A GOVERNMENT-run research body has found that the past 110 years of ocean warming has been good for the growth of corals spanning more than 1000km of Australia’s coastline.
The findings undermine predictions that global warming will devastate coral reefs, and add to a growing body of evidence showing corals are more resilient than previously thought – up to a certain point.
The study by the Australian Institute of Marine Science, peer-reviewed findings of which were published today in the leading journal Science, examined 27 samples from six locations from the West Australian coast off Geraldton to offshore from Darwin.
At each site, scientists took cores from massive porites corals – similar to a biopsy in humans – and counted back to record their age in much the same way tree rings are counted.
Although some cores extended to the 18th century, they focused on the period from 1900 to 2010.
The researchers found that, contrary to their expectations, warmer waters had not negatively affected coral growth.
In fact, for their southern samples, where ocean temperatures are the coolest but have warmed the most, coral growth increased most significantly over the past 110 years.
For their northern samples, where waters are the warmest and have changed the least, coral growth still increased, but not by as much.
“Those reefs have actually been able to take advantage of the warmer conditions,” said Janice Lough, a senior AIMS research scientist and one of the study’s authors.
The key question is how warm the water can get before the positive effects are reversed.
Lab studies have typically measured the effect of short-term, rapid changes in temperature and water chemistry; these mimic, for example, coral-bleaching events that are known to be devastating.
Much harder to measure are the long-term effects of gradual warming, such as those caused by climate change.