Making amends for our impact

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

What? Is this person saying that 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 leafing through the pages of a textbook on historical geology and I chanced on this passage: “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.”

Human beings are uncomfortable with this fact because we feel guilty for accelerating the extinction of so many other species. Our attempts to make amends began with simple measures like nesting boxes for rare owls and wildlife bridges over busy highways — local fixes for local problems — but global warming requires more complex interventions.

Consider the ringed seals of Lake Saimaa, the biggest lake in Finland. They are freshwater seals unique to this lake, and 30 years ago they were nearing extinction. In winter, they used to build shelters into snowbanks on the ice to protect their pups from storms and predators, but in a warming climate the deep snowbanks have disappeared.

So people from Finnish parks and wildlife agencies are going out each winter to create manmade snowdrifts. They even stomp the piled snow down tight, although they leave the final excavation of the dens to the seals themselves. And the seal population has recovered on Lake Saimaa — up to 400 adults at last count.

It’s a much bigger deal when an entire existing ecosystem threatens to go extinct, but the first such event is now knocking at our door: the mass death of the coral reefs.

Almost all the world’s shallowwater coral reef systems are 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.

The thousands of coral species 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.

However, the current array of coral species has a certain economic value to human beings. Moreover, the corals have a powerful emotional importance to the divers (including my family) who 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 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 IVF” (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 the gametes in a net and move them to heat-devastated areas when they can create new colonies.

And then there is the direct method: marine cloud brightening. Stop the bleaching at source by putting a very fine mist of seawater into low-lying clouds so that they reflect incoming sunlight and cool the reefs beneath.

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