(CNN)Australia’s Great Barrier Reef has likely experienced its most widespread bleaching event on record, according to a US government scientist who monitors the world’s coral reefs.

This marks the third mass bleaching event on the reef in just the last five years.
And scientists say that the rapid warming of the planet due to human emissions of heat-trapping gases are to blame.
On the heels of severe bleaching events in 2016 and 2017 that left half of the coral on the Great Barrier Reef dead, scientists fear this one could be a devastating blow.
“If we do not deal with climate change quickly … we are going to continue to see more severe and more frequent bleaching, and we are going to see the loss of coral reefs in much of the world,” said Dr. C. Mark Eakin, coordinator of the National Oceanic and Atmospheric Administration’s (NOAA) Coral Reef Watch.
The mass bleaching conditions were observed by Coral Reef Watch, which uses remote sensing and modeling to predict and monitor for signs of bleaching.
Eakin says that the bleaching in 2016 and 2017 was extremely intense, but severe damage was concentrated in a few hotspots in the northern and central parts of the reef.
Early indications show that this latest event was not as damaging, but that much a larger area of reef experienced at least some bleaching.
Past bleaching events have typically occurred in years with a strong El Niño-Southern Oscillation, a climate phenomena that can increase the odds of a host of extreme weather events around the globe.
El Niño is characterized by warmer waters in the Pacific ocean, which makes bleaching events in the region more likely. But there is no El Niño currently