About 14% of the world’s coral has been lost in less than a decade, a study on the health of coral reefs has found.
In the largest ever analysis of the health of coral reefs, scientists found that between 2009 and 2018, the world lost approximately 11,700 km² of coral – the equivalent of more than all living corals in Australia.
Meanwhile, the report, released Tuesday by the Global Coral Reef Monitoring Network, found that reef algae, which thrives when coral is under stress, climbed 20% between 2010 and 2019.
The report presents data collected by more than 300 scientists from 73 countries over 40 years, including 2 million individual observations.
The study, which analyzed 10 regions with coral reefs, found that coral bleaching events caused by rising sea surface temperatures were the main driver of coral loss. He found that such a mass bleaching event in 1998 resulted in the loss of 8% of the world’s corals, or about 6,500 km², with the greatest impact seen in the Indian Ocean, Japan and the Caribbean.
Experts said the decline of the past decade occurred against a backdrop of continuously rising sea surface temperatures. They called for urgent action and said climate degradation was the greatest threat to the world. the reefs of the world.
However, the report also offers signs of hope. Scientists have found that despite the pressures on the reefs, many remain resilient and have the potential to recover under the right conditions, especially if immediate action is taken to stop global warming.
“The news is mixed,” said Paul Hardisty, managing director of the Australian Institute of Marine Science. “There are clearly troubling trends in coral loss, and we can expect them to continue as warming continues. Despite this, some reefs have shown a remarkable ability to rebound, which gives hope for the future recovery of degraded reefs.
“A clear message from the study is that climate change is the greatest threat to the world’s reefs, and we must all do our part in urgently reducing global greenhouse gas emissions and alleviating the pressures. local. “
Coral reefs cover only 0.2% of the ocean floor, but are home to at least a quarter of all marine species. They provide vital habitat, as well as an important source of protein, medicine, food and employment, as well as protection from storms and erosion for millions of people.
While over the past decade mass bleaching events have been so frequent that corals have not had time to recover, scientists have noticed some recovery in 2019 when reefs recovered 2%. of coral cover. This, they say, gives rise to hope that if the factors putting pressure on reef ecosystems diminish, it is possible to recover within a decade to pre-1998 levels.
Other pressures on coral come from overfishing, unsustainable coastal development and declining water quality.
The latest findings follow a separate analysis last month that found global coverage of coral reefs had halved since the 1950s.