San Juan, Nov 1 (IANS/EFE): The small islands of the Caribbean will be the first territories in the region to suffer the effects of rising sea levels due to climate change, threatening their tourism industries and, eventually, their very existence.

That was the warning Achim Steiner, executive director of the UN Environment Programme (UNEP, issued Friday in an interview with Efe news agency.

Sea-level rise will have an "immediate impact in economic terms" on the Caribbean Small Island Developing States (SIDS), he said by telephone from Nairobi ahead of Sunday's release of the Fifth Assessment Report from the Intergovernmental Panel on Climate Change.

In the case of the Caribbean SIDS, their tourism infrastructure is "99 percent along the coastline", Steiner pointed out.

"Many small island nations are in a far more exposed situation simply because their territory is sometimes only two, three, four metres above sea level, therefore their very existence is being threatened," he said.

"The changes also in, for instance, coral reefs and mangroves that are natural barriers and help strengthen the resilience of these countries, if coral reefs are dying then clearly countries become more vulnerable," the UNEP director said.

He also cited the impact of more intense hurricanes and other extreme weather events on countries whose economies cannot bear the cost of reconstruction.

On a more hopeful note, he praised proactive efforts by some Caribbean countries such as Barbados, where "energy efficiency efforts and renewable deployment are now on the agenda of investment and national development planning".

The efforts of the Barbadian government were one reason the UN decided to mark 2014 World Environment Day in Barbados.