Thank you for joining us to examine
the history of mass extinction, and
possibly the future of mass extinction.
Please take a moment now to do the usual,
and turn off your cellphones and devices.
Also, if you need to leave before
the program is over, please exit through
the door up the stairs, and out the rear
of the theater, to minimize interruptions.
A cursory Internet search of
the term mass extinction,
returns alarming results,
over 5 million alarming [LAUGH] results.
The message which blasts from just page
one of a Goggle search is unequivocal.
Some examples are, earth is on
the brink of a sixth mass extinction,
scientists say.
Frog mass extinction is on the horizon.
Without a doubt,
a sixth mass extinction event is here.
And finally, the sixth mass extinction
event is underway, and we're the cause.
So tonight we're hoping to
take a little less alarmist,
a little more contemplative, but
no doubt cautionary view at this
mass extinction that is underway.
We will watch the film Mass Extinction,
Life at the Brink,
which examines these ideas.
And we'll hear from two
prominent scholars of the topic,
who will offer historical context to
the phenomenon of mass extinction,
as well as assess where we stand and
the steps we can take to slow the process.
Jonathan Payne is a Stanford geologist,
who is featured in the film, and
Sarah Holt is the producer, director, and
writer of the film we're about to see.
First, Jonathan will offer an intro
detailing some of his work,
as as well as some background to
the science that we'll see in the film.
We'll watch the movie, and
then Sarah will join Jonathan
on stage to have a conversation.
Then finally, the audience will have
the opportunity to ask questions.
Without further adieu,
please join me in welcoming Dr.
Jonathan Payne to the stage.
>> [APPLAUSE]
>> Here you go.
>> Okay [COUGH] so, oops.
Hi everyone, I cannot see you.
I'm sure you can see me.
>> [LAUGH]
>> And here are my slides, so.
The welcome was right on target.
What I wanted to start with was the fact
that there is, as we now already know,
much talk in the media about the topic of
mass extinction and the possibility that
the Earth is undergoing mass
extinction at the present time.
In particular, this extinction is often
referred to as the sixth extinction.
The first mention that I came across
was the title of Richard Leakey and
Roger Lewin's book from the 1990s.
There's a recent book by
Elizabeth Colbert from the past year.
This has made it into the culture not just
around the reporting of biodiversity and
conservation, but in fact it is now the
title of a novel as well as a rock band.
>> [LAUGH]
>> So
the concept of this extinction is
clearly permeating our culture.
What I wanted to do ahead of the film was
to give you a little bit of historical
background so that you understand
exactly where this term comes from.
So the first scientist to talk seriously
about the idea of extinction was
Georges Cuvier.
And Cuvier essentially proposed the idea
of extinction by taking careful
anatomical examination of fossil mammals,
especially mastodons.
And by comparing them to known living
species, showing that morphologically,
they were distinct from any
species alive on earth today,
or in the early 1800s in this case.
And Cuvier, therefore,
argued that these must be species that are
actually extinct from the planet today.
Further, if you realize that there were
actually a number of fossil mammals that
are present in relatively
young sedimentary rocks but
are not alive on the planet.
And so he proposed that, in fact, not
just one but many species went extinct.
And in contemplating this idea of
how extinction might work said,
all these facts consistent
among themselves, and
not opposed by any report, seemed to
me to prove the existence of a world
previous to ours destroyed
by some kind of catastrophe.
And so this is really as far as I can see,
the first scientific argument for
a mass extinction as a catastrophe.
Cuvier, of course,
is writing prior to Darwin and
the publication of The Origin of Species,
so
he's not thinking about evolution in the
way that we think about evolution today.
But he understands that there's
biodiversity on the planet and
that that biodiversity may have
been lost catastrophically.
Interestingly, the contrary
line of thought here
largely comes from Charles Darwin himself.
And so, as Darwin was arguing for
how species are created generation by
generation through natural selection
on small variations in morphology.
He viewed extinction as a similar
kind of gradual process and
ended up arguing in The Origin of
Species that as species are produced and
exterminated by slowly acting and
still existing causes, and
not by miraculous acts of creation and
by catastrophes.
And so
we can see that he's extending this logic,
not just to the creation of species but
to their extinction as well.
And so, his view and a contrary view
to the interpretation of mass extinctions
for many years, has been that
mass extinctions may be an artifact to the
fossil record that represent missing time.
And so if we miss a lot of time,
a lot of extinctions may occur,
just because they accumulate gradually and
not because of any catastrophe.
And, of course, if we think back to
Cuvier, Cuvier's understanding of
what a geological catastrophe might be,
was not quite the same as ours today.
And so he imagined things like mountain
ranges being built on time scales of
the human lifetime or shorter.
And so these kinds of things Darwin
viewed as not being realistic
interpretations of the rock record and
argued back against them as well
as against the catastrophic
extinction of species.
So, how we study mass extinctions today,
really comes into how we study
the history of biodiversity.
And this effort really
started in the 1930s, so
we're moving ahead nearly a century
from the work of Cuvier and Darwin.
And what happens when we study
biodiversity in the false record is
we have a geological time scale.
And you can see that time scale
here running from left to right
across the bottom of this graph.
And for any given species or for any given
and higher taxon, so a genus or a family.
We can go through all known
fossil occurrences and
try to find the first occurrence
of that species or genus and
the last occurrence of that species or
genus.
And essentially, all we need to do is
assume between that first occurrence and
that last occurrence, the species
was alive somewhere on the planet.
And so
by finding these stratigraphic ranges,
which are the horizontal blue lines
that you see, we can then go through and
add up how many species were alive at
any given point in geological time, and
develop a what we might call
a diversity curve, right?
So here on the bottom,
we are now plotting biodiversity
as a function of geological time.
Okay, so efforts to do this
actually started also in the 1860s,
and this is work of John Phillips
who using the fossil record of
Great Britain developed a schematic
curve for what he believed the fossil
diversity of the British fossil record
to be, running from the Paleozoic.
So the beginning of the Paleozoic,
over on the left,
would have been about 550
million years ago and
running up to the end of the Cenozoic,
which would be the present day.
Phillips, of course, we did not
have a radiometric time scale yet,
so Phillips didn't know how
much time was involved in this.
But, in fact, if you look at the relative
durations of the Paleozoic, Mesozoic, and
Cenozoic based on the thicknesses
of rocks that he was looking at,
they end up actually being quite close to
the relative durations that we know now
from radiometric dating
of geological materials.
The next really rigorous attempt to
quantify diversity in the fossil record
came in the 1960s.
And this is a graph from work
by Jim Valentine in 1969,
showing the number of animal
families in the marine
fossil record plotted as
a function of geological time.
The key thing to see here is,
this is the first time we
really have quantitative data.
You can see that the lines are actually
broken up into segments, and
those segments represent the intervals of
geological time that Valentine was able to
resolve.
So in this case, his time intervals
are about 30 million years long.
And that relates to how well he can divide
up time in rocks all the way around
the world.
And so we can do better if we stay in
a small geographic area, but if we wanna
know about global diversity, our time
resolution is necessarily a bit lower.
And so, here in this plot, we can see that
animal diversity started low, over on
the left in the Cambrian, and ends up
high in the present day, at the Cenozoic.
And there's at least one interval
of fairly substantial decline in
biodiversity.
If we look over here,
between the Cretaceous and the Cenozoic.
This is where the extinction
of the dinosaurs would fall.
And we can see that there's not any
obvious decline in biodiversity across
that boundary.
And that really has to do with
these limits of time resolution.
The time interval after
the end-Cretaceous extinction is so
long that it captures
a lot of the recovery,
and therefore, we don't actually
see a decline in biodiversity.
Going forward a decade from Valentine's
work, Jack Sepkoski, pictured here
on the bottom, in collaboration with
his University of Chicago colleague,
David Rout, pictured here on the top,
recompiled biodiversity data.
And they did so at a finer level
of stratigraphic resolution,
using about 5 to 7 million
year time intervals instead of
intervals that were more in
the 20 to 30 million year window.
And so for the first time,
they were actually able to resolve several
dramatic and rapid drops in
biodiversity over geological time.
And those are numbered
here one through five.
I think you can imagine now where this
term sixth extinction comes from.
They argued statistically that
there were five extinction events
that fall out relative to what's
going on in the background.
And so the key thing to remember here is
that biodiversity over time reflects not
just extinction but also origination.
And so what they wanted to do then was
to look specifically at extinction.
How much of the decline and diversity
reflects more than usual extinction,
as opposed to less than usual origination.
And so in this same paper from 1982,
they created a graph that showed
the rate of loss of animal
families across geological times,
so going from 600 million years ago or
so, up to the present day.
And what they argued is that,
from a statistical standpoint,
there is a population of events that
encompass most geological time intervals,
what we call stages or ages.
And those they defined as
background extinctions, so this,
from a statistical standpoint,
is anything within two standard deviations
of the best fit regression line.
If you don't wanna think about statistics,
these are just where
most of the data fall.
And then what they said is after we
look at where most of the data fall,
there are a number of events that fall
very far above that background rate.
And so they termed those mass extinctions.
And so they were making here not
just a sort of observation, but
a real statistical argument that there
are five intervals of geological time.
One at the end of the Devonian here,
the Ashgillian.
A few intervals that they lumped together
in the late Devonian, the Givetian,
Frasnian, and Famennian stages.
Two that they lumped together in the end
of the Permian, with the Guadalupian and
the on this.
And so this will be one of the extinctions
we talk about in the film,
the end-Permian mass extinction.
An extinction at the end of
the Triassic period, the Norean,
and then an extinction at the end
of the Maastrichtian stage.
This is the end-Cretaceous
extinction which
eliminates the dinosaurs
among many other organisms.
And so the two that we'll talk about today
are the Maastrichtian and the end-Permian.
And then they were doing
some other things,
occasionally in the fossil record they're
intervals where we will get unusually good
preservation of fossils which
can drive diversity up.
So these little Xs that you see sticking
up into the mass extinction realm,
here back in the Cambrian and one here up
in the Jurassic, are related to what would
happen if we include all of these very
unusual fossil deposits that record soft
bodies as opposed to the skeletons that
are more typical of the fossil record.
Okay, so that's where the sixth extinction
idea comes from, these are the data that
underlie it and I just want to mention
very briefly before we start the film.
One other thing, which is after mass
extinction, what happens with a recovery.
And so recovery occurs on a number
of different time scales in
regional disturbances.
Here's a satellite image of Mount St.
Helens from 1974.
I guess much of the audience can
guess what's gonna come next.
Which is 1980,
after the eruption of Mount St.
Helens, we can see this large area
of devastation near the mountain.
Come back in 2011 and
the forest are regrowing and
the ecosystems are back in business.
So decades are the time scales that
it takes to recover from a regional
disturbance under most circumstances.
Climate change is a bit different.
When we put a lot of carbon into
the atmosphere and cause climate to warm,
the geological processes that remove
carbon from the atmosphere and
cause climate to cool again
run on a slower clock.
And so here is a graph of the best studied
warming event in the geological record.
This is the warming event at
the end of the Paleocene, so
about 55 million years ago.
And these are dated,
these are measurements of the ratio
of oxygen 18 to oxygen 16 in fossils.
The key thing is that these
are a proxy for temperatures, so
you can read a temperature
axis here over on the right.
And here, we can see this
rapid warming event at 55 for
just a little less than
55 million years ago.
And you can see that over an interval
of 100,000 to 200,000 years,
temperatures come back to where they were.
And that's the process of
the geological removal of the carbon,
putting it back into the geological record
as limestone and as organic matter.
So that's the time scale
climate takes to recover.
If we go and look at biodiversity we can
see that after these mass extinction
events, these time intervals
are 5 million years long.
And so for these mass extinction events
to show up as dips in biodiversity, that
means that the recovery of biodiversity
is on a timescale of millions of years,
generally 5 to 10 million years.
So bionic recovery, the recovery of
biodiversity and ecosystem function,
is much slower than the recovery of
climate after very large disturbances.
Finally, the thing I wanted
to leave you with is,
here's our biodiversity curve, right?
This is the history of animal life
over the last 600 million years.
It's a tiny fraction of Earth history.
But building up a planet that is habitable
for animals takes a much longer time,
it takes billions of years.
And so if we look at the formation
of the Earth 4.56 billion years ago.
For the first half of Earth history, we
didn't even have oxygen in the atmosphere.
And then oxygen shows up at
about 2.35 billion years ago.
And oxygen levels that would be breathable
for almost any animal on the planet,
really probably don't show up until very
soon before the actual appearance of
animals in the fossil record,
about 6 or 700 million years ago.
And so, if we think about
recovery from a disaster beyond
what we've experienced in
the history of animal life,
the time scale of recovery would
likely be billions of years.
If we want to think about
the recovery of animals, so
that's a little bit of background which
I hope will make seeing this film
even more informative for you, so
with that I will leave you with the film.
[APPLAUSE]
[MUSIC]
>> There's a mass extinction
occurring on the planet today.
>> There has never been anything
like this in human history.
You know,
humans have never seen anything like this.
[MUSIC]
>> In many ways,
it's the biggest crisis since we came out
of our caves 10,000 years ago, no less.
>> Our estimates of how many will be lost
if we're on this path are pretty good, and
they're really big numbers.
>> We may well lose half of
the world's biological diversity.
[MUSIC]
>> When we wipe out populations and
species of other organisms,
we're sawing off the limb
that we're sitting on.
>> During the last 50 years while
I've been involved in conservation,
I've noticed that the amount of money
going into conservation has increased
five times over.
And the amount of scientific understanding
we've got has increased five times over.
The number of citizens involved in
this game increased five times over.
And yet,
our cause is still going down the tubes.
The mass extinction is
gathering pace more than ever.
So what's going on?
We need to attack the root
causes of our problems.
>> [NOISE] No way!
>> When you think about it, what does our
culture offer us in the way of wisdom,
to deal with any kind of difficulty?
Our cultural wisdom is buy this,
it'll make you happy.
>> The most optimistic scenario is
that by mid-century there will be nine
billion of us
>> And
all of those people want to live
as well as we do in the West.
[MUSIC]
>> Preventing extinction is gonna be
a big challenge for human society, but
it's certainly one that
we're capable of doing.
>> This is something
that we have to do now.
It’s not something that we can postpone
to our children or our grandchildren,
it’s up to us.
This is the responsibility that
our generation has uniquely.
[MUSIC]
>> Well, I just wanted to thank
everybody tonight for coming.
And to thank the museum for
having the screening.
It's always a little bit of
a downer at the end of this film,
but I hope people will really
pay attention to, I think,
Tony Bernavsky's last fight, that there's
still this window of opportunity.
And we have the ability
to actually reverse
a lot of the things that
are happening right now.
>> So is your putting the film together,
how did, how
does one link the catastrophes they see
in the geological record with the modern,
without putting us on
this course to disaster?
How do you go about thinking about
the story-telling aspect of that?
Did you feel like you needed
to end on a positive note?
>> You know, I think films have this
kind of organic way of evolving and
they almost feel like two separate films.
The very first film,
the very first part of
the film was really an effort to kind of
take on the whole issue of denialism.
And we thought if we showed people the
scientific process, and the real data, and
the evidence, and how you actually figure
out what happened millions of years ago
even though there are no witnesses,
that we would begin to build a case for
these geological events occurring.
And by the time we got to the last act,
it was really the hardest,
because the broadcaster wanted to hit
it hard and make it very sensational.
Our funder, how his medical institute
wanted careful science and I
think somehow Tony Bernavsky really struck
a balance that everyone could live with.
It wasn't like the sky was falling, but he
also put enough urgency to the situation.
I think that it made the film moving.
>> And.
So, I guess, one of the big challenges
I see, as a scientist working on this,
is how I take what seems like a great
mundane activity actually most
of the time, and turn that into
something watchable for 45 minutes.
How challenging do you find that when,
do scientists come
naturally to turning this
into tellable material or.
>> It varies.
>> Yeah.
>> And you know, I mean like,
I went with my husband.
I brought him on the shoot to China,
and we were at the bout,
the extinction boundary and
his reaction was,
we came halfway around
the world to film muddy rocks.
[LAUGH] Initially.
I mean they dug out this boundary.
And they'll say to you, that's where
one world ended and the other began.
And you knew that if a scientist
wasn't there helping you see it,
you would just walk by.
But when you really begin to look at
the fossils they were finding and
look at the extinction boundaries,
I noticed by the end of the shoots like in
the Badlands,
we started off staring up at the vistas.
By the end of the shoot everyone was
staring at the ground because there are so
many fossils.
But as you said when I
came out to film with you,
that you put rocks in the machines,
you close the machines, there's
nothing really interesting to watch.
You get little bits of data, and
then you get an a-ha moment,
like, there's a real change in
the carbon across these rocks, and
it really tells us something
about the atmosphere.
So, as a film-maker you're always
trying hard to make your films visual.
You're always trying to get to
those a-ha moments quickly.
>> Mm-hm, and for visualizing that I
can see that with the asteroid impact.
[INAUDIBLE] something catastrophic and
instantaneous that's easy to visualize.
How do you think about visualizing
processes that happen over thousands or
tens of thousands of years?
>> Well I mean time lapse photography?
No, but I mean I think in the Permian, the
asteroid impact was almost instantaneous,
but the volcanic eruptions, I mean still
60,000 years, it seems like a long time.
I know in geologic time its nothing,
but it still seems like a long time.
Today, I think what's so
hard to get our mind around is that
it's hard to put together all the pieces
of evidence, but you fly over Yellowstone
and you see forest after forest
that's gone up above the tree line,
and you realize, okay, the temperature's
changed two degrees here.
Two degrees.
And it's allowing a beetle that's always
lived here not to get killed off and
to do this kind of devastation.
So I think, for me to step back and
to try to get a sense in so
many different ways, that the stress.
I mean, the interesting thing about
the past mass extinctions is that,
rapid global climate change was
the unifying theme in all of them.
And today, it's the first time ever we've
had one species driving the extinction of
other species, destroying habitats,
over fishing, over hunting.
And then we have the added
stress of climate change.
So I mean, it's always
a challenge to visualize a film.
>> Mm-hm.
When you are thinking about visualizing,
telling this story,
who is the audience that you have in mind?
I think, for myself, I watch these kinds
of documentaries, kids who are four and
seven will also sit down and watch them,
and as I looked at the film,
I realized just Hhw much science is
underneath what's presented here,
that's really backed it up.
I could teach a whole course to
give you enough background to.
How do you think about that audience?
Do you have a person in mind?
>> Well I mean-
>> Who is
sort of your
>> I mean.
>> Idealize.
>> I've been thinking about
the average television viewer.
This is on the Smithsonian channel.
>> Yeah.
>> And if a word that was too scientific
crept into the script it would be
quickly marked out by the executives.
[LAUGH] Get that word out of there.
So You're trying to make it, I mean,
I mean the challenges, it's, I know,
our funder, feels like people
can handle more information, and
science programs are getting dumbed down.
And they wanted to have
a certain level of science.
And you try to simplify it, and
make it accessible to everybody.
>> And so thinking more broadly then what
is the limiting factor the resources for
producing these kinds of films?
I remember in our conversations
earlier that you mentioned that
you left a lot of material on the cutting
room floor that at least it sounded to me,
could make another you
know fascinating story.
>> It could have been a two hour film.
>> Yeah.
>> So it's.
There's so much that's crammed in.
There's so
much that you have to leave out, and
the hardest thing is
what do you leave out.
Just, when I was with you,
one of the, I loved, for instance,
you were looking at, first of all,
you kind of determined how much carbon was
probably released during
the Siberian eruptions.
You wanna tell the audience?
>> Right, so
>> Yeah, how to tell it quickly.
So we were looking at these changes
in carbon isotope ratios and
we knew how much the amount of carbon
13 versus carbon 12 had changed.
The problem is that we didn't know
If it was a little bit of carbon that
had lots and lots of carbon12 in it, or
a lot of carbon that had only
a bit of carbon12 in it.
>> It's probably getting
very technical [LAUGH].
>> Right.
>> Yeah.
>> So if we think about,
thinking about your bathtub, right.
Thinking about
as being the temperature
of your bath water, right.
If you wanna make it warmer You can put
in a little water that's boiling hot.
Or you can put in a lot of water
that's a bit warmer than the water in
your tub right?
Either way you end up with
the same average temperature.
>> Right.
>> And
[INAUDIBLE] that we are trying to figure
out is a lot of carbon would change
the climate.
A little bit of carbon wouldn't
change the climate as much.
And so It turned out that the carbon
by itself, you don't know the answer.
So we had to go in and
measure the calcium so
we're measuring limestones which
are made out of calcium carbonate so
it's the calcium, carbine,
and so oxygen in there.
By looking at the isotopes
of calcium as well,
we're ultimately able to calculate
how much carbon is released and
it turns out to be probably at
least twice as much as, would
be released if we burned all of the fossil
fuels that are available to us today.
It could be as much as ten times as
much as that, for the end-Permian.
And, so, these were just
sort of staggering numbers.
When you dump that much carbon in,
if you take,
50 trillion tons of carbon, And
turn it all into carbon-dioxide.
So this would have been mostly
carbon in Limestones and
coals that those Siberian lavas
were burning their way through.
If that all went into the atmosphere at
once you'd end up with something like
thirty thousand ppm CO2 in the atmosphere
as opposed to 400 ppm today.
>> Which is today.
>> About a hundred times
what we have today.
And that would make
the planet extremely warm.
>> So, when you ran it
through these climate models,
how hot do we think the temperatures were
getting right after this extinction?
>> Right.
So, the data we have at the end of
the Permian indicate about 20,
almost 20 degree fahrenheit warming
in the tropics or 10 degrees celsius.
And this could have led to continental
interior temperatures that might have
been on the order of 60 degrees Celsius,
which I think would be about 140 degrees
Fahrenheit and these are temperatures that
most animals can't live at permanently.
>> Right.
>> Right,
they can survive briefly, we can go into
a room that's 140 Fahrenheit Probably for
a minute or two but [LAUGH] you wouldn't
want to spend much time on that.
>> So, one of the things that I would've
loved to included in the film was you
telling me you began to realize what the
ocean looked like after the extinction.
>> Yeah.
>> You had a, what did you call it?
Slime world.
>> Right and so a lot of, I talked
a bit about the chemistry in this film.
In fact, most of my time and interest
is devoted more toward the paleontology
And so when we're looking
at the Permian extinction.
The rocks that you looked at
were more deeper water deposits.
And so
you can see those ammonite fossils and
then they're all gone after
the Permian extinction.
In shallow water, where we were working
in another part of South China.
We were looking at ancient reef deposits.
So you could see deposits that
would have been equivalent
to the Great Barrier Reef today.
And immediately on top of them
are deposits that are made up of
bacterial mats on the sea
floor turned into rock.
So this really would've been green
slime sitting on the sea floor and
the reefs are gone.
And so it's not just that
the diversity is gone but
in fact the entire structure
of the reef itself is gone.
All the individual organisms,
smaller of this species are gone.
And that the real challenge when we
look at this data sets that I presented
before the film,
we knew even back in the 1960s and 1970s
that a lot of diversity was lost over
some six or seven million year window.
And what's amazing about going out to
look at the rocks is that it turns out
you can put your fingernail on the spot
where all the diversity was lost.
Meaning the time window for these
losses of diversity is extremely Short.
>> Yeah.
>> And this makes a lot of sense.
When we think about biology.
If we change the environment, if we do it
slowly organisms have a chance to evolve.
And if they don't have a chance to evolve,
they may at least have a chance
to change their behaviors or
the way in which they develop.
The faster we change the environment,
the less opportunity the organisms
have to adapt to that.
>> So, I think the amazing thing,
for me as I realize,
the world has been a lot
hotter than it is today.
There's been far more carbon dioxide in
the atmosphere than there is today, but
what's kind of frightening about
today is the rate of change.
Things are changing in a few
hundred years that took
tens of thousands of years in these
past mass extinctions, and so
it's really hard for
a lot of animals to adopt that fast.
>> Yeah, I think the rate of
change is certainly very fast.
Of course, the rate of change at the end
of the cretaceous would have been
enormously fast.
I think the thing that's really different
and strikes me in the film is that,
and I think that the film did a nice
job of balancing these two things,
is the one thing that's going
on today is the climate change.
But I think the other thing that was
very clear from the film is that
direct human impact through hunting,
through fishing,
through land use is actually right now
the biggest threat that most species face.
And so to me that actually seems
like a hopeful message, and
maybe something that's worth emphasizing
in Tony Burnoski message is that- If
it were climate change alone,
or if climate change were
the primary threat that this species faced
we would actually be in a boatload of
trouble because as I mentioned
before in the film, it takes 100 or
200 thousand years to get that carbon
dioxide back out into the atmosphere.
So once we burn our fossil fuels
we're committing to having You know,
very high PCO2, high carbon
dioxide levels in the atmosphere,
very high temperatures for
as long as we can foresee.
Long beyond any of
the societies within today.
In the case where direct human activity
is what's threatening most species,
then a change in human behavior
can have almost immediate impact.
Right, and that came up in the case of
the population size of the grizzly bears.
It comes up in the conservation of
mammals in Africa, for example.
And so I think that the fact that human
activity is the largest threat we face at
the moment in terms of extinction
is good news because it means that
when we change our behaviors,
we have an opportunity to very quickly
allow populations to respond to that.
Adding climate change on top
of that though potentially
makes recovery much, much harder.
>> Does anyone here have any questions?
Should we open it up to questions?
>> I think we should, and
of course, we can't see any of you,
so-
>> Now we can, yeah.
>> I believe the organizers
are gonna be coming around, too.
>> Are we going back to Malthus?
Are we going back to Malthus and
the population?
Is that where we're headed?
Is that what we need to do?
>> Well, you wanna answer that?
>> Do we need to do it?
I sure hope not.
So it's, I suspect
that human population size is going to
respond over time scales of generations,
largely through changes in birth rates,
right?
And that's a lot of what we see today,
is that the human population growth is
slowing down because birth rates in
developed nations are slowing down.
And so
I think that human behavior can change
the population without violent deaths or
deaths through famine.
We look back through human history.
In fact we live in one of the safest ages
that there's ever been on this planet for
people.
Fewer people die violent deaths at
the hands of other people today than
they ever have in human history.
So I'm actually very optimistic on
that front, that the time scale over
which we'll adjust will be fast enough and
largely happen through birth rate
as suppose through some sort of violent-
>> I think the bigger worry is that so
many people today want the same standard
of living that we have in this country,
which is incredibly wasteful.
And that's gonna be hard for
the planet to sustain.
>> Yeah.
>> So the next question over here.
>> I'm curious about
the specifics of change,
like when you talk about human behavior or
even population growth.
But what about the urbanity of the world
and cities becoming more and more popular.
What can we do from an infrastructural
standpoint to change
our behavior that would accelerate this
recovery or this reversal of fortune?
I guess my take would be that
from a conservation standpoint,
urban environments are probably actually,
I would guess,
in many cases better than non-urban
because the people are concentrated in
a much smaller part of the land surface,
which leaves potentially more of the land
surface open to other organisms,
other animals.
I would think the big challenge
would be that feeding 9 or
10 billion people means that all that land
we're not living on needs to be farmed.
So figuring out how we create farming
landscapes that are also useful landscapes
to wild animals, I would think would be
one of the major challenges on that front.
>> Tony Barnosky,
the last scientist in the film,
wrote a book called Dodging Extinction
which he actually tries to take on
the things we can do to try to
avert this next extinction.
One, if we all become vegetarian we're not
gonna have as big a carbon footprint and
we'll maybe be able to feed
the growing number of people.
Cuz we're gonna go to probably 10
billion people by mid century,
by the end of the century.
But the other thing is just we
have a chance right now to still
try to save a lot of
the species on the planet,
by protecting their habitat,
connecting their habitats.
There's still time.
We're gonna lose a fair number.
We'll probably lose elephants in ten
years, but it's not a done deal.
>> Next question over here.
>> I understand that the [COUGH],
excuse me,
the Alvarez hypothesis is like largely
been accepted by the public and
many scientists but what, since you
studied the Siberian Traps, what's your
thoughts on the Deccan Trap eruptions
that occurred at 66 million years ago?
>> Yeah, the Deccan Traps certainly
were erupting at the time
of the end Cretaceous extinction.
The coincidence of the extinction of
species with very well resolved records
with the actual impact has been
statistically extremely well established.
And so it's certainly possible
that the Deccan Traps predisposed
the world to being more sensitive
to this asteroid impact.
My personal suspicion is that no matter
what was happening on the planet,
if you have that asteroid impact,
you have an extinction more or
less on the scale of
the end of the Cretaceous.
One idea that was put forth very recently,
just in the last few weeks in
Science Magazine, is that there may have
been an acceleration of Deccan volcanism
in the immediate aftermath of the impact,
and potentially triggered by it, right?
The impact would have created
an enormously powerful seismic wave.
And so, exactly what effect that they
would have had on the Deccan Traps,
I think is still an area
that isn't settled.
But this idea that the impact may have
actually may have influenced the amount of
volcanism in the Deccan Traps is
certainly one that'll be explored for
the next few years.
>> In the Badlands they wondered if the
dinosaurs were already on their way out,
if the environment was so
stressed they were going extinct.
And they actually didn't find any
difference between the number of dinosaurs
at the bottom of the formation all
the way up until the asteroid hit.
So at least in that one area,
they could not say dinosaurs were
going extinct before the asteroid hit.
>> We have next question over here.
>> Both of you surfaced a lot of trends
that were very interesting on clarifying
not only the troughs, but
the peaks where it seemed like,
leading up to this time, there's been
almost an all time high of diversity.
And I'm wondering maybe as we head off
some of the changes we might bring,
what do you learn from that as to
factors that can cause it to go up?
>> Yeah, so it does appear
that diversity on Earth today
is as high as it's ever been,
which is great news.
That's a nice point to be starting from.
One of the very interesting things that
we see in the fossil record is that
especially in terms of ecosystem
structure, the recovery from mass
extinctions actually appears to stimulate
the discovery of new ecological types
that were not in ecosystems prior
to the mass extinction events.
And so if your concern is diversity,
if you're essentially viewing Earth as
a Martian, and looking down and saying,
what's good for diversity on Earth,
if I wanna wait around 100 million years?
The mass extinction event might
actually be very good news.
>> [LAUGH]
>> If your concern is, say,
the next decade, or the next century,
or the next million years,
a mass extinction event
is not good news at all.
So what we see is that broadly diversity
has been increasing over geological time.
There are more and
more animal species over time.
A little bit of that is probably
due to the fact that it's easier to
sample the rock record as we
get towards the present, and
it's a little bit easier
to distinguish species.
Partly because we know more
about living species, and
partly because the The fossils are often
preserved in material that's not
consolidated in a rock yet, so it's
just easier to get the fossils back out.
So there's a little bit of that but the
general trend toward increasing diversity
seems to be a real one and it seems to be
stimulated in part by extinction events.
So one would hope that if you come back
100 million years from now that there will
be even more animal diversity on
the planet than there is today.
What we hate to see is that dip
that lasts 10 million years and
starts right when human society develops.
>> And I think Tony Bernofsky
would say that if we don't change
the trajectory we're on right now,
that in 2 to 300 years,
75% of the animals that you look around
and see in the world today will be gone.
I mean,
that's what the numbers are saying.
So it doesn't mean that's the end of
life on Earth, but I think we're headed
towards a crisis point if things
keep going on this same trend.
>> Okay, next question is over here.
>> To sort of stem off of that, so
I'm really passionate about this and
I've had this event on my calendar for
weeks.
But a lot of the people who hold the purse
strings might not necessarily have had
this event on their calendar, and so my
question is, we're at this crisis point,
or rapidly approaching this crisis point,
how do we get people to care?
I mean this is a cool event,
this is a free event, and
we haven't even filled this auditorium.
So how do we get people to care,
and how do we get that change to
happen that we need to have happen?
I know that a small group of concerned
citizens can change the world,
but how do we get that
small group to be bigger?
And how do we get people to
actually really care about this?
>> I wish I knew the answer.
I found the Republican debate
incredibly discouraging in
the inability to acknowledge what's
happening to the climate, and
the impact on the world, but
I really don't know the answer to that.
But I do feel like, is that all of
the problems, we have the technology and
the ingenuity to solve them.
We have the ability to feed the world,
we have the ability to reduce our carbon
footprint, we could save animals.
There's a huge amount we could do
getting the political will and
getting people to actually understand.
I mean, my younger son said to me,
we're doomed.
And I'm like no, we're not.
And he said, what we can we do?
And so I was rattling off things from Tony
Barnosky's book of the things he could do,
like cut your electrical consumption 25%.
Don't eat endangered species, vote for
people that care about these issues.
I mean I just,
there are things that can be done.
I don't really know how
to make people care.
I wish I did.
I mean one of the reasons we tried
to make this film was we thought,
if we could show you it's happened in
the past, and really present the evidence,
that it really makes the case
that it can happen again.
And in fact,
it looks like it's happening again.
>> Yeah, I think that it's important to
keep in mind, right, that a large fraction
of our population lives in conditions
where they're worried about tomorrow,
and not about biodiversity 100 years
from now, or even 10 years from now.
And so I think that in some ways one of
the concepts that's coming in part out of
my ecology colleagues at Stanford
is this idea of ecosystem services.
And if you want to look at it,
instead of taking an altruistic view
that diversity is intrinsically good,
essentially they're arguing that
diversity is economically good for you.
And I think that if we
want mass action on that,
that's probably the arguments that
are ultimately going to be most effective,
is to show people that conserving
diversity is good for you.
It's good for you in terms of
providing fresh, clean drinking water.
In terms of avoiding flooding,
avoiding catastrophic storms.
In terms of preventing the spread
of tropical diseases, right?
In California, for example, we're starting
to get populations of more tropical
mosquitoes that at least potentially
can carry things like dengue fever.
None of us want that, nobody anywhere
in the world wants dengue fever.
And so I think that there are a lot
of ways in which it doesn't
need to look like an argument about making
sacrifices in order to preserve diversity,
but rather that a lot of
the things that we do that end up
conserving diversity are actually good for
almost everybody.
So I think that that's gonna be the key.
If we want mass action on that,
we need people to see
it as something that's going to
immediately benefit themselves.
If we don't do it that way,
then it's going to be those
of us that have the luxury
of having our material needs met easily
all the time, who can then step back.
And say we should also
be conserving diversity.
But that's not the majority of
the people in this country.
It is, sadly, not a majority
of the people in this country.
Sadly, not a majority of
the people on the planet.
>> Next question, over here.
>> What was the cause for
the other three mass extinctions?
Is there conclusions?
>> Yeah, so, let's see.
So, going from oldest
to youngest let's say.
The Ordovician extinction appears to be
largely related to a major glaciation
event.
Then there may also have been changes
in the amount of oxygen in sea water.
The Devonian and end Permian extinctions
seem to be related to climate warming,
decreases in the amount of oxygen
in seawater, ocean acidification.
The end Triassic mass extinction looks
very similar to the end Permian in
terms of even having another large flood,
the salt province,
that's erupting at the same time.
And then the end Cretaceous has this
giant impact event that doesn't
seem to have any real counterpart
with any of these other events.
It does have this volcanic province, that
came up in one of the earlier questions,
that was erupting at the same time,
as well.
>> Okay,
we send the next question over here.
>> You just answered it.
[LAUGH] I have heard in various cultures
that there was the great flood and so
I wondered if you had, anybody had
found that was one of the cases.
>> No, no.
>> I actually have a question
while I have the mic over here.
A lot of these extinction animals,
we're talking about macroscopic scale,
I mean even the tiny little
ones are still macroscopic.
Do we know anything about the bacteria
that existed millions of years ago,
or even today and how any of the
extinctions may have affected bacteria,
if that is included in the 50% or
75% of all life?
>> Yeah so bacteria are tough
because they're very small and
they don't have hard shells, so they don't
preserve in the fossil record very often.
And when they do, they don't have
a lot of different morphologies and
the morphology doesn't tell you much
about what species you're looking at.
But it does turn out that some of
the organic molecules that they produce
are preserved in rocks.
The oil that we burn
to heat our houses and
the gasoline we drive to run our cars
is made up of these kinds of molecules.
And so some of those can actually tell
us something about what's going on.
At the end of the Permian, these kinds of
molecules have actually been very useful.
One thing that they've shown us is
that bacteria in general became more
important after the extinction event,
whereas eukarorytic cells,
the cells with nuclei, which includes
a lot of the algae in the oceans,
as well as animals and plants,
became less important.
It looks like after the end Permian,
broadly speaking,
there were a lot of bacteria.
That doesn't mean that there
were lots of species, but
it means at least some of
the species were doing very well.
There are a few molecules that
actually tell us about certain groups.
So, there's one kind of molecule
that is used for photosynthesis.
So it's actually the molecule
that takes in the photon
to get energy from the light.
And it's only used by bacteria that
photosynthesize where there's no oxygen.
And so this is one important piece of
evidence that we have areas of the ocean
that are very shallow,
shallow enough that light is penetrating.
And there's no oxygen in that water,
and so that's been an important part
of understanding what the conditions
were after the end Permian extinction.
So in terms of diversity of bacteria,
we don't know a whole lot.
Most people suspect that there are
probably not big effects on the diversity
of bacteria.
We have to actually go much farther back
in the geological record to find events
that probably had a big
effect on bacteria.
And so if you go back to the Achaeans,
if you go back to the interval between say
3.8 billion years ago and
two and half billion years ago.
Especially between 3.8 and
3 billion years ago, there're some very,
very large impact events that would
put the end Cretaceous to shame.
And in those events,
they would have evaporated
substantial fractions of sea water.
And so,
then you're getting temperatures that
would affect a lot of microscopic life.
And so it's possible during those
kinds of events that there may
have been large effects on
the bacterial life as well.
So if animals were around then it
would have been very bad news.
So the planet is probably
a little bit safer than it was
when it was forming in the early on and
there were still a lot of large objects
in the solar system waiting to hit us.
>> Next question here.
>> Sarah, I saw this, the last time
you showed it here, in December.
>> Mm-hm.
And so this, is this just the second time,
the only time since then or
are you showing it every other
day all over the country?
>> [LAUGH]
>> No, this was broadcast last
November and
it's now being streamed online for free.
And the museum of science someone at that
screening asked me if I would come and
do the screening.
So the film has been out for
about nine months.
>> Well what I'm interested in
is the new element in the sixth
extinction underway is the human element,
right?
>> Yes.
>> So
a lot of talk about biodiversity, but
what's happening to humans, in as far
a diversity goes, is just the opposite.
Everything I see is about
a mass communications,
mass opinion molding instantly.
Sound bites taking over from literature.
Everything about the culture
of the humans in the plant.
The new element is going
directly in the opposite
direction of diversity,
does anybody agree?
>> What do you think?
>> I think I'd respectfully
disagree on that.
I think that certainly,
so a, we're talking about two
different things here, right?
We're talking about cultural
diversity versus genetic.
Where we talk about species we're
talking about genetic diversity.
When we talk about people and
communication,
we're really talking
about cultural diversity.
And so
certainly there are aspects of that right.
Lots of people on the planet from
all different kinds of places
have contact with one another.
On the other hand, we're educating
a much larger fraction of the human
population than we did in the past.
And so there are many more people
with much more knowledge than we
had previously, which I think is a very,
very good thing.
They still have very
different experiences.
One of the things I think that Sarah's
film did so nicely was showing us how
solving these geological problems is
really a globe trotting exercise.
And one of the things I find fascinating
in terms of doing that is just how
different every country is that I go
to and how different the people are.
But they know enough about each
other not to fear each other and
not to hate each other immediately, right?
Which is a nice thing.
And so
my personal take on it is I think that
there are certainly negative
aspects to this, right?
But by and large I think the fact that
we're educating so many more people and
that so many more people have
access either through videos, or
through tweets, or
whatever form of communication.
They have access to the thoughts
of people all over the world and
I think that that's
certainly a good thing.
>> Facebook.
>> And Facebook.
>> [LAUGH]
>> Okay, the next question's over here.
>> So this film does a wonderful
job of walking us, the audience,
through the unraveling of these
two scientific mysteries.
And then presents the third scenario,
the sixth extinction,
as a question of what can we
do to address this process
that's already under way.
But I wondered for both of you,
what are the questions that you
still have on this subject.
Jonathan, in your work what
are you focused on and
what are the mysteries of mass
extinctions that aren't solved yet.
And Sarah what are the questions that you
as a filmmaker still had after you had put
together this story.
>> You know something I think that
in terms of what I don't understand,
it's actually comes to one of
the questions that Sarah and
I were discussion on the way over here.
Which is we tend, I think the way we tell
the stories about mass extinction in
the easiest way to conceptualize them for
many of us, certainly for me,
is sort of direct death in response
to some environmental stress, right.
Too hot, too little food,
too cold, too little oxygen.
What's much harder to figure out and
reconstruct is how secondary
extinctions might happen.
So if a few species die because it's
too hot or there's too little oxygen,
how many of the species extinctions
that we're seeing are cascades
that aren't directly related to
the environmental change but
are secondary effects of
some other extinctions.
And that, I think, we have very
little handle on at this point, and
very little understanding of does that
vary from one extinction event to another?
Is it unimportant at the end Cretaceous,
but very important at the end Permian or
vice versa?
I don't feel like we understand
that terribly well at all yet.
In terms of telling the stories.
>> I think one of the frustrations that
I had was, that this was just an hour.
And we really couldn't even talk at
all about, what to do going forward.
The things that we could do,
that's really another film.
And I guess the big question in my
mind is, are we gonna sit back and
watch this train wreck and I feel like
we see super drought seen super storms.
We’re looking all this refugees
in Europe and I'm realizing,
soon we're gonna have
environmental refugees.
So, when I sometimes try to think about
what film I might do next, the question
is what would be another way to try to
address this issue in a different way.
I think a lot of films now
are coming out recently.
>> This is gonna be our
last question up here.
>> Thank you.
So what would you say to
all those people who said,
it was the coldest winter on record.
There's no such thing as climate change.
>> Yeah, so,
the weather varies from day to day, right?
And the regional climate
varies from place to place.
And so it's certainly possible for
certain parts of the earth to have
a very cold winter in any given year.
What we understand now from satellites is
we can measure the temperature
of the whole planet, right.
And when we measure the temperature of the
whole planet, it's very clear that year on
year, the average temperature
of the entire planet is warming.
And so this really becomes a question
of long-term trends versus short-term
variation.
And so if you go from say winter to summer
in Boston, on average it goes from cold
to warm, but you can have days in January
that are warmer than days in May.
It doesn't happen too often,
but it does happen.
And that's essentially the same thing
that's going on a different scale there,
is that certain parts of
the Earth will have cold winters.
But if we ask what's the warmest
February on record, right, this year.
What's the second warmest
February on record, last year.
When are the warmest years,
they're almost all in the last 15 years.
And so, the data that the planet
is warmer now than it was in
the past are exceedingly clear.
>> Okay, thank you so much for coming.
>> [APPLAUSE]
[APPLAUSE]
>> Thank you very much for coming.
>> Thank you Sarah Holt and
Jonathan Payne for joining us tonight.
>> [APPLAUSE]
>> I
wanted to call attention to the biological
murder mystery that we had on our hands.
That was great phrase in the movie.
And I want to admire the dedication
the scientists solving these mysteries.
But concentrate on how to prevent
future Jonathan Paynes and Alvereses
from trying to figure out what caused
the end of mammals all of the sudden.
So we can concentrate on
potentially being vegetarian.
We can certainly concentrate on
responsible food sourcing and land use.
Remembering that change in human
behavior can have an enormous impact,
to concentrate on economically beneficial
arguments and finally to vote well.
Thank you very much folks,
have a great night.
>> [APPLAUSE]
