GUY RAZ, HOST:
OK. So it may still be possible to appreciate nature in the future, even as we continue to change what nature is. But we also can't deny that change - it's massive. And in geological time, massive change usually means one thing - extinction.
PETER WARD: Geological time is really a history of gravestones.
RAZ: This is paleontologist...
WARD: Hello, hello. Peter Ward here.
RAZ: ...Peter Ward.
WARD: I am a professor of biology and a professor of Earth and Space Sciences at the University of Washington.
RAZ: And Peter says the age of humans - the Anthropocene - will not just be about how we change the planet, it'll be about what disappears from the planet.
WARD: If you name a new period, it's probably because a lot of stuff died out in the period before. And lo and behold, that certainly has happened.
RAZ: In fact, Peter says most of the species that ever lived on planet Earth have disappeared...
WARD: Oh, yes.
RAZ: ...In five mass extinctions.
WARD: Each of these big mass extinctions has at least half of the species going extinct, and probably way more than that.
RAZ: You probably know about my personal favorite 65 million years ago, when something really big...
WARD: Exactly, a big comet or a big asteroid.
RAZ: ...Slammed into Earth...
RAZ: ...Right near the Gulf of Mexico. And that one asteroid wiped out the dinosaurs and pretty much everything else.
RAZ: And we know of at least one other mass extinction caused by something similar, a giant comet or asteroid. But the other three? Those were caused by big changes in the climate.
WARD: The first of these is the Ordovician Period, somewhere 450 million years ago that particular mass extinction happened.
RAZ: And what happened? It just, like, things just started dying?
WARD: Well, this is the most peculiar and relatively unknown of the five big mass extinctions known from the time of animals. Lots of things started dying. And the things that died mostly were coral reef-type animals, including lots and lots of corals. It's very mysterious, but you had a pretty much reliably tropical world from pole-to-pole.
And all of a sudden, we seem to have gone into a short period of global cooling. And just as if we were to take the beautiful Indo-Pacific coral reefs - the Great Barrier Reef - and stick icebergs around it for a few millennia, I guarantee the Great Barrier Reef would be really dead.
RAZ: So lots of things die, and most of it's sea life in the Ordovician Period. And then I guess about 100 million years later, the - another mass extinction.
WARD: Yes. And the second one is called the Devonian Mass Extinction. And this is one that wasn't caused by it getting colder. This one really appears to have been caused by - it suddenly got really, really hot.
RAZ: And presumably, this was also a problem for the oceans, right?
WARD: Well, heat is a very good killer. And the trouble with - when you heat an ocean, you lose the ability of the upper surface waters to continue to oxygenate the deep waters. And once you stop letting the deep ocean bottoms have oxygen upon them, it kills all the animals.
RAZ: But there was one mass extinction that completely dwarfed the others.
WARD: This was dubbed the mother of all mass extinctions.
WARD: The Permian Extinction.
WARD: The Permian, 251 million years ago. And we had the largest extensive upwelling and extrusion of lava that the world has ever seen.
RAZ: And for reasons that still aren't totally clear, the Earth suddenly got a lot more volcanic. And lava flows spread all across the Earth, giving off massive amounts of CO2.
WARD: These things cover the landscape. But what made the Permian a special killer is that all of these nasty volcanic layers moved into coal-bearing strata and began burning the coal subterranean. And that produced even more carbon dioxide. And so we had this really fast, fast, fast, fast, fast heat spike.
RAZ: Most of been unpleasant?
RAZ: This was known as a runaway greenhouse effect. More CO2 in the atmosphere kept things hotter, kept the lava flowing, which burned more coal, which released more CO2 into the atmosphere, which made things hotter. You get the idea, right? And Peter Ward says that should sound very familiar.
WARD: Oh, absolutely. I mean, what's the difference between a volcano and a Volvo in terms of the gas that comes out of it? I shouldn't say that, I love my Volvo.
WARD: I'm a college professor, come on, what do you think I'm going to drive?
RAZ: Of course.
WARD: So what we're doing is we're starting again one of these - what we call greenhouse extinctions that are caused largely by carbon dioxide and heating. So we are absolutely creating a case where we are killing off species.
RAZ: Peter Ward explains more from the TED stage.
(SOUNDBITE OF TED TALK)
RAZ: We can really now predict what's going to happen to our particular planet. We are right now in the beautiful oreo of existence - of at least life on planet Earth. In the Cambrian explosion, life emerged from the swamps, complexity arose. And from what we can tell, we're halfway through. So our planet, like us, is going to have an age and an old age. And we are in its golden summer age right now.
The Earth has never had any ice on it when we've had a thousand parts-per-million CO2. We are at 380 and climbing. We should be up to 1,000 in three centuries at the most. But my friend David Vatisti (ph) in Seattle says he thinks 100 years. So there goes the ice caps, and there comes 240 feet of sea level rise. I live in a view house now. I'm going to have waterfront.
RAZ: Along with sea level rise, what else is going to happen?
WARD: Well, you could take the optimistic view, or what I think is the realistic view. I think realistically, we are not going to stop fossil fuels being burned, and that we're going to continue to cause carbon dioxide oxide to go up. And we're going to continue to cause sea level to go up. And so that means moving into new areas that perhaps at the moment haven't been formed, and that means deforestation.
So once you do deforestation, then you're taking out a great number of endemic species that we don't see in the fossil record, the insects for instance. The really - creatures that have no latitude in what they eat and where they live and the temperatures, these are the ones that go out. Darwin used the analogy of the wedge - that if there's a new species, it has to wedge something out. Well, we're not just wedging. We're splitting the log in half. And in this particular case, we are - we're certainly dooming a huge number of species from habitat destruction.
RAZ: OK. If that's not enough, there is one final thing we haven't mentioned that could mean even more trouble for the Anthropocene.
WARD: The final aspect of the mass extinction here and the one that should be scariest to us is that people are really watching what's going on in the oceans. We are seeing increasingly low-oxygen areas covering parts of the oceans because we're changing the velocity and the nature of the currents that take oxygen from the surface to the deep.
RAZ: You might remember that happens when the ocean gets warmer. And it causes animals to die. But something else happens, too.
WARD: Four of the 5 mass extinctions were not just accompanied by volcanic gases in the atmosphere. There was also the formation of toxins coming out of bacteria. One of the worst of these is hydrogen sulfide, which is very, very poisonous. And that is what people are most worried about.
(SOUNDBITE OF TED TALK)
WARD: Hydrogen sulfide is very fatal to humans. As small as 200 parts per million will kill you. You only have to go to the Black Sea and a few other places - some lakes - and get down. And you'll find that the water itself turns purple.
It turns purple from the presence of numerous microbes which have to have sunlight and have to have hydrogen sulfide. Now, the worst effect of global warming, it turns out - hydrogen sulfide being produced out of the oceans.
We can easily go back to the hydrogen-sulfide world. Give us a few millennia. And we humans should last those few millennia. Will it happen again? If we continue, it'll happen again. We have a huge problem facing us as a species. We have to beat this.
RAZ: So how are humans different from, you know, all these other species that have gone extinct in the past?
WARD: Oh, humans - come on. We have the golden ticket. We're able to put a coat on if it gets cold. And we're able to build air conditioners if it's too hot. So I think we are essentially extinction-proof. And I fight this concept that we are endangered.
I think we are the least-endangered species on the planet in many respects simply because we have not just the experience but the intelligence to deal with so many of these challenges. And I just think we are going to be the long-term survivals. Now, happiness might be something else.
RAZ: Yeah. I mean, what kind of planet will we survive on, right?
WARD: Well, there's that. I mean, you certainly see all the post-apocalyptic thrillers and the depressing sort of looks into the future. But it really doesn't need to be that way. I think we're just going to see an increasingly manicured planet, an increasingly ordered planet where the wild becomes not wild at all. It's managed wild.
Human civilization - there's no reason that we just can't continue for millions of years into the present with just a modicum of civilization and technology. You can get around this stuff through intelligence.
RAZ: Paleontologist Peter Ward - watch his entire talk at ted.npr.org.
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