Coral reefs are declining rapidly almost everywhere in the world

Its area is moderate, but its gravitational pull is enormous: coral does not occupy more than 0.2% of sea level, but its rocks contribute to their enormous biodiversity and at least 25% of marine species. However, his health is very worrying. Worldwide, between 2009 and 2018, 14% of coral reefs died, or nearly 11,700 square kilometers, more than anyone living on Australia’s coral reefs. Decline is seen almost everywhere on the planet.

This is the sad observation of a very detailed analysis dedicated to this very special race. Released on Tuesday, October 5, it is the result of the work of 300 researchers participating in the International Coral Initiative (ICRI) International Monitoring Network, and it is based on more than 2 million data collected over forty years (1978 to 2019) on more than 12,000 sites in 73 countries.

These detailed analyzes show that heat waves are currently at major risk because they generate frequent bleaching events. Between the two stress episodes the rocks no longer have time to regenerate themselves. These results are echoed by the IPCC (Government Panel on Climate Change), which, in its 2019 Special Report on the Ocean and Cryosphere, estimates that 70 ° to 90% of coral will disappear with a 1.5 ° C temperature increase. With an additional 2 C, almost all, 99% will be destroyed.

Before and after 1998

Serge Airways, CNRS’s research director, did not share this poor prognosis. “It is fair to say that 80% or 90% of corals – 1,200 species – will evolve. They will continue to perform some ecosystem functions, but it will no longer have the same diversity of shapes and colors.”, One of the co-authors of the ICRI report assures this crypto expert.

According to this document, it exists before and after 1998. In that year, Marked by the most intense El Nino climate events ever recorded, a The heat wave caused severe flooding, especially in the Indian Ocean, Japan and the Caribbean. About 8% of corals die within a few months.

As this bleach occurs – a sign of a breakdown in the symbiosis between the animal and the juxtaposition, the photosynthetic unicellular algae and energy that stay in its tissues – gradually absorb the algae. “The balance of the environment is disturbed when algae mats 5 to 10 cm high are formed in the coral substrate, which loses the organism’s light.”, Refers to Serge flights.

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