ECOSYSTEMS CRITICAL ECHO-BELLS : STUDENTS WORLD ESSAY.

NEARLY all of the world's shallow-water coral reefs, famous for their riot of color and life,  have now been classified as critically endangered by experts who assess ecosystem collapse.

Heat stress because of climate change is the overwhelming reason for the finding, it was announced recently by the  International Union for Conservation of Nature's Red List of Ecosystems.

It was the group's first global assessment of shallow-water reef ecosystems. The scientists grouped reefs into 127 regions based on the location and the unique species present.

They found that 96 percent were critically endangered, including those in Australia's  Great Barrier Reef, the Coral Triangle in the western Pacific, the Mesoamerican Barrier Reef System in the Caribbean and Florida reefs.

The classification means that they face an extremely high risk of collapse within 50 years.

Shallow-water reefs support around a quarter of ocean species at some point in their life cycle, scientists estimate. Hundreds of millions of people rely on those ecosystems for fish and coastal protection.

Scientists emphasized that the reefs are not yet lost. The finding is based on the current estimated trajectory of climate change. If countries do more to slow warming, the outcome for reefs could improve.

'' There's a small and narrowing window of opportunity here to prevent the worst outcomes if we act quickly,'' said Mishal Gudka, the assessment's scientific lead and a research fellow at the University of Melbourne.

Shallow-water reefs are sometimes called the rainforests of the sea because of their astounding biodiversity.

Recent years have brought a growing chorus of  alarm bells from scientists about the ability of coral reefs to withstand climate change.

Reef-building corals are tiny animals that create limestone structures, and host  photosynthesizing algae in their tissue.

The algae provide the coral reef with most of its nourishment. But under certain stressful  conditions, including too much heat, corals expel the algae in a process known as bleaching.

If the adverse conditions persist for too long, coral will starve and die.

!WOW! thanks The NYTs and Catrin Einhorn.