AUSTRALIA: The Reefs Are Going Down Under.

MAGNETIC ISLAND IS LIKE CATALINA WITH DEATH ADDERS. "They like to lie under piles of leaves," Ann Tager advises, as she shows me her wooded backyard. The most visited of the Great Barrier Reef islands, Magnetic is a half hour ferry ride from the city of Townsville, half way down the 1,200-mile length of the reef. Rich in birds and wildlife, it's home to adders, pythons, rock wallabies, sea eagles, flying foxes, curlews, koalas and equally cute marsupial possums. It also has its own living reefs, but no longer in Nelly Bay.

The hottest year on record, 1998, saw a global outbreak of coral bleaching, as coral reefs' thermal tolerances were exceeded by a combination of gradually warming sea temperatures spiked by that year's El Nino phenomena.

The idea that climate change is accelerating El Nino warming and the La Nina ocean cooling that follows has become a subject of scientific concern. The U.S. State Department's Coral Reef Task Force reported that the unprecedented 1998 global bleachings were a direct result of climate change caused by the burning of fossil fuels.

"When we saw 1,000-year-old coral colonies bleaching and dying, that's something new, at least in recorded human history," agrees Paul Hough, a friendly, sun-reddened Magnetic Island resident and research scientist with the Great Barrier Reef Marine Park Authority.

Hough specializes in coral reproduction. "I was looking at the corals that didn't die, and found their reproduction was down to 40 percent of normal the first year after the bleaching and was at 80 percent the second year. Now they're experiencing 1.5-degree below normal water temperature from La Nina, so we've had a four-degree swing in four years. And with greater frequency and severity of El Ninos, that's going to make it more difficult for corals to recover from these impacts. I think we're seeing not a crash, but a slow decline of the [reef] system."

My visit to Magnetic Island followed the two wettest months in North Queensland's history. Big gum trees and foliage were still down from Cyclone Tessa, which struck two weeks earlier. The island's once-healthy Nelly Bay reef is one of Hough's seven study sites. "The cyclone following repeated bleachings was the final nail in its coffin," Hough tells me. I decide to visit it anyway.

I head down to the beach past stately banyan trees, hoop pines, coconut palms and a sign that reads: "WARNING--MARINE STINGERS--are Dangerous ... Flood sting with vinegar. If breathing stops give artificial respiration."

Luckily, I've borrowed a stinger suit (what we Yanks call a dive skin) from Ann's husband Jeremy, who's also coordinator of the North Queensland Conservation Council. I swim out to the black buoy that marks Hough's research site and begin free diving. The bottom is a rubble field of broken branch corals, dead bleached and gray silt-covered hard corals, and a few small fish. A burrowing clam is encased in the limestone skeleton of a dead rock coral. Its blubbery mantle is striped and spotted with the blue, purple and green colors of healthy symbiotic algaes, giving it the look of a fashion model posing in a cemetery.

"Climate impact has happened. The four most serious bleaching events were in 1987 and 1988, 1992, 1994 and 1998--which was the biggest," explains Katharina Fabricius, a bright, vivacious research scientist with the Australian Institute of Marine Science, also a Magnetic Island resident.

"Corals can take a fair amount of disturbance--they're not fragile," she tells me. "But if these disturbances become more frequent, weedy species will take over. You already see branching species replacing massive slow-growing brain corals. We lost a 1,000-year-old coral head off Pandora Reef in '98. These reefs are really the canaries in the coal mine, and you now see a whole ecosystem being impacted."

I tell her I know an Antarctic scientist who thinks his penguins are the canaries for climate change. "Ten years ago people were blase about this being a pristine area," she says. "Now with climate change even the most conservative projections are pretty bleak. And if the Australian government wants to sell brown coal, they may not be likely to consider alternative fuels or solar or other changes that need to take place."

In fact, local environmentalists are now fighting a plan to start mining shale oil in the rainforests of North Queensland, arguing that the last thing the world needs is new sources of fossil fuels. Still, not everyone is convinced.

"In many ways the jury's still out on the global climate effect on coral bleaching," claims Virginia Chadwick, a former regional tourism minister and the political appointee who chairs the Great Barrier Reef Marine Park Authority. "Not to say this apparent correlation between bleaching and temperature isn't a worrying trend," she adds. "From a local management agency point of view, we're wondering about adaptability, about corals' ability to adapt to temperature changes."

"We've no evidence corals can adjust to rapid temperature changes--maybe over hundreds of thousands of years, but that's not the scale we're now dealing with," counters Fabricius.

Having seen dead coral, I decide to take a dive trip to Kelso, one of the outer reefs that's recovered from the little bleaching it did suffer in '98. It's nice to be in a living aquarium again, with big coral walls and bommies (coral heads) and canyons littered with fish: There are purple starfish and cushion-like sea cucumbers, trigger, trumpet, red emperor and unicorn fish, and lots of bright juvenile fry hugging the reef for protection. A black-tip reef shark cruises past adding a dash of predatory grace to the mystery and magic of a healthy reef.

"Ours is a large reef region, more robust than the Florida Keys or the Caribbean with over 420 species of corals, six to seven times as diverse as your Atlantic reefs," Paul Hough explains to me. What does that mean in terms of long-term projections, I wonder. "Larger, more diverse communities [like the Great Barrier Reef] will last longer," he says. "North America's gonna get hammered." CONTACT: Australian Institute of Marine Science, (61-7)47534444, www.aims.gov.au; North Queensland Conservation Council, (61-7)4771-3226, www.nqcc.org.au.

DAVID HELVARG is an investigative journalist and author of the forthcoming book Blue Frontier: The Fight to Save America's Living Seas (W. H. Freeman).