The Great Barrier Reef is suffering yet another mass coral bleaching event, scientists announced on Sunday, the latest gut punch delivered to the planets largest living structure by humanity.

Researchers at Australias ARC Centre of Excellence for Coral Reef Studies announced the somber prognosis following an aerial survey of more than 5,000 miles of the reef, similar to those conducted in 2016 that revealed widespread devastation . Despite hope that this years bleaching wouldnt be anything like last year , scientists returned with disheartening news.

Spurred by record-breaking temperatures , some 900 miles of coral was hit with back-to-back bleaching, particularly affecting the middle third of the structure that stretches along Australias northeastern coast. Last years mass bleaching hit the northern third of the reef the hardest, meaning only the southern portion has been left relatively unscathed.