The chatter of gossip distracts us from the really big story, the Anthropocene: the new geological era we are bringing about. Here’s something that should be dominating the headlines: Most of the Great Barrier Reef, the world’s largest coral reef system, now looks like a ghostly graveyard.
Most corals are colonies of tiny genetically identical animals called polyps. Over centuries, their skeletons build up reefs, which are havens for many kinds of sea life. Some polyps catch their own food using stingers. But most get their food by symbiosis! They cooperate with single-celled organism called zooxanthellae. Zooxanthellae get energy from the sun’s light. They actually live inside the polyps, and provide them with food. Most of the color of a coral reef comes from these zooxanthellae.
When a polyp is stressed, the zooxanthellae living inside it may decide to leave. This can happen when the sea water gets too hot. Without its zooxanthellae, the polyp is transparent and the coral’s white skeleton is revealed—as you see here. We say the coral is bleached.
After they bleach, the polyps begin to starve. If conditions return to normal fast enough, the zooxanthellae may come back. If they don’t, the coral will die.
The Great Barrier Reef, off the northeast coast of Australia, contains over 2,900 reefs and 900 islands. It’s huge: 2,300 kilometers long, with an area of about 340,000 square kilometers. It can be seen from outer space!
With global warming, this reef has been starting to bleach. Parts of it bleached in 1998 and again in 2002. But this year, with a big El Niño pushing world temperatures to new record highs, is the worst.
Scientists have being flying over the Great Barrier Reef to study the damage, and divers have looked at some of the reefs in detail. Of the 522 reefs surveyed in the northern sector, over 80% are severely bleached and less than 1% are not bleached at all. The damage is less further south where the water is cooler—but most of the reefs are in the north:
The top expert on coral reefs in Australia, Terry Hughes, wrote:
I showed the results of aerial surveys of bleaching on the Great Barrier Reef to my students. And then we wept.
Imagine devoting your life to studying and trying to protect coral reefs, and then seeing this.
Some of the bleached reefs may recover. But as oceans continue to warm, the prospects look bleak. The last big El Niño was in 1998. With a lot of hard followup work, scientists showed that in the end, 16% of the world’s corals died in that event.
This year is quite a bit hotter.
So, global warming is not a problem for the future: it’s a problem now. It’s not good enough to cut carbon emissions eventually. We’ve got to get serious now.
I need to recommit myself to this. For example, I need to stop flying around to conferences. I’ve cut back, but I need to do much better. Future generations, living in the damaged world we’re creating, will not have much sympathy for our excuses.