Scientists 'crying wolf' over coral, say Australian marine researcher

Jamie Walker, The Australian 19 Dec 09;

A SENIOR marine researcher has accused Australian scientists of "crying wolf" over the threat of climate change to the Great Barrier Reef, exposing deep division about its vulnerability.

Peter Ridd's rejection of the consensus position that the reef is doomed unless greenhouse emissions are checked comes as new research on the Keppel group, hugging Queensland's central coast, reveals its resilience after coral bleaching.

Professor Ridd, a physicist with Townsville's James Cook University who has spent 25 years investigating the impact of coastal runoff and other problems for the reef, challenged the widely accepted notion that coral bleaching would wipe it out if climate change continued to increase sea surface temperatures.

Instead of dying, the reef could expand south towards Brisbane as waters below it became warmer and more tolerable for corals, he said.

His suggestion is backed up by an Australian Institute of Marine Science research team headed by veteran reef scientist Ray Berkelmans, which has documented astonishing levels of recovery on the Keppel outcrops devastated by bleaching in 2006.

Professor Ridd said scientists who predicted corals would be mostly extinct by mid-century had a credibility problem because the Great Barrier Reef was in "bloody brilliant shape".

He said the reef had defied predictions that it would be overwhelmed by crown of thorns starfish, smothered in sediment from river runoff or poisoned by sediment and chemicals washed on to corals from the mainland. He accepted that ocean acidification associated with climate change was a genuine danger because it could impede the process of coral calcification, destroying the reef's building block. Scientists responsible for "crying wolf" over lesser threats had done the research community a disservice, he said.

"Ten years ago, I was told that the coral was going to die from sediment, and we have proved that is complete rubbish," Professor Ridd told The Weekend Australian.

"They are saying that pesticides are a problem, but when you look at the latest data, that is a load of rubbish. They are saying bleaching is the end of the world, but when you look into it, that is a highly dubious proposition.

"So when something comes along like the calcification problem, you are sort of left with this wolf story . . . they are crying wolf all the time."

Leading scientists including former AIMS chief scientist Charlie Veron and reef research pioneer Ove Hoegh-Gulberg, who attended the Copenhagen talks on climate change, have warned that the Great Barrier Reef will be destroyed by the middle of the century if ocean temperatures continue to rise, unleashing more frequent and lethal bleaching.

Mass bleaching was recorded on the Great Barrier Reef in 1998 and 2002, affecting up to 60 per cent of all corals. The last severe outbreak, in which stressed corals eject the symbiotic algae that provide them with nutrients, causing many to die, was localised on the Keppel reefs three years ago.

More than 95 per cent of the corals were affected, of which about a third died. The corals became stressed after the water temperature topped 28.5C and began to die when it hit 30C and stayed at that level for a week or more, with limited wind or cloud cover to ease the heating.

Scientists have found the tolerance level of corals varies. Reefs around Magnetic Island, off Townsville, can withstand water temperatures in the low 30s, while those off Yemen, at the foot of the Arabian peninsula, live in temperatures that can reach 34C.

As The Weekend Australian reports today, some of the corals on the Keppel outcrops are more thickly covered in coral than before bleaching in 2006, raising hope the living heart of the reef can acclimatise to spikes in water temperature through a remarkable process of algal shuffling.

"That was a real surprise," Dr Berkelmans said, conducting us on an underwater tour of what he calls his "lab rat" reefs at the bottom of the Great Barrier Reef.

He said the findings made him more optimistic about the ability of corals to adapt to climate change, especially on inshore reefs such as those in the Keppels.

"People say the reef is dying," Dr Berkelmans said. "The Great Barrier Reef is 2000km long, with 3000 reefs. Are you telling me all of it is going to die?

"I don't think so. There are some areas that are naturally more resilient than others, there are some areas that see warmer temperatures less frequently because of favourable oceanography or other factors . . . We might lose species, and we might lose them at many reefs. The Great Barrier Reef would look vastly different, but the reef would still be there."

Great Barrier Reef Marine Park Authority chairman Russell Reichelt, a former AIMS scientist who worked on crown of thorns outbreaks, said Professor Ridd had cherrypicked data to support his thesis that the threat to the reef was exaggerated. "I would liken it to the medical debate around `Does smoking cause cancer?'," Dr Reichelt said.