The recent news that coral had grown back in record amounts in just two years on the Great Barrier Reef (GBR) punctured the 25-year-long scare story that ‘global warming’ was rapidly killing it off. Now the scare seems dead and buried, after a 10-year survey of a remote reef 1,200 kms south of Hawaii has established beyond any reasonable doubt that coral bleaching is caused by natural sudden changes in local water temperature. The decade-long survey found coral quickly recovers when normal conditions return.
The survey was taken at Palmyra Atoll, where there’s little nearby human habitation, and the reefs examined were in pristine condition. Between 2009 and 2018, a group of researchers from the San Diego-based Scripps Institution of Oceanography took copious records across 80 plots of coral. In 2009 and 2015-16, two natural El Niño events struck suddenly, warming waters by up to 3°C. The graph below plots the changes in temperature at Palmyra.
El Niño is a natural weather oscillation arising in the Pacific that causes sudden sea temperature spikes. The 2015-16 spike led to major damage at Palmyra, bleaching up to 90% of the coral. But the researchers found that a year later, only 10% of the coral had died. Within two years, the reefs had returned to pre-bleached levels. The researchers concluded that across the 10-year period surveyed and after two bleaching events, the structures “show evidence of long-term stability”.
In fact, the findings at Palmyra mirror the experience at the much larger Great Barrier Reef. The last decade has been particularly hard on the coral in this area with cyclone damage, starfish attacks and the same two powerful El Niño events. Climate alarmists have had a field day.