Global warming is ‘devastating’ the Great Barrier Reef – ‘These kinds of temperatures in the future will become normal’

Desdemona Despair

By John Upton
28 April 2016

(Climate Central) – Warm ocean waters that sucked the color and vigor from sweeping stretches of the world’s greatest expanse of corals last month were driven by climate change, according to a new analysis by scientists, who are warning of worse impacts ahead.

Climate change made it 175 times more likely that the surface waters of the Coral Sea, which off the Queensland coastline is home to Australia’s Great Barrier Reef, would reach the record-breaking temperatures last month that bleached reefs, modeling analysis showed.

The scientists found March Coral Sea temperatures are likely to be 1.8°F (1°C) warmer now than before humans polluted the atmosphere. Temperatures recorded by the Australian government last month were slightly higher than that, in part because of a fierce El Niño.

“We’ve had evidence before” that “human-induced climate change is behind the increase in severity and frequency of bleaching events,” said David Kline, a Scripps Institution of Oceanography coral reef scientist who wasn’t involved with the new analysis. “But this is the smoking gun.”

The new findings suggest similar temperatures will become commonplace by the 2030s, potentially destroying the reef and the tourism and fishing industries that rely on it. The reef’s tourism sector employs 64,000 people.

“There may still be corals, but it’ll look like a very sad reef,” Kline said. “There will probably be a few weedy species that can handle these nasty conditions, but we’ll lose a lot of the biodiversity.”

The warm Coral Sea waters have fueled the worst mass coral bleaching ever recorded on the World Heritage-listed reefs, which are withering from warming and acidifying waters, coral-eating pests and agricultural pollution. […]

“Because this is happening now, we wanted to do this quickly and get it in the public sphere,” said Andrew King, one of two University of Melbourne researchers who worked on the analysis. University of Queensland and University of New South Wales researchers also contributed. “We will write up a paper after this.”

By the 2030s, the modeling showed this year’s coral bleaching temperatures could become average and after that they may start to seem cool.

“These kinds of temperatures in the future will become normal,” King said. “They’re high for the current period, but by the 2030s it’s going to be about average.” [more]

Climate Change is ‘Devastating’ The Great Barrier Reef

By Andrew King, David Karoly, Mitchell Black, Ove Hoegh-Guldberg, and Sarah Perkins-Kirkpatrick
28 April 2016

(The Conversation) – The worst bleaching event on record has affected corals across the Great Barrier Reef in the last few months. As of the end of March, a whopping 93% of the reef has experienced bleaching. This event has led scientists and high-profile figures such as Sir David Attenborough to call for urgent action to protect the reef from annihilation.

There is indisputable evidence that climate change is harming the reef. Yet, so far, no one has assessed how much climate change might be contributing to bleaching events such as the one we have just witnessed.

Unusually warm sea surface temperatures are strongly associated with bleaching. Because climate models can simulate these warm sea surface temperatures, we can investigate how climate change is altering extreme warm conditions across the region.

We examined the Coral Sea region (shown above) to look at how climate change is altering sea surface temperatures in an area that is experiencing recurring coral bleaching. This area has recorded a big increase in temperatures over the past century, with March 2016 being the warmest on record.

To find out how climate change is changing the likelihood of coral bleaching, we can look at how warming has affected the likelihood of extremely hot March sea temperature records. To do so, we use climate model simulations with and without human influences included.

If we see more very hot March months in simulations with a human influence, then we can say that climate change is having an effect, and we can attribute that change to the human impact on the climate.

This method is similar to analyses we have done for land regions, such as our investigations of recent Australian weather extremes.

We found that climate change has dramatically increased the likelihood of very hot March months like that of 2016 in the Coral Sea. We estimate that there is at least a 175 times increase in likelihood of hot March months because of the human influence on the climate. [more]

Great Barrier Reef bleaching would be almost impossible without climate change