Australia’s Great Barrier Reef offers dramatic evidence of the reality of climate change. Scientists have found an astonishing two-thirds of the reef undergoing mass coral bleaching as warmer ocean temperatures are basically boiling them to death. James Kerry, a scientist with the ARC Centre of Excellence for Coral Reef Studies, told CNN when ocean temperatures are hot for long periods of time, corals don’t simply bleach but “cook and they die very quickly.”

ARC Centre of Excellence for Coral Reef Studies, Australia, Great Barrier Reef, coral, coral reef, coral reefs, coral bleaching, bleached coral, mass bleaching, mass bleaching event, global warming, climate change, environment, environmental destruction

2016 saw a bleaching event that was the worst coral die-off we’ve ever recorded, and now a 2017 event makes matters worse. ARC Centre director Terry Hughes said the impact of back-to-back bleaching sprawls across 900 miles; only the southern third of the Great Barrier Reef is unharmed. It’s the second time in only 12 months scientists have recorded mass bleaching in the reef after aerial surveys.

Related: Great Barrier Reef bleaching is the “worst coral die-off” in recorded history

ARC Centre of Excellence for Coral Reef Studies, Australia, Great Barrier Reef, coral, coral reef, coral reefs, coral bleaching, bleached coral, mass bleaching, mass bleaching event, global warming, climate change, environment, environmental destruction

And 2017’s bleaching can’t be explained away by El Niño. Hughes said the bleaching “is caused by record-breaking temperatures driven by global warming.”

The Great Barrier Reef has experienced severe bleaching in 1998, 2002, and now 2016 and 2017, according to scientists. Kerry said bleached corals don’t always die, but take at least a decade to make a full recovery, so with back-to-back bleaching they expect coral loss. Tropical Cyclone Debbie didn’t help either. The storm may have left damage in its wake when it hit part of the Great Barrier Reef at the end of March.

ARC Centre of Excellence for Coral Reef Studies, Australia, Great Barrier Reef, coral, coral reef, coral reefs, coral bleaching, bleached coral, mass bleaching, mass bleaching event, global warming, climate change, environment, environmental destruction

Hughes said in a statement, “Clearly the reef is struggling with multiple impacts. Without a doubt the most pressing of these is global warming. As temperatures continue to rise the corals will experience more and more of these events: one degree Celsius of warming so far has already caused four events in the past 19 years. Ultimately we need to cut carbon emissions, and the window to do so is rapidly closing.”

Via the ARC Centre of Excellence for Coral Reef Studies and CNN

Images via Bette Willis and Ed Roberts/ARC Centre of Excellence for Coral Reef Studies