Planet: Released on the 5th of this month on the website of the United Nations Environment Program (UNEP), the report “State of the World’s Coral Reefs: 2020” is the largest analysis of the global health of coral reefs ever carried out. Produced by the Global Coral Reef Monitoring Network (GCRMN), the document reveals the worrying loss of 14% of the world’s coral reefs from 2009 to 2020.
The report was compiled from data collected by more than 300 scientists in more than two million observations carried out at approximately 12,000 sites in 73 countries, over 40 years. His main focus of observation was global coral mass bleaching events, observed with increasing frequency since 1998, and caused by rising sea surface temperatures.
In addition to warming caused by global climate change, other local pressures such as overfishing, unsustainable coastal development and loss of water quality put an unbearable stress on coral reefs. As a result, they lose their photosynthetic algae – the zooxanthellae – that live inside the polyps. Without algae, these organisms lose color, become sick from lack of nutrients, and can die.
Importance of coral reefs for the environment
Coral reefs are present in more than 100 countries and territories worldwide and, despite covering only 0.2% of the sea floor, they provide critical habitat for at least 25% of the planet’s marine species. It is estimated that hundreds of millions of people in the world depend on these organisms as a source of food, employment and natural protection against storms and erosion.
The GCRMN study revealed that between 2009 and 2018, the planet lost around 11,700 square kilometers of coral, which corresponds to Australia’s entire coral population. Looking forward, “there are clearly unsettling trends for coral loss, and we can expect them to continue as warming persists,” the report says.
The good news is that, despite all the stress, some recovery events were observed in 2019, with reefs regaining 2% of their coral cover. This indicates that not only are coral reefs resilient, but also that an eventual reduction in anthropogenic pressures on these ecosystems could result in their full recovery in just over a decade.
“But we have to act now,” says UNEP Executive Director Inger Andersen.