[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:02.00,Default,,0000,0000,0000,,So, I want to start out with
Dialogue: 0,0:00:02.00,0:00:04.00,Default,,0000,0000,0000,,this beautiful picture from my childhood.
Dialogue: 0,0:00:04.00,0:00:06.00,Default,,0000,0000,0000,,I love the science fiction movies.
Dialogue: 0,0:00:06.00,0:00:08.00,Default,,0000,0000,0000,,Here it is: "This Island Earth."
Dialogue: 0,0:00:08.00,0:00:10.00,Default,,0000,0000,0000,,And leave it to Hollywood to get it just right.
Dialogue: 0,0:00:10.00,0:00:12.00,Default,,0000,0000,0000,,Two-and-a-half years in the making.
Dialogue: 0,0:00:12.00,0:00:15.00,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:00:15.00,0:00:18.00,Default,,0000,0000,0000,,I mean, even the creationists give us 6,000,
Dialogue: 0,0:00:18.00,0:00:20.00,Default,,0000,0000,0000,,but Hollywood goes to the chase.
Dialogue: 0,0:00:20.00,0:00:24.00,Default,,0000,0000,0000,,And in this movie, we see what we think is out there:
Dialogue: 0,0:00:24.00,0:00:27.00,Default,,0000,0000,0000,,flying saucers and aliens.
Dialogue: 0,0:00:27.00,0:00:30.00,Default,,0000,0000,0000,,Every world has an alien, and every alien world has a flying saucer,
Dialogue: 0,0:00:30.00,0:00:34.00,Default,,0000,0000,0000,,and they move about with great speed. Aliens.
Dialogue: 0,0:00:35.00,0:00:38.00,Default,,0000,0000,0000,,Well, Don Brownlee, my friend, and I finally got to the point
Dialogue: 0,0:00:38.00,0:00:41.00,Default,,0000,0000,0000,,where we got tired of turning on the TV
Dialogue: 0,0:00:41.00,0:00:44.00,Default,,0000,0000,0000,,and seeing the spaceships and seeing the aliens every night,
Dialogue: 0,0:00:44.00,0:00:47.00,Default,,0000,0000,0000,,and tried to write a counter-argument to it,
Dialogue: 0,0:00:47.00,0:00:51.00,Default,,0000,0000,0000,,and put out what does it really take for an Earth to be habitable,
Dialogue: 0,0:00:51.00,0:00:53.00,Default,,0000,0000,0000,,for a planet to be an Earth, to have a place
Dialogue: 0,0:00:53.00,0:00:56.00,Default,,0000,0000,0000,,where you could probably get not just life, but complexity,
Dialogue: 0,0:00:56.00,0:00:58.00,Default,,0000,0000,0000,,which requires a huge amount of evolution,
Dialogue: 0,0:00:58.00,0:01:01.00,Default,,0000,0000,0000,,and therefore constancy of conditions.
Dialogue: 0,0:01:01.00,0:01:04.00,Default,,0000,0000,0000,,So, in 2000 we wrote "Rare Earth." In 2003, we then asked,
Dialogue: 0,0:01:04.00,0:01:09.00,Default,,0000,0000,0000,,let's not think about where Earths are in space, but how long has Earth been Earth?
Dialogue: 0,0:01:09.00,0:01:11.00,Default,,0000,0000,0000,,If you go back two billion years,
Dialogue: 0,0:01:11.00,0:01:13.00,Default,,0000,0000,0000,,you're not on an Earth-like planet any more.
Dialogue: 0,0:01:13.00,0:01:17.00,Default,,0000,0000,0000,,What we call an Earth-like planet is actually a very short interval of time.
Dialogue: 0,0:01:17.00,0:01:19.00,Default,,0000,0000,0000,,Well, "Rare Earth" actually
Dialogue: 0,0:01:19.00,0:01:22.00,Default,,0000,0000,0000,,taught me an awful lot about meeting the public.
Dialogue: 0,0:01:22.00,0:01:25.00,Default,,0000,0000,0000,,Right after, I got an invitation to go to a science fiction convention,
Dialogue: 0,0:01:25.00,0:01:28.00,Default,,0000,0000,0000,,and with all great earnestness walked in.
Dialogue: 0,0:01:28.00,0:01:30.00,Default,,0000,0000,0000,,David Brin was going to debate me on this,
Dialogue: 0,0:01:30.00,0:01:34.00,Default,,0000,0000,0000,,and as I walked in, the crowd of a hundred started booing lustily.
Dialogue: 0,0:01:34.00,0:01:37.00,Default,,0000,0000,0000,,I had a girl who came up who said, "My dad says you're the devil."
Dialogue: 0,0:01:37.00,0:01:41.00,Default,,0000,0000,0000,,You cannot take people's aliens away from them
Dialogue: 0,0:01:41.00,0:01:45.00,Default,,0000,0000,0000,,and expect to be anybody's friends.
Dialogue: 0,0:01:45.00,0:01:47.00,Default,,0000,0000,0000,,Well, the second part of that, soon after --
Dialogue: 0,0:01:47.00,0:01:50.00,Default,,0000,0000,0000,,and I was talking to Paul Allen; I saw him in the audience,
Dialogue: 0,0:01:50.00,0:01:52.00,Default,,0000,0000,0000,,and I handed him a copy of "Rare Earth."
Dialogue: 0,0:01:52.00,0:01:56.00,Default,,0000,0000,0000,,And Jill Tarter was there, and she turned to me,
Dialogue: 0,0:01:56.00,0:01:59.00,Default,,0000,0000,0000,,and she looked at me just like that girl in "The Exorcist."
Dialogue: 0,0:01:59.00,0:02:01.00,Default,,0000,0000,0000,,It was, "It burns! It burns!"
Dialogue: 0,0:02:01.00,0:02:03.00,Default,,0000,0000,0000,,Because SETI doesn't want to hear this.
Dialogue: 0,0:02:03.00,0:02:06.00,Default,,0000,0000,0000,,SETI wants there to be stuff out there.
Dialogue: 0,0:02:06.00,0:02:09.00,Default,,0000,0000,0000,,I really applaud the SETI efforts, but we have not heard anything yet.
Dialogue: 0,0:02:09.00,0:02:11.00,Default,,0000,0000,0000,,And I really do think we have to start thinking
Dialogue: 0,0:02:11.00,0:02:14.00,Default,,0000,0000,0000,,about what's a good planet and what isn't.
Dialogue: 0,0:02:14.00,0:02:17.00,Default,,0000,0000,0000,,Now, I throw this slide up because it indicates to me that,
Dialogue: 0,0:02:17.00,0:02:21.00,Default,,0000,0000,0000,,even if SETI does hear something, can we figure out what they said?
Dialogue: 0,0:02:21.00,0:02:23.00,Default,,0000,0000,0000,,Because this was a slide that was passed
Dialogue: 0,0:02:23.00,0:02:27.00,Default,,0000,0000,0000,,between the two major intelligences on Earth -- a Mac to a PC --
Dialogue: 0,0:02:27.00,0:02:30.00,Default,,0000,0000,0000,,and it can't even get the letters right --
Dialogue: 0,0:02:30.00,0:02:32.00,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:02:32.00,0:02:34.00,Default,,0000,0000,0000,,-- so how are we going to talk to the aliens?
Dialogue: 0,0:02:34.00,0:02:37.00,Default,,0000,0000,0000,,And if they're 50 light years away, and we call them up,
Dialogue: 0,0:02:37.00,0:02:39.00,Default,,0000,0000,0000,,and you blah, blah, blah, blah, blah,
Dialogue: 0,0:02:39.00,0:02:42.00,Default,,0000,0000,0000,,and then 50 years later it comes back and they say, Please repeat?
Dialogue: 0,0:02:42.00,0:02:44.00,Default,,0000,0000,0000,,I mean, there we are.
Dialogue: 0,0:02:44.00,0:02:47.00,Default,,0000,0000,0000,,Our planet is a good planet because it can keep water.
Dialogue: 0,0:02:47.00,0:02:51.00,Default,,0000,0000,0000,,Mars is a bad planet, but it's still good enough for us to go there
Dialogue: 0,0:02:51.00,0:02:53.00,Default,,0000,0000,0000,,and to live on its surface if we're protected.
Dialogue: 0,0:02:53.00,0:02:56.00,Default,,0000,0000,0000,,But Venus is a very bad -- the worst -- planet.
Dialogue: 0,0:02:56.00,0:02:59.00,Default,,0000,0000,0000,,Even though it's Earth-like, and even though early in its history
Dialogue: 0,0:02:59.00,0:03:02.00,Default,,0000,0000,0000,,it may very well have harbored Earth-like life,
Dialogue: 0,0:03:02.00,0:03:05.00,Default,,0000,0000,0000,,it soon succumbed to runaway greenhouse --
Dialogue: 0,0:03:05.00,0:03:07.00,Default,,0000,0000,0000,,that's an 800 degrees [Fahrenheit] surface --
Dialogue: 0,0:03:07.00,0:03:10.00,Default,,0000,0000,0000,,because of rampant carbon dioxide.
Dialogue: 0,0:03:10.00,0:03:13.00,Default,,0000,0000,0000,,Well, we know from astrobiology that we can really now predict
Dialogue: 0,0:03:13.00,0:03:16.00,Default,,0000,0000,0000,,what's going to happen to our particular planet.
Dialogue: 0,0:03:16.00,0:03:19.00,Default,,0000,0000,0000,,We are right now in the beautiful Oreo
Dialogue: 0,0:03:19.00,0:03:22.00,Default,,0000,0000,0000,,of existence -- of at least life on Planet Earth --
Dialogue: 0,0:03:22.00,0:03:25.00,Default,,0000,0000,0000,,following the first horrible microbial age.
Dialogue: 0,0:03:25.00,0:03:28.00,Default,,0000,0000,0000,,In the Cambrian explosion, life emerged from the swamps,
Dialogue: 0,0:03:28.00,0:03:30.00,Default,,0000,0000,0000,,complexity arose,
Dialogue: 0,0:03:30.00,0:03:33.00,Default,,0000,0000,0000,,and from what we can tell, we're halfway through.
Dialogue: 0,0:03:33.00,0:03:36.00,Default,,0000,0000,0000,,We have as much time for animals to exist on this planet
Dialogue: 0,0:03:36.00,0:03:38.00,Default,,0000,0000,0000,,as they have been here now,
Dialogue: 0,0:03:38.00,0:03:40.00,Default,,0000,0000,0000,,till we hit the second microbial age.
Dialogue: 0,0:03:40.00,0:03:42.00,Default,,0000,0000,0000,,And that will happen, paradoxically --
Dialogue: 0,0:03:42.00,0:03:44.00,Default,,0000,0000,0000,,everything you hear about global warming --
Dialogue: 0,0:03:44.00,0:03:47.00,Default,,0000,0000,0000,,when we hit CO2 down to 10 parts per million,
Dialogue: 0,0:03:47.00,0:03:49.00,Default,,0000,0000,0000,,we are no longer going to have to have plants
Dialogue: 0,0:03:49.00,0:03:53.00,Default,,0000,0000,0000,,that are allowed to have any photosynthesis, and there go animals.
Dialogue: 0,0:03:53.00,0:03:55.00,Default,,0000,0000,0000,,So, after that we probably have seven billion years.
Dialogue: 0,0:03:55.00,0:03:58.00,Default,,0000,0000,0000,,The Sun increases in its intensity, in its brightness,
Dialogue: 0,0:03:58.00,0:04:03.00,Default,,0000,0000,0000,,and finally, at about 12 billion years after it first started,
Dialogue: 0,0:04:03.00,0:04:06.00,Default,,0000,0000,0000,,the Earth is consumed by a large Sun,
Dialogue: 0,0:04:06.00,0:04:09.00,Default,,0000,0000,0000,,and this is what's left.
Dialogue: 0,0:04:09.00,0:04:13.00,Default,,0000,0000,0000,,So, a planet like us is going to have an age and an old age,
Dialogue: 0,0:04:13.00,0:04:17.00,Default,,0000,0000,0000,,and we are in its golden summer age right now.
Dialogue: 0,0:04:17.00,0:04:19.00,Default,,0000,0000,0000,,But there's two fates to everything, isn't there?
Dialogue: 0,0:04:19.00,0:04:22.00,Default,,0000,0000,0000,,Now, a lot of you are going to die of old age,
Dialogue: 0,0:04:22.00,0:04:25.00,Default,,0000,0000,0000,,but some of you, horribly enough, are going to die in an accident.
Dialogue: 0,0:04:25.00,0:04:27.00,Default,,0000,0000,0000,,And that's the fate of a planet, too.
Dialogue: 0,0:04:27.00,0:04:31.00,Default,,0000,0000,0000,,Earth, if we're lucky enough -- if it doesn't get hit by a Hale-Bopp,
Dialogue: 0,0:04:31.00,0:04:35.00,Default,,0000,0000,0000,,or gets blasted by some supernova nearby
Dialogue: 0,0:04:35.00,0:04:38.00,Default,,0000,0000,0000,,in the next seven billion years -- we'll find under your feet.
Dialogue: 0,0:04:38.00,0:04:40.00,Default,,0000,0000,0000,,But what about accidental death?
Dialogue: 0,0:04:40.00,0:04:42.00,Default,,0000,0000,0000,,Well, paleontologists for the last 200 years
Dialogue: 0,0:04:42.00,0:04:44.00,Default,,0000,0000,0000,,have been charting death. It's strange --
Dialogue: 0,0:04:44.00,0:04:47.00,Default,,0000,0000,0000,,extinction as a concept wasn't even thought about
Dialogue: 0,0:04:47.00,0:04:50.00,Default,,0000,0000,0000,,until Baron Cuvier in France found this first mastodon.
Dialogue: 0,0:04:50.00,0:04:52.00,Default,,0000,0000,0000,,He couldn't match it up to any bones on the planet,
Dialogue: 0,0:04:52.00,0:04:54.00,Default,,0000,0000,0000,,and he said, Aha! It's extinct.
Dialogue: 0,0:04:54.00,0:04:57.00,Default,,0000,0000,0000,,And very soon after, the fossil record started yielding
Dialogue: 0,0:04:57.00,0:05:00.00,Default,,0000,0000,0000,,a very good idea of how many plants and animals there have been
Dialogue: 0,0:05:00.00,0:05:02.00,Default,,0000,0000,0000,,since complex life really began to leave
Dialogue: 0,0:05:02.00,0:05:05.00,Default,,0000,0000,0000,,a very interesting fossil record.
Dialogue: 0,0:05:05.00,0:05:08.00,Default,,0000,0000,0000,,In that complex record of fossils,
Dialogue: 0,0:05:08.00,0:05:10.00,Default,,0000,0000,0000,,there were times when lots of stuff
Dialogue: 0,0:05:10.00,0:05:12.00,Default,,0000,0000,0000,,seemed to be dying out very quickly,
Dialogue: 0,0:05:12.00,0:05:14.00,Default,,0000,0000,0000,,and the father/mother geologists
Dialogue: 0,0:05:14.00,0:05:16.00,Default,,0000,0000,0000,,called these "mass extinctions."
Dialogue: 0,0:05:16.00,0:05:18.00,Default,,0000,0000,0000,,All along it was thought to be either an act of God
Dialogue: 0,0:05:18.00,0:05:20.00,Default,,0000,0000,0000,,or perhaps long, slow climate change, \N
Dialogue: 0,0:05:20.00,0:05:22.00,Default,,0000,0000,0000,,and that really changed in 1980,
Dialogue: 0,0:05:22.00,0:05:25.00,Default,,0000,0000,0000,,in this rocky outcrop near Gubbio,
Dialogue: 0,0:05:25.00,0:05:28.00,Default,,0000,0000,0000,,where Walter Alvarez, trying to figure out
Dialogue: 0,0:05:28.00,0:05:31.00,Default,,0000,0000,0000,,what was the time difference between these white rocks,
Dialogue: 0,0:05:31.00,0:05:33.00,Default,,0000,0000,0000,,which held creatures of the Cretaceous period,
Dialogue: 0,0:05:33.00,0:05:35.00,Default,,0000,0000,0000,,and the pink rocks above, which held Tertiary fossils.
Dialogue: 0,0:05:35.00,0:05:39.00,Default,,0000,0000,0000,,How long did it take to go from one system to the next?
Dialogue: 0,0:05:39.00,0:05:41.00,Default,,0000,0000,0000,,And what they found was something unexpected.
Dialogue: 0,0:05:41.00,0:05:44.00,Default,,0000,0000,0000,,They found in this gap, in between, a very thin clay layer,
Dialogue: 0,0:05:44.00,0:05:47.00,Default,,0000,0000,0000,,and that clay layer -- this very thin red layer here --
Dialogue: 0,0:05:47.00,0:05:49.00,Default,,0000,0000,0000,,is filled with iridium.
Dialogue: 0,0:05:49.00,0:05:52.00,Default,,0000,0000,0000,,And not just iridium; it's filled with glassy spherules,
Dialogue: 0,0:05:52.00,0:05:54.00,Default,,0000,0000,0000,,and it's filled with quartz grains
Dialogue: 0,0:05:54.00,0:05:58.00,Default,,0000,0000,0000,,that have been subjected to enormous pressure: shock quartz.
Dialogue: 0,0:05:58.00,0:06:00.00,Default,,0000,0000,0000,,Now, in this slide the white is chalk,
Dialogue: 0,0:06:00.00,0:06:03.00,Default,,0000,0000,0000,,and this chalk was deposited in a warm ocean.
Dialogue: 0,0:06:03.00,0:06:05.00,Default,,0000,0000,0000,,The chalk itself's composed by plankton
Dialogue: 0,0:06:05.00,0:06:09.00,Default,,0000,0000,0000,,which has fallen down from the sea surface onto the sea floor,
Dialogue: 0,0:06:09.00,0:06:12.00,Default,,0000,0000,0000,,so that 90 percent of the sediment here is skeleton of living stuff,
Dialogue: 0,0:06:12.00,0:06:14.00,Default,,0000,0000,0000,,and then you have that millimeter-thick red layer,
Dialogue: 0,0:06:14.00,0:06:16.00,Default,,0000,0000,0000,,and then you have black rock.
Dialogue: 0,0:06:16.00,0:06:19.00,Default,,0000,0000,0000,,And the black rock is the sediment on the sea bottom
Dialogue: 0,0:06:19.00,0:06:21.00,Default,,0000,0000,0000,,in the absence of plankton.
Dialogue: 0,0:06:21.00,0:06:25.00,Default,,0000,0000,0000,,And that's what happens in an asteroid catastrophe,
Dialogue: 0,0:06:25.00,0:06:28.00,Default,,0000,0000,0000,,because that's what this was, of course. This is the famous K-T.
Dialogue: 0,0:06:28.00,0:06:30.00,Default,,0000,0000,0000,,A 10-kilometer body hit the planet.
Dialogue: 0,0:06:30.00,0:06:34.00,Default,,0000,0000,0000,,The effects of it spread this very thin impact layer all over the planet,
Dialogue: 0,0:06:34.00,0:06:37.00,Default,,0000,0000,0000,,and we had very quickly the death of the dinosaurs,
Dialogue: 0,0:06:37.00,0:06:39.00,Default,,0000,0000,0000,,the death of these beautiful ammonites,
Dialogue: 0,0:06:39.00,0:06:41.00,Default,,0000,0000,0000,,Leconteiceras here, and Celaeceras over here,
Dialogue: 0,0:06:41.00,0:06:43.00,Default,,0000,0000,0000,,and so much else.
Dialogue: 0,0:06:43.00,0:06:45.00,Default,,0000,0000,0000,,I mean, it must be true,
Dialogue: 0,0:06:45.00,0:06:48.00,Default,,0000,0000,0000,,because we've had two Hollywood blockbusters since that time,
Dialogue: 0,0:06:48.00,0:06:51.00,Default,,0000,0000,0000,,and this paradigm, from 1980 to about 2000,
Dialogue: 0,0:06:51.00,0:06:56.00,Default,,0000,0000,0000,,totally changed how we geologists thought about catastrophes.
Dialogue: 0,0:06:56.00,0:06:59.00,Default,,0000,0000,0000,,Prior to that, uniformitarianism was the dominant paradigm:
Dialogue: 0,0:06:59.00,0:07:02.00,Default,,0000,0000,0000,,the fact that if anything happens on the planet in the past,
Dialogue: 0,0:07:02.00,0:07:06.00,Default,,0000,0000,0000,,there are present-day processes that will explain it.
Dialogue: 0,0:07:06.00,0:07:09.00,Default,,0000,0000,0000,,But we haven't witnessed a big asteroid impact,
Dialogue: 0,0:07:09.00,0:07:11.00,Default,,0000,0000,0000,,so this is a type of neo-catastrophism,
Dialogue: 0,0:07:11.00,0:07:14.00,Default,,0000,0000,0000,,and it took about 20 years for the scientific establishment
Dialogue: 0,0:07:14.00,0:07:16.00,Default,,0000,0000,0000,,to finally come to grips: yes, we were hit;
Dialogue: 0,0:07:16.00,0:07:20.00,Default,,0000,0000,0000,,and yes, the effects of that hit caused a major mass extinction.
Dialogue: 0,0:07:21.00,0:07:23.00,Default,,0000,0000,0000,,Well, there are five major mass extinctions \N
Dialogue: 0,0:07:23.00,0:07:26.00,Default,,0000,0000,0000,,over the last 500 million years, called the Big Five.
Dialogue: 0,0:07:26.00,0:07:29.00,Default,,0000,0000,0000,,They range from 450 million years ago
Dialogue: 0,0:07:29.00,0:07:31.00,Default,,0000,0000,0000,,to the last, the K-T, number four,
Dialogue: 0,0:07:31.00,0:07:35.00,Default,,0000,0000,0000,,but the biggest of all was the P, or the Permian extinction,
Dialogue: 0,0:07:35.00,0:07:37.00,Default,,0000,0000,0000,,sometimes called the mother of all mass extinctions.
Dialogue: 0,0:07:37.00,0:07:40.00,Default,,0000,0000,0000,,And every one of these has been subsequently blamed
Dialogue: 0,0:07:40.00,0:07:42.00,Default,,0000,0000,0000,,on large-body impact.
Dialogue: 0,0:07:42.00,0:07:44.00,Default,,0000,0000,0000,,But is this true?
Dialogue: 0,0:07:45.00,0:07:48.00,Default,,0000,0000,0000,,The most recent, the Permian, was thought to have been an impact
Dialogue: 0,0:07:48.00,0:07:50.00,Default,,0000,0000,0000,,because of this beautiful structure on the right.
Dialogue: 0,0:07:50.00,0:07:53.00,Default,,0000,0000,0000,,This is a Buckminsterfullerene, a carbon-60.
Dialogue: 0,0:07:53.00,0:07:56.00,Default,,0000,0000,0000,,Because it looks like those terrible geodesic domes
Dialogue: 0,0:07:56.00,0:07:58.00,Default,,0000,0000,0000,,of my late beloved '60s,
Dialogue: 0,0:07:58.00,0:08:00.00,Default,,0000,0000,0000,,they're called "buckyballs."
Dialogue: 0,0:08:00.00,0:08:02.00,Default,,0000,0000,0000,,This evidence was used to suggest
Dialogue: 0,0:08:02.00,0:08:06.00,Default,,0000,0000,0000,,that at the end of the Permian, 250 million years ago, a comet hit us.
Dialogue: 0,0:08:06.00,0:08:09.00,Default,,0000,0000,0000,,And when the comet hits, the pressure produces the buckyballs,
Dialogue: 0,0:08:09.00,0:08:11.00,Default,,0000,0000,0000,,and it captures bits of the comet.
Dialogue: 0,0:08:11.00,0:08:15.00,Default,,0000,0000,0000,,Helium-3: very rare on the surface of the Earth, very common in space.
Dialogue: 0,0:08:16.00,0:08:18.00,Default,,0000,0000,0000,,But is this true?
Dialogue: 0,0:08:18.00,0:08:22.00,Default,,0000,0000,0000,,In 1990, working on the K-T extinction for 10 years,
Dialogue: 0,0:08:22.00,0:08:25.00,Default,,0000,0000,0000,,I moved to South Africa to begin work twice a year
Dialogue: 0,0:08:25.00,0:08:27.00,Default,,0000,0000,0000,,in the great Karoo desert.
Dialogue: 0,0:08:27.00,0:08:30.00,Default,,0000,0000,0000,,I was so lucky to watch the change of that South Africa
Dialogue: 0,0:08:30.00,0:08:33.00,Default,,0000,0000,0000,,into the new South Africa as I went year by year.
Dialogue: 0,0:08:33.00,0:08:35.00,Default,,0000,0000,0000,,And I worked on this Permian extinction,
Dialogue: 0,0:08:35.00,0:08:38.00,Default,,0000,0000,0000,,camping by this Boer graveyard for months at a time.
Dialogue: 0,0:08:38.00,0:08:41.00,Default,,0000,0000,0000,,And the fossils are extraordinary.
Dialogue: 0,0:08:41.00,0:08:43.00,Default,,0000,0000,0000,,You know, you're gazing upon your very distant ancestors.
Dialogue: 0,0:08:43.00,0:08:45.00,Default,,0000,0000,0000,,These are mammal-like reptiles.
Dialogue: 0,0:08:45.00,0:08:48.00,Default,,0000,0000,0000,,They are culturally invisible. We do not make movies about these.
Dialogue: 0,0:08:48.00,0:08:50.00,Default,,0000,0000,0000,,This is a Gorgonopsian, or a Gorgon.
Dialogue: 0,0:08:50.00,0:08:54.00,Default,,0000,0000,0000,,That's an 18-inch long skull of an animal
Dialogue: 0,0:08:54.00,0:08:58.00,Default,,0000,0000,0000,,that was probably seven or eight feet, sprawled like a lizard,
Dialogue: 0,0:08:58.00,0:09:00.00,Default,,0000,0000,0000,,probably had a head like a lion.
Dialogue: 0,0:09:00.00,0:09:02.00,Default,,0000,0000,0000,,This is the top carnivore, the T-Rex of its time.
Dialogue: 0,0:09:02.00,0:09:04.00,Default,,0000,0000,0000,,But there's lots of stuff.
Dialogue: 0,0:09:04.00,0:09:06.00,Default,,0000,0000,0000,,This is my poor son, Patrick.
Dialogue: 0,0:09:06.00,0:09:07.00,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:09:07.00,0:09:10.00,Default,,0000,0000,0000,,This is called paleontological child abuse.
Dialogue: 0,0:09:10.00,0:09:12.00,Default,,0000,0000,0000,,Hold still, you're the scale.
Dialogue: 0,0:09:12.00,0:09:17.00,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:09:18.00,0:09:21.00,Default,,0000,0000,0000,,There was big stuff back then.
Dialogue: 0,0:09:21.00,0:09:24.00,Default,,0000,0000,0000,,Fifty-five species of mammal-like reptiles.
Dialogue: 0,0:09:24.00,0:09:27.00,Default,,0000,0000,0000,,The age of mammals had well and truly started
Dialogue: 0,0:09:27.00,0:09:29.00,Default,,0000,0000,0000,,250 million years ago ...
Dialogue: 0,0:09:29.00,0:09:32.00,Default,,0000,0000,0000,,... and then a catastrophe happened.
Dialogue: 0,0:09:32.00,0:09:34.00,Default,,0000,0000,0000,,And what happens next is the age of dinosaurs.
Dialogue: 0,0:09:34.00,0:09:38.00,Default,,0000,0000,0000,,It was all a mistake; it should have never happened. But it did.
Dialogue: 0,0:09:38.00,0:09:40.00,Default,,0000,0000,0000,,Now, luckily,
Dialogue: 0,0:09:40.00,0:09:43.00,Default,,0000,0000,0000,,this Thrinaxodon, the size of a robin egg here:
Dialogue: 0,0:09:43.00,0:09:46.00,Default,,0000,0000,0000,,this is a skull I've discovered just before taking this picture --
Dialogue: 0,0:09:46.00,0:09:48.00,Default,,0000,0000,0000,,there's a pen for scale; it's really tiny --
Dialogue: 0,0:09:48.00,0:09:52.00,Default,,0000,0000,0000,,this is in the Lower Triassic, after the mass extinction has finished.
Dialogue: 0,0:09:52.00,0:09:55.00,Default,,0000,0000,0000,,You can see the eye socket and you can see the little teeth in the front.
Dialogue: 0,0:09:55.00,0:10:00.00,Default,,0000,0000,0000,,If that does not survive, I'm not the thing giving this talk.
Dialogue: 0,0:10:00.00,0:10:04.00,Default,,0000,0000,0000,,Something else is, because if that doesn't survive, we are not here;
Dialogue: 0,0:10:04.00,0:10:08.00,Default,,0000,0000,0000,,there are no mammals. It's that close; one species ekes through.
Dialogue: 0,0:10:08.00,0:10:11.00,Default,,0000,0000,0000,,Well, can we say anything about the pattern of who survives and who doesn't?
Dialogue: 0,0:10:11.00,0:10:13.00,Default,,0000,0000,0000,,Here's sort of the end of that 10 years of work.
Dialogue: 0,0:10:13.00,0:10:16.00,Default,,0000,0000,0000,,The ranges of stuff -- the red line is the mass extinction.
Dialogue: 0,0:10:16.00,0:10:18.00,Default,,0000,0000,0000,,But we've got survivors and things that get through,
Dialogue: 0,0:10:18.00,0:10:22.00,Default,,0000,0000,0000,,and it turns out the things that get through preferentially are cold bloods.
Dialogue: 0,0:10:22.00,0:10:26.00,Default,,0000,0000,0000,,Warm-blooded animals take a huge hit at this time.
Dialogue: 0,0:10:27.00,0:10:29.00,Default,,0000,0000,0000,,The survivors that do get through \N
Dialogue: 0,0:10:29.00,0:10:32.00,Default,,0000,0000,0000,,produce this world of crocodile-like creatures.
Dialogue: 0,0:10:32.00,0:10:36.00,Default,,0000,0000,0000,,There's no dinosaurs yet; just this slow, saurian, scaly, nasty,
Dialogue: 0,0:10:36.00,0:10:41.00,Default,,0000,0000,0000,,swampy place with a couple of tiny mammals hiding in the fringes.
Dialogue: 0,0:10:41.00,0:10:44.00,Default,,0000,0000,0000,,And there they would hide for 160 million years,
Dialogue: 0,0:10:44.00,0:10:47.00,Default,,0000,0000,0000,,until liberated by that K-T asteroid.
Dialogue: 0,0:10:47.00,0:10:49.00,Default,,0000,0000,0000,,So, if not impact, what?
Dialogue: 0,0:10:49.00,0:10:53.00,Default,,0000,0000,0000,,And the what, I think, is that we returned, over and over again,
Dialogue: 0,0:10:53.00,0:10:56.00,Default,,0000,0000,0000,,to the Pre-Cambrian world, that first microbial age,
Dialogue: 0,0:10:56.00,0:10:58.00,Default,,0000,0000,0000,,and the microbes are still out there.
Dialogue: 0,0:10:58.00,0:11:00.00,Default,,0000,0000,0000,,They hate we animals.
Dialogue: 0,0:11:00.00,0:11:02.00,Default,,0000,0000,0000,,They really want their world back.
Dialogue: 0,0:11:02.00,0:11:06.00,Default,,0000,0000,0000,,And they've tried over and over and over again.
Dialogue: 0,0:11:06.00,0:11:09.00,Default,,0000,0000,0000,,This suggests to me that life causing these mass extinctions
Dialogue: 0,0:11:09.00,0:11:12.00,Default,,0000,0000,0000,,because it did is inherently anti-Gaian.
Dialogue: 0,0:11:12.00,0:11:17.00,Default,,0000,0000,0000,,This whole Gaia idea, that life makes the world better for itself --
Dialogue: 0,0:11:17.00,0:11:21.00,Default,,0000,0000,0000,,anybody been on a freeway on a Friday afternoon in Los Angeles
Dialogue: 0,0:11:21.00,0:11:23.00,Default,,0000,0000,0000,,believing in the Gaia theory? No.
Dialogue: 0,0:11:23.00,0:11:26.00,Default,,0000,0000,0000,,So, I really suspect there's an alternative,
Dialogue: 0,0:11:26.00,0:11:28.00,Default,,0000,0000,0000,,and that life does actually try to do itself in --
Dialogue: 0,0:11:28.00,0:11:30.00,Default,,0000,0000,0000,,not consciously, but just because it does.
Dialogue: 0,0:11:30.00,0:11:34.00,Default,,0000,0000,0000,,And here's the weapon, it seems, that it did so over the last 500 million years.
Dialogue: 0,0:11:34.00,0:11:37.00,Default,,0000,0000,0000,,There are microbes which, through their metabolism,
Dialogue: 0,0:11:37.00,0:11:39.00,Default,,0000,0000,0000,,produce hydrogen sulfide,
Dialogue: 0,0:11:39.00,0:11:42.00,Default,,0000,0000,0000,,and they do so in large amounts.
Dialogue: 0,0:11:42.00,0:11:45.00,Default,,0000,0000,0000,,Hydrogen sulfide is very fatal to we humans.
Dialogue: 0,0:11:45.00,0:11:49.00,Default,,0000,0000,0000,,As small as 200 parts per million will kill you.
Dialogue: 0,0:11:51.00,0:11:55.00,Default,,0000,0000,0000,,You only have to go to the Black Sea and a few other places -- some lakes --
Dialogue: 0,0:11:55.00,0:11:59.00,Default,,0000,0000,0000,,and get down, and you'll find that the water itself turns purple.
Dialogue: 0,0:11:59.00,0:12:02.00,Default,,0000,0000,0000,,It turns purple from the presence of numerous microbes
Dialogue: 0,0:12:02.00,0:12:05.00,Default,,0000,0000,0000,,which have to have sunlight and have to have hydrogen sulfide,
Dialogue: 0,0:12:05.00,0:12:09.00,Default,,0000,0000,0000,,and we can detect their presence today -- we can see them --
Dialogue: 0,0:12:09.00,0:12:11.00,Default,,0000,0000,0000,,but we can also detect their presence in the past.
Dialogue: 0,0:12:11.00,0:12:13.00,Default,,0000,0000,0000,,And the last three years have seen
Dialogue: 0,0:12:13.00,0:12:16.00,Default,,0000,0000,0000,,an enormous breakthrough in a brand-new field.
Dialogue: 0,0:12:16.00,0:12:18.00,Default,,0000,0000,0000,,I am almost extinct --
Dialogue: 0,0:12:18.00,0:12:20.00,Default,,0000,0000,0000,,I'm a paleontologist who collects fossils.
Dialogue: 0,0:12:20.00,0:12:23.00,Default,,0000,0000,0000,,But the new wave of paleontologists -- my graduate students --
Dialogue: 0,0:12:23.00,0:12:25.00,Default,,0000,0000,0000,,collect biomarkers.
Dialogue: 0,0:12:25.00,0:12:29.00,Default,,0000,0000,0000,,They take the sediment itself, they extract the oil from it, \N
Dialogue: 0,0:12:29.00,0:12:31.00,Default,,0000,0000,0000,,and from that they can produce compounds
Dialogue: 0,0:12:31.00,0:12:35.00,Default,,0000,0000,0000,,which turn out to be very specific to particular microbial groups.
Dialogue: 0,0:12:35.00,0:12:39.00,Default,,0000,0000,0000,,It's because lipids are so tough, they can get preserved in sediment
Dialogue: 0,0:12:39.00,0:12:42.00,Default,,0000,0000,0000,,and last the hundreds of millions of years necessary,
Dialogue: 0,0:12:42.00,0:12:44.00,Default,,0000,0000,0000,,and be extracted and tell us who was there.
Dialogue: 0,0:12:44.00,0:12:47.00,Default,,0000,0000,0000,,And we know who was there. At the end of the Permian,
Dialogue: 0,0:12:47.00,0:12:49.00,Default,,0000,0000,0000,,at many of these mass extinction boundaries,
Dialogue: 0,0:12:49.00,0:12:53.00,Default,,0000,0000,0000,,this is what we find: isorenieratene. It's very specific.
Dialogue: 0,0:12:53.00,0:12:57.00,Default,,0000,0000,0000,,It can only occur if the surface of the ocean has no oxygen,
Dialogue: 0,0:12:57.00,0:13:00.00,Default,,0000,0000,0000,,and is totally saturated with hydrogen sulfide --
Dialogue: 0,0:13:00.00,0:13:03.00,Default,,0000,0000,0000,,enough, for instance, to come out of solution.
Dialogue: 0,0:13:03.00,0:13:07.00,Default,,0000,0000,0000,,This led Lee Kump, and others from Penn State and my group,
Dialogue: 0,0:13:07.00,0:13:10.00,Default,,0000,0000,0000,,to propose what I call the Kump Hypothesis:
Dialogue: 0,0:13:10.00,0:13:13.00,Default,,0000,0000,0000,,many of the mass extinctions were caused by lowering oxygen,
Dialogue: 0,0:13:13.00,0:13:17.00,Default,,0000,0000,0000,,by high CO2. And the worst effect of global warming, it turns out:
Dialogue: 0,0:13:17.00,0:13:20.00,Default,,0000,0000,0000,,hydrogen sulfide being produced out of the oceans.
Dialogue: 0,0:13:20.00,0:13:22.00,Default,,0000,0000,0000,,Well, what's the source of this?
Dialogue: 0,0:13:22.00,0:13:26.00,Default,,0000,0000,0000,,In this particular case, the source over and over has been flood basalts.
Dialogue: 0,0:13:26.00,0:13:29.00,Default,,0000,0000,0000,,This is a view of the Earth now, if we extract a lot of it.
Dialogue: 0,0:13:29.00,0:13:31.00,Default,,0000,0000,0000,,And each of these looks like a hydrogen bomb;
Dialogue: 0,0:13:31.00,0:13:33.00,Default,,0000,0000,0000,,actually, the effects are even worse.
Dialogue: 0,0:13:33.00,0:13:36.00,Default,,0000,0000,0000,,This is when deep-Earth material comes to the surface,
Dialogue: 0,0:13:36.00,0:13:38.00,Default,,0000,0000,0000,,spreads out over the surface of the planet.
Dialogue: 0,0:13:38.00,0:13:41.00,Default,,0000,0000,0000,,Well, it's not the lava that kills anything,
Dialogue: 0,0:13:41.00,0:13:43.00,Default,,0000,0000,0000,,it's the carbon dioxide that comes out with it.
Dialogue: 0,0:13:43.00,0:13:46.00,Default,,0000,0000,0000,,This isn't Volvos; this is volcanoes.
Dialogue: 0,0:13:46.00,0:13:48.00,Default,,0000,0000,0000,,But carbon dioxide is carbon dioxide.
Dialogue: 0,0:13:49.00,0:13:52.00,Default,,0000,0000,0000,,So, these are new data Rob Berner and I -- from Yale -- put together,
Dialogue: 0,0:13:52.00,0:13:54.00,Default,,0000,0000,0000,,and what we try to do now is
Dialogue: 0,0:13:54.00,0:13:57.00,Default,,0000,0000,0000,,track the amount of carbon dioxide in the entire rock record -- \N
Dialogue: 0,0:13:57.00,0:14:00.00,Default,,0000,0000,0000,,and we can do this from a variety of means --
Dialogue: 0,0:14:00.00,0:14:02.00,Default,,0000,0000,0000,,and put all the red lines here,
Dialogue: 0,0:14:02.00,0:14:05.00,Default,,0000,0000,0000,,when these -- what I call greenhouse mass extinctions -- took place.
Dialogue: 0,0:14:05.00,0:14:07.00,Default,,0000,0000,0000,,And there's two things that are really evident here to me,
Dialogue: 0,0:14:07.00,0:14:10.00,Default,,0000,0000,0000,,is that these extinctions take place when CO2 is going up.
Dialogue: 0,0:14:10.00,0:14:13.00,Default,,0000,0000,0000,,But the second thing that's not shown on here:
Dialogue: 0,0:14:13.00,0:14:16.00,Default,,0000,0000,0000,,the Earth has never had any ice on it
Dialogue: 0,0:14:16.00,0:14:20.00,Default,,0000,0000,0000,,when we've had 1,000 parts per million CO2.
Dialogue: 0,0:14:20.00,0:14:22.00,Default,,0000,0000,0000,,We are at 380 and climbing.
Dialogue: 0,0:14:22.00,0:14:25.00,Default,,0000,0000,0000,,We should be up to a thousand in three centuries at the most,
Dialogue: 0,0:14:25.00,0:14:29.00,Default,,0000,0000,0000,,but my friend David Battisti in Seattle says he thinks a 100 years.
Dialogue: 0,0:14:29.00,0:14:31.00,Default,,0000,0000,0000,,So, there goes the ice caps,
Dialogue: 0,0:14:31.00,0:14:35.00,Default,,0000,0000,0000,,and there comes 240 feet of sea level rise.
Dialogue: 0,0:14:35.00,0:14:37.00,Default,,0000,0000,0000,,I live in a view house now;
Dialogue: 0,0:14:37.00,0:14:39.00,Default,,0000,0000,0000,,I'm going to have waterfront.
Dialogue: 0,0:14:39.00,0:14:43.00,Default,,0000,0000,0000,,All right, what's the consequence? The oceans probably turn purple.
Dialogue: 0,0:14:43.00,0:14:46.00,Default,,0000,0000,0000,,And we think this is the reason that complexity took so long
Dialogue: 0,0:14:46.00,0:14:48.00,Default,,0000,0000,0000,,to take place on planet Earth.
Dialogue: 0,0:14:48.00,0:14:51.00,Default,,0000,0000,0000,,We had these hydrogen sulfide oceans for a very great long period.
Dialogue: 0,0:14:51.00,0:14:55.00,Default,,0000,0000,0000,,They stop complex life from existing.
Dialogue: 0,0:14:55.00,0:15:00.00,Default,,0000,0000,0000,,We know hydrogen sulfide is erupting presently a few places on the planet.
Dialogue: 0,0:15:00.00,0:15:04.00,Default,,0000,0000,0000,,And I throw this slide in -- this is me, actually, two months ago --
Dialogue: 0,0:15:04.00,0:15:08.00,Default,,0000,0000,0000,,and I throw this slide in because here is my favorite animal, chambered nautilus.
Dialogue: 0,0:15:08.00,0:15:12.00,Default,,0000,0000,0000,,It's been on this planet since the animals first started -- 500 million years.
Dialogue: 0,0:15:12.00,0:15:15.00,Default,,0000,0000,0000,,This is a tracking experiment, and any of you scuba divers,
Dialogue: 0,0:15:15.00,0:15:18.00,Default,,0000,0000,0000,,if you want to get involved in one of the coolest projects ever,
Dialogue: 0,0:15:18.00,0:15:20.00,Default,,0000,0000,0000,,this is off the Great Barrier Reef.
Dialogue: 0,0:15:20.00,0:15:21.00,Default,,0000,0000,0000,,And as we speak now, \N
Dialogue: 0,0:15:21.00,0:15:24.00,Default,,0000,0000,0000,,these nautilus are tracking out their behaviors to us.
Dialogue: 0,0:15:24.00,0:15:28.00,Default,,0000,0000,0000,,But the thing about this is that every once in a while
Dialogue: 0,0:15:28.00,0:15:30.00,Default,,0000,0000,0000,,we divers can run into trouble,
Dialogue: 0,0:15:30.00,0:15:32.00,Default,,0000,0000,0000,,so I'm going to do a little thought experiment here.
Dialogue: 0,0:15:32.00,0:15:35.00,Default,,0000,0000,0000,,This is a Great White Shark that ate some of my traps.
Dialogue: 0,0:15:35.00,0:15:38.00,Default,,0000,0000,0000,,We pulled it up; up it comes. So, it's out there with me at night.
Dialogue: 0,0:15:38.00,0:15:41.00,Default,,0000,0000,0000,,So, I'm swimming along, and it takes off my leg.
Dialogue: 0,0:15:41.00,0:15:44.00,Default,,0000,0000,0000,,I'm 80 miles from shore, what's going to happen to me?
Dialogue: 0,0:15:44.00,0:15:46.00,Default,,0000,0000,0000,,Well now, I die.
Dialogue: 0,0:15:46.00,0:15:48.00,Default,,0000,0000,0000,,Five years from now, this is what I hope happens to me:
Dialogue: 0,0:15:48.00,0:15:51.00,Default,,0000,0000,0000,,I'm taken back to the boat, I'm given a gas mask:
Dialogue: 0,0:15:51.00,0:15:54.00,Default,,0000,0000,0000,,80 parts per million hydrogen sulfide.
Dialogue: 0,0:15:54.00,0:15:58.00,Default,,0000,0000,0000,,I'm then thrown in an ice pond, I'm cooled 15 degrees lower
Dialogue: 0,0:15:58.00,0:16:02.00,Default,,0000,0000,0000,,and I could be taken to a critical care hospital.
Dialogue: 0,0:16:02.00,0:16:04.00,Default,,0000,0000,0000,,And the reason I could do that is because we mammals
Dialogue: 0,0:16:04.00,0:16:07.00,Default,,0000,0000,0000,,have gone through a series of these hydrogen sulfide events,
Dialogue: 0,0:16:07.00,0:16:09.00,Default,,0000,0000,0000,,and our bodies have adapted.
Dialogue: 0,0:16:09.00,0:16:13.00,Default,,0000,0000,0000,,And we can now use this as what I think will be a major medical breakthrough.
Dialogue: 0,0:16:13.00,0:16:15.00,Default,,0000,0000,0000,,This is Mark Roth. He was funded by DARPA.
Dialogue: 0,0:16:15.00,0:16:19.00,Default,,0000,0000,0000,,Tried to figure out how to save Americans after battlefield injuries.
Dialogue: 0,0:16:19.00,0:16:21.00,Default,,0000,0000,0000,,He bleeds out pigs.
Dialogue: 0,0:16:21.00,0:16:24.00,Default,,0000,0000,0000,,He puts in 80 parts per million hydrogen sulfide --
Dialogue: 0,0:16:24.00,0:16:27.00,Default,,0000,0000,0000,,the same stuff that survived these past mass extinctions --
Dialogue: 0,0:16:27.00,0:16:29.00,Default,,0000,0000,0000,,and he turns a mammal into a reptile.
Dialogue: 0,0:16:29.00,0:16:33.00,Default,,0000,0000,0000,,"I believe we are seeing in this response the result of mammals and reptiles
Dialogue: 0,0:16:33.00,0:16:36.00,Default,,0000,0000,0000,,having undergone a series of exposures to H2S."
Dialogue: 0,0:16:36.00,0:16:38.00,Default,,0000,0000,0000,,I got this email from him two years ago;
Dialogue: 0,0:16:38.00,0:16:41.00,Default,,0000,0000,0000,,he said, "I think I've got an answer to some of your questions."
Dialogue: 0,0:16:41.00,0:16:43.00,Default,,0000,0000,0000,,So, he now has taken mice down
Dialogue: 0,0:16:43.00,0:16:47.00,Default,,0000,0000,0000,,for as many as four hours, sometimes six hours,
Dialogue: 0,0:16:47.00,0:16:49.00,Default,,0000,0000,0000,,and these are brand-new data he sent me on the way over here.
Dialogue: 0,0:16:49.00,0:16:54.00,Default,,0000,0000,0000,,On the top, now, that is a temperature record of a mouse who has gone through --
Dialogue: 0,0:16:54.00,0:16:56.00,Default,,0000,0000,0000,,the dotted line, the temperatures.
Dialogue: 0,0:16:56.00,0:16:58.00,Default,,0000,0000,0000,,So, the temperature starts at 25 centigrade,
Dialogue: 0,0:16:58.00,0:16:59.00,Default,,0000,0000,0000,,and down it goes, down it goes.
Dialogue: 0,0:16:59.00,0:17:01.00,Default,,0000,0000,0000,,Six hours later, up goes the temperature.
Dialogue: 0,0:17:01.00,0:17:06.00,Default,,0000,0000,0000,,Now, the same mouse is given 80 parts per million hydrogen sulfide
Dialogue: 0,0:17:06.00,0:17:08.00,Default,,0000,0000,0000,,in this solid graph,
Dialogue: 0,0:17:08.00,0:17:10.00,Default,,0000,0000,0000,,and look what happens to its temperature.
Dialogue: 0,0:17:10.00,0:17:12.00,Default,,0000,0000,0000,,Its temperature drops.
Dialogue: 0,0:17:12.00,0:17:16.00,Default,,0000,0000,0000,,It goes down to 15 degrees centigrade from 35,
Dialogue: 0,0:17:16.00,0:17:19.00,Default,,0000,0000,0000,,and comes out of this perfectly fine.
Dialogue: 0,0:17:19.00,0:17:22.00,Default,,0000,0000,0000,,Here is a way we can get people to critical care.
Dialogue: 0,0:17:22.00,0:17:27.00,Default,,0000,0000,0000,,Here's how we can bring people cold enough to last till we get critical care.
Dialogue: 0,0:17:28.00,0:17:32.00,Default,,0000,0000,0000,,Now, you're all thinking, yeah, what about the brain tissue?
Dialogue: 0,0:17:32.00,0:17:35.00,Default,,0000,0000,0000,,And so this is one of the great challenges that is going to happen.
Dialogue: 0,0:17:35.00,0:17:37.00,Default,,0000,0000,0000,,You're in an accident. You've got two choices:
Dialogue: 0,0:17:37.00,0:17:40.00,Default,,0000,0000,0000,,you're going to die, or you're going to take the hydrogen sulfide
Dialogue: 0,0:17:40.00,0:17:43.00,Default,,0000,0000,0000,,and, say, 75 percent of you is saved, mentally.
Dialogue: 0,0:17:43.00,0:17:45.00,Default,,0000,0000,0000,,What are you going to do?
Dialogue: 0,0:17:45.00,0:17:48.00,Default,,0000,0000,0000,,Do we all have to have a little button saying, Let me die?
Dialogue: 0,0:17:48.00,0:17:50.00,Default,,0000,0000,0000,,This is coming towards us,
Dialogue: 0,0:17:50.00,0:17:52.00,Default,,0000,0000,0000,,and I think this is going to be a revolution.
Dialogue: 0,0:17:52.00,0:17:55.00,Default,,0000,0000,0000,,We're going to save lives, but there's going to be a cost to it.
Dialogue: 0,0:17:55.00,0:17:57.00,Default,,0000,0000,0000,,The new view of mass extinctions is, yes, we were hit,
Dialogue: 0,0:17:57.00,0:17:59.00,Default,,0000,0000,0000,,and, yes, we have to think about the long term,
Dialogue: 0,0:17:59.00,0:18:01.00,Default,,0000,0000,0000,,because we will get hit again.
Dialogue: 0,0:18:01.00,0:18:03.00,Default,,0000,0000,0000,,But there's a far worse danger confronting us.
Dialogue: 0,0:18:03.00,0:18:06.00,Default,,0000,0000,0000,,We can easily go back to the hydrogen sulfide world.
Dialogue: 0,0:18:06.00,0:18:08.00,Default,,0000,0000,0000,,Give us a few millennia --
Dialogue: 0,0:18:08.00,0:18:10.00,Default,,0000,0000,0000,,and we humans should last those few millennia --
Dialogue: 0,0:18:10.00,0:18:14.00,Default,,0000,0000,0000,,will it happen again? If we continue, it'll happen again.
Dialogue: 0,0:18:14.00,0:18:16.00,Default,,0000,0000,0000,,How many of us flew here?
Dialogue: 0,0:18:16.00,0:18:18.00,Default,,0000,0000,0000,,How many of us have gone through
Dialogue: 0,0:18:18.00,0:18:21.00,Default,,0000,0000,0000,,our entire Kyoto quota
Dialogue: 0,0:18:21.00,0:18:23.00,Default,,0000,0000,0000,,just for flying this year?
Dialogue: 0,0:18:23.00,0:18:26.00,Default,,0000,0000,0000,,How many of you have exceeded it? Yeah, I've certainly exceeded it.
Dialogue: 0,0:18:26.00,0:18:29.00,Default,,0000,0000,0000,,We have a huge problem facing us as a species.
Dialogue: 0,0:18:29.00,0:18:31.00,Default,,0000,0000,0000,,We have to beat this.
Dialogue: 0,0:18:31.00,0:18:35.00,Default,,0000,0000,0000,,I want to be able to go back to this reef. Thank you.
Dialogue: 0,0:18:35.00,0:18:41.00,Default,,0000,0000,0000,,(Applause)
Dialogue: 0,0:18:41.00,0:18:43.00,Default,,0000,0000,0000,,Chris Anderson: I've just got one question for you, Peter.
Dialogue: 0,0:18:43.00,0:18:45.00,Default,,0000,0000,0000,,Am I understanding you right, that what you're saying here
Dialogue: 0,0:18:45.00,0:18:47.00,Default,,0000,0000,0000,,is that we have in our own bodies
Dialogue: 0,0:18:47.00,0:18:51.00,Default,,0000,0000,0000,,a biochemical response to hydrogen sulfide
Dialogue: 0,0:18:51.00,0:18:54.00,Default,,0000,0000,0000,,that in your mind proves that there have been past mass extinctions
Dialogue: 0,0:18:54.00,0:18:56.00,Default,,0000,0000,0000,,due to climate change?
Dialogue: 0,0:18:56.00,0:18:58.00,Default,,0000,0000,0000,,Peter Ward: Yeah, every single cell in us
Dialogue: 0,0:18:58.00,0:19:01.00,Default,,0000,0000,0000,,can produce minute quantities of hydrogen sulfide in great crises.
Dialogue: 0,0:19:02.00,0:19:03.00,Default,,0000,0000,0000,,This is what Roth has found out.
Dialogue: 0,0:19:03.00,0:19:05.00,Default,,0000,0000,0000,,So, what we're looking at now: does it leave a signal?
Dialogue: 0,0:19:05.00,0:19:07.00,Default,,0000,0000,0000,,Does it leave a signal in bone or in plant?
Dialogue: 0,0:19:07.00,0:19:10.00,Default,,0000,0000,0000,,And we go back to the fossil record and we could try to detect
Dialogue: 0,0:19:10.00,0:19:12.00,Default,,0000,0000,0000,,how many of these have happened in the past.
Dialogue: 0,0:19:12.00,0:19:14.00,Default,,0000,0000,0000,,CA: It's simultaneously
Dialogue: 0,0:19:14.00,0:19:17.00,Default,,0000,0000,0000,,an incredible medical technique, but also a terrifying ...
Dialogue: 0,0:19:17.00,0:19:20.00,Default,,0000,0000,0000,,PW: Blessing and curse.