IUCN assessment warns 96 percent of shallow-water coral reefs at high risk of collapse

A global assessment by the International Union for Conservation of Nature warns that 96 percent of shallow-water coral reefs face ecological collapse by 2075 due to heat stress from climate change.

The first systematic survey of 127 tropical and subtropical coral reef systems, presented at the United Nations COP17 biodiversity summit in Armenia, classified nearly all shallow reefs as critically endangered. While 24 percent of these ecosystems are currently in this high-risk category, the figure jumps to 96 percent when scientists include projected heat stress from global warming. Researchers identified rising temperatures as the most consistent threat to these habitats, which currently cover roughly 188,000 square kilometers.

According to the IUCN and Deutsche Welle, the assessment utilized a climate scenario where global temperatures rise by approximately 2.7 degrees Celsius by 2100. This level of warming leads to repeated bleaching events, where corals expel the algae that provide their food. Conservation news reported that one ecosystem, the Western Galapagos Islands, has already collapsed. Other regions at extreme risk include the Great Barrier Reef, the Red Sea, and the Coral Triangle in Southeast Asia.

Beyond climate change, the report cites overfishing of species like parrotfish and grouper as a significant factor that hinders reef recovery. Deutsche Welle noted that coastal development, pollution, and increasingly severe storms further degrade these environments. If hard corals disappear, they are often replaced by algae and rubble, creating a less biodiverse ecosystem that cannot support the same variety of fish, sea turtles, and sharks.

Despite the dire findings, experts told The Guardian and Conservation news that total collapse is not yet inevitable. Dr. Mishal Gudka, the scientific lead for the assessment, called the report a wake-up call, emphasizing that reefs could survive if there are rapid cuts to fossil fuel emissions alongside local conservation efforts. Marcos Valderrábano of the IUCN added that reducing pollution and protecting remaining corals are essential steps to help these ecosystems recover from heatwaves.

Background

Coral reefs cover less than 1 percent of the ocean floor but support roughly 25 percent of all marine life. Over the last 50 years, these ecosystems have faced steady declines due to human activity, impacting food security and livelihoods for hundreds of millions of people who rely on them.