Credit: N. WU/SCIENCE FACTION/CORBIS

Belize's barrier-reef system (pictured) — the largest of its kind in the Northern Hemisphere — has been put on a danger list by the World Heritage Committee to encourage international support for its preservation.

The committee, part of the United Nations Educational, Scientific and Cultural Organization (UNESCO), included the reef because it is threatened by development and the cutting back of mangroves. It has been on the World Heritage List of naturally important sites since 1996.

Also placed on the danger list is the Los Katios National Park in Colombia, which is at risk from logging. UNESCO added a further two natural sites to its World Heritage List: the Wadden Sea wetlands belonging to Germany and the Netherlands, and the Dolomites mountain range in Italy.