IUCN warns 96% of world's coral reefs now critically endangered

The International Union for Conservation of Nature (IUCN) has classified 96 percent of the world's coral reef systems as "critically endangered", its highest risk category, warning that almost all shallow-water reefs face an extremely high risk of collapse within the next 50 years and that total extinction is possible by 2075.

The assessment was released on Thursday and presented at a news conference at the UN's COP17 biodiversity summit in Yerevan, Armenia.

"The future threat of climate change is looming and severe, and that poses a very high risk to the survival of these ecosystems," said Mishal Gudka, scientific lead of the IUCN Red List of Coral Reef Ecosystems assessment.

Why reefs are at risk

Corals are heat-sensitive and particularly vulnerable to human-driven climate change, which is warming the world's oceans and increasing how often and how severely bleaching events occur. When a reef collapses, hard corals disappear and are replaced by algae, rubble and sponges, and the reef can no longer support a diverse ecosystem that ranges from tiny invertebrates to reef fish such as grouper.

Gudka said the emergence this year of a "super" El Nino, the natural warming phenomenon, also presents a risk to corals.

The IUCN used the "middle-of-the-road" scenario from the UN's panel of climate experts, which projects global temperatures rising 2.7C above pre-industrial levels by 2100. Its analysis examined 127 tropical and subtropical coral systems covering 188,362 square kilometres.

Which reefs are affected

Most of the world's famous reef systems are critically endangered, according to the assessment, including the Great Barrier Reef in Australia, the Coral Triangle in the Western Pacific Ocean and Southeast Asia, the Mesoamerican Barrier Reef System and the Red Sea coral reefs.

Often described as "rainforests of the sea", reefs hold some of the world's richest biodiversity, supporting a quarter of marine species as well as coastal communities and businesses. They are important sources of seafood and tourism and frequently act as buffers against coastal erosion and storms.

The warning follows other recent findings. A week ago, an IUCN study in the journal Nature found that nearly 44 percent of reef-building coral species face an elevated risk of extinction due to climate change. A year ago, a survey found that harmful bleaching of the world's coral had grown to include 84 percent of the ocean's reefs, the most intense of its kind in recorded history.

Despite its warning, the IUCN said coral reefs in most parts of the world "are not yet lost".

"Coral reefs have shown a remarkable ability to bounce back from devastating bleaching events," Gudka said. "Pockets of surviving, resilient coral reefs can still remain in the future, so we must do everything within our reach to set them up for success."

Source: Al Jazeera.