Posted on 08/12/2003 8:22:20 AM PDT by bedolido
Sydney - Australia's Great Barrier Reef - the world's largest chain of living coral - could be devastated by global warming in the next 50 years unless drastic action was taken, a report said on Monday.
The Australian Institute of Marine Science and other agencies warned that without tough restrictions on greenhouse gas emissions, sea temperatures could rise to a level that would bleach and kill vast tracts of coral.
"The appearance of coral reefs and thus their amenity for tourism may be seriously compromised, and their productivity and biodiversity decimated," the report said.
Coral bleaching - when colourful reefs turn white - occurs when the water temperature gets so high that it kills the algae which populate and build the corals. It can occur if the water temperature rises by as little as one degree above the monthly summer average.
The reef is also threatened by overfishing and pollution Water temperatures in the reef vary between 22°C in winter and 29°C in summer.
The report said climate change could raise ocean surface temperatures by up to 4,5°C. Even with low greenhouse gas emissions, the ocean surface was expected to warm by 1,5°C, it said.
The report did not say what current bleaching levels were, although it is a naturally occurring problem.
The Great Barrier Reef spans an area of almost 350 000 square kilometres along Australia's north-east coast in Queensland.
State premier Peter Beattie said the news had steeled his resolve to protect the reef.
"Climate change is threatening the Great Barrier Reef, which earns more than A$2-billion (almost R10-billion) a year, supports industries such as tourism and fishing and may hold the keys to prevention and cure of a range of illnesses," Beattie said.
The reef is also threatened by overfishing and pollution. - Sapa-AP
They don't give a flying flip about the reef. It's the "dratsic action" they crave.
I've GROWN living corrals before, and they're not affected by small, gradual changes in temperature, salinity, or current. The temp and salinity can drift above or below the ideal range of 73-78f and 1.020-1.023sg for short periods of time with no detrimental effect.
They also are quite tolerant of lighting changes due to cloud cover, or tidal changes in the depth of the water, which filters out vast amounts of light.
Let me guess what their "drastic steps" are: Eliminate all fossil-fuel engines on the planet tomorrow, shut down all coal and nuclear powerplants, and stop[ farmers from irrigating their fields. Yep, that ought to fix everything.
--Boris
That's the real cause. Excessive fertilizer runoff.
Of course, God had other plans and that seems to really piss them off.
What about extended periods of time? Do you know why there was a bleaching event last year, and not during the El Nino of 1998, on the Great Barrier Reef? I do.
They also are quite tolerant of lighting changes due to cloud cover, or tidal changes in the depth of the water, which filters out vast amounts of light.
Light tolerance and requirements are species-specific. Why do you think nearly all of the elkhorn coral in the Florida Keys has died off? Mainly because of increased turbidity due to more nutrients and runoff. Elkhorn is a shallow-water coral that needs lots of light.
While there is no easy solution, and currently excess nutrients are a much bigger threat to coral reefs than rising atmospheric CO2, there is a lot more to know about coral and coral reefs than what you can learn by raising them in an aquarium.
There are a couple of diseases affecting corals right now (notably "black-band" disease) which might be related to dust-borne pathogens, but this is not related to coral bleaching events.
That and raw sewage, and poorly-treated wastewater, which can cause coral die-off either due to sunlight restriction or actual disease. But it doesn't cause bleaching; high water temperatures cause coral bleaching. (And the corals recover if the water temperature cools off.)
You can have zero global warming and still have El Nino events that may cause high water temperatures on the Great Barrier Reef.
The article admits that the normal temperature range was not broken, just that it was warmer than usual for that time.
"Do you know why there was a bleaching event last year, and not during the El Nino of 1998, on the Great Barrier Reef? I do."
Then I'm sure you realise this article is nothing but complete BS.
"While there is no easy solution, and currently excess nutrients are a much bigger threat to coral reefs than rising atmospheric CO2...."
Ah-HA! See, you do know that blaming "Global Warming" on corral reef problems is unfounded, eco-extremist, scare-tactic "science." The real truth is this planet is one day going to be a cold, dead rock, and there's NOTHING man can do to change it in any significant way. Fragile eco-systems like corral reefs will always be the first casualty of a naturally occuring metamorphisis of this planet.
Exactly. Warmer-than-normal temps put coral under stress, and they bleach in response. They will and do recover when water temperature cools off.
Regarding the bleaching of last year, and not 1998, it was due to the fact that the warmest water tempertures during the 1998 El Nino were not on and adjacent to the GBR.
Warmest Seas on Record Stress Great Barrier Reef
"The coral becomes stressed, or bleached, when warmer temperatures break down the symbiotic relationship between coral and algae living inside. During bleaching, the algae leaves the coral, disrupting the growth as well as color of the coral, leaving it white. In severe cases the coral will die. The report comes from the Australian Institute of Marine Science, which just completed an atlas of sea temperatures over the past decade and amalgamated it with historical data to show 2002 was the warmest year for water temperatures off northeast Australia since 1870. "Unless the corals can adapt and become acclimatized, then obviously the long-term future for the coral is at risk," said Craig Steinberg, an oceanographer at AIMS, an Australian government agency. "The outlook isn't good. If coral can't adapt then they're going to bleach and you get mass mortality." The sea temperature over the last century has risen by just half a degree Celsius. But corals tend to live within 1 to 2 degrees of their maximum temperature threshold, and a tiny increase is therefore enough to ensure a major impact."
Remote Sensing of Sea Surface Temperatures during 2002 Barrier Reef Coral Bleaching
Check the figure on the bottom of page 1 of this PDF. During 1998, despite the severity of El Nino, the warm water stayed south of the GBR. During 2002, not during an El Nino, warmer-than-normal summer water temperatures were right on top of the GBR, and a large area of the reef bleached.
Then I'm sure you realise this article is nothing but complete BS.
No, I don't realize that. If sea surface temperatures trend warmer than normal over the next decades, there will be coral death and coral reef changes due to this trend. Combined with the other more damaging factors (which I cited in the post to which you replied), this is predicted to lead to significant coral reef degradation.
I think much of the degradation could be prevented without worrying about global warming, and SHOULD be. If 2% of the money spent on global warming programs was spent on better sewage treatment plants for coastal areas in Third World and island nations, a lot of the stress on coral reefs would be reduced, and the reefs would then be better able to cope with any warming-related stress.
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