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■The Great Barrier Reef is one of the seven natural wonders of the world. Earth’s biggest structure made by living organisms and spanning more than 2000km along the north-eastern coast of Australia, it is home to thousands of species of plants and animals. But is this national treasure doomed, as most scientists believe, or not? Seanna Cronin meets two scientists on either side of the great debate


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he Great Barrier Reef is the jewel in Australia’s crown, but the natural wonder that attracts people from all over the world might disappear within a lifetime. According to many scientists, politicians and reports the reef is under threat on all fronts – the rising sea level, high temperatures, pollution, smothering by sediment, fishing pressures from man and now acidification. A recent study in Science journal claims if bleaching doesn’t kill off coral reefs in the near future, acidification of the oceans will by as soon as 2050. But not everyone agrees. One scientist, Dr Peter Ridd, is offering a small voice of hope in what is an almost overwhelming flood of majority opinion that the reef will wither and die. They conclude so because as the oceans absorb more and more carbon dioxide from the atmosphere, the water in turn becomes more acidic. Scientists predict it will become harder for corals to build their calcium carbonate skeletons – the framework of all corals reefs. The plight of coral reefs will continue to be a major issue this year, which is the International Year of the Reef. While the Great Barrier Reef seems like a permanent fixture on Australia’s marine landscape, sheltering the northern half of coastal Queensland from the waves of the Coral Sea, the reef is a newcomer geologically speaking. As the earth emerged from the last ice age 20,000 years ago, the ocean was 120m lower than it is today in Australia. The continental shelf was a vast plain dotted with hills. Aborigines living in the area of Townsville would have had to walk 70km to the nearest beach. Coral reefs lined the edge of the continental shelf which was in shallow water. As the ice melted, the sea level steadily rose for 14,000 years, slowly flooding the continental shelf and turning hills into islands. Around these islands, fringing reefs formed and when the islands were submerged, the corals covered them in slowly growing shells of reef called bommies. Tiny coral polyps from an estimated 350 species of coral built the massive reef millimetre by millimetre, expanding into new areas as the rising sea made them available. A few hills survived total submersion, and are popular tourist destinations such as Magnetic and Lizard islands and the Whitsundays. Thanks to the warm, shallow waters of the flooded continental shelf and the wave action around the islands, the corals flourished and spread in a massive network that would become the world’s single largest structure made by living organisms. The reason there aren’t other barrier reefs of the same scale in other parts of the world is because the Great Barrier Reef formed under just the right conditions. If the continental shelf had been deeper, or a dead-flat plain without hills around which the corals could form fringing reefs,

or the water had been colder, the Great Barrier Reef never would have formed. Now comprised of nearly 3000 separate reefs stretching over 2000km, the reef generates $5 billion a year in tourism alone and is an iconic symbol of Queensland. More than 60,000 people depend on the Great Barrier Reef for full-time jobs but reefs are transient features of the marine landscape, forming and disappearing as conditions change. If the sea level rises, as predicted over the next century, not enough of the sun’s rays will reach the deeper corals and if sea level drops much of the reef would be hung out to dry, literally. Individual corals can live in incredibly deep and cold water, but they only build reefs in tropical waters to between 30 and 40m deep. Sea level determines where coral reefs will be found, but myriad factors can

cyanide or copper sulphate in an effort to stop outbreaks. Corals are some of the oldest animals on earth and won’t just lie down and take it, but many scientists think abuse on so many fronts is overwhelming reefs. In its fourth assessment report, the UN’s Intergovernmental Panel on Climate Change projected by as early as 2030 there could be annual bleaching on the Great Barrier Reef and a 3C rise in temperature by 2100 would cause widespread die-offs of corals around the world. In the midst of these doom and gloom predictions, one Queensland scientist is questioning just how it’s possible that the largest and most protected coral reef system in the world is suddenly in danger of disappearing in a few decades. Dr Peter Ridd, a physicist from James Cook University in Townsville, has long been a sceptic of the science that fuels

‘‘

We worry about the Great Barrier Reef, even though it must be the least damaged of all the ecosystems we have . . .

’’

Dr Peter Ridd, of James Cook University, is a sceptic of the effects of the likes of climate change on the Great Barrier Reef interfere with the health of these complex ecosystems. Water that is too warm can stress corals and cause them to expel their symbiotic zooxanthellae that turn sunlight into energy, known as bleaching, which can kill the coral if the water stays hot for too long. Over fishing of animals that eat algae or too many nutrients in the water can tip the tenuous balance in favour of large algae, which compete with corals for space and sunlight. Development on the land can drastically increase the amount of sediment dumped on reefs near rivers or after heavy rains, suffocating and sometimes burying coral. Crown of thorns starfish eat the fleshy parts of coral and outbreaks have decimated reefs throughout the Pacific. Some countries have gone as far as sending divers out to inject the coralmunching starfish with poisons such as

political crusades and believes we’re all being swindled by climate campaigners. As someone who has lived most of his life near – and scientific career studying – the Great Barrier Reef, he wanted to weigh in on the one-sided discussion of its fate. In July, Dr Ridd published an essay titled The Great Barrier Reef Swindle. The waves it stirred up in the scientific community are still being felt today. ‘‘People are going on about the synergistic (combined) effects, that not only is it global warming but that we’re polluting and over fishing,’’ he says in his cluttered lab at JCU’s main campus. ‘‘Yes, that’s probably true for the rest of the world but not for Australia.’’ Dr Ridd is unhappy that the Great Barrier Reef is being lumped together with other reefs that aren’t protected by marine parks or have been fished and polluted to their very limits. Weekend Bulletin

‘‘We worry about the Great Barrier Reef, even though it must be the least damaged of all the ecosystems we have because it’s 100km away.’’ He points out how even though the Great Barrier Reef stretches for 2000km along Queensland’s coast, it is adjacent to only half a million people, while many reefs in the Caribbean are near populations of more than 50 million. But distance from man’s abuse isn’t the Great Barrier Reef’s only saving grace, according to Dr Ridd, who pushed the buttons of biologists when he compared corals with cockroaches in his essay and on several national radio interviews. ‘‘They (biologists) really hate that, because this is their creature and they’re in love with these animals,’’ he says. ‘‘I really am quite sure that if things really do go belly-up, and we get a 5C or 10C degree warming, the Great Barrier Reef might be buggered but there will be coral somewhere down in Tasmania. ‘‘I’m not sure whether mankind will survive, but I’m quite sure that corals and cockroaches would be around.’’ When it comes to the latest threat to the world’s reefs, Dr Ridd is just as sceptical about acidification as he is about bleaching. ‘‘We’ve seen crown of thorns (coraleating starfish), smothering by sediments, too many nutrients and bleaching, so I’m naturally very sceptical about this one too,’’ he says. ‘‘There’s going to have to be a bit more science done to convince me.’’ The cornerstone of the calls to protect coral reefs from climate change is a paper published in Science journal in 2003 by Dr John Pandolfi, which outlines the methods scientists can use to determine the longterm decline of coral reefs. The paper predicts a grave outcome for the world’s reefs, claiming some reefs were degraded by as much as 75 per cent and the Great Barrier Reef was 30 per cent affected. Dr Ridd picked the Pandolfi paper apart, bit by bit, critiquing each point in his own paper published in UK journal Energy & Environment. ‘‘I call it a fairytale because it’s the only way I can describe it,’’ says Dr Ridd. The most influential flaw of the report, in Dr Ridd’s opinion, is how the author places reefs in one of four categories ranging from pristine to ecologically extinct. ‘‘All you have to do is show one fish or one coral has been removed and automatically it’s not pristine,’’ he says. ‘‘But what happens is the smallest change can represent a 25 per cent degradation and that’s really what the whole thing is based on.’’ He is particularly worried about the political impact of the report, which has been cited by the Minister for the Environment Peter Garrett, Nobel Prize winner Al Gore and more recent reports like the IPCC’s Fourth Assessment. ‘‘You have to get media coverage to partly justify your existence, and if you’re an organisation that’s looking at ecological things, you have to have a problem to get funding,’’ he says. PARADISE, March 15-16, 2008 - PAGE 15


‘‘Organisations from the Australian Institute of Marine Science (AIMS) to the Great Barrier Reef Marine Park Authority (GBRMPA) to the CSIRO have their PR people who know precisely how to feed stuff to the media and get politicians talking about how we’re going to save the Great Barrier Reef.’’ Dr Ridd wants to ensure no one confuses his critique of the so-called death of the Great Barrier Reef with an attack on global warming. ‘‘My point is that if we get a 5C, 6C or even 9C rise in temperature, we’re not going to be worried about the Great Barrier Reef because everything else will be affected so much worse – the reef will be the least of our worries,’’ he says. ‘‘If you’re worried about an ecological issue in Australia, worry about things on the land. The issues I would worry about are feral animals, noxious weeds and our growing population.’’ Dr Ridd wants to move away from critiquing what he considers bad science and get back into his research projects. ‘‘I sometimes feel that all I end up doing is science to try to disprove what some people are saying rather than doing anything constructive,’’ he admits. ‘‘I feel it’s very destructive and a very unrewarding way of carrying out your scientific work, so I don’t want to do that with the rest of my career.’’ Dr Ridd is fine-tuning instruments he developed with two graduate students to measure dredging operations off Western Australia. He is also working out how to calculate the flushing time of the Great Barrier Reef and has begun to look at how carbon dioxide moves in and out of the ocean. ‘‘As far as the Great Barrier Reef is concerned, I think it’s in very good shape,’’ he says. ‘‘In many regards, with the exception of only Antarctica, the Great Barrier Reef is the best protected, most pristine and remote ecosystem on earth.’’ If Dr Ridd represents the minority voice in the debate about how climate

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Professor Ove Hoegh-Guldberg and (inset) a crown of thorns starfish and blue heeler cod on Queensland’s Great Barrier Reef change will affect the Great Barrier Reef, then there is another Queensland scientist who embodies the majority viewpoint. Dr Ove Hoegh-Guldberg is the director of the Centre for Marine Studies at the University of Queensland who has spent the past 10 years studying the impact of climate change on coral reefs. He is widely considered an expert on the subject of coral bleaching, on which he did pioneering research in the Caribbean as a PhD student with renowned coral biologist Dr Leonard Muscatine from the University of California at Los Angeles. Dr Hoegh-Guldberg was awarded the Eureka Prize for Research in 1999 and has been a dedicated campaigner for an immediate reduction of carbon dioxide emissions. ‘‘I believe the writing is on the wall for coral reefs under climate change,’’ says Dr Hoegh-Guldberg. ‘‘Studies from the best laboratories project coral reefs as we know them may largely disappear under rapid climate change.’’ He considers climate change to be the

PARADISE, March 15-16, 2008

number one threat to coral reefs and thinks that Dr Ridd is confusing the issue of corals becoming extinct with survival of coral reef communities. ‘‘The literature says corals are fairly robust as a species in geological time but as for communities of corals, we’re finding they’re extremely sensitive,’’ said Dr Hoegh-Guldberg during a heated debate with Dr Ridd on a current events radio program. ‘‘If you look at the last couple of massive bleaching events on the Great Barrier Reef, even though they are small relative to a very large reef system, they are still significant.’’ Dr Hoegh-Guldberg says even though only five per cent of the corals died in the 1998 and 2002 bleaching events, that still means that 2000sq km of coral on the Great Barrier Reef died. ‘‘That’s not a small amount and we may have a great reef but it is now showing signs of wear and tear,’’ he says. Dr Hoegh-Guldberg was one of the first scientists to link corals expelling their symbiotic zooxanthellae with heat stress

and is now developing models that will project future coral bleaching trends. ‘‘One of the projections we are almost 100 per cent certain of is that mass bleaching events will become increasingly frequent and severe,’’ he says. While the coral biologist admits his projections may not always become reality, there is something he is certain of. ‘‘Carbonate (reef) systems like the Great Barrier Reef do not grow at concentrations of carbon dioxide beyond 450 parts per million (ppm) and we have to take urgent action to avoid getting to that point.’’ Currently sitting at around 380ppm, the concentration of carbon dioxide will slowly increase as the oceans continue to absorb the gas from the atmosphere. ‘‘Just because we have one of the most intact coral reef ecosystems doesn’t mean it is not threatened in the longer term,’’ says Dr Hoegh-Guldberg. Another point over which he and Dr Ridd lock proverbial horns is whether corals can adapt quickly enough to cope with how fast problems such as temperature and acidity are predicted to change over the next century. ‘‘If you take the rate of change over the last 50 years, it is a similar temperature change as when we came out of the last ice age,’’ says Dr Hoegh-Guldberg.


are trends in every facet of life and it’s simply part of the process. ‘‘Scientists who share common perspectives will engage naturally in discussion around common themes,’’ he says. ‘‘But scientists are also compelled to undermine the work of others using data and analysis – this is the real driver within science and the progress of knowledge.’’ The consensus on the effects of climate change is finally coming under the scrutiny Dr Hoegh-Guldberg says drives the progress of scientific knowledge. The IPCC’s peer review process and projections have come under fire from scientists and America’s House of Representatives. The IPCC’s projections are based on computer models (CGMs), which speculate about what may happen in the future based on factors such as carbon emissions. As alarming as some of the projections are, they are ‘what if’ scenarios based on an assumption carbon emissions are the cause of climate change and climate change is bad. There is no question the globe is warming, only how much of that warming can be contributed to man and how much to natural climate change. Either way, scientists are trying to understand what that warming and other changes will mean for coral reefs. Scientific knowledge of reefs and oceans is developing and changing as discoveries are made. Just last month a 15-year international study headed by an Australian scientist found the rising sea level around Antarctica is primarily due to expansion of the oceans as they warm. Before the study was released, the rising sea level in the Southern Ocean over the past decade was assumed to be melting ice. ‘‘In some cases, seemingly good scientific ideas and conclusions will be overturned and replaced by better information,’’ says Dr Hoegh-Guldberg. Only more research into the predictions of climate campaigners and critics will provide the insight into the future of reefs as we know them. ■

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‘‘But it’s not happening over five to 10 thousand years; it’s happening over 50 years.’’ Dr Ridd argues the Great Barrier Reef will cope with a rise in temperature because many of the same species grow equally well in the warmer waters of Papua New Guinea. But Dr Hoegh-Guldberg says corals become acclimatised like people do, except corals can’t just get up and move to more comfortable places. ‘‘Corals are adapted locally to those temperatures, so the problem is you have hundreds of miles between those areas (Great Barrier Reef and PNG) and coral doesn’t move more than about 10km to 20km each generation,’’ says Dr Hoegh-Guldberg. ‘‘It takes a while for biology to catch up.’’ Even though there has only been a 0.7C rise in ocean temperature so far, Dr Hoegh-Guldberg says the amount of coral die-off from this small increase should raise alarm bells. ‘‘We’re seeing it all over the world in almost every ecosystem we look at,’’ he says. He points to studies from around the world stating coral reefs are suffering due to climate change. ‘‘There are hundreds of papers that point in the same direction and very few that point in the opposite direction.’’ That is the heart of the debate between these two scientists and indeed the global discussion about climate change. Does a scientific consensus on the demise of coral reefs confirm the worst or are scientists jumping on the bandwagon? Dr Hoegh-Guldberg says the public should find confidence in consensus like the 2500 scientists who signed their names to the conclusions of the IPCC’s fourth assessment. He says a wide-scale consensus on the effects of climate change within a group of ‘natural dissenters’ sends a powerful message. Dr Hoegh-Guldberg argues there have always been trends in science, just as there

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PARADISE, March 15-16, 2008 - PAGE 17

Great Barrier Grief  

The debate about coral bleaching heats up as one James Cook University researcher speaks out against the majority.

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