Corals will regenerate, even if humans aren't here to see it

Evolution a continuous cycle of extinction, diversification

“Without extinction, there would likely be insufficient ecological space available for new species.”

What? Is this person saying extinction is a good thing? But what about the scarlet-throated goat-botherer? There's only 23 of them left in the wild, and half of them live on the slopes of an active volcano. We must do something.

Not necessarily. I was idly leafing through the pages of a textbook on historical geology, and I chanced on the following sentence:

“The pattern we see in the fossil record is not one of continuous diversification with new species being added, but none ever removed. Instead, the average species lasts a few million years, and then vanishes forever from the face of the planet. It goes extinct.”

It's a kind of consolation, although not a very warm one. And it's relevant to our current situation, because the first extinction of an entire existing ecosystem is now knocking at our door: the mass death of the coral reefs.

Almost all the world's shallow-water coral reef systems are now suffering bleaching episodes that leave them severely damaged or dead. It's a direct result of global warming: the added heat causes the little coral animals to expel the algae that provide most of their food. Then, they starve to death, leaving only the bleached “bones” behind.

That's a poor design for the present circumstances, although it must have had some

Given how many other environmental crises we are facing, however, we could be excused for letting the corals go.

practical benefit in the past to make it through the evolutionary process at all. Given how many other environmental crises we are facing, however, we could be excused for letting the corals go.

After all they died back, or even died out, in each of the five great extinction episodes of the past half-billion years, only for identical or similar creatures to recolonize the reefs when the climate moderated again. As Ariel suggests in William Shakespeare's The Tempest, nothing is ever really lost. It just “suffers a sea change into something rich and strange.”

However, the current array of coral species is estimated to have an economic value to human beings (though surely not the $6 trillion claimed by the World Wildlife Fund). Moreover, they have a powerful emotional importance to the divers (including my entire family) who actually spend time with them. So, many people are trying to save them.

The effort that has made the most progress is an attempt at assisted evolution. It's really a glorified form of selective breeding, choosing the most heat-resistant of each generation of coral polyps as the parents of the next generation and discarding the rest. This may or may not include direct genetic modification of the corals or their symbiotic algae.

A second intervention is working on a sort of coral in vitro fertilization in which the goal is to ensure a large proportion of the gametes (male and female) that are released into the ocean when corals breed actually take root.

This may involve coral condoms to capture large numbers of the fertilized gametes in a cone-shaped net and move them to heat-devastated areas when they can create new colonies. Weirdly intrusive, but it seems to work.

And then, there is the direct method: Marine cloud brightening (MCB). Put a very fine mist of sea water into low-lying clouds so they reflect incoming sunlight and cool the reefs beneath. Stop the bleaching at source.

And if it all fails, don't feel bad. The corals will be back for the next iteration, even if we aren't.