ABC News Online, Posted 2 hours 12 minutes ago
Updated 1 hour 52 minutes ago
- Audio (Highly recommended): Coral study finds slowest growth in 400 years (AM)
New research on the Great Barrier Reef says coral growth has fallen to the slowest rate in more than 400 years.
The tipping point for catastrophic climate change is an issue of dispute between politicians and environmentalists but on the climate vulnerable great barrier reef, researchers have been surprised to discover that a tipping point for coral growth has already been reached. In the journal Science this morning, they reveal that it was reached eighteen years ago, as Noni Walsh reports.
The Australian Institute of Marine Science's Glenn De'ath says banding like tree rings on the giant Porites coral reveals a massive decline in the growth history.
"Prior to about 1990 coral growth was fairly consistent but round about 1990 things have changed and we're suggesting this is a tipping point. What's happened, basically, coral calcification - that's a measure of how corals grow - has decreased by about 14 per cent since then," he said.
In the journal Science the research team says ocean absorption of atmospheric carbon may be as much of a problem as rising temperatures.
"The increased acidity levels in the ocean, we believe, is affecting things that calcify, things like corals," Dr De'ath said.
He says the decline in growth is unprecedented.
"It was relatively consistent over those 400 years or so, there would be small undulations, where as now we are experiencing growth which is consistently declining," he said.
Dr De'ath says a rough estimate suggests that coral growth could hit zero by 2050.