No End In Sight For Global Coral Bleaching; Kiribati 1-5% Of Reef Survived; GBR - 93% Bleached

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From October of 2014 through June of 2016, the world was in the grips of a powerful El Nino. And throughout this event, the oceans spewed back some of the massive volume of heat they’ve been accumulating in their depths due to global warming. As a result, atmospheric and ocean surface temperatures hit new record highs. And during 2016, global surface temperatures will likely average 1.2 C hotter than 1880s levels. This amount of warming is as considerable as it is harmful.

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(A global coral bleaching event that began in 2014 continues. It is the longest coral bleaching event on record. But unless oceans somehow cool off, it won’t really end. With only a weak La Nina emerging following a strong El Nino and a record spike in global temperatures, there is some risk that this ongoing event will ebb and flare on a nearly indefinite basis. Continued fossil fuel burning, meanwhile, will continue to add heat to the global climate system — presenting worsening medium and long term bleaching pressure for corals. Image source: Coral Reef Watch.)

This new record spike in global surface temperatures set off the worst coral bleaching event ever recorded. Around the world, reef systems came under severe stress as sea surface and near surface temperatures exceeded 28-30 degrees Celsius. Among the hardest hit regions were the reefs of Kiribati. There, sea surface temperatures hit up to 31.4 C on an extended basis. Such hot waters are now expected to have wiped out all but 1 to 5 percent of Kiribati’s living corals. So, for all practical purposes, the reefs of that island republic have been wiped out.

Overall, the event was very wide ranging — impacting corals throughout the Pacific, Atlantic, and Indian Oceans as well as in the Persian Gulf, Mediterranean, and Red Sea. As an example, 95 percent of corals in US territories from Florida to the Gulf of Mexico, Caribbean, and Pacific experienced some level of bleaching.

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(A weak La Nina has probably already cooled ocean surfaces as much as they will be cooled during 2016 and 2017. But despite this cooling, ocean near-surface waters are still too hot for corals in many places. Relative, if mild, ocean surface warming should occur as ENSO is predicted to shift into neutral status. If coral bleaching is ongoing through La Nina, then it is unlikely to cease as the global ocean starts to warm again. Global sea surface temperature anomaly image source: Earth Nullschool.)

In Australia, the Great Barrier Reef (GBR) also saw its worst bleaching event on record. There, 93 percent of corals are reported to have experienced bleaching. Meanwhile, about 50 percent of corals have died in the northern section of the GBR. In the media, a controversy has raged over whether or not this event is the start of the great reef’s swansong. To be clear, the GBR was not killed off by the most recent large bleaching event. But it was dealt a very severe blow. With the world continuing to warm as fossil fuel burning remains ongoing, a similar blow could occur as soon as the next El Nino or the one after. And the story for many of the world’s remaining reefs could well be the same.

EDIT

https://robertscribbler.com/2016/11/22/why-the-global-coral-bleaching-event-that-began-in-2014-may-just-keep-going-and-going/

[OKIsItJustMe]

1. Marine disease likely to follow Great Barrier Reef coral bleaching

http://mediarelations.cornell.edu/2016/11/28/marine-disease-likely-to-follow-great-barrier-reef-coral-bleaching/

[font face=Serif][font size=5]Marine disease likely to follow Great Barrier Reef coral bleaching[/font]

November 28, 2016 By Melissa Osgood

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“Although the Great Barrier Reef was badly hit, the epicenter of this 2016 event is actually in the middle of the Indo-pacific, at Palmyra atoll and Kiribati where temperatures reached four degrees about the seasonal baseline for over a month. Over 90 percent of corals died on many of those reefs.

“This is the worst bleaching event of the northern great barrier reef. Mid and southern sections were also hit with a 2002 event that caused mass bleaching and outbreaks of infectious disease. We typically do see outbreaks of disease following the bleaching events, because of the double whammy of the corals being stressed and warm temperatures favor infectious microorganisms.

“Outside magazine published an article called ‘An Obituary for the Great Barrier Reef.’ The event was bad, but the central and southern regions of the Great Barrier Reef are quite healthy, so that article was over-stated. You don’t call a forest dead just because 50 percent of the trees are dead, but it is an extreme event.

“It is useful to realize this is the third straight year in a row of record-breaking temperature. Each year from 2014-2016 was successively the warmest year on record, assuming this year will once again break records and now be the warmest year on record.”

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[OKIsItJustMe]

2. Life and death following Great Barrier Reef bleaching

https://www.jcu.edu.au/news/releases/2016/november/bleaching

[font face=Serif]Tue, 29 Nov 2016

[font size=5]Life and death following Great Barrier Reef bleaching[/font]

[font size=4]Scientists have confirmed the largest die-off of corals ever recorded on Australia’s Great Barrier Reef.[/font]

[font size=3]The worst affected area, a 700 km swath of reefs in the northern region of the Great Barrier Reef has lost an average of 67% of its shallow-water corals in the past 8-9 months. Further south, over the vast central and southern regions of the Great Barrier Reef, the scientists were relieved to find a much lower death toll.

“Most of the losses in 2016 have occurred in the northern, most-pristine part of the Great Barrier Reef. This region escaped with minor damage in two earlier bleaching events in 1998 and 2002, but this time around it has been badly affected,” says Professor Terry Hughes, Director of the Australian Research Council (ARC) Centre of Excellence for Coral Reef Studies based at James Cook University, who undertook extensive aerial surveys at the height of the bleaching.

“The good news is the southern two-thirds of the Reef has escaped with minor damage. On average, 6% of bleached corals died in the central region in 2016, and only 1% in the south. The corals have now regained their vibrant colour, and these reefs are in good condition,” says Professor Andrew Baird, also from the ARC Centre, who led teams of divers to re-survey the reefs in October and November.

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“We found a large corridor of reefs that escaped the most severe damage along the eastern edge of the continental shelf in the far north of the Great Barrier Reef,” says Professor Hughes.

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