How we can revive Planet Earth in less than 20 years | Sean B. Carroll

• Gauging the human impact on life on the planet, that's a pretty touchy subject because on the one hand, humans are a pretty remarkable species. Heck, we're the only species that's left the planet. At the same time, supporting an eight-billion human population is a big burden on the planet. And so, for a lot of biodiversity on the planet, that's been bad news.

But biodiversity is really important to our existence because we rely upon fresh air, fresh water, healthy land, healthy oceans for our own existence. And that's largely the work of creatures on this planet. From earthworms and fungi in our soil to plants and trees that generate the oxygen. And while the loss of biodiversity is extremely concerning, the silver lining here, you might just say the ray of hope that is not talked about nearly enough, is nature's resilience. And how if given a chance, nature can rebound, and nature can rebound dramatically. So let me talk a little bit about the resilience of nature.

1960's: the crisis was things like bald eagles and Peregrine falcons were disappearing. We were down to fewer than 500 breeding pairs of bald eagles in the lower 48 states. That's the national symbol, right, of the United States. When it was discovered that that was because of the use of the DDT pesticide. This DDT was making, for example, their eggs very fragile, and reproduction of these birds collapsed. When DDT was removed from the environment, these populations rebounded. So for example, today, there's more than 70,000 breeding pairs of bald eagles.

Turn of the last century, the fur trade loved otter fur, right? Well, we almost drove otters along the Pacific Rim to extinction. Perhaps down to as few as 1,000 animals. When that trade was banned in the early 20th century, otters came roaring back, and now otter populations are back up 100,000+, etc. Same thing has been seen with whales. Same with manatees, same with Grizzly bears. Take the pressure off, their numbers come back.

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In the 1960s, there was a park really in the geographical center of Mozambique called 'Gorongosa.' It was an incredible concentration of wildlife in the center of the park. Elephants and buffalo, and hippo, and lions, and all that. But Mozambique in the mid-70s after its independence from Portugal had a horrific civil war. Killed a million people, five million people were displaced. And Gorongosa was pretty much the geographic center of that conflict between rebels and government. And so, wildlife were killed for meat. They were poached for things like ivory to be sold on the black market.

Such that by the mid-1990s, you probably had maybe 98% of the large animals of Gorongosa had been decimated. And that's really the way things might exist today if not for an American philanthropist named Greg Carr and the Mozambique government, who formed a partnership in the early 2000s to try to restore Gorongosa National Park.

And I'm really happy to report that Gorongosa is now home to probably 50 times as many large animals as existed there 20 years ago. That the herds of elephant are thriving. That the hippo numbers are growing. That the lions have rebounded from virtually gone to perhaps about 180 individuals. It's a remarkable comeback story because Gorongosa was given up for dead. But it illustrates the general principle that given some seed stock—what was left—and a little bit of introduction, but really small numbers of animals—that nature is resilient.

And not only can nature come back, it can come back in a time period right under our own eyes. We have a stake in the ecological health of the planet. That's just a scientific fact. Let's just take one aspect of something we know we need. We need fresh water.

Well, polluted water doesn't do us much good. Silty water doesn't do us much good. Algal-choked water doesn't do us much good. All those things are the result of not managing the systems around water sensibly. Out in nature, when you see a nice clean stream running off a mountain, the mountain, the soil, and the trees are doing a lot of the work to make that water clear. When we denude a mountain, we cut down the whole forest, and all the dirt runs into the water, then we now have not only silty water, but that will affect the ability of the land to hold the water, and essentially release it slowly over the seasons.

So we're learning—or we've certainly learned sometimes the very hard way—that we need the fresh water. It just turns out that we're given that fresh water by keeping the ecosystem intact. So co-existence could be intentional, it could also just be a by-product of managing ecosystems more sensibly, even for our own benefit.

So the really important fact about biodiversity loss is this generally due to local factors. The silver lining to that is that local action can restore it. I understand with respect to climate change—'cause we globally share a climate—that we need treaties, we need global action, we need countries to act in concert, etc.

And that seems, you know, overwhelming to an individual. But I think there's a lot of room for initiative, a lot of room for joining action in small numbers, and small groups. And that some of this is really just our learning how to coexist. And we don't necessarily have to inconvenience ourselves too much, to just make things a bit more hospitable.

To participate may simply mean thinking about the plants you plant in your garden, or on a windowsill. What you use on your lawn; clean up a pond, or clean up a lake, or something like that. And I don't think it pollyannish. There is time to change the road we're on because in fact, nature can rebound so quickly.

We heard a lot of anecdotes during COVID of animals appearing on our doorsteps, or on a coastline, or whatever it might be. And that's probably just a glimpse of, you know, the way nature would be if we weren't in the way. If I said to you, you know, "In a hundred years things might be better." It's like, "Well, gee—"

But if I tell you that in 5 or 10 years, you'll see an impact of accommodating this ecosystem, or accommodating this species, and in 20 years you might see full recovery—man, that is, that should be motivating. And you know, in some ways it sort of goes to a more philosophical question of, you know, 'What are we doing with our time we spend here on the planet?'

Do we wanna sit in our arm chairs and essentially just forecast doom? Or do we wanna get off our asses and do something?

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