The Great Barrier Reef in Australia is the world's largest coral reef stretching over 1400 miles and in just the last two years over two-thirds of it has bleached. Died.

Getty Images Climate Change

Warm waters have severely bleached enormous parts of its corals for the second year in a row in a deadly one-two punch.

Coral bleaching occurs when unusually warm ocean waters stress the living corals. That in turn triggers the coral to expel the algae that gives the coral the amazing colors people travel worldwide to see. It leaves behind a white bleached color. The stronger the bleaching and the longer it goes on, the more likely corals will die.

Getty Images Great Barrier Reef

In 2016 two-thirds of the corals in the northern sector of the reef died after severe bleaching from unusually warm waters. Now this year, researchers say the reef's central  sector has been hit by another year of damaging warmth. This the first time ever the reef has been hit with back-to-back years of devastating bleaching.

Getty Images UNESCO

If the Great Barrier Reef is on your Bucket List, and it's on mine, I do believe a bump up a number of notches on the countdown is warranted. Biggest mover of the week, actually.