- Coral reefs harbour the highest biodiversity of any ecosystem globally and directly support over 500 million people worldwide, mostly in poor countries.
- They are among the most threatened ecosystems on Earth, largely due to unprecedented global warming and climate changes, combined with growing local pressures.
- Over the last three years, reefs around the world have suffered from mass coral bleaching events as a result of the increase in global surface temperature caused by anthropogenic greenhouse gas emissions.
- According to UNESCO, the coral reefs in all 29 reef-containing World Heritage sites would cease to exist by the end of this century if we continue to emit greenhouse gases under a business-as-usual scenario.
- Limiting global average temperature to well below 2°C above pre-industrial levels in line with the Paris Agreement provides the only chance for the survival of coral reefs globally.
Coral reefs harbour the highest biodiversity of any ecosystem globally. Despite covering less than 0.1% of the ocean floor, reefs host more than one quarter of all marine fish species, in addition to many other marine animals. Additionally, reefs provide a wide variety of ecosystem services such as subsistence food, protection from flooding and sustaining the fishing and tourism industries. Their disappearance will therefore have economic, social and health consequences.
Photo: The IUCN Red List Index of species survival 1980-2012, showing corals species are deteriorating the fastest. A RLI value of 1.0 means that all species are not expected to become extinct in the near future. An RLI value of 0 indicates that all species have gone extinct. © IUCN 2015
Coral reefs are estimated to directly support over 500 million people worldwide, who rely on them for daily subsistence, mostly in poor countries. A 2014 assessmentpublished in the journal Global Environmental Change estimated the social, cultural and economic value of coral reefs at US$1 trillion. A 2015 study by WWF projects that the climate-related loss of reef ecosystem services will cost US$500 billion per year or more by 2100.
Coral reefs are also key indicators of global ecosystem health. They serve as an early warning sign of what may happen to other less sensitive systems, such as river deltas, if climate change is not urgently addressed. Once the tipping point for the survival of coral reefs is passed, the deterioration of other systems may cascade more quickly and irreversibly.
Photo: Tropical fish and coral reefs around the Fakarava atoll in French Polynesia. IUCN Photo Library / © Catherine Gras