Record ocean temperatures have produced mass bleaching along Australia’s Great Barrier Reef for the second year in a row.
The latest aerial surveys released by scientists this month show a recent bleaching event almost as severe as the record bleaching of 2016 that left two-thirds of the reef damaged.
Bleaching occurs when extreme heat forces algae to abandon coral, turning them pale white.
Bleaching is not necessarily fatal for coral, but 2016 was also the highest level of coral mortality ever recorded on the Great Barrier Reef.
Bleached coral reefs can recover, but rising ocean temperatures are making this increasingly difficult. Scientists have now documented four major bleaching episodes along the Great Barrier Reef; 1998, 2002, 2016, and now 2017; which means that most of the reef has undergone some form of severe bleaching in the past 18 years.
Recovery is a slow and uneven process, particularly for coral that are centuries old.
“It takes at least a decade for a full recovery of even the fastest-growing corals, so mass bleaching events 12 months apart offers zero prospect of recovery for reefs that were damaged in 2016,” said James Kerry, one of the researchers at James Cook University’s Australian Research Council Center of Excellence for Coral Reef Studies, in a statement on the most recent findings.
Complicating coral recovery now is the fact that the bouts of bleaching are growing longer and more severe, while the much-needed recovery periods are shorter and less frequent.
NOAA’s Coral Reef Watch recorded abnormal heat stress at nearly every point along Australia’s eastern coast from February 21 to 27, 2017.
Mark Eakin, the coordinator of Coral Reef Watch, told NASA that this is alarming because the current bleaching along the Great Barrier Reef is ongoing.
“It has been the longest, most widespread, and most damaging coral bleaching event ever recorded.”
What’s more, some experts believe efforts to combat coral bleaching have been in vain.
The real answer to stopping coral bleaching lies in reducing our CO2 emissions, which are causing ocean waters to warm.
Emissions are not on track to stay below the 1.5 degrees Celsius threshold, and coral reefs could perish if the planet continues to warm.
As Terry Hughes, head of the Australian Research Council Center of Excellence for Coral Reef Studies said in a statement, the “Window to do so is rapidly closing.” Otherwise, we are looking at unabated bleaching of the reef.
Source – Vox