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Ghostly coral bleachings haunt the world's reefs

By Michael PerryFri Mar 17, 8:10 AM ET

When marine scientist Ray Berkelmans went diving at Australia's Great Barrier Reef earlier this year, what he discovered shocked him -- a graveyard of coral stretching as far as he could see.

"It's a white desert out there," Berkelmans told Reuters in early March after returning from a dive to survey bleaching -- signs of a mass death of corals caused by a sudden rise in ocean temperatures -- around the Keppel Islands off Queensland.

Australia has just experienced its warmest year on record and abnormally high sea temperatures during summer have caused massive coral bleaching in the Keppels. Sea temperatures touched 84 Fahrenheit, the upper limit for coral.

High temperatures are also a condition for the formation of hurricanes, such as Katrina which hit New Orleans in 2005.

"My estimate is in the vicinity of 95 to 98 percent of the coral is bleached in the Keppels," said Berkelmans from the Australian Institute of Marine Science.

Marine scientists say another global bleaching episode cannot be ruled out, citing major bleaching in the Caribbean in the 2005 northern hemisphere summer, which coincided with one of the 20 warmest years on record in the United States.

"In 2002, it would appear the Great Barrier Reef went first and then the global bleaching followed six to 12 months later. Is it the same this time around? No," said Berkelmans.

"The Caribbean beat us to it. We seem to be riding on the back of that event. We don't know what is ahead in six months for the Indian Ocean reefs as they head into their summer."

"This might be part of a global pattern where the warm waters continue to get warmer."

Other threats to coral reefs -- vast ecosystems often called the nurseries of the seas -- include pollution, over-fishing, coastal development and diseases.

CAN CORAL RECOVER?

Corals are vital as spawning grounds for many species of fish, help prevent coastal erosion and also draw tourists.

Bleaching is due to higher than average water temperatures, triggered mainly by global warming, scientists say. Higher temperatures force corals to expel algae living in coral polyps which provide food and color, leaving white calcium skeletons. Coral dies in about a month if the waters do not cool.

Berkelmans said the Keppels had previously bounced back from bleaching once the waters had cooled. But if temperatures remained abnormally high then that would be much more difficult.

Many scientists say global temperatures are rising because fossil fuel emissions from cars, industry and other sources are trapping the earth's heat. Experts worry some coral reefs could be wiped out by the end of the century.

Global warming could also damage corals by raising world sea levels by up to a meter by 2100. That could result in less light reaching deeper corals, threatening the important algae.

The Great Barrier Reef -- the world's largest living reef formation stretching 1,250 miles north to south along Australia's northeast coast -- was the first to experience what turned out to be global coral bleaching in 1998 and 2002.

The Keppels bleaching is as severe as those two events and scientists say the threat of widespread bleaching is moderate.

"Sea temperatures in all regions of the Great Barrier Reef are at levels capable of causing thermal stress to corals," said the Great Barrier Reef Marine Park Authority's February report.

The U.S. National Oceanic and Atmospheric Administration's Coral Reef Watch said the 2005 Caribbean bleaching centered on the U.S. Virgin Islands, but stretched from the Florida Keys to Tobago and Barbados in the south and Panama and Costa Rica.

Reef Watch said sea temperature stress levels in the Caribbean in 2005 were more than treble the levels that normally cause bleaching and almost double the levels that kill coral.

"Time will tell whether there was large-scale mortality or not," said Professor Robert Van Woesik from the Florida Institute of Technology in a statement issued by Australia's Queensland University. He said corals did have some ability to bounce back but that this was an unusually warm event.

DANGEROUS TERRITORY

Queensland University's Professor Ove Hoegh-Guldberg, head of a group of 100 scientists monitoring bleaching, said scientists were concerned about how close in time the two severe bleaching episodes were.

"The 2006 Great Barrier Reef event comes soon after the worst incidence of coral bleaching in the Caribbean in October 2005," said Hoegh-Guldberg who also went diving on the Keppels where he said damage was extensive.

"The traces suggest we are tracking the temperature profile of 2001-2002, which led to the worst incidence of coral bleaching ... for the Great Barrier Reef," he said.

In 2002, between 60 and 95 percent of the reefs that make up the Great Barrier Reef were bleached. Most corals survived but in some locations up to 90 percent were killed.

Hoegh-Guldberg said projections from 40 climate models suggested that oceans would warm by as much as three to four degrees Celsius in the next 100 years.

"We're starting to get into very dangerous territory where what we see perhaps this year will become the norm and of course extreme events will become more likely," he said.

"The climate is changing so quickly that coral reefs don't keep up ... the loss of that ecosystem would be tremendous."

Reuters

Global bleaching is very real and Belize should be concerned about this very immenent threat to our ecosystem. The reefs are in danger, lets plan something that will work..Just a Suggestion..

I was in the Maldives in '98, at the start of the warm episode there, and the water temperature was 93F. Bleaching was evident everywhere, but apparently temperatures did drop and the coral recovered. I'm a scientist by training though not practice and not a marine scientist, and I've read widely on global warming. No-one seems in any doubt that it is happening, but what is causing it and what the prognosis is are less clear. The Greenland ice sheet is moving and in effect melting much faster than has ever been measured before, but that doesn't mean that it is caused by human activities. The geological record is complex and interpretations of it vary widely, but what is clear is that we do not live in a world of gradual steady climate trends. Just like evolution, it may be that climate change moves lumpily, with little change for some time followed by a period of extreme change.

Because the whole of human recorded history is so short in geological terms, maybe 5-7000 years, we probably have a distorted view of normality. Even in that timescale, though, there have probably been major local changes in climate that occurred in areas for which human recorded history isn't even that old. In the time of the ancient Babylonians, followed by the Egyptians, it seems likely that much of the arid deserts which span the middle east were green and fertile. Certainly much of current Iraq was fertile, which is why people chose to live there. We are still in "the last" ice age, because we still have polar ice caps and a massive ice sheet covering Greenland. The geological record suggests that this will all melt, and with the growing understanding of geological "lumpiness" we see that this has in the past happened over a short period of time. Maybe what is now happening is a repeat of what is believed to have happened in aeons past. There have been a number of ice ages and what is happening now has happened before - we just weren't around to see it.

The melting of the Greenland ice cap will raise sea levels about 23 feet, and I imagine the ice caps will add to that. Certainly all low lying land in the world will be inundated and hundreds of millions of people displaced. Some countries will vanish altogether, such as the Maldives. Much of Belize will end up under water. There is little doubt that this is going to happen, the
only question is to what timescale. There are estimates that we could see much of the above within 20-50 years, but the point is that nobody knows, nor do we have any means of finding out.

Many scientists believe that global warming is not of human making, and any effect that humans have had is marginal at most. When you compare the emissions of say Mount St. Helens with mankinds entire production of greenhouse gases over a ten year period this is quite persuasive.

So I think that, sad as it is, the state of coral reefs is of trivial significance compared to what is coming. And if we accept that mankind has not caused global warming and is unable to prevent it (different points, but both widely believed to be true) then we should be concerning ourselves instead with how to survive it. It will be a global catastrophe that will will reduce the world human population drastically. Whether it actually kills people will depend on the timeframe, but I fear it will.

Already we see millions of people dying of famine in several parts of the world, and though social factors (wars, mismanagement, etc) have contributed, the fact remains that areas that used to produce ample food are now unable to do so. Just as the area that is now the Sahara was cultivated by humans thousands of years ago. Bad agricultural practices clearly accelerate local degradation, such as deforestation which allows topsoil erosion, but there will be underlying factors at work.

I don't see this as simply "doom and gloom", but I do see it as a major change in our physical environment that one way or another we will adapt to, just as we did in the past. Whether we use the tremendous capabilities that modern civilisation has equipped us with to alleviate the effects of this totally natural change depends on attitudes. I think that the belief that the problem is man-made and capable of man-made solution is short-sighted in the extreme and guaranteed to fail. We must accept the inevitability of what is happening and devote our efforts to understanding it, trying to predict its timing, and dealing with its effects. This
will involve wholesale movements of people from low lying land and from land that has ceased to be arable, and plans for the urgent cultivation of potentially arable land that is not currently used.

So, sad as coral bleaching and dying is, I just accept it as part of the natural order of things.

You really are George Bush, right? Or are you one of his minions?

Bravo Perdro 2 and well said but all you had to say was the last sentence- it said it all.
The audacity of man to think he could destroy the planet. When we are all just dust, Mother, will be here and shake off our existence like a passing fly!

Too bad you won't be around to live with the results. Your grandchildren will remember you for your brilliance,

And lets here your brilliance, let me guess....you
've stop using aerosal cans? That would be about on target!

The Left speaks, as usual no answers just blame and of course as we all know George Bush is causing the Polar Caps to melt and the oceans to warm,yada, yada, yada same ole tired BS go suck on an exhaust pipe

(not you Marty...Editor at SPD :rolleyes:

Excellent read pedro2. I wholeheartedly agree with all you've written here. Indeed global warming is not caused by human deeds...Bravo.
Is is very sad to see coral bleaching indeed it is a small part of inevitable, unstopable evolution. I think we an use this as an excuse that we all need to dive and snorkel as much as we can!