Delegates to discuss climate impact on reefs

Delegates to discuss climate impact on reefs

ABCUpdated July 10, 2012, 9:29 am


Delegates at the International Coral Reef Symposium in Cairns will today turn their attention to the impact of climate change on coral reefs around the world.

More than 2,500 scientists met yesterday to discuss the Consensus Statement on Climate Change and Coral Reefs and heard reefs are in danger from rising sea temperatures and over-development.

Dr Alana Grech from James Cook University says current development decisions will have long-term impacts on reefs.

She has called for governments to design “mega-ports” similar to airport hubs to lessen the impact of the shipping trade on the Great Barrier Reef.

A foundation of facts established that ocean temperatures have climbed by half a degree in the past decade, ocean acidity has increased by 25 per cent and sea levels have risen by around 30 centimetres.

The Australian Institute of Marine Science’s Peter Doherty says those changes have had a negative effect.

“I have certainly witnessed many changes in the places that I used to go to 30 years ago and almost none of those changes are for the better,” he said.

The Director of the Global Change Institute, Ove Hoegh-Guldberg, says ocean acidification poses a huge challenge for organisms on the reef.

“Carbon dioxide doesn’t just stay in the atmosphere, and a lot of it is going into the ocean,” he said.

“When it goes into the ocean it reacts with the water, it changes the chemistry, and part of that chemistry is that it becomes more acidic and that has consequences for marine life.”

Dr Hoegh-Guldberg the scale of the change threatens the existence of the reef in its current form.

“What we expect to see in the coming decades is some corals doing better and others doing worse, and that probably goes for a lot of other organisms as well,” he said.

“But in the long term, because we’re pushing conditions well beyond those we’ve seen for the last million – possible 40 million years, it’s likely that organisms like cyanobacteria, which is the slimy green thing that goes over rocks, that may be ultimately the winner.”

To fast to adapt?

He says climate change is affecting the ocean environment at rates beyond what has been experienced before.

“On the issue of adaptation the jury’s out, what we do know is that things are changing more rapidly than they have in the past, phenomenal rates of change compared to even an Ice Age transition,” he said.

“So this is really testing long-lived organisms like corals to be able to rapidly adapt. Most scientists are feeling there are big questions about whether biology will keep up.”

Dr Hoegh-Guldberg also says evidence of coral being found in waters previously too cold to survive in, is not enough to compensate for the destruction of existing reefs.

“Well, there is no question that some organisms as waters are warming that they’re being able to penetrate those,” he said.

“But the important issue here is that a single coral arriving on a reef at a high [or low] latitude is not the same as key coral with all the ecosystems that depend on it arriving.

“I think it’s put into sharp relief when you consider how fast the reef would have to move to higher latitudes if it’s to keep up with climate change.

“And that number, which is essentially moving from the north to the south of the Great Barrier Reef, is between 15 and 20 kilometres per year.”

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