Great Barrier Reef suffers worst decline in history in 2024

Rebecca Wright/CNN

The Great Barrier Reef, one of the most iconic and biodiverse ecosystems on the planet, recorded in 2024 the largest annual drop in coral cover since monitoring began nearly 40 years ago. The warning came in a report released this week by the Australian Institute of Marine Science (AIMS), which attributes the historic loss mainly to rising sea temperatures driven by climate change.

Record decline across all regions

The damage was felt across the entire 2,300 km stretch of reef along Australia’s northeastern coast:

• Northern Region (Cape York to Cooktown): loss of 25%, falling from 39.8% to 30% coral cover.

• Central Region (Cooktown to Proserpine): drop of 14%, from 33.2% to 28.6%.

• Southern Region (Proserpine to Gladstone): decrease of nearly one-third, from 38.9% to 26.9%.

According to AIMS, the losses in the north and south represent the largest declines ever recorded since surveys began in 1986.

The invisible threat of heat

The main driver behind the destruction was mass bleaching — a phenomenon where corals expel the symbiotic algae that give them color and nutrients due to thermal stress. In 2024, the reef experienced its fifth major bleaching event since 2016. Record sea temperatures, combined with extreme weather events such as cyclones and floods, and outbreaks of crown-of-thorns starfish, worsened the damage.

Researcher Mike Emslie from AIMS warns that the reef is now in a phase of high volatility, alternating between periods of recovery and sudden declines in short spans of time. “This instability is a sign that the ecosystem is under increasing pressure,” he says.

A race against time

The situation is so critical that scientists and environmental advocates warn: the next Australian government may represent the last chance for the survival of the Great Barrier Reef. They stress that local protection efforts are not enough — urgent cuts to greenhouse gas emissions and a reassessment of fossil fuel expansion policies are essential.

Despite the severity of the crisis, experts highlight that there is still room for recovery. “The reef has proven it can regenerate, but the window is closing quickly,” Emslie emphasizes.