Coral conundrum confuses scientists

Warming seas and corals As many readers know, considerable fear surrounds the future of the world’s coral reefs. Catastrophic declines have already occurred in some places, usually as a result of climate change combined with human activity like the dumping of sewage.
Now, however, comes a bit of good news. In research conducted off western Australia, scientists found that coral growth in that region had accelerated through the 20th century as ocean temperatures warmed. The effect was most pronounced at higher latitudes where the ocean tends to be colder — a strong indication that the warming caused by human release of carbon dioxide is benefiting corals in that region.
“It was very surprising,” Timothy Cooper, the lead scientist on the study, told the journal Science, which published the research on Thursday.
The situation in western Australia contrasts sharply with that of the Great Barrier Reef in eastern Australia, where coral growth has slowed. Scientists so far do not understand the differences, although Dr. Cooper pointed out that western Australia is far less populous, with less chemical runoff and fewer human impacts on corals.
He also suspects that corals may benefit from warming only up to a point. Scientists know that excessively high or low temperatures can damage or kill coral reefs. So while the corals of western Australia may have enjoyed more optimal growing temperatures through the 20th century, there’s no guarantee they would continue thriving as the ocean warms further.
Moreover, the carbon dioxide that is washing out of the atmosphere and into the ocean is raising the seawater’s acidity level, which is expected to damage many coral reefs over the long haul.
Still, Dr. Cooper’s unexpected findings certainly help to complicate the scientific understanding of what happens to coral reefs as a result of climate change, and they raise a question: Are other reefs winning rather than losing from the changes in the climate seen so far?