►
From YouTube: 2nd PAWS Webinar
Description
The second webinar from the Paleoclimate Advances Webinar Series (PAWS) which took place on April 15th 2022.
Dr. James Rae discussed "Constraints on past CO2 change on glacial to Cenozoic timescales" and Dr. Yige Zhang discussed "Global Climate Change Driven by Marine Methane Hydrate Dissociation: Reality or Fiction?"
For more information and to signup for the PAWS Google Group visit:
https://www.cesm.ucar.edu/events/webinars/paws/
B
All
right,
I
hope
everyone
can
hear
me
okay
and
see
the
slides
so
welcome
to
our
second
pause
webinar.
So,
just
as
a
quick
reminder
of
the
format
we'll
have
20
minutes
per
each
talk
with
a
5-minute
q,
a
for
each
speaker
and
then
10
minutes
for
a
general
discussion.
I
will
be
giving
the
speakers
a
reminder
when
they
have
about
two
minutes
left
just
to
keep
us
on
track
and
because
we're
trying
to
foster
respectful
dialogue.
B
B
B
He's
an
erc
grant
awardee
and
a
fellow
of
the
young
academy
of
scotland
and
he'll
be
presenting
constraints
on
past
co2
change
from
glacial
to
cenozoic
time
scales
and
dr
yiga
zhang
is
a
professor
at
texas,
a
m
university.
He
said
he's
past
biogeochemical
cycles
using
organic
proxies,
which
are
very
close
to
my
heart.
He's
also
associate
editor
of
paleo
oceanography
and
paleoclimatology
is
a
member
of
the
advisory
committee
for
scientific
ocean
drilling
and
a
clark
medalist
from
the
geochemical
society.
B
C
So
the
relationship
between
co2
and
past
climate
change
actually
has
a
really
long
history,
a
history
of
study
that
is
about
as
long
as
our
knowledge
of
co2
as
a
greenhouse
gas
itself.
So
indeed,
in
the
first
scientific
study
of
the
heat
trapping
properties
of
co2,
which
was
conducted
by
this
amazing
amateur
female
scientist
from
the
us
in
1856,
eunice
newton
foot.
C
C
If
you
like,
of
co2's
impact
on
global
climate
and
then
having
gone
through
page
after
page
after
page
of
calculations
that
apparently
he
was
doing
in
part
as
a
side
project
from
his,
you
know
physical
chemistry,
nobel
prize
winning
work,
it
was
a
side
project
to
kind
of
ease
his
way
his
mind
through
a
messy
divorce.
He
he
gets
on
to
this
wonderful
section.
Five
of
this
paper,
which
you
know
as
an
earth
scientist,
makes
your
heart
grow
vlad
geological
consequences
and
it
opens.
C
I
should
certainly
not
have
undertaken
these
tedious
calculations
if
an
extraordinary
interest
had
not
been
connected
with
him,
and
he
goes
on
to
describe
that.
There
have
been
ice
ages
that
co2
was
probably
connected
with
those
and
that
co2
would
have
been
connected
with
the
walmart
climates,
the
distant
past,
and
indeed,
that
rising
co2
due
to
the
industrial
revolution
had
the
potential
to
warm
climate
in
the
future.
C
So
arenas
made
all
these
hypotheses
well
over
100
years
ago,
and
it's
been
the
work
of
a
whole
variety
of
paleoclimatologists
from
different
fields
to
follow
up
those
ideas
with
data
now
one
of
the
most
iconic
records.
Of
course,
of
past
co2
change,
is
this
the
compilation
of
co2
records
from
bubbles
in
antarctic
ice?
This
is
our
fossil
record
of
the
atmosphere
from
antarctica,
and
it
has
these.
C
You
know
beautiful,
well-ordered,
glacial
interglacial
co2
cycles,
and
indeed
one
of
the
big
focuses
of
my
research
group
is
is
looking
at
these
glacial
interglacial
co2
cycles.
But
today
I'm
going
to
focus
on
on
something
else.
I'm
going
to
talk
about
some
more
recent
work,
we've
been
doing
on
high
co2
worlds
and
it's
of
course
motivated
by
the
fact
that
co2
today
is
416
ppm.
A
C
Question
we
need
to
go
deeper
into
earth's
past,
so
how
do
we
do
that?
Well,
we
run
out
of
ice,
but
we
have
amazing
records
over
the
last
60
or
even
100
million
years
from
marine
modules,
and
so
we
need
to
look
to
records
preserved
in
those
mod
cores
to
help
us
understand
past
climate,
and
I'm
going
to
focus
today
on
the
kind
of
specialty
of
my
research
group,
which
is
the
boron
isotope
paleo,
ph
meter
and
and
without
going
too
far
at
the
moment
into
the
nitty-gritty
of
ocean
carbonate
chemistry.
C
You
know
the
central
point
really
is
that
co2
is
a
weak
acid.
So
when
you
have
more
co2
in
water,
it
follows
the
set
of
reactions
that
release
protons,
that
release
h,
plus
ph.
The
h
is
a
measure
of
of
these
protons
here.
So
if
we
can
constrain
c
ph
in
the
past,
we
can
put
some
quite
close
constraints
on
co2,
so
I'm
going
to
quickly
run
through
the
mechanisms
of
how
this
works.
C
C
C
We
push
this
reaction
this
way
and
we're
going
to
be
100,
boric
acid,
so
boric
acid
has
to
carry
the
isotopic
composition
of
seawater
and
there'd
be
an
infinitesimal
amount
of
borate
iron
offset
below
it
by
the
isotopic
fractionation
factor.
Vice
versa,
super
high
ph
would
be
dominated
by
the
borate
iron.
That
would
have
the
composition
of
seawater.
C
So
if
we
had
a
way
of
working
out
the
composition
of
borate
in
the
past,
we
could
read
along
this
graph
and
calculate
ph,
and
the
way
we
can
do
that
is
that
the
boratine
is
preferentially
incorporated
into
growing
calcium
carbonate,
and
this
has
been
the
subject
of
lots
of
work
by
a
variety
of
groups
to
look
at
the
kind
of
calibration
of
this
proxy.
I'll
briefly,
just
show
one
summary
figure
of
that
from
work.
I
did
in
my
phd
here.
C
C
So,
armed
with
this
technique,
we're
going
to
look
at
how
co2
change
deeper
in
time-
and
here
is
the
kind
of
starting
point.
This
is
co2
reconstruction,
circa,
2008
and
you
know,
there's
some
kind
of
absolutely
pioneering
early
work
here,
which
shows
us
that
co2
is
higher
in
the
warm
climates
of
the
early
cenozoic
and
it
falls
into
the
cooler
climates
of
the
latest
cenozoic,
but
in
detail.
This
is
slightly
kind
of
oddly
spiky
in
the
early
part
of
this
record
and
I'll
be
flat
in
the
later
part.
C
You
might
also
like
to
check
out
some
of
the
this
work
within
companion
website
here,
which
focuses
on
the
marine
methods
of
co2
reconstruction,
boron,
isotopes
and
forearms.
The
thing
I'm
going
to
focus
on
today,
but
also
alkanones,
which
you
may
talk
about
too,
and
then
there
are
of
course
a
broader
range
of
other
co2
archives
as
well,
and
the
great
paleo
co2
website
details
these
proxies
as
well.
C
And
you
can
see
that
you
know
over
the
course
of
the
cenozoic,
just
the
kind
of
raw
boron
ices
of
data
itself,
it
it
kind
of
m.
It
echoes
the
the
record
of
climate
encapsulated
in
in
benthic
before
minifera,
which
which
is
a
pretty
kind
of
promising
sign
so
lower.
It's
plus
it
upside
down,
lower
delta
ambient
bore
rate
would
be
lower,
ph
or
higher
co2,
and
so
you
can
see
that
there's
some
some
structure
here.
C
C
So
I'll
illustrate
that,
with
this
kind
of
quite
extreme
example,
imagine
I've
got
a
measurement
of
boron,
isotopes
and
carbonates.
If
I've
got
modern-day,
does
not
be
a
seawater
of
about
40.
I'd
read
off
the
graph
like
this,
but
if
that
whole
ocean-born
isotope
composition
were
to
be,
you
know
changed
to
30.
I'd
get
a
very
different
ph
now.
C
The
isotopic
composition
of
seawater
hasn't
changed
by
that
much,
but
this
is
still
a
pretty
active
area
of
research
to
try
and
narrow
down
these
constraints
on
devlin
bfc
water.
Nonetheless,
with
the
available
constraints
that
we
have,
we
can
produce
this
fairly
coherent
record
of
ph
change
and
then,
finally,
to
go
from
ph
to
co2.
We
need
to
know
something
else
about
the
ocean
carbonate
system.
This
is
something
that
you
might
learn
in
a
chemical
oceanography
class
that
the
co2.
D
C
B
C
Often
sound
a
wee
bit
daunting
like
okay,
you've
been
talking
a
lot
about
these
ph
records,
but,
oh,
my
goodness,
do
you
not
need
something
else
that
is
almost
as
well
constrained
as
ph,
but
actually
here
the
the
kind
of
covariances
within
the
carbonate
system
help
us
out,
and
one
way
to
illustrate
that
is
on
this
plot
of
dic.
The
total
dissolved
inorganic
carbon
versus
ocean
alkalinity.
These.
D
C
Even
if
I
put
just
a
very
broad
constraint
on
alkalinity,
as
indicated
by
this
faint
gray
rectangle,
where
those
two
overlap
in
this
kind
of
thicker
gray
band,
that's
actually
quite
a
well-constrained
co2
space.
So,
although
there
is
still
some
work
to
do
on
trying
to
improve
the
constraints
on
the
secondary
parameters
of
the
carbonic
system,
if
you
have
a
good
record
of
ph,
you
can
produce
fairly
tight
constraints
on
co2
and
some
of
those
different
options
for
secondary
carbonate
system
parameters
are
shown
in
the
different
colors
down
here.
C
Okay.
So
what
we
left
with
here
is
our
updated
cenozoic
co2
record
from
boron
isotopes
in
the
dark
blue
circles
and
alkanones
in
the
lighter
blue
pluses
plotted,
alongside
a
recent
compilation
of
benthica
18,
which
is
a
general
kind
of
measure
of
climate
via
temperature
and
iceborn,
and
you
can
see
that
suddenly
compared
to
some
of
those
earlier
records.
Here
we
see
this
much
tighter
coupling
between
climate
has
encapsulated
with
iot
and
co2,
from
desolation
b
and
alkanes.
C
So,
let's
kind
of
step
through
some
of
the
stages
of
what
has
happened
over
the
kind
of
fascinating
history
of
co2
and
climate
change
encapsulated
with
in
the
cenozoic.
So
we'll
start
here
at
the
kind
of
peak
eocene
greenhouse
the
early
ear
scene,
this
I'll
play
these
wee
animations
as
well.
This
is
from
the
amazing
climate
archive
website,
which
has
a
whole
brilliant
set
of
interactive
kind
of
model
output
for
different
paleo
climates.
C
C
This
is
associated
with
co2
levels
of
around
800
ppm
and
then
our
cooling
continues
into
into
the
myosin.
So
in
the
myosin
we
have
co2
levels
of
of
around
five
to
six
hundred.
There
is
an
increase
in
co2
in
this
myosin
climatic
optimum
associated
with
some
some
meltback
of
antarctic
ice,
and
then
we
see
the
kind
of
regrowth
and
stabilization
of
that
ice
sheet
as
we
move
into
a
more
modern
world
with
more
modern
continents
and
flora
and
fauna.
C
D
C
Levels:
five
to
even
25
meters
higher
than
today,
okay,
so
I'm
going
to
finish
out
my
last
couple
of
minutes
with
a
couple
of
interesting
implications
of
this
work.
We
we
do
find
across
the
centers
out
this
close
coupling
between
co2
and
climates,
and
you
can
see
that
in
just
a
basic
cross
plot
of
co2
versus
benthico
routine
or
if
we
convert
that
into
temperature
and
when
plotted
in
a
space
with
co2
in
in
log
2
units.
C
This
is
showing
temperature
sensitivity
to
co2
doublings,
which
are
shown
by
these
different
dashed
lines.
You
can
see
that
across
the
cenozoic
as
a
whole,
the
earth
system,
sensitivity
and
note
this
is
not
the
same
as
equilibrium
sensitivity,
because
it
also
will
include
changes
in
slow-moving
components,
particularly
continental
ice.
C
Finally,
what
drives
this
long-term
co2
change?
Well
enough,
in
a
very
kind
of
simple
level,
the
cenozoic
co2
change
reflects
the
balance
between
co2
supply
to
the
ocean
atmosphere
system
in
a
sense.
In
essence,
adding
dissolved
in
organic
carbon
into
the
ocean
versus
the
supply
of
alkalinity
by
the
weathering
of
silicate
rocks
from
the
ocean
takes
this
mix
of
dic
and
alkalinity
and
via
the
carbonate
system,
sets
co2.
C
So
over
the
thousand,
we
have
about
a
thousand
ppm
of
co2
decline
over
the
cenozoic
and
about
two-thirds
of
that
is
driven
by
that
big
kind
of
picture
change
in
the
balance
of
dic
supply
to
alkalinity
supply,
and
the
remaining
third
is
is
in
essence,
a
kind
of
in
part
of
feedback
due
to
changes
in
the
equilibrium
constants
of
the
carbonate
system
as
a
function
of
changes
in
temperature
and
the
major
ion
composition
of
the
ocean.
Okay,
so
I
will
wrap
up
there.
C
This
is
work
that
we
are
continuing
to
do
with
a
current
erc
project
and
I'll
just
kind
of
finish
by
by
noting
you're
the
the
pretty
stark
message
that
paleo
co2
provides
for
modern
and
future
co2
change.
You
know
we
are
already
at
pliocene
type,
co2
levels
and
myosin
or
rheoscene
levels
are
possible
depending
on
our
energy
choices,
and
we
really
don't
want
a
world
with
arctic
alligators.
B
C
I
think
I
think
the
kind
of
quick
answer
to
that
is
actually
when
we
have
a
bunch
of
overlapping
data
for
for
the
acronyms
and
boron.
We
actually,
you
know,
there's
a
bunch
of
pretty
good
agreement
in
here.
The
thing
that
really
draws
the
eye
with
the
elkanones
is
is
the
kind
of
earliest
the
legacy
in
here
and
and
actually
there's
really
there's
there's
some
overlapping.
C
The
data
sets
around
here,
but
there's
just
that
present
no
boron
isotope
data
in
the
legacy
we
have
actually
just
been
funded,
along
with
bridget
wade,
she's
leading
a
project
to
to
add
some
newborns
to
derive
co2
constraints
for
the
legacy.
So
that
is
something
to
look
out
for
in
the
next
week
while-
and
I
think
also
oh
yeah-
that
I
think
that's
that's
enough
of
an
answer-
yeah
jang,
I
can
see
you've
got
your
hand
up
as
well.
C
C
A
D
C
There's
it's
pretty
interesting
time.
You
know
the
there's.
You
know
a
pretty.
You
know
striking
change
in
in
antarctic
ice.
Around
this
time
I
mean,
according
to
the
miller
reconstruction
we
get
back
to
something
you
know.
That's
almost
close
to
you
know
the
latest
ear
scene
and-
and
there's
certainly
a
you
know,
a
pretty
striking
bump
in
in
co2
at
that
time.
This
this
was
one
of
the
first
paleo
co2
records
that
I
made
the
one
published.
C
It's
foster
ray
and
leer
in
2012..
I
can
remember
sitting
as
a
phd
student
on
the
mass
spec
that
night
watching
the
data
come
in
and
kind
of
sketching
them
out
in
my
lab
book,
on
top
of
a
graph
of
the
oat
change
and,
just
being
so
excited
to
see
us
kind
of
reproduce
that
kind
of
structure
that
you
see
in
in
the
year,
18
record
there.
C
C
We
know
it
pretty
well,
and
so
so
that
means
that
for
kind
of
the
pliocene
you
can
make
you
know
pretty
precise
reconstructions
by
the
time
you
get
into
the
myocyte
you,
the
the
isotopic
composition
of
seawater
has
the
potential
to
have
been
different,
and
that
starts
to
introduce
more
uncertainty
and
you're.
Trying
to
nail
down
that
uncertainty.
Better
is,
is
a
big
part
of
the
work
that
we're
currently
doing
and
and
yeah
I'll
leave
it
at
that
in
the
interest
of
time.
E
All
right
everybody
can
see.
This
can
hear
me.
Okay,
thank
you,
tripty
and
thanks
to
all
of
the
organizers.
Thank
you
for
having
me
and
it's
a
brave
of
you
to
have
two
geocameras.
I
guess
who
are
hardcore
jewel
comments
to
talk
to
you
this
morning
and
I
love
talking
to
climate
modelers,
climate
dynamicists
very
early
on
from
my
career.
I
realized
that
you
know
we
talk
about
climate.
E
Sometimes
we
geochemists
have
our
ideas,
but
it's
always
wise
to
check
with
climate
dynamicists
to
make
sure
it's
not
too
crazy,
so
james
layout
very
nicely
about
the
co2.
I
will
talk
about
another
greenhouse
gas
this
morning
I
will
focus
on
methane
and
I
will
try
to
make
it
less
geochemistry
intense,
but
you
probably
have
heard
there's
currently
no
proxy
for
methane
right,
but
people
still
talk
about
methane,
especially
a
little
while
ago.
E
There
are
a
lot
of
ideas
about
methane,
hydrate
release,
dissociation,
a
huge
amount
of
methane
released
into
the
atmosphere
and
causing
major
climate
changes
like
pedm
or
even
mass
extinctions,
but
you
might
also
notice
that
people
talk
less
about
it
over
the
recent
few
years.
So
that's
what
I'm
gonna
do.
I'm
gonna,
you
know
really
think
about.
Is
this
a
reality
or
is
it
fiction?
Okay
and
share
with
you
our
recent
results
on
this
perspective?
E
E
E
So
probably
the
most
famous
example
of
that
is
the
payload
used
in
thermal
maximum,
and
I
guess
most
people
are
familiar
with
this.
We
see
this
rapid
warming
at
about
56
million
years
ago.
You
guys
can
see
my
cursor
right,
okay,
so
that's
the
o-18
represents
the
warm,
a
and
c13
representing
the
light
carbon
being
released
into
the
surface
system,
and
if
we
look
at
carbon
accounting,
we
see
at
these
south
atlantic
sites,
carbonate
percentage
dropped
from
like
90
to
almost
like
zero
percent,
so
we're
having
rapid
global
warming.
E
So
that
sounds
like
exactly
what
we're
doing
today
and
where
do
those
carbon
come
from
back
in
1995
jared
dickens
and
other
people
use
the
mass
balance
calculations
to
show
that
methane
hydrate
is
possibly
the
source
of
the
carbon,
and
we
know
methane
is
very
isotopically
light.
So
in
that
sense
we
don't
need
a
lot
of
methane
to
push
the
mass
balance
to
give
us
the
isotopic
excursion.
E
So
it's
a
very
famous
idea
and
after
this
you're
looking
at
a
lot
of
like
later
studies.
Basically,
whenever
we
see
in
earth's
history
there
is
this
rapid
warming
and
c13
negative
excursion,
then
the
first
thing
I
got
to
pop
into
people's
mind
is
that
oh,
it
has
to
be
method.
So
methane
has
been
used
to
explain
the
termination
of
the
snowball
earth
like
and
triassic
mass
extinction
or
mid
cretaceous
warming.
You
know
you
name
it.
E
There
are
a
lot
of
work
on
this
front,
but
if
we
look
more
recent
history,
if
we
look
at
the
quaternary
the
pleistocene
when
we
know
things
better
there
is
this
hypothesis
called
the
cooperate,
gun
and
jim
kenneth.
Other
folks
wrote
a
book
not
just
a
paper
but
a
book
of
this,
so
they
call
it.
They
coined
it
the
crossword
gun,
because
basically,
they
see
in
santa
barbara
basin
sites.
This
is
a
shorter
time
scale.
This
is
thousands
of
years,
so
this
is
the
last
glacial.
This
is
interglacial
to
glacial
and
holocene.
E
So
that's
their
basis
for
this
idea.
They
think
the
class
rate
gun
basically
fires
whenever
there
is
this
warming.
So
if
this
is
real,
then
this
is
a
big
deal
right.
It
clearly
shows
that
methane
played
a
huge
role
in
regulating
global
climate,
but
ideas
like
this
face
a
lot
of
challenges.
You
know
right
after
the
publication
of
this
paper,
people
were
arguing.
Are
these
c13
signals
are
real
or,
alternatively,
we
know
that
carbonates
are
easily
subject
to
diagenesis.
E
So
this
is
measuring
methane
trapped
in
ice
core
and
for
radiocarbons
c14,
and
these
folks
did
deuterium
isotope
of
them,
and
we
know
that
during
the
deglaciation
increase
of
methane.
If,
if
that
methane
comes
from
hydrate,
then
they
are
going
to
be
very
negative,
irradial
carbon,
because
hydrate
is
old,
carbon
they're
going
to
be
radioactively
dead,
so
this
dashed
line
here
shows
the
classroom
gun
basically
scenario,
but
this
is
their
actual
measurement.
E
Okay,
it
does
not
match.
So
this
is
a
strong
evidence
that
the
methane
increase
during
deglaciation
probably
did
not
come
from
quadratic
dissociation.
Okay,
so
that's
that's
a
major
challenge
to
all
of
these
methane
hypothesis
right.
The
second
challenge
is
that
you
know
over
recent
years
there's
more
better
observation
and
modeling
of
methane
flu
coming
out
of
the
sea
floor,
and
this
is
what
they
see.
They
don't
make
it.
They
don't
make
it
to
the
atmosphere,
they
quickly
dissolve
in
the
ocean
and
they
dissipate
into
the
ocean.
They
accept
very,
very
shallow
sites.
E
They
usually
don't
make
it
to
the
atmosphere,
so
they
cannot
directly
contribute
to
the
greenhouse
effect
of
of
methane
in
the
atmosphere.
So
that's
the
second
challenge
for
all
of
these
ideas.
So
this
leads
us
to
this
question.
Is
this
real
or
is
it
just
a
fiction
right?
So,
in
my
opinion,
to
answer
this
question,
we
got
to
figure
out
two
things.
First,
one
is
what
are
the
right
tools
to
try
hydrate
dissociation
and
methane
release
in
earth's
history.
E
E
For
those
who
know
what
I
do,
I'm
an
organizer
thomas-
and
you
know
I'm
going
to
argue
that
organic
geochemistry,
what
the
biomarkers
are
the
best
way
to
learn
about
methane.
But
I
think
it's
the
real,
because
if
you
look
at
the
methane
cycle
in
sediment
right,
they're,
hydrates,
they're,
methane,
hydrates
they're,
released
in
the
vitamin
or
in
the
water
column
and
very
very
quickly,
microbes
are
going
to
move
in
and
they're
going
to
oxidize
methane,
either
aerobically
with
the
presence
of
oxygen
or
anaerobically.
E
Consequences
of
this
I'll
talk
about
that
later,
but
all
of
that
is
done
by
microbes
right,
like
anaerobic
oxidation,
aom,
that's
done
by
methanotrophic
archaea,
the
amine
group
and
sulfate
reducing
bacteria
so
b
and
they
have
their
diagnostic
lipid
biomarkers,
preserved
in
a
sediment
for
millions
of
years.
Proceeding
here
as
an
example
and
if
aerobic
oxidation,
that's
done
by
bacteria
and
bacteria,
have
these
opanoids
also
tend
to
be
preserved
in
sedimentary
records?
E
Okay,
and
by
looking
at
these
biomarkers,
we
know
that
whether
it
is
aerobic
or
anaerobic
oxidation
aerobic,
it's
going
to
be
archaea,
so
we
have
rtr
dhe,
crow
city
pmi,
whole
bunch
of
these
biomarkers
aerobic,
a
bacterial
origin
opanoid.
So
we
have
diplotrols
developed
tea
and
there
are
diegenetic
products.
E
At
the
same
time,
we
can
actually
use
the
gdgts
to
monitor
the
release
of
methane
in
the
sediment.
So
this
is
my
master's.
This
is
work
where
we
show
there
are
messe,
there's
going
to
be
metatrophic,
archaea,
community
and
they're,
going
to
make
the
gdg
profile
look
very
different
from
normal
marine.
E
So
clearly,
this
is
when
you
can't
apply
these
kind
of
gdgt's
to
look
at
taxi,
dcx
and
c
surface
temperature,
but
you
can
calculate
methane
index.
Okay,
massive
index
varies
between
0
to
one
and
anything
above
like
point
three
to
point
five,
then
you
know
that's
probably
related
to
the
presence
of
methane
in
the
sediment.
Okay
and
a
good
thing
about
methane
index,
is
that,
like
I
said,
there
are
thousands
of
reported
gdgt
data
and
gdgt
is
easier
to
measure
so
that
solves
the
problem
of
you
know.
E
If
you
use
other
biomarkers,
you
might
be
like
trying
to
find
a
needle
in
a
haystack
if
you
want
to
identify
a
mapping
release
event,
but
people
like
to
measure
gdgt.
So
there
are
data
there
and
they're
easy
to
measure
new
data.
So
that's
what
we're
going
to
take
advantage
of
and
lastly,
about
the
proxy
itself.
We'll
just
comment
very
briefly
that
my
student
bonshu
and
I
are
working
on
developing
this
methane
index.
E
More
as
a
quantitative
proxy-
and
we
see
it
is
related
in
the
modern
profile
to
methane,
flux
and
sulfate
flux
and
the
transition
zone
between
sulfate
and
methane.
So
if
it
works,
then
potentially
you
know
we
can
use
these
measurements
to
reconstruct
the
methane
flux
from
the
geological
past.
So
those
are
the
tools
that
we're
going
to
use.
E
So
I
guess
that
helps
answer
our
number
one
question:
how
do
we
track
the
history
of
methane
and
our
number
two
question
is:
does
it
matter
if
there
were
methane
right
and
we
think
it
does,
because
there
are
two
ways
that
we
oxidize
this
methane
one
is
anaerobic.
We
use
sulfate
and
we're
going
to
produce
bicarbonate,
which
increases
alkalinity
in
the
pore
water
and
in
seawater.
So
that's
why
it
often
facilitates
precipitation
of
carbonates.
E
So
you
often
find
these
oxygenic
carbonates
at
aom,
sites
versus
a
more
rapid
release
of
methane.
You
know
they're
going
to
be
oxidized
by
oxygen,
and
this
is
a
picture
from
a
deep
water
horizon
incident
back
in
2010
in
the
gulf
of
mexico.
We
know
it's
a
tragedy,
but
it's
also
an
experiment
for
people
to
see
that
a
huge
amount
of
methane
was
released
into
the
water.
What's
gonna
happen.
What's
gonna
happen
after
that?
Okay,
this
isn't
monitoring
what
happened
in
the
northern
part
of
the
gulf.
E
E
So
this
is
what
we
think
if
there's
a
huge
amount
of
methane
released
into
the
water
column,
it's
still
going
to
matter
because
potentially
it
could
cause
hypoxia
and
ocean
acidification,
and
if
that
ocean
is
in
equilibrium
with
the
atoms
here,
that
means
something
for
atmospheric
is
co2
as
well.
So
that's
the
idea,
so
here
I'm
filling
in
the
answers.
A
little
bit.
Biomarkers
and
aerobic
oxidation
potentially
causes
hypoxia
and
acidification.
E
Okay,
I
don't
know
if
that
makes
sense
to
you,
but
now,
let's
look
at
one
example:
okay,
I'm
going
to
show
you
one
example-
and
this
is
a
graph
that
james
just
showed
us
famous
exactly
curve
that
you
know
illustrates
the
climate
change
over
the
last
66
million
and
the
particular
time
interval
I'm
going
to
focus
on
is
actually
over
here.
So
this
is
the
eo
transition.
E
But
strangely
enough
you
see
that
this
rebound
right
things
just
pretty
much
went
back
to
previous
conditions,
so
this
is
a
glaciation
people,
call
it
mm1
glaciation,
but
it
is
a
more
or
less
a
transient
one.
I
like
the
oi
one.
So
what
happened
and
what's
the
role
of
method
during
this
climatic
event?
So
that's
what
we're
going
to
do.
E
So
we
look
at
three
sites
from
the
south
southern
ocean
right.
There
are
two
of
them
close
to
tasman
sea
and
one
closer
to
antarctica.
Okay
and
a
paleogeography
placed
them
all
in
the
southern
ocean.
During
the
a
legacy
myosin
boundary
now
I'm
going
to
show
you
the
results:
okay,
so
two
panels,
the
attachment
sea
sides
are
gonna
be
shown
over
here
and
the
antarctica
side
is
going
to
shown
over
here,
and
here
is
the
oat.
E
So
you
see
the
mi1
glaciation,
you
see
the
rebound,
and
here
is
the
reconstructed
sea
level
during
this
time.
So
during
the
peak
of
the
glaciation
sea
level,
dropped
by
dropped
by
about
50
meters
or
so
okay.
So
what
I'm
going
to
show?
You
first
is
methane
index.
Okay,
remember
that
anything
that
is
above
0.3
to
0.5
that
marks
the
presence
of
methane
in
the
sediment
all
right.
So
now
I'm
going
to
click
there
we
go
so
these
two
sides
and
this
one
side
look
at
that
the
background
value.
E
This
is
pre-events
more
or
less
background
value
and
during
the
peak
of
the
glaciation,
these
high
values
showed
up.
So
there
were
metha
in
these
sediments,
okay
and
also
over
here.
So
this
is
the
occurs
in
three
sites
that
are
separated
by
hundreds
to
thousands
of
kilometers
and
the
methane
showed
up
at
the
same
time.
At
the
same
time,
across
all
three
sites-
so
that's
probably
not
a
coincidence,
and
then
we
look
further
into
additional
evidence.
E
We
look
at
other
biomarkers
and
their
isotopic
values,
so
you
see
the
other
biomarkers
they
only
show
up
when
we
have
high
mapping
index
values
and
they're
below
detection,
when
it's
more
or
less
normal
and
their
isotopic
values
also
confirmed
that
they
are
related
to
methane.
Okay.
So
I
think
we
have
pretty
strong
evidence
for
all
three
sites
to
show
that
methane
occurred
during
the
peak
of
the
glaciation.
E
E
We
think
the
causes
could
be
sea
level,
because
when
we
lose
that
50
meters,
we
reduce
hydrostatic
pressure
and
when
we
do
that,
we're
going
to
destabilize
the
stability
zone
of
methane
hydrates.
So
we're
going
to
lose
this
wedge
right
over
here
we're
going
to
lose
them
to
methane
oxidation
in
the
poor
water.
You
know
anaerobic
oxidation
and
possibly
also
in
the
water
column,
aerobic
oxidation.
E
Okay.
So
that's
the
reason
why
we
see
these
biomarkers
occurring
right
over
here
and
we
took
a
step
further.
You
know
we
use
the
thermodynamics
to
look
at
how
much
methane
are
going
to
lose
due
to
the
sea
level
change.
So
we
calculated
the
hydro
stability
zone,
changes
at
different
water
depths
and
we
at
different
weather
climate
zonation
across
different
depths,
and
we
use
the
paleo
bathymetry
and
integrated
all
of
them
to
come
up
with
a
global
picture.
Okay,
so
here's
the
take
home.
The
total
message.
E
Release
due
to
this
sea
level
drop
perhaps
is
about
200
gigatons.
That's
not
a
huge
number.
I
mean
if
we
assume
80
of
that
is
aerobically
oxidized
and
convert
that
using
seawater
chemistry
to
co2.
That's
related
to
about
38
ppm
of
co2
increase
during
the
deglaciation
phase
of
the
imi-1
event.
It's
not
huge,
but
it's
a
significant
number.
It
contributes
to
that
co2
rebound
and
climate
rebound
during
the
deglaciation.
E
So
I
hope
I
I
convince
you
that
the
home
is
that
little
biomarkers
are
powerful
tools
to
trace
past
methane
release
and
we
can
even
work
with
open
ocean
environments.
Where
you
know
things
are,
you
know,
there's
not
no
huge
amount
of
methane,
no
problem.
We
see
them
in
the
biomarker
evidence
and
ocean
acidification
and
hypoxia
due
to
methane
aerobic
oxidation
could
be
more
important
than
you
know,
directly
having
them
coming
into
the
atmosphere
and
contributing
to
the
radiative
effect.
E
A
E
Running
out
of
time,
so
very
very
briefly:
I'm
just
going
to
show
a
little
primer
about
the
petm,
because
that's
the
holy
grail
of
methane
hydra
study.
I
guess-
and
we
focus
on
the
arctic
ocean,
because
arctic
is
gonna,
be
it's
first.
It's
a
low,
sulfate
world
and
second
arctic
is
a
very
fresh
world
during
the
petm.
E
E
Okay,
so
maybe
a
smaller
anaerobic
flux,
but
a
higher
aerobic
flux
in
an
arctic,
and
we
do
find
evidence
of
that.
So
here's
a
the
gas
chromatography-
and
here
is
our
favorite
compound.
That
is
the
compound
related
to
aerobic
methane
oxidation.
So
we
see
them
right
here
during
the
carbon
isotopic
excursion
and
they
are
isotopically
depleted.
E
So
probably
we
had
methane
released
into
the
water
column
in
the
arctic
during
the
petr,
which
played
a
role
for
the
petf
climatic
and
environmental
changes.
Okay.
So
I'm
going
to
stop
over
there
and
I'd
like
to
thank
the
founding
agencies
to
thank
in
my
group.
A
wonderful
group
of
students
and
bangsu
is
right
over.
There
is
our
local
expert
on
methane
biomarkers
and
thank
you
very
much.
B
B
C
Really
enjoyed
that.
Thank
you.
I
was
just
wondering
if
you,
you
think
that
the
myosin
the
legacy
myosin
transition,
was
likely
to
have
a
higher
kind
of
background
amount
of
methamphetamine
to
be
able
to
invoke
than
than
either
you
know
more
recent
climates
or
perhaps
speculation
on
earlier
climates,
because
you
know
what
you
point
out
via
sea
level
becomes
quite
a
general
mechanism
that
we
might
expect
to
come
into
play
for
other
glacial
cycles.
E
Yeah,
that's
a
great
question
james.
I
put
in
some
thoughts
into
that.
I
and
I
had
the
same
question
like
why?
Don't
we
see
it
over
the
more
recent
plyoplysis
pleistocene,
where
we
have
larger,
even
larger
cycles
of
glacial
integration
and
simultaneous
variations?
And
I
think
maybe
the
answer
lies
into
the
the
concept
of
this
hydrate
being
like
a
capacitor
or
a
reservoir.
E
That
needs
a
recharge
time.
So
I
would
argue
that
maybe
in
the
earlier
part
of
the
phanerozoic
you
know
we
didn't
have
that
much
of
these
huge
sea
level,
variations
that
provided
longer
recharge
time
for
the
system
versus
during
the
pleistocene.
You
know
this
thing
happens
every
100
000
years,
and
maybe
they
don't
have
time
to
accumulate
that
much
in
that
capacitor.
So
that's
just
my
thought
apparently
lacks
you
know,
calculations
and
modeling.
D
Yep,
sorry,
I
couldn't
unmute
myself
perhaps
intended.
This
is
mostly
for
james,
I
guess,
but
maybe
for
both,
but
so
james.
You
showed
that,
like
the
early
cenazoic
has
really
large
variability
in
reconstructed
co2
and
that
there
is
some
like
orbital
scale
cyclicity,
and
so
I
guess
like
can
you
suggest
some
hypothesized
mechanisms
where
you
can
get
orbital
scale,
cyclicity
that
in
the
absence
of
continental
glaciation
and
perhaps
also
at
the
scale
that
you
see,
you
know
it's
like
swinging
between
400
and
2000
ppm?
It's
pretty
huge.
C
B
C
Of
of
places
in
glacial
cycles,
then
so,
but
what
about
the
the
earlier
cenozoic?
Well
today
we
don't
really
have
orbital
resolution
in
those
records.
We
do
have
some
variability.
The
the
biggest
kind
of
spikes
that
you
can
see
in
variability
are
the
ptm
and
the
kpg
impact.
So
you
know
both
times
where
you
know.
C
There's
quite
a
lot
of
you
know
big
picture
stuff
going
on
so
some
you
know
a
bunch
of
quite
viable
mechanisms
for
big
changes
in
ocean
carbonate,
chemistry,
but
something
we
are
now
working
on
is
producing
more
orbitally
resolved
records
in
this
window,
and
it
will
be
really
interesting
to
see
as
we
do
that
you
know.
Does
some
of
you
know
the
variability
within
the
data?
C
Does
that
kind
of
resolve
into
orbital
cyclicity
and
did
you
I
think,
you're
kind
of
touching
on
a
really
really
fascinating
point,
which
is
you
know
that
there
are?
You
know
pretty
big
changes
in
in
climate
in
in
the
year
scene,
on
an
orbital
scale,
and
yet
you
know
co2,
the
kind
of
baseline
is
higher
and
so
to
get
your
changes
from
that
higher
state.
You
need
more
co2
given
as
it
scales
with
doublings,
so
so
that
kind
of
raises
some
quite
interesting
pictures
about
carbon
sources.
C
On
the
one
hand,
though,
on
the
other
hand,
is
slightly
kind
of
counterbalanced
by
the
the
concept
that
actually
in
the
scene,
you
have
a
higher
climate
sensitivity
world.
So
yes,
I
hope
that
gives
a
kind
of
a
bit
of
a
flavor
of
of
an
answer
and
and
watch
this
space
for
more
of
that
orbitally
resolved
data.
A
Okay,
so
I
have
a
related
question,
because
here
you
see
that
say
for
the
use
and
climate
optimum,
we
have
a
lot
of
variability
in
the
co2
reconstruction.
My
question
is
from
climate
modeling
perspective.
If
we
want
to
use
the
co2
in
our
model
simulations
right
now,
I
think
we
are
using
a
bulk
average.
C
C
C
C
B
If
I
can
jump
in
unless
there
are
any
other
questions,
this
is
more
a
question
for
yiga.
If
I
understand
it
right,
you're
planning
on
going
back
through
the
the
data
we
have
for
gdgt
distributions
to
calculate
method
index,
can
you
speak
a
little
bit
about
that
work
and
sort
of
the
challenges
posed
by
maybe
different
standards
of
data?
Archiving.
E
E
So
we
are
actually
able
to
screen
the
data
and
we
saw
some
interesting
trends
over
the
mesozoic
and
phenotypes
when
gdgs
are
available
and
they
might
be
tied
to
some.
Like
general,
you
know
the
climate
and
environmental
scheme
of
the
mesozoic
and
phenolic,
but
that's
a
preliminary
work.
Well,
we.
We
are
not
fully
understanding,
but
we
do
see
some
interesting
patterns
over
that
long
term.
When
do
mapping
occur
and
whether
they're
correlated
with
factors
such
as
sulfate
concentration
or
you
know
that
kind
of
thing.
We
do
see
that.
A
E
C
C
Nice
to
see
again
and
nice
to
actually
kind
of
talk
about
this.
This
is
something
that,
in
normal
times,
I
have
you
know,
talked
about
while
kind
of
developing
a
lot
of
this,
and
actually
it
was
like.
You
know
a
lot
of
time
spent
in
our
spare
bedroom
in
lockdown.
You
know
sweating
over
pulling
together
these
data
sets.
This
is
actually
first
time
I
actually
talked
about
it
out
loud.
I
hope
it
wasn't
too
intensely.
Geochemical.