Coral Bleaching in the Great Barrier Reef | Years of Living Dangerously

This year is the warmest on record, and with ocean temperatures reaching dangerously high levels, a major coral bleaching event is predicted to hit the Great Barrier Reef. It's a race against time to document these reefs before climate change alters conditions. Here, the XL Catlin C View survey uses cameras to take high numbers of 360° photographs of the bottom of the sea, effectively mapping the sea floor, like Google Street View maps land. With this technology, scientists are able to establish a baseline for the coral reefs so that after a bleaching event, they can figure out how much was actually lost.

It's part of the largest visual stock take of corals on the planet ever done. After today's dives, I'm actually feeling hopeful—the reefs here are thriving. But then I learned my optimism may be misplaced. Ove has footage from other reefs around the world, and he says what's happening there will eventually happen here too.

Now, this is largely a healthy reef right now. If you look at a reef that's under stress, like this one here, and there's bleaching all over the place, right? That's what all these white patches are. That's right; it looks like it's snowed underwater. Some of that might recover if it gets cooler sooner, but a lot of that will die either directly or it'll die of starvation or disease.

So, if you look at the healthy reef on the left-hand side, with reefs that have now started to bleach, like the one on the right, and we're talking—wow, wow! That's only a couple of months of it being under that stress. It is surprising to see how quickly it happens; that is shocking.

The first time people saw, you know, a mass bleaching event was in the early 1980s—never before then. But in 1998, we had the first global event. Then you go to 2010, and it happens again. 2015, 2016, and it's happening again. All that while, it appears that the interval between these events is shortening and their intensity is increasing. We're now in the third global mass bleaching event. This year, we had very warm conditions coming into the summer, plus a strong El Niño, and that then pushed sea temperatures, you know, right to the limit over most of the reef.