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Scientists say coral bleaching occurs too often for reefs recover.

Scientists said that coral reefs experience bleaching so often, they don't have the time to recover before another one strikes. The global coral cover is now below "normal" levels and faces irreversible decline.

Coral reefs are vital to the world, supporting a quarter all marine life. They also make coasts more resilient, and provide food and livelihoods to millions. But their survival is threatened by pollution, and by mass bleaching due to rising ocean temperatures.

In a report that was based on data collected over 40 years from more than 37,000 reef sites in 120 countries, the Global Coral Reef Monitoring Network, a group?of scientists?, said that there is now a five- or six-year gap between bleaching.

Manuel Gonzalez Rivero, the lead author of the article, said: "They have a capacity to recover if we give them enough space." But we haven't yet seen that amount of time allowed. The frequency of these bleaching events have almost doubled.

Corals can bleach when they expel the colorful algae that live in their tissues. Corals become pale, and more susceptible to disease and starvation without the algae. A bleached coral is not dead but the ocean temperature must be cooled if there is any hope for recovery.

The release of the report coincides with the gathering of Pacific leaders in Palau, Monday, for their annual Pacific Islands Forum. Leaders are expected to coordinate their climate priorities ahead of the COP31 conference in December.

The findings show that the climate change has a negative impact on coral reef ecosystems. Hard coral cover is down 9.5% from the historical average between 2020 and 2024.

Gonzalez Rivero stated that coral cover had been relatively constant for 40 years around the globe. Since 2010, there has been an extremely steep change.

STAIRCASE OF DECLINE

Scientists have recorded three mass bleaching events since 2010.

Reefs recover quickly when temperatures drop. Reefs recovered?6% of their coral cover between 2017 and 2019, nearly compensating for the 6.6% that was lost during the 2016 bleaching.

The most recent bleaching of 2023 affected 77% of coral reefs around the world, as part of what Gonzalez?Rivero called a "staircase decline".

He said that with El Nino intensifying weather patterns and ocean surface temperature reaching a record high of 21 degrees Celsius (69.98 deg F) on August 22, a second bleaching event may strike the world's coral reefs this year.

The temperatures make it very likely.

The report stated that rapid cuts in emissions and management of local threats -- such as unsustainable fishing or excessive coastal development -- can limit further losses.

David Obura is the chair of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. He said: "We need to act now to stop this decline and invest into solutions that reduce pressures and increase resilience."

Delay in action can lead to irreversible loss.

(source: Reuters)