Grim Revelations on the World’s Coral Reefs Ecosystems


Aneesh Anand


A report released by the Global Coral Reef Monitoring Network (GCRMN), an operational network of the International Coral Reef Initiative, has made grim revelations about the perilous state of the world’s coral reefs ecosystems. The report reveals that between the years 2008 and 2019, almost 14% of the world’s total coral cover was lost due to the combined effect of coral bleaching and local or regional disturbances. Major episodes of coral decline correspond with elevated sea surface temperatures which remain a constant worry as the Earth continues to warm.


Coral reefs occur in more than 100 countries and territories. They cover only about 0.2% of the seafloor but support at least 25% of marine species. These crucial ecosystems underpin the safety, coastal protection and food and security of hundreds of millions of people. An estimated value of $2.7 trillion per year is generated by goods and services provided by coral reefs including the coral reefs tourism which is valued at $36 billion.


Coral reefs are also among the most vulnerable ecosystems on the planet to anthropogenic pressures, which includes – threats from climate change and ocean acidification, marine pollution, overfishing and destructive fishing practices.


Source : Fullbright Australia

It is crucial to maintain the integrity and resilience of coral reefs ecosystems for the well-being of tropical coastal communities worldwide which forms a critical part of the solution for achieving the SDGs under the 2030 Agenda for Sustainable Development.


The 6th edition of GCRMN’s Status of Coral Reefs of the World, the first since 2008, describes the status and trends of coral reefs worldwide. The report is based on global dataset spanning more than 40 years from 1978 to 2019 and has been compiled from raw monitoring data contributed by more than 300 network members.


Live hard cover, a globally accepted and universally used indicator of coral reef health, is a measure of the percentage of reef surface covered by live hard coral instead of sponges, algae, or other organisms and Algae cover is an indicator of stress on coral reefs. These were measured in a sufficiently consistent manner by different monitoring programs.


Coral reefs support high biodiversity along with sustaining reef-dependent communities; but when coral reefs are degraded and the algae becomes dominant, the services rendered by the coral reefs will also be lost.


The Key Findings of the Report


Large-scale coral bleaching events are believed to the be greatest disturbance to world’s coral reefs – the first major bleaching event in 1998 killed approximately 8% of the world’s coral reefs but between the years 2008 and 2019, there was a progressive loss amounting to almost 14% of the world’s total coral reefs. The increasing frequency and geographic extent of mass coral bleaching events have arrested the recovery of coral cover. The reports states that local and regional disturbances like coral diseases, tropical storms, destructive fishing activities and poor water quality resulting from land-based pollution have played an important role in the decline of coral reefs.


Elevated sea surface temperatures (SST) are the greatest disturbance to the world’s coral reefs – the report suggests that there is strong evidence which establishes the relationship between strong positive global SST anomalies and major episodes of coral decline.



Estimated global average hard coral cover with the sea surface temperature (SST) anomaly from 1977 to 2020 is superimposed in Figure 1. The impacts of the 1998 bleaching were observed in the Indian Ocean, Japan and the Caribbean with smaller impacts observed in the Red Sea, the northern Pacific in Hawaii, and Caroline Islands, and the southern Pacific in Samoa and New Caledonia. But after 2010, almost all regions exhibited a decline in the average hard coral cover – a suggestion that at the global level, strong positive SST anomalies correspond with major episodes of coral decline.


Reduction in local pressures on coral reefs is critical to ensure and maintain their resilience while the global threats posed by climate change are addressed – local pressures such as coastal development, land-based and marine pollution, unsustainable fishing activities and tropical storms must be investigated, and their impacts must be mitigated.


A Glimmer of Hope – increases in global coral cover between 2002 and 2009, and more recently in 2019, offers hope. A 2% recovery of the previously lost coral cover was observed in 2019. The coral reef in East Asia’s Coral Triangle region, which contains almost 30% of the world’s coral reefs, had more corals in 2019 than it did three decades ago. These reefs were less impacted by thermal disturbances. It is believed that high coral cover and diversity may confer a degree of natural resistance to elevated surface temperatures (SST).


The Way Forward!


It is almost given that sharp declines in coral cover corresponds with rapid increases in sea surface temperatures – which indicates their vulnerability to marine heatwaves. As the planet gets warmer, the frequency of marine heatwaves will most likely increase.


A collective, global action is crucial for the future of coral reefs – reduction in global emissions is necessary for the future of coral reef ecosystems and the hundreds of millions of people who are dependent on them.


The report also shows that many of the world’s coral reefs are still resilient and have the capacity to bounce back. Protecting the coral reef is equivalent to protecting the ocean ecosystem. Governments and individuals can make a difference for their marine ecosystems in their home countries. Hawaii banned sunscreen, thought to threaten coral health, in 2018. Cutting down the usage of single-use plastics, which break down into microparticles, can help stop the influx of microplastic pollution.


With a little tinkering, easing of local pressures, proper interventions, and accurate, timely and collaborative coral reef monitoring, we can support coral reef conservation.



The author is a postgraduate in International Relations and Area Studies from the School of International Studies, Jawaharlal Nehru University. His research interest is located at the intersection of Climate, Politics and Policy. He derives great joy out of reading and running! He expresses his thoughts regularly through his blog indeliblyinked16.wordpress.com




51 views0 comments