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Global warming kills 14 percent of world’s corals in a decade: Survey

Oceans absorb more than 90 percent of excess heat from greenhouse gas emissions (File)

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Dynamite fishing and pollution – but mostly global warming – wiped out 14 percent of the world’s coral reefs from 2009 to 2018, according to the largest ever survey of coral health, the graveyards of bleached skeletons where vibrant ecosystems once thrived. Were.

More than 300 scientists from the Global Coral Reef Monitoring Network reported that the hardest hit were in South Asia and the Pacific, around the Arabian Peninsula and off the coast of Australia.

“Climate change is the biggest threat to the world’s reefs,” co-author Paul Hardisty, CEO of the Australian Institute of Marine Science, said in a statement.

Oceans absorb more than 90 percent of excess heat from greenhouse gas emissions, shielding land surfaces, but generating huge, long-lasting marine heatwaves that are pushing many species of coral beyond their tolerance limits. Huh.

In 1998 a so-called bleaching event caused by warm water wiped out eight percent of all corals.

Coral reefs cover only a tiny fraction – 0.2 percent – ​​of the ocean floor, but they are home to at least a quarter of all marine animals and plants.

In addition to strengthening marine ecosystems, they also provide protein, jobs, and protection from storms and shoreline erosion for hundreds of millions of people worldwide.

The report said the value of goods and services from coral reefs is about $2.7 trillion a year, which includes $36 billion in tourism.

Coral loss from 2009 to 2018 varied by region, ranging from five percent in East Asia to 95 percent in the eastern tropical Pacific.

‘Coral Triangle’

“Since 2009 we have lost more coral worldwide than all living coral in Australia,” said UNEP Executive Director Inger Andersen.

“We can reverse the damage, but we have to act now.”

The UN’s Climate Science Advisory Panel, the IPCC, projects with “high confidence” that global warming of 1.5 °C above pre-industrial levels will lead to the disappearance of 70 to 90 percent of all corals.

In a 2C world, less than one percent of global corals will survive.

Earth’s average surface temperature has already risen by 1.1C from that benchmark.

The report, titled “Status of Coral Reefs of the World: 2020”, found reasons for cautious optimism.

“Some rocks have shown a remarkable ability to bounce back, which offers some hope for future recovery of degraded reefs,” Hardisty said.

The “Coral Triangle” of East and Southeast Asia – which comprises about 30 percent of the world’s coral reefs – was less affected by warming waters over the past decade, and in some cases showed a recovery.

The authors said this resilience may be due to species unique to the region, potentially offering strategies to promote coral growth elsewhere.

Based on nearly two million data points from 73 countries and 12,000 sites spanning 40 years, the report is the sixth such global survey and the first since 2008.

To measure change over time, the researchers compared areas covered by healthy living hard coral with areas occupied by algae, a sign of coral distress.

The report was launched with support from UNEP and the International Coral Reef Initiative, a partnership of governments and research organizations focused on preserving coral reefs and related ecosystems.

(Except for the title, this story has not been edited by NB staff and is published from a syndicated feed.)

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