Hexbyte Glen Cove Corals doomed even if global climate goals met: study

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An average increase of 1.5 degrees Celsius above pre-industrial levels would see more than 99 percent of the world’s coral reefs unable to recover from ever more frequent marine heat waves.

Coral reefs that anchor a quarter of marine wildlife and the livelihoods of more than half-a-billion people will most likely be wiped out even if global warming is capped within Paris climate goals, researchers said Tuesday.

An average increase of 1.5 degrees Celsius above pre-industrial levels would see more than 99 percent of the world’s coral reefs unable to recover from ever more frequent marine heat waves, they reported in the journal PLOS Climate.

At two degrees of warming, mortality will be 100 percent according to the study, which used a new generation of climate models with an unprecedented resolution of one square kilometre.

“The stark reality is that there is no safe limit of global warming for coral reefs,” lead author Adele Dixon, a researcher at the University of Leeds’ School of Biology, told AFP.

“1.5C is still too much warming for the ecosystems on the frontline of climate change.”

The 2015 Paris Agreement enjoins nearly 200 nations to keep global heating “well below” 2C (36 degrees Fahrenheit).

But with more deadly storms, floods, heatwaves and droughts after only 1.1C of warming to date, the world has embraced the treaty’s more ambitious aspirational goal of a 1.5C limit.

A landmark report in August by the UN’s IPCC climate science panel said global temperatures could hit the 1.5C threshold as soon as 2030.

In 2018, the IPCC predicted that 70 to 90 percent of corals would be lost at the 1.5C threshold, and 99 percent if temperatures rose another half-a-degree.

The new findings suggest those grim forecasts were in fact unduly optimistic.

Marine heatwaves

“Our work shows that corals worldwide will be even more at risk from climate change than we thought,” Dixon said.

How coral bleaching happens.

The problem is marine heatwaves and the time it takes for living coral to recover from them, a healing period known as “thermal refugia”.

Coral communities usually need at least 10 years to bounce back, and that’s assuming “all other factors”—no pollution or dynamite fishing, for example—”are optimal”, said co-author Maria Beger, also at Leeds.

But increased warming is reducing the length of thermal refugia beyond the ability of corals to adapt.

“We project that more than 99 percent of coral reefs will be exposed at 1.5C to intolerable thermal stress, and 100 percent of coral reefs at 2C,” Beger told AFP.

Australia’s Great Barrier Reef, the largest coral system in the world, has seen five mass bleaching events in the last 25 years.

An unpublished study obtained by AFP, written by experts at the US National Oceanic and Atmospheric Administration’s Coral Reef Watch unit, says the Great Barrier Reef was in the grips of a record-breaking heat spell yet again in November and December.

Oceans absorb about 93 percent of the excess heat from greenhouse gas emissions, shielding land surfaces but generating huge, long-lasting marine heatwaves that are already pushing many species of corals past their limits of tolerance.

A single so-called bleaching event in 1998 caused by warming waters 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.

Besides supporting marine ecosystems, they also provide protein, jobs and protection from storms and shoreline erosion for hundreds of millions of people worldwide.

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

Global warming, with the help of pollution, wiped out 14 percent of the world’s coral reefs from 2009 to 2018, leaving graveyards of bleached skeletons where vibrant ecosystems once thrived, recent research has shown.

Loss of coral during that period varied by region, ranging from five percent in East Asia to 95 percent in the eastern tropical Pacific.



More information:
Future loss of local-scale thermal refugia in coral reef ecosystems, PLoS Climate, DOI: 10.1371/journal.pclm.0000004

© 2022 AFP

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Corals doomed even if global climate goals met: study (2022, February 6)
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Hexbyte Glen Cove New project to track endangered species coming back from brink thumbnail

Hexbyte Glen Cove New project to track endangered species coming back from brink

Hexbyte Glen Cove

The Green status suggests the California condor would have gone extinct in the wild without conservation.

After decades of recording alarming declines in animals and plants, conservation experts have taken a more proactive approach, with a new “Green Status” launched on Saturday, billed as the first global measurement for tracking species recovery.

Since 1964, the International Union for the Conservation of Nature (IUCN) has assessed some 138,000 species for its Red List of Threatened Species, a powerful tool to highlight the plight of wildlife facing extinction.

Some 28 percent are currently at risk of vanishing forever.

Its new Green Status will act as a companion to this survival watchlist, looking at the extent to which species are depleted or restored compared to their historical population levels.

The initiative aims “to measure species recoveries in a standardised way, which has never been done before”, Green Status co-chair Molly Grace told a news conference Saturday during the IUCN congress in Marseille.

But it also looks to “incentivise action”, with evaluations of how well past preservation efforts have worked, as well as projections for how effective future ones will be.

It was born of a realisation that “preventing extinction alone is not enough”, said Grace, a professor at the University of Oxford.

Beyond the first step of stopping a species from disappearing entirely, “once it’s out of danger, what does recovery look like?”

Efforts to halt extensive declines in numbers and diversity of animals and plants have largely failed to stop losses in the face of rampant habitat destruction, overexploitation and .

In 2019 the UN’s biodiversity experts warned that a million species were nearing extinction.

The burrowing bettong now exists in just 5 percent of its indigenous range.

‘Invisible’ work

The Green of over 180 species have been assessed so far, although the IUCN hopes to one day to match the tens of thousands on the Red List.

They are classified on a sliding scale: from “fully recovered” through “slightly depleted”, “moderately depleted”, “largely depleted” and “critically depleted”.

When all else has failed, the final listing is “extinct in the wild”.

While these categories mirror the Red List rankings, “they’re not simply a Red List in reverse”, said Grace.

She gave the example of a pocket-sized Australian marsupial, the burrowing bettong, whose numbers have plummeted and which now exists in just five percent of its indigenous range.

Successful conservation efforts have seen populations stabilise, with a Red List rating improving from endangered to near threatened in recent decades.

But Grace said the Green Status assessment underscores that the species is not out of the woods, with a listing of critically depleted that suggests: “We have a long way to go before we recover this species.”

The listing also incorporates an assessment of what would have happened if nothing had been done to save a given species.

The California condor, for example, has been classified as critically endangered for three decades, despite major investment in its preservation.

“Some people might think: ‘We’ve been trying to conserve the condor for 30 years, its red list status has been critically endangered for all those 30 years, what is conservation actually doing for this ?'” said Grace.

But she said her team’s evaluation of what would have happened without these protection efforts found that it would have gone extinct in the wild.

“What this does is it makes the invisible work of conservation visible. And this is hopefully going to be really powerful in incentivising and justifying the amazing work that conservationists do,” said Grace.



© 2021 AFP

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New project to track endangered species coming back from brink (2021, September 4)
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