Climate Diaries: Mini-satellites help map the Great Barrier Reef

So-called ocean heat waves are happening more often, lasting longer, and becoming more severe. Researchers compare the phenomenon to wildfires on land. But instead of wiping out forests, they destroy kelp, sea grass, and coral reefs underwater. One group of scientists is trying to save coral reefs by cataloging all 150,000 of them worldwide. For his Climate Diaries series, Mark Philips swam along on a recent expedition to the most famous coral reef in the world.