenges in a region where many governments carry heavy debts and have few new revenue streams.