Coral Reefs ‘Will Be Overwhelmed By Rising Oceans’

The Guardian - Robin McKie

Study finds fragile marine ecosystems cannot grow fast enough to keep pace with sea levels

Australia’s Great Barrier Reef is already suffering coral ‘bleaching’ from rising temperatures. Photograph: Greg Torda/EPA

Scientists have uncovered a new threat to the world’s endangered coral reefs.
They have found that most are incapable of growing quickly enough to compensate for rising sea levels triggered by global warming.
The study suggests that reefs – which are already suffering serious degradation because the world’s seas are warming and becoming more acidic – could also become overwhelmed by rising oceans.
The research – led by scientists at Exeter University and published in Nature this week – involved studying growth rates for more than 200 tropical western Atlantic and Indian Ocean reefs. It was found only 9% of these reefs had the ability to keep up with even the most optimistic rates of sea-level rises forecast by the Intergovernmental Panel on Climate Change.
“For many reefs across the Caribbean and Indian Ocean regions, where the study focused, rates of growth are slowing due to coral reef degradation,” said Professor Chris Perry, of Exeter University. “Meanwhile, rates of sea-level rise are increasing – and our results suggest reefs will be unable to keep up. As a result, water depths above most reefs will increase rapidly through this century.”
Sea levels rose by several inches over the past century and measurements indicate the speed of this increase is now rising significantly. Two key factors are involved: climate change is making ocean water warmer and so it expands. And as ice sheets and glaciers melt, they increase amounts of water in the oceans.
At the same time, reefs are being weakened by ocean warming and also by ocean acidification, triggered as more and more the seas absorb more and more carbon dioxide. These effects lead to bleaching events that kill off vast stretches of coral and limits their ability to grow.
“Our predictions, even under the best case scenarios, suggest that by 2100 the inundation of reefs will expose coastal communities to significant threats of shoreline change,” said co-author Prof Peter Mumby of Queensland University.
This point was backed by US marine scientist Ilsa Kuffner writing in a separate comment piece for Nature. “The implications of the study are dire. Many island nations and territories are set to quickly lose crucial natural resources.”

Links

• Saving The World’s Coral To Avert A Wipeout Of Irreversible Costs
• Losing Nemo? Wider Effects Of Mass Great Barrier Reef Bleaching Emerge
• World's Coral Reefs Face New Peril From Beneath Within Decades
• Global Warming’s Toll On Coral Reefs: As If They’re ‘Ravaged By War’
• Can Corals Survive Climate Change?
• Coral Bleaching: Researchers Struggle To Find Anywhere In Pacific Ocean Untouched
• Countries With Coral Reefs Must Do More On Climate Change – UNESCO
• 50 Reefs: World-First Global Plan Says Only 10 Pc Of Coral Reefs Can Be Saved From Extinction
• Enough PR Spin: We Need A Real Plan For The Reef That Includes Ditching Coal
• Great Barrier Reef: Most Coral Now Dead North Of Port Douglas Off Far North Queensland, Scientists Say
• NASA Begins Study Of Australia's Great Barrier Reef

It's Been 30 Years Since The First Alarm On Global Warming Was Sounded

Fairfax - Peter Hannam

After leading NASA climate scientist James Hansen told the US Congress 30 years ago this week global warming was already worsening heatwaves, many of his colleagues figured politicians would heed the warning.
"When I heard this news, I thought it was time somebody made such a clear message," said Stefan Rahmstorf, then a PhD student in New Zealand and now at Germany's Potsdam Institute for Climate Impact Research.

James Hansen, director of NASA's Goddard Institute for Space Studies in New York, warned the US Congress in 1988 that human-induced global warming was already underway and 'may have important implications other than for human comfort'. (This photo taken in 1989.) Photo: AP

To be sure, Hansen wasn't the first to detect a warming trend distinct from natural climate variability. Graeme Pearman, who would later head CSIRO's atmospheric unit for a decade, had been toiling for years to draw attention to climate change.
"There are issues here for all disciplines," Pearman said this week, explaining the rationale for organising a five-day summit in 1987 that drew biologists, economists and insurers together with physicists.
But it was Hansen's testimony - made on a sweltering summer's day during then the hottest year on record - that put climate change on the front page of newspapers.

How the New York Times covered the 1988 speech by James Hansen. Photo: NYT, via Yale Climate Connections

With "99 per cent confidence", the 0.4 degree spike in temperatures over the preceding three decades could be ascribed to increased levels of greenhouse gas emissions, he said, adding the trend would have "implications other than for creature comforts".
"30 years later, it's clear [the model] simulations were skillful," Gavin Schmidt, who succeeded Hansen as head of NASA's Goddard Institute for Space Studies in 2014, tells Fairfax Media. "The predictions were quite good."


NOAA: May 2018 marks the 401st consecutive month with temperatures, at least nominally, above the 20th century average for the globe.

What was not so accurate was the expectation that politicians would listen to scientists, and act.
By 1990, the first Intergovernmental Panel on Climate Change report was demanding strong measures to curb carbon pollution. "I thought we'd see nations acting and a decline in total emissions," Pearman said.
Instead, we've had about 0.5 degrees further warming since 1988 as emissions have climbed, Rahmstorf said. Political leaders have attended dozens of United Nations conferences - where "they are deeply convinced we have to stop global warming very quickly" - only to drop the issue as a priority as soon as they return home.
"All their goals in life, as politicians, are under threat if we don't get global warming under control," he said.

Diminishing Arctic ice: researchers look out from the Finnish icebreaker MSV Nordica as the sun sets over sea ice in the Victoria Strait along the Northwest Passage in the Canadian Arctic Archipelago in July 2017. Photo: David Goldman/AP

Few weeks go by without peer-reviewed research detailing significant impacts of climate change or projections of the damage to come.
Heatwaves are among the clearest signals, with record-warm months now five times more likely than without the background warming, Rahmstorf says.
With half of the corals killed in the Great Barrier Reef's back-to-back bleaching over two summers, "it should be in the heart of every Australian to stop global warming," he said.
Up north, summer Arctic ice - important for reflecting solar radiation back to space - has lost three-quarters of its volume and half its area, Rahmstorf, an oceanographer, says.
Meanwhile, research out this month showing Antarctic ice sheets are melting at an increasing rate - pouring 200 billion tonnes of ice into the ocean annually - was "extremely concerning", NASA's Schmidt says.  The results "astonished me", he says. "It's clear things are changing very rapidly."


Antarctic Ice Mass

One effect of melting ice is that sea level rises are accelerating - although most of the increase so far is caused by thermal expansion as oceans absorb the bulk of extra heat being trapped by greenhouse gases.

Rising seas: People sit in a flooded St. Mark's Square in Venice, Italy, as high tides inundated the city in March 2018. Photo: Antonio Calanni/AP

Since the effect of gases already emitted take decades to play out, "it's likely we have 0.5 to 1 degree warming possibly, regardless of what we do with our emissions", Schmidt says.
Pearman's concerns include our lack of understanding on how our ecosystems will respond to rapid warming and other changes. South-western WA's rainfall has already dropped a third in recent decades, while eastern states' forests are becoming more bushfire prone, he says.
Rahmstorf worries extreme weather events are already causing "massive refugee movements" and the threat of governments "descending into chaos" are only going to increase.
Hansen himself has become increasingly frustrated most leaders have merely agreed "there's a problem". Promises like the Paris agreement to keep warming to well below 2 degrees "don’t mean much, it’s wishful thinking. It’s a hoax that governments have played on us since the 1990s”, he told The Guardian this week.

Smoke rises behind a destroyed apartment complex in December 2017 after a wildfire burnt through Ventura, California. Photo: Noah Berger/AP

But causes for optimism remain, such as emissions starting to fall in Europe and the US - but not Australia. Prices of renewable energy also continue to slide, dislodging fossil fuels, the main emissions source.
"We can turn this around," Schmidt says. "It's not hopeless."
Or as Rahmstorf puts it less encouragingly: "It's never too late to prevent even worse disasters".

Links

• Americans 'under siege' from climate disinformation – former NASA chief scientist
• NASA full of 'fear and anxiety' since Trump took office, ex-employee says
• It's 50 years since climate change was first seen. Now time is running out
• We have every reason to fear Trump’s pick to head Nasa
• Americans 'under siege' from climate disinformation – former Nasa chief scientist
• The Guardian view on climate change: good news – but not yet good enough
• US emissions set to miss 2025 target in Paris climate change deal, research finds
• Nasa scientist: climate change is a moral issue on a par with slavery
• Climate change: the world looks to Washington
• Climate change policies failing, Nasa scientist warns Obama