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The Great Great Barrier Reef Swindle

22, July 2007

Peter Ridd
On Line Opinion, 19 July 2007  

Those of you who watched the ABC’s presentation of The Great Global Warming Swindle might not have been convinced by the arguments challenging the conventional wisdom that carbon dioxide is responsible for global warming. However, it should be apparent that scientists and politicians such as Al Gore, who have been telling us that the science is unquestionable on this issue, have been stretching the truth. It seems that there are some good reasons to believe that we may have been swindled.

Closer to home, there is a swindle by scientists, politicians and most green organisations regarding the health of the Great Barrier Reef (GBR). We are told that the reef is a third of the way to ecological extinction, is being smothered by sediments, is polluted by nutrients and pesticides, and is being cooked by global warming. Some scientists and organisations give the reef only a couple of decades before it is finished.

In the light of all this dismal news comes a new study by Scientists from the Australian Institute of Marine Science (AIMS) which indicates that the corals are more tolerant to rising waters temperatures than first thought by most people.

Under conditions of extremely high water temperature, corals expel the symbiotic algae called zooxanthelae that reside within the polyp making them appear bleached white. Some coral die from this bleaching and there have recently been some major mass bleaching events in the Great Barrier Reef and around the world, particularly in 1998 and 2002. The AIMS work shows that the corals can adapt to rising water temperatures by using strains of zooxanthelae that make them tolerant to higher temperatures.

In biological circles, it is common to compare coral reefs to canaries, i.e. beautiful and delicate organisms that are easily killed. The analogy is pushed further by claiming that, just as canaries were used to detect gas in coal mines, coral reefs are the canaries of the world and their death is a first indication of our apocalyptic greenhouse future. The bleaching events of 1998 and 2002 were our warning. Heed them now or retribution will be visited upon us.

In fact a more appropriate creature with which to compare corals would be cockroaches - at least for their ability to survive. If our future brings us total self-annihilation by nuclear war, pollution or global warming, my bet is that both cockroaches and corals will survive.

Their track-record is impressive. Corals have survived 300 million years of massively varying climate both much warmer and much cooler than today, far higher CO2 levels than we see today, and enormous sea level changes. Corals saw the dinosaurs come and go, and cruised through mass extinction events that left so many other organisms as no more than a part of the fossil record.

Corals are particularly well adapted to temperature changes and in general, the warmer the better. It seems odd that coral scientists are worrying about global warming because this is one group of organisms that like it hot. Corals are most abundant in the tropics and you certainly do not find fewer corals closer to the equator. Quite the opposite, the further you get away from the heat, the worse the corals. A cooling climate is a far greater threat.

The scientific evidence about the effect of rising water temperatures on corals is very encouraging. In the GBR, growth rates of corals have been shown to be increasing over the last 100 years, at a time when water temperatures have risen. This is not surprising as the highest growth rates for corals are found in warmer waters. Further, all the species of corals we have in the GBR are also found in the islands, such as PNG, to our north where the water temperatures are considerably hotter than in the GBR. Despite the bleaching events of 1998 and 2002, most of the corals of the GBR did not bleach and of those that did, most have fully recovered.

Of course, some corals on the Queensland coast are regularly stressed from heat, viz. the remarkable corals of Moreton Bay near Brisbane which are stressed by lack of heat in winter. A couple of degrees of global warming would make them grow much better.

Even the GBR has seen massive changes in its comparatively short life. Eighteen thousand years ago, the GBR did not exist as water levels were about 100m lower than today. At that time, the Australian coast was about 100km from its present position, and the small hills upon which the reefs were to form dotted a broad and flat coastal plain that would become the GBR lagoon. When the sea level started to rise at the end of the ice age, the coast eroded at a phenomenal rate. The Aboriginal people living on these coastal plains lost land at a rate of about 50m each year as they witnessed the birth of one of the natural wonders of the world.

The reef was born in conditions that most biologists would regard as horrific for corals and far worse than what most of the present GBR would see: rising temperatures, high water turbidity due to the erosion, high nutrient concentrations due to erosion and the closer proximity of river mouths, rising CO2 concentrations, and rapidly rising sea levels (10mm per year). These are all factors presently regarded as threats to the GBR.

A few millennia later, Aboriginal people were to witness the greatest loss of coral ever seen by humans in Australia, for about 5,000 years ago, whilet civilisations were being born around the world, the sea level of eastern Australia started to fall. The coral reefs that had grown rapidly upwards to the low tide level were now exposed to the air and sun during spring tides. They died and formed the extensive dead areas called reef flat that make up a large proportion of many reefs in the GBR. It is ironic that if we see a modest sea level rise of one metre due to global warming, these dead areas of reef will explode into life, potentially doubling the coral cover. Sea level rise will be bad for Bangladesh and Venice but it will be good for the GBR.

Other threats are also overstated. Studies have shown that the quantity of sediment in rivers’ plumes that wash out into the lagoons is much less than sediment that is resuspended from the seabed every time the south-easterly trade winds blow. Pollution due to nutrients is also probably restricted to a few reefs close to a couple of river mouths as the rest of the lagoon receives relatively small nutrient loads from rivers compared to other sources, and the water is rapidly flushed to the Coral Sea.

Fishing pressure is very limited. The coast adjacent to the GBR contains about half a million people compared with 50 million for the similarly sized Caribbean reefs. Most Queenslanders never visit the reef and do not use it as a significant food source unlike most other reefs around the world. The northern 1,000 kilometres of the reef has a population that can be counted in 100’s. It has been barely touched by mankind.

With the exception of Antarctica, I challenge anyone to name an ecosystem better preserved than the GBR. The sheer lack of people pressure on this huge system, and its distance from the coast has saved the GBR from the fate that has befallen the Caribbean and other areas. It did not suffer the equivalent of land clearing for agriculture, cities, dams and roads. It does not have problems with infestations of noxious weeds and feral animals such as cats and cane toads, or the mass species extinctions of the Australian land.

Apart from a reduction in turtles and dugongs, it is doubtful that Captain Cook would notice any difference to the GBR if he sailed up this coast again. Pity we cannot say the same about the land that he visited. Whereas the coral reef that he struck near Cooktown is alive and healthy, the land around Botany Bay would be unrecognisable.

So why have we been swindled into believing this almost pristine system is just about to roll over and die when it shows so few signs of stress. There are many reasons and processes that have caused this and some of them are the same as why we should all be more than a little sceptical about the hypothesis that CO2 is causing global warming.

The first reason is that there is some very bad science around. Second, a mainly biological oriented scientific community seems to take little heed of the geological history of corals. Third, we have many organisations and scientists that rely for funding on there being a problem with the GBR. Most grant applications on the GBR will mention at some stage that a motivation for the work is the threat to which it is exposed. I confess that I do this in all my applications - it’s the way the game works.

Why does a scientist and environmentalist such as myself worry about a little exaggeration about the reef. Surely it’s better to be safe than sorry. To a certain extent it is, however, the scientist in me worries about the credibility of science and scientists. We cannot afford to cry wolf too often or our credibility will fall to that of used car salesmen and estate agents - if it is not there already. The environmentalist in me worries about the misdirection of scarce resources if we concentrate on “saving” a system such as the GBR. Better we concentrate on weeds and overpopulation and other genuine problems.

So I’m thinking of asking Martin Durkin to come over to Australia and do another show called The Great Great Barrier Reef Swindle. I’d have to make sure he got all his graphs right and did not talk to anybody who thought smoking didn’t cause cancer, but I reckon he could put a very compelling case that the GBR is in great shape and that there is little to fear, especially relative to other environmental issues, such as overpopulation and invasive species.

Peter Ridd is a Reader in Physics at James Cook University specialising in Marine Physics. He is also a scientific adviser to the Australian Environment Foundation.

Published in On Line Opinion

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