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.
"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."
I would have to say that since they only have reliable data for 1-200 years, this represents a blip in a sliver. That means it has happened before, and the reefs recovered.
"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."
Agreed. Notice the bold that I used for emphasis, those are still pretty big ifs given our relative lack of historical sea temps in the areas.
"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."
Exactly. Global warming is the least proved theory of reef degradation. If we concentrated our efforts (read: $$$$) on precisely the proven problems you mentioned, we'd save the reefs, save our cars and air conditioners, save our money, and save our sanity.