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- My name is Vince Resh.
I'm professor of the graduate
school in the Department of
Environmental Science
Policy and Management,
and I'm chair of the
Hitchcock Lecture Committee.
We're pleased, along with
the graduate counsel,
to present Dr. Ralph Cicerone,
this year's speaker as the Charles M.
and Martha Hitchcock lecture speaker.
As a condition of the original bequest,
we're obliged and happy to tell you about
how this endowment came to Berkeley
because it's a story that exemplifies
the many ways this campus is linked
both to the history of
California and to the Bay Area.
Dr. Charles Hitchcock was
a physician for the US Army
who came to San Francisco
during the gold rush
and set up a private practice
that was actually quite thriving.
In 1885, he established a
professorship here at Berkeley
as an expression of his
long-held interest in education.
His daughter, a very familiar
name, Lillie Hitchcock Coit,
still treasured in San Francisco
for a colorful personality,
as well as their generosity,
greatly expanded her
father's original gift
to establish a professorship
at UC Berkeley,
making it possible for us to present
a series of annual lectures.
The Hitchcock Fund has become
one of the most cherished
endowments of the university,
recognizing the highest distinction
of scholarly thought and achievement,
and we really want to thank
both Lillie and Charles Hitchcock
for making this possible
for so many decades.
And now, let me give you a few words
about our speaker, Dr. Cicerone.
Dr. Ralph J. Cicerone is president
of the National Academy of Sciences
and chair of the National
Research Council.
His research is focused
on atmospheric chemistry,
the radiative forcing of climate
change due to trace gases
and the sources of atmosphere
methane, nitrous oxide
and methyl halide gases.
Cicerone has been credited
with shaping science
and environmental policy
both nationally and internationally.
He received the 1990 Bauer award and prize
for achievement in science
from the Franklin Institute
for his fundamental contributions
to the understanding
of greenhouse gases and ozone depletion,
and for his public policy leadership
in protecting the global environment.
In 2001, he led a National
Academy of Science study
on the current state of climate change
requested by President Bush.
Dr. Cicerone notes that
in today's lecture,
he'll use up-to-date data to illustrate
the driving forces of greenhouse gases
and contemporary climate change.
Tomorrow, we'll hear the second
lecture in the same place
where he will compare
successful initiatives
to protect the ozone layer
with the to-date unsuccessful initiative
to stabilize global climate.
A prolific author, Dr.
Cicerone has co-authored
scores of publications,
including the article
Trends of Extreme
Precipitation in Eastern China
and their Possible Causes.
He's also contributed to a
wide variety of other articles,
including Physiological,
Biochemical Controls
over Methyl Halide
Emissions from Rice Plants,
and Biogeochemical Aspects
of Atmospheric Methane,
a wide variety of topics.
Our speaker holds a BS
in Electrical Engineering
from Massachusetts
Institute of Technology,
and a PhD from the University of Illinois.
In 1970, he began his research career
at the University of Michigan
where the Ralph J. Cicerone
Distinguished University Professorship
of atmospheric sciences
was established in 2007.
He performed further research
at Scripps Institute of Oceanography
at the University of California San Diego
and the National Center
for Atmospheric Research
in Boulder, Colorado.
In 1989, he joined the
University of California
Irvine faculty, where he
served as the founding chair
of the Department of Earth System Science
and the Daniel G. Aldrich
professor of Earth System Science.
He was also dean of the
School of Physical Science
and chancellor of the university.
In 2005, he was elected the president
of the Academy of Sciences.
Please join me in welcoming
Dr. Cicerone to Berkeley.
(clapping)
- Well, thank you for
the kind introduction
and also the opportunity to
be here in the first place.
I've already had a very stimulating day
meeting with some Berkeley students
and faculty members in research,
and that it's really a fun
place as it always has been.
I enjoyed hearing that brief history
of the Hitchcock influence here so,
that was really endearing in a way
and shows the value of support, I hope.
What I want to do today,
as Dr. Resh just mentioned,
tomorrow, I'm going to give a second talk,
focused much more on how
the world is responding
to these physically identified
and measured challenges
to the the physical
environment that supports us.
Today, I'm going to focus more
on the science behind climate change,
largely showing data
of some key variables,
what's actually being measured,
and what do we know
and what we don't know,
and then I'll end with a few comments
on how to advance that science.
So, let me show you an outline
of what I want to do here.
This is an outline of
what I'd like to cover.
First of all, a concept that I think
is a really good organizing concept
for trying to understand the
climate of this entire planet.
It's largely a global scale argument
but it's physically sound.
Then I'll get right into the data,
things that are being measured,
the observed changes in recent decades
in important variables,
the temperature of air
the temperature of water,
the budget of the ice masses hung up
on the continents of
Greenland on Antarctica,
a little bit about sea ice,
sea-level rise, Arctic sea
ice, and then a reminder
of what one of the
major driving forces is,
human use of energy from fossil fuels,
and then some comments about
moving the science forward,
because an ultimate goal of this science
is not only to understand and to measure
what's happening and detect the changes,
but to try to anticipate what's coming
so that human adaptation as
well as mitigation efforts
can come into play more effectively,
and then, of course, try
to predict those changes
at the same time.
So, the first concept is simply that
the energy balance of the planet
controls the Earth's climate.
This is not an astounding observation,
but it's an organizing framework
that really allows us to
focus on important variables
and to measure just how far away
from a static situation
we are, for example.
So, this is more or less a
cartoon looking at the Earth
with the Sun not to scale,
but to a very good first approximation,
very good approximation.
The energy budget of the Earth is balanced
by incoming sunlight,
largely visible sunlight,
some infrared, that's important,
and outgoing radiation from the planet,
which is planetary infrared radiation.
So, the balance is, these
quantities have been measured
fairly well to within 1% of
almost everything I show here.
Coming in from the Sun on average
is 341 watts per meter squared
so it's energy per unit
time per meter squared
and about a little bit less than 1/3,
30% of that energy, 102
watts per square meter
is reflected back out to space
before it's ever received
by the Earth's surface
by white things, by light-colored objects,
whether it's clothing or whether it's ice
and reflective water.
So the net, 341 minus 102
watts per square meter,
is the net incoming radiation from the Sun
and the outgoing is, as
I said, infrared light
at 239 watts per square meter.
And these two quantities
are remarkably well-balanced
from all the measurements
that have been made
largely by Earth-orbiting satellites.
The shuffling around of that energy,
once it's absorbed by the
dark surfaces on the Earth
and re-emitted and in the form of either
measurable or infrared radiation,
bounces around here and
it maintains a temperature
where the Earth's surface is higher than
that of the atmosphere and so forth,
and the numbers are fairly
well-known on average.
So, to a first approximation,
that's the budget
and anything that can be
done to perturb that budget
is capable of changing the
climate, either towards,
let's say, a planetary
average lower temperature
or a higher temperature.
This picture, this graph,
was created in 1972
from one of the first
Earth-orbiting satellites
that was looking down at
the Earth in the infrared.
And what it shows is, as
a function of wavelength,
10 micrometers and so forth,
how much radiation was seen
by the satellite looking
down on the Earth,
and if the Earth were radiating
just as a blackbody radiator,
you would have these curve, dashed curve
if the temperature were 300 Kelvin
or 27 degrees centigrade,
or if the Earth were very, very cold,
you would get this curve,
but what was actually
measured has structure in it
and they indicate the
presence of greenhouse gases
in the atmosphere, that is,
chemicals that float around
in the air in gaseous form
that have the ability
to intercept outgoing
infrared radiation, this
energy that I referred to.
So, this absorption is
mostly by atmospheric ozone.
This absorption is due
to mostly carbon dioxide.
In between, there's a lot
of water vapor absorption
so the point is, there's no mystery here.
One can go into the laboratory and measure
the wavelength dependence of the way
these gases interact with
infrared light, for example,
and do quantitative calculations,
and you can calculate that
this is what you should see
looking down on the
Earth, things like that.
So, just to do a rough calculation.
This idea was pointed
out probably 40 years ago
that we can calculate the temperature
of different planets,
Earth, Venus and Mars,
the ones that we know the best.
So, for example, if you do
this calculation for Mars,
this equation applies in a steady state,
that is, nothing's changing with time.
We now know that things
are changing with time,
but just to a first approximation,
if you know the total amount
of sunlight energy coming in
and the fraction 30% is reflected,
that means that 70%,
one minus point three,
is absorbed by the
Earth and the atmosphere
that should be equal to
the outgoing radiation,
which, in equilibrium, would be
the Sigma T to the fourth law,
so, S is measured, alpha is measured,
Sigma is a constant, you
can calculate temperature
just by taking the fourth
root of the equation
and you get, for Mars,
that the temperature is something like
minus 28 degrees centigrade,
and it's the right answer
within a few degrees
if you averaged over day and night.
If you do the same calculation for Earth,
you don't calculate the right number,
you calculate that Earth
is freezing everywhere all the time.
And what's missing here
is the greenhouse effect
of the gases that I just mentioned.
Mars has a very thin
low pressure atmosphere.
There's not much in the atmosphere
that interferes with the light coming in
or the infrared going out,
so you can calculate
Mars in this simple way,
the temperature very accurately.
With Earth, as I said, you miss by
about 50 degrees centigrade.
And for Venus, you really miss
because the atmosphere
of Venus is very thick,
pressure, 100 times that of Earth
loaded with carbon dioxide
and other greenhouse gases.
So this calculation illustrates that
right away, you're pretty
close to the right answer
just by including greenhouse
effect and clouds.
Well, why is all this important?
Because we know now that
the chemical composition
of Earth's atmosphere is changing.
This is the iconic series of data
taken mostly by people
at Scripps Institution of Oceanography.
David Keeling, who's now deceased,
and his son who's a professor there,
Ralph Keeling has
continued the measurements.
Every black dot, if you can see it,
represents the average of measurements
of carbon dioxide in air
up the slopes of Mauna Loa
on the Big Island of Hawaii,
sampled every one hour.
So every black data point, as
I said, is the monthly average
of measurements made every hour.
And what you see is the
underlying trend has gone up
starting from 312 parts
per million in 1957
up to about 400 last year.
Although this graph
was updated in January,
the red curve is the
same kind of measurements
from the South Pole.
So there's a few months
lag time when they ship
these little containers
of gas back-and-forth.
On top of that underlying rise
is this annual cycle wiggling
of the carbon dioxide amounts,
which is really quite beautiful
and it's telling us something
about the Earth as a living planet.
In the summer and spring, for example,
the northern hemisphere months,
when photosynthesis is
happening in green plants
and algae and water bodies
are sucking in carbon
dioxide for photosynthesis,
the carbon dioxide amount is drawn down
and then in the fall and winter,
subsequent respiration and decay of that,
some of that new organic
matter takes place.
So every year, there's an annual cycle,
drawing down CO2, reintroducing CO2
into the atmosphere, on and on and on.
There's an offset from the South Pole
for other explainable technical reasons
and there's not much land
surrounding the South Pole
so the air that one samples doesn't show
this kind of seasonal wiggles.
There isn't much
photosynthesis there at all
even in the surrounding waters.
Okay, let's now get down to variables
that are being observed that tell us
something about climate change.
First of all, air temperatures.
In another slide, I'll show you the names
of some Berkeley people who've done
some similar analysis, but first of all,
this temperature scale, zero
does not mean zero degrees.
It means a reference point,
and that reference point
is the average of all
the temperatures measured
between 1950 and 1980, so
it's a 30-year data set
which is used to establish an average
and in this case, the
average was 1950 to 1980,
so zero corresponds to the
average of this 30-year period.
Anything that's negative from that zero
represents times when the
Earth's temperature on average
averaged over all
latitudes and longitudes,
day and night, was lower than the zero
and of course, in later
years, beginning about 1975,
the measurements of these air temperatures
have gone up more or less monotonically.
There are a few hundred million
data points in this data set
and the statistics are pretty good.
You'll see that the record year of 2015
really was high compared
to all previous years.
A previous El Nino year
when the eastern tropical
Pacific waters are warm
was 1998, which was also a high year
but the underlying trend again
is increasing air temperatures
all over the world.
There are several other laboratories.
These data happen to come
from a NASA laboratory
in New York City, or the Goddard
Institute for Space Studies
which is the reference here, which you can
pull these off of their website any time.
Very well-documented,
all the changes in the
record are explained.
Any so-called corrections to the data,
adjustments to the data stream,
are explained in great
detail, very well-documented.
And there are three or
four labs around the world
who do similar work with
slightly different approaches
and different data sets, and
I'll mention that in a minute.
Just to show you the kind
of detail that's available
to start to break this down,
because a global average temperature,
in the words of someone one time long ago,
he said, "That doesn't
make my knuckles white."
He didn't know how to respond to that.
So, a global average
temperature is relevant
because of the framework that I mentioned,
the concept of a planetary energy balance,
but it doesn't really tell
us a lot about what's coming.
The Berkeley Earth temperature
project which I mentioned
examined the same kind of
data over a period of years,
and overlaid over the previous
data of the NASA data,
you'll see that they obtained
very, very similar results
but with very different approaches.
They used different data sets.
They tried to introduce
different ways of correction
for things like the
urban heat island effect.
In many of the places, for example,
in developed countries
like the United States
where temperature recording
instruments have been put out,
cities have grown around them
and surrounded the place with black top,
and you can see the
urban heat island effect
all over the world.
And this Berkeley project
led by Rich Muller
but also the other people listed here,
not all of whom were from Berkeley,
they tried to see what the
sensitivity of the record is
if they cut the data up
into different pieces,
removed individual
stations from the record
of which they were suspicious,
gave more weighting to the ones
that looked like they were
well-maintained and so forth,
and on this scale, the
results are the same,
at least on the global
average temperature.
This is a very valuable
project that was performed here
that I think answered a lot of
serious questions very well.
Now let's break the data down a little bit
into all land and ocean
areas north of the equator,
northern hemisphere, annual
mean versus southern hemisphere.
And you'll see that the
northern hemisphere in the red
has warmed up more than the
southern hemisphere in blue.
Now, that's logical because
the southern hemisphere
has more ocean area in it
than the northern hemisphere does,
so the heat capacity near
the surface is greater.
And if, for example, this is being forced,
these changes are being forced
by the physical imposition of new energy
like this greenhouse
effect that's growing,
you would expect to see a lag
that the southern hemisphere
would warm more slowly.
So not only are these data real
but they seem to be consistent
with the underlying premise here.
If you break those data down further
and these are now surface temperatures
measured at different
places around the world,
so here's an outline of South America,
North America, Africa, and so forth,
you can see the outlines
with false color codings
showing three of the warmest winters
in this 135-year record.
The 2015 was the warmest at all
and you'll see the preponderance
of really hot areas
where the temperature is four
or five degrees centigrade
warmer than the average
period over an entire year
and a little bit of cooling,
and part of the Antarctic sector.
Most parts of the world though are showing
excess warmth, higher temperatures.
When you plot 10 or 20 years together,
you find that there's
virtually no place on the Earth
that has remained at its average
or as below average, everything is up.
So 2015 looked like this,
2010 was like this,
even more pronounced warming
over this part of the
Arctic, and so forth.
There's a month-by-month
record of this anomaly.
Again, that is the amount
over the 30-year average
and it shows the hottest years.
So, for example, 2014 in green
shows the global average
temperature month-by-month,
September, October, November,
December and so forth,
and some ups and downs during the year.
2015, the record for any month before 2015
as this black line, and then in 2015,
records were set over the
135-year period of observations
for the months of October,
November, December
and they continued into
January of this year.
So this is now a plot of
January mean surface temperature
over these parts of the world
where now this pink is the hottest of all.
Parts of the Arctic are 10
and 12 degrees centigrade
above the 30-year average.
This turns out to be a puzzle.
It's hard to say why
the Arctic is warming up
maybe twice as fast as
anybody expected it to.
So the point is these data are available
pretty much on a monthly basis.
You can track these things
and in even more detail
because most of the
significance of climate change
impact on humans and
ecosystems and so forth
will be regional in individual locations,
but this globally averaged picture
and the geographical projection,
different parts of the world,
is still interesting to understand.
So here's January of 2016
compared to all previous hot Januarys.
It's way out there.
Now, temperatures of ocean.
It's harder to get really tight data
on ocean water temperatures
because they're not as well-sampled.
The sampling is much coarser
geographically and in time,
but over the last few years,
due to some very careful work,
this graph happens to be
from somebody named Levitus
who's recently retired
from our National Oceanic
and Atmospheric Administration,
they have plotted the
change in the heat content
of water bodies around the world.
This is a little bit
complicated, but zero would be
if there were no change
in the heat content.
So, here is a graph of the
world ocean heat content
broken down, versus altitude
below the surface of the ocean
so the thermocline,
the body of ocean water
which is pretty well-mixed
above 700 meters,
below that point, 700
meters below the surface,
has increased by a few hundredths
of 10 to the 22 joules per year
but you can see that
it's as if a heat pulse
is sinking now into the ocean.
And it is seen first
at the lower depths, a few hundred,
the more shallow depths,
and it's propagating now
down into the deeper depths,
the greater depths, with time.
And when you do the numbers
and add it up globally,
this amount of extra heat
that's being observed
by real measurements in the ocean
is compatible with the budget figures
that I'm showing you on
Earth's energy budget.
This kind of data is now
becoming much more available
due to the invention of some
automated floating devices
which go around the world's oceans
and measure several things
about the ocean waters
and that they can bob up
and down under control
and sample great depths
and they do it repeatedly.
It's a fantastic set of instruments,
so these data sets are growing.
These are some of the first
patterns that are emerging.
These graphs may be a
little easier to see.
It shows what's observed
in the zero to two kilometers depth,
so the increasing heat content,
which is essentially temperature
with time at all depths.
Again, the data are still coarse.
There are some undersampled regions.
In fact, this bar gives you a measure
of whether or not the
layers are being based
and what fraction of the
waters around the world
are being measured at various steps,
so these data are increasing.
They also show a warming,
especially over the last 30
or 40 years, or 50 years,
all around the world.
It's clear that the rate at which
the heat is being sucked
into the world's oceans
is not very predictable at this time.
It happens somewhat sporadically
at different latitudes
but on average, the numbers
are looking pretty consistent
with all this other picture.
You've probably seen photographs
or some kinds of measures
of the amount of ice
floating on the Arctic Ocean.
Now that floating ice is not
serious in terms of sea level
because it's already floating.
It changes from solid to liquid,
it doesn't change the sea level,
but from a point of view of navigation,
mineral exploration,
commerce, military security,
the amount of sea ice is important
and it's an interesting variable,
so these data are reported almost daily
from a remote sensing device
that has been operating since about 1980.
So the gray plot here, the shadowed plot,
represents the amount of
sea ice measured in extent
millions of square
kilometers on the Arctic sea
plus or minus two standard
deviations of the average,
so if you take this 35-year
average of these measurements,
they all fall within this gray band.
2015-2016 is scraping the very bottom.
It's down two standard
deviations or so from the average
and this is pretty much
typical of the last few years.
2012 was also very low, a little
bit of recovery in between
but the new norm is the
Arctic sea ice disappearing.
One of the plots that's
a little bit more telling
is take just the month of
January every year since 1979
and ask, how has the average
amount of ice in January
and the Arctic Ocean changed?
And it's going down monotonically.
In fact, because of those
very high temperatures
seen in the Arctic that
I pointed out earlier,
in the air temperatures
this January of 2016,
it's pretty low.
There are similar plots for June
and they showed similar patterns,
that the amount of ice
floating in the Arctic
is decreasing pretty well monotonically
over the entire period of measurements.
There are other measurements
which I'm not going to show here
of the thickness of the sea ice,
the ice that a submarine
would have to penetrate
to get out of the ocean.
And due to some military
data from the U.S.
and the former Soviet Union
that's been declassified,
we can see about a 60% decrease
in the Arctic sea ice thickness
over the last 40 or 50 years.
So these data are also consistent.
The Antarctic is a little more complicated
and the data are not so clear
and I won't show them here.
One of the most stunning measurements,
which I can explain a little
later but it takes more time,
is how the mass of ice on
Greenland and Antarctica
is being measured.
It's done by remote
sensing with an instrument
that actually measures small perturbations
in the Earth's otherwise
spherical gravitational force.
It's a very neat technical
setup and what they have shown,
these data only go up to about 2014,
is that there are seasonal changes
in the amount of ice on Greenland
but generally speaking, the
annual average has decreased
and it's decreased by, on average,
260 gigatons of ice per year
that it is falling off
the Greenland continent
or melting directly into seawater.
And if you'll notice,
that's an inverted parabola.
It's not a straight line.
It shows an acceleration
of the rate of loss
of about 30, I think it is,
yeah, 28 gigatons per year
per year as an acceleration.
And these data are not only
really high-tech and well-done,
but they're confirmed by other
measurements of the height
of the ice extending over
the Greenland continent.
Similarly for Antarctica,
this was just a huge drop in one year
but there were some recovery after that.
These data are from Isabella
Velicogna and her colleagues.
She's a physicist in my home department,
Earth System Science at Irvine.
Her senior colleague,
John Warren, unfortunately
died a couple of about
eight months ago now,
but this data set continues.
Okay, when they look at Antarctica,
they find a similar picture
with more variability.
Again, over the 12, 11-year period,
there's been a loss of the
ice mass on Antarctica.
It's been not as strong, a
lot more annual variability.
In fact, they can now
focus the instrument better
on sectors of Antarctica where they find
that there is one sector of Antarctica
which is not gaining ice,
and that a major part of
Antarctica is losing ice
but it's more messy data.
But they also find an accelerated loss
of mass and ice on Antarctica.
Now the reason this is important is
when you lose ice from a continent
and put it in the ocean, sea-level rises.
So if you add the
contribution to sea-level rise
of Greenland and Antarctica,
you've got numbers that
I'm getting to now,
which is pretty well explaining
the observed sea-level rise.
This graph is a record of
rather old measurements
of sea-level over the
beginning of the 20th century
all the way through the 21st century.
And most of these data in the black curve
were obtained by basically tide gauges,
stakes and poles pounded
into the coastal environment,
fairly primitive instruments,
but very, very careful record-keeping
has allowed a reconstruction of sea-level
over the 20th century, about
110-year period up to 1992.
If you average all of
these tide gauge records
from all over the world,
you see this indicator
of global sea-level rise.
And there are certainly some spots
which are geologically
active, tectonically active,
where the rise has been
less or more over time.
The statistics of these measurements
are a little bit scattered,
but beginning in the year 1992,
Earth-orbiting satellites
with radar ranging devices
and some interferometry added to it
have shown the red part of the data,
which is a somewhat
faster rise in sea-level,
which is a better global average,
much more precise, better sampling.
It shows,
since 1992, here's what
that record looks like.
The observed sea-level rise,
the best fit to the data, is about double
what I showed from the
old tide gauge record.
It's three point three
millimeters per year
over this modern record of altimetry
from remote sensing satellites.
So the question arises, has
sea-level rise accelerated
because the earlier result was about
one point six centimeters over 100 years,
or about one point six
millimeters per year
compared to this three point three double.
Well, recently,
a couple of people have analyzed
these old records and they think that
the statistics are a better fit
to a slower rate of sea-level rise here,
increasing more to match
the red modern observations.
So it's a minor refinement,
but it adds evidence to the idea
that sea-level rise is accelerating.
The budget now of where
the water is coming from
gives a pretty good first approximation
to this observed rate of sea-level rise.
These data are also updated
every three or four months
by a group at University of Colorado
who are in charge of this
remote sounding instrument.
And you can see that the last
few months have been higher
but the best fit to the
data will probably be
still about three point four,
three point five millimeters per year.
Now, where does that come from?
The very fact that sea
surface temperatures
are being warmed, the temperatures rising,
causes a thermal expansion
of layers of ocean
and that accounts for
maybe a third or a half
of this observed sea-level rise
over the last 30 to 40 years.
The rest of the rise in sea-level
is coming from new water being dumped in
from melting ice in
Greenland and Antarctica
and some inland glaciers.
There's also a drawdown which
can actually be measured
in some of these wiggles.
When there are huge dumps of rain
as there was in Australia in 2010, 11,
there was enough water dumped in Australia
that did not make its
way off of the continent
into the oceans, to cause
a decrease in sea-level.
So, these instruments
are quite capable now,
but that's the rough picture.
So, going back to the
carbon dioxide record,
I want to make the point now
of something being unusual here,
namely, we now have
observations from ice cores
in Greenland and Antarctica
that have been dated.
That is, you can drill down
and take a vertical core out of the ice
and put dates on it.
This was from 100 years ago,
a little bit deeper
was from 200 years ago,
a thousand years ago, and so forth.
One of the most important sets of data
came from an international
collaboration led by French
who drilled a very deep
ice core at the Vostok
area of Antarctica.
And it's so deep that it
went back 450,000 years
from the present, before present,
200,000 years before present,
300,000 years before
present, and so forth.
And what they found was
by slicing up the ice at different depths,
and crushing the ice,
they could extract the gas
that was trapped in that old ice,
for example, carbon dioxide.
So this is a physical measurement
of how much carbon dioxide was in the air
100,000 years ago, 150,000
years ago and so forth.
It's a direct measurement.
So this is a major accomplishment
and what it shows is
that there have been different ice ages.
There was an ice age about
20,000 years ago that hit,
and then 140,000 years
ago, another ice age,
about 250,000 years ago, and so forth.
When it was cold, the carbon
dioxide amounts in the air
were not 400 parts per
million like it is now
but 180 parts per million,
and when it was warm in between ice ages,
it was about 270 or 280 parts per million.
So going back one ice age, I just did,
going back two ice ages, also low,
in between ice ages, high,
namely 280 parts per million,
in between ice ages and so forth.
So whatever is causing this,
it shows that the chemical composition
of the air today is unprecedented.
The last four global ice ages,
and the last four in
between warmer periods,
had carbon dioxide bracketed
at concentrations down here
and where we are now is
completely out of that range.
So there are many ways to prove
that the excess carbon dioxide today
is due to fossil fuel burning.
And I won't go into them now.
I could illustrate it later,
but whatever the cause is,
we can prove definitely
that the carbon dioxide content
of Earth's atmosphere today
is above where it's ever been
in this kind of recorded history.
We think that 50 million years
ago, Carboniferous period,
100 million years ago, there
was more carbon dioxide
but it's, of course, hard to be sure.
The same is true of another
greenhouse gas, methane,
where the blue curve here
is a proxy measurement
of what the temperature was,
inferred from ice amounts
and the isotopic content of the ice cores,
but when it was cold, methane amounts
were about 1/3 of a part per million,
and when it was warm in between ice ages,
methane amounts were about
2/3 of a part per million.
Methane amounts in today's atmosphere
about one point nine parts per million,
so two to five times what
has ever been seen before.
So this set of ice cores from the French,
the Danes, the Russians,
with some contribution from Americans,
is really very important.
It tells something
about where we are today
being unprecedented in
terms of climate history,
at least back 800,000 years,
that the data have now been
extended back 800,000 years.
This is just an example to show
what we see in nitrous oxide measurements,
another greenhouse gas
whose origin is not as clear
but it seems to be involved
with a number of human activities,
including artificial nitrogen produced
for fixed nitrogen for fertilizers.
So, what does that have to do
with the energy budget of the planet?
Now we can take and have taken
over the last 35 years or so
laboratory measurements that
tell how these gases interact
with outgoing planetary radiation
that would otherwise escape to space.
We can do quantitative calculations then,
knowing the amounts of these
chemicals added to the air
since the Industrial Revolution,
determined by measurements
of recent ice cores
in the same way, compared
to what's measured now
and when you do that,
you can then calculate
what is the change to
the Earth's energy budget
at the surface.
So just the carbon dioxide added amount
gives you almost two
watts per square meter
extra energy per unit time
trapped in the Earth's
lower surface areas.
Methane gives this
contribution, nitrous oxide,
some fluorocarbon replacement chemicals,
hydrofluorocarbons, some
perfluorinated chemicals,
CFCs, and then ozone
in the lower atmosphere
and the answer comes up to be about,
if you add all these together,
almost three watts per square meter.
We call it radiative forcing
but it means forcing
that will directly affect
the Earth's climate.
There are most complications
in this radiative forcing
which I'll mention also later,
but that's the simple side of it.
So there's something else that's different
about these last 30 or
40 years in addition to
what I've just showed you
of the actual measurements
of air and water temperatures,
ice amounts, sea-level rise,
and that is it's the first
time in human history
that we've been able to
measure the output of the Sun
with enough stability
and precision to say,
well, maybe the Sun's
energy reaching the Earth
has just increased at the same time,
maybe these warming phenomena
are simply due to extra
energy coming from the Sun.
Well, the answer is no.
These results were published about 2005
by Judith Lean, who's a scientist
with the US Naval Research Lab,
and a colleague, Klaus
Froehlich, in Switzerland
that shows that over this period
of satellite observations of
the Sun with some precision,
there was no change in
the amount of energy
coming out of the Sun
except for a little
bit of an 11-year cycle
that correlates with sunspots
which we've known about for a long time.
And, in fact, this whole change
is about point one percent
from top to bottom.
Well, the number I just showed you,
the radiative forcing
due to greenhouse gases,
are about one and a half percent
and the change due to solar irradiance
is about 1/10th or 1/20th of that amount.
The difference here is you have to get,
there's a geometrical
factor, the amount of energy
actually being intercepted by the Earth
is this number divided by four.
Some of you who are arithmetic freaks
may have already realized
that if you divide this number by four,
you get 341 watts per square meter,
which was on my first cartoon slide.
That's the geometrical factor.
Now that record has been
difficult for Froehlich and Lean
to put together because it
required stringing together
satellite observations with high precision
that weren't meant to be used that way
but they've continued the work
and this is Klaus
Froehlich's recent update
showing now three or three
and a half solar cycles,
four solar cycles, again, with a cycle.
So the radiative forcing
due to the greenhouse gases
is not a cycle.
It's a sustained elevation
in the energy budget of the Earth
whereas these cycles are just that.
They're imposed by solar activity changes
and they're smaller, so
the greenhouse gas forcing
is about, at the surface, about
three watts per square meter
and this one is point 25
watts per square meter
wiggling around.
So, those of us who thought and hoped
that maybe the Sun's output
was causing these changes,
when we were thinking of
this back in the early 80s,
we no longer have a leg to stand on.
The evidence is really clear
that these physical changes
that are being observed
are very strongly linked
with human activity.
The numbers add up, the processes add up,
the mechanics, the underlying premise.
Well, I'm gonna close in a few minutes
but, you know, why do we care?
And is this likely to continue?
Well, if you just look at
one of the greenhouse gases,
carbon dioxide, where it's coming from,
of course, you all know about
the burning of fossil fuels,
that is, burning of
substances like natural gas,
coal, wood, that contains carbon,
the very act of burning this stuff in air
creates carbon dioxide.
And the thermodynamics
is that the heat released
in that oxidation of carbon
to release carbon dioxide
is what gives us the heat and the energy.
So it's very valuable right now.
However, if you look at
the carbon part of it
and how much carbon
dioxide is being released,
there's this figure called global.
This is from a woman
named Corinne Le Quere
with a paper that was just
released a month or two ago
where they've gone back
over all the carbon budgets.
They didn't do this alone.
There were many, many, many
assessments before they did this
but this is in a peer-reviewed journal
showing that if you just
look at the fossil fuels
being consumed around the Earth
and ask how much carbon is being released
in the form of carbon dioxide,
the number today, 2012 or 14,
is about 10 billion
tons of carbon per year.
So obviously, carbon dioxide is
44 divided by 12 times as much
but just look at the carbon
released as carbon dioxide,
it's 10 or a little bit
more than 10 gigatons,
10 billion tons.
A breakdown is that on
the lower graph here,
about 40% of that carbon is being released
from coal combustion,
about 30% from oil combustion,
and you see gas and cement manufacture,
which also releases
carbon as carbon dioxide.
Well, this source of
energy for human activities
is about 80% of all the energy
that humans use on the planet,
that is, for manufacturing,
for transportation,
for production of
electricity, you name it.
The remaining 20% is from
hydropower, nuclear power,
solar and wind power,
which of course are gaining
but they all add up to only 20%.
So, for the foreseeable future,
there will be continued large emissions
of carbon dioxide into the atmosphere.
And I can give you more
evidence on why we know
that this is from humans
and got the numbers right.
It's pretty compelling evidence,
but even as the world
tries to conserve energy,
to be more efficient, and
to use renewable energy,
it's very hard to escape
that there will be
continued large emissions
of carbon dioxide.
For one thing, just for transportation,
when you burn gasoline or diesel
to drive a car or a truck,
it's actually a pretty well-suited fuel
because you don't have to carry
the oxidizer around with you.
You've got the oxidizer
oxygen out of air for free
and you don't have to transport
it while you're going.
You're carrying only the minimum
load of fuel that you need.
You don't have to carry
the oxygen with you.
It's not like a spaceship where you have
to carry the oxidizer with you.
So hydrocarbon fuels have a big advantage
and they're not gonna be displaced easily.
It costs virtually nothing to extract them
from the ground, and so forth.
On the other hand, the progress
in providing energy for industry
and residents and everything else,
electricity from renewable power
and from progressively
better nuclear power,
it's non-trivial but it can't
handle much of the load.
This is a further breakdown
of Le Quere's data,
nation-by-nation for a few nations
showing the fabulous
economic growth in China.
China is now the world's
number one CO2 emitter.
It's not only due to their economic growth
but the displacement of heavy industry
from the United States and
other countries to China.
So there's been a structural
change in their economy.
They're doing more of
the heavy manufacturing,
which has also led them
to release more CO2.
India's growing fast, but per capita,
you can see that the per capita emissions,
that is, tons of carbon
per person per year,
the U.S. is still the
most at about almost,
what does that say, about
five tons per person per year.
The global total, the
global average is less
because India and China
and the European Union
and so forth, emit less per person.
So, no matter how you slice it,
these global data tell you that
there's gonna be very
hard to change this trend.
So that means that whatever
is happening with climate,
we really have to get
better at making predictions
and assessing it, so
just a few observations
on how we can move the science forward,
and some of you here are doing
some very important work in this regard,
but to make the science
more understandable,
more definite, to refine the trends,
and to make better estimates
of what's gonna happen in the future,
let alone predictions,
we clearly have to extend and improve
the observational record, for example,
the ocean measurements
and the ice measurements.
We have to create longer records
and deduce the trends and
patterns more carefully.
For example, sea-level rise,
extreme weather events,
is really where a lot of the action is.
It's not just average temperatures
that we're concerned about.
It's precipitation events,
how many big rain dumps and
big snow dumps do people get,
how long are the heat waves,
how long are the droughts,
what is the odds of floods happening.
Some of the world leaders
in these questions
are insurance companies,
and the reinsurance
industry largely in Europe.
They probably have the best
statistics on what's happening
and they break it down
into physical events
as well as financial claims
that they have to pay.
But the physical predictions
are pretty difficult,
and yet they're incredibly important.
It's not just the averages,
it's what are the extremes
that are happening, and I'll
give you example of this.
Then we also want to know whether
the changes that we are observing
in the frequency of these extreme events,
what does it mean in terms of attributing?
Has a particular storm happened
because of climate change,
or has it just happened randomly?
And what are the return times?
You hear these stories about
one in 500-year floods,
one in 100-year floods,
do we really know that
that's a typical return time?
And how can we do a better job
at estimating those return times
for better public planning,
for insurance applications and so forth.
Let me go to the next slide
and show you something.
If you take the same temperature data
that I showed you earlier,
this happens to be again
the NASA (mumbles) data,
and you go decade-by-decade,
in the reference period, the
30-year reference period,
this is now northern hemisphere land
in June, July and August,
you could divide up what looks like
a normal distribution of
temperatures into three parts:
the lowest 1/3 of temperatures on average
in that northern hemisphere summer period,
the middle part which also contains
a third of the observations,
and the upper part, the
highest temperatures.
Now march that forward to the
actual data in the next decade
and you'll see things
shifting to the right.
Although this is 1983 to
1993, in that lower third,
you now only have 23% of the data,
in the middle third, you
have whatever that number is,
and 47, 48% in the upper right.
If you go now into the
latest decade, 2005 to 2015,
look what's happened to that distribution.
It has shifted to the right.
These are actual data, and you see
that what used to be the population
in the lower 1/3 of the data,
it's now only about, I think it's 12%,
I can't quite read it.
In what used to be the normal distribution
is now characterized by
these higher temperatures
that used to be a couple of
standard deviations to the right
now showing up 67% of the time,
and places way to the right,
like four standard
deviations above normal,
are now happening 15% of the time.
So a slight shift to the right
gives you a much larger frequency
of high temperature events
and a much lower frequency
of low temperature events,
but this is now averaged
over a big piece of land,
the northern hemisphere over the summer.
If you do the same thing,
northern hemisphere in the winter,
you get similar results.
So this is one kind of low-level reason
to expect the frequency of
extreme events to change.
Hotter temperatures in
the summer over land,
and warmer temperatures
in the winter over land,
with less real freezing events.
I mentioned radiative forcing before.
There are complications to
those numbers I showed you.
Floating aerosol materials,
some of them have ability
to reflect sunlight
back out to space, visible sunlight,
especially sulfur-containing particles,
so trying to do these
calculations in a reliable way
is difficult because we don't
actually know at any one time
how much of this floating
aerosol material there is
in the air from
sulfur-containing fossil fuels
that when burnt, creates sulfur pollution.
This input is probably
being reduced worldwide now,
but when you try to add that
to the radiative forcing
numbers I showed you,
we got big uncertainties of about a watt
per square meter, that could be negative.
We also don't know the
geographical distribution
and temporal changes in
that aerosol material,
so it's a measurement challenge.
Ice losses and sea-level rise
are particularly important
because of all the climate changes
that you want to talk about,
the most dangerous kinds, the worst risks
are changes that are irreversible,
such as sea-level rise,
or irreversible, for
example, biodiversity loss.
You can't replace species.
At least, those are two examples.
So with sea-level rise, the good news is
so much has been learned in
the last six or seven years
about where the ice is plunging off
of Greenland and Antarctica.
There are specific sites
where the ice mass loss is happening
due to ice sliding down
the sloping continent
that is being held up by an ice shelf
and as the shelf gets
undercut by warm water
and gets dissolved,
then you get an
acceleration of the ice mass
sliding down the slope.
These sites have now been
mapped out pretty well
and there are a lot of
unknowns but at least,
people know where to do the measuring now,
where to measure the water temperatures
and how much the melting of the shelf
is being undercut and
the ice can slide off.
So that's progress and it will represent
a better predictive capability.
There's still some argument
whether ice shelf melting
that I just illustrated with my hands
is the dominant mechanism
or is it simply ice fracturing.
It's probably more ice shelf melting
undercutting the ice shelf.
But then, as this accelerates
and more of this cold
water comes running off
of Greenland and Antarctica,
it's going to affect ocean circulation.
There is a very strong new,
somewhat speculative
paper published last week
by Jim Hansen's group with 15 co-authors
on what happens as the ice melts
and it's like you're hosing the ocean
with a hose of cold water being sprayed
around Greenland and Antarctica,
which will somewhat change
the ocean circulation there,
causing more or less deep water formation
and saltiness that will
change the circulation.
So, for example, one prediction
out of this new paper
is we will see cooling of
surface waters around Antarctica
in the coming several decades.
So instead of seeing a
warming due to global warming,
the feedback there will be
to cool the ocean waters somewhat.
So it's a big prediction,
we'll see if it happens.
Then the whole issue of the
oceanic uptake of energy
is a major one, because
this so-called hiatus
that happened in global
warming in the last 15 years
until the last two years was,
assuming the measurements
are all accurate,
probably due to increased uptake of heat
by the world's oceans,
that can happen again,
or it could shut off.
You got an additional stability
as you warm the ocean surface waters.
It's harder to move things vertically
if hot water is on top,
but there are many other forces
at play in ocean circulation.
My last slide is simply to
say a couple more things.
Whether we like it or not,
this mathematical modeling
of climate is essential
so the people doing this
work are some of the hottest
young scientists around the world.
The solving leaves this
interlocking system
of partial differential equations
that try to go from first
principles explaining
the energy budget of the Earth's surface,
the energy being moved
between phase changes
in solid, liquid and vapor water,
how you transport all that stuff
through a rotating global atmosphere,
so some of the key questions are
how to continue to improve this,
the geographical
resolution of these models
so that, for example, Iowa and Minnesota
are represented individually in pieces
rather than being lumped
together in one big piece,
or regions that have
mountains versus plains
can be separated, and
then the cloud formations,
and the rainfall events can be broken down
much more mechanistically.
A couple of major questions are
in these mathematical models
which turn out to be
numerically solved on computers.
Can we trigger and exit ice
ages over long periods of time?
Can someone actually explain
to scientific satisfaction
what causes ice ages?
What triggers it?
What kinds of feedback
mechanisms are in play?
And how in the world
we get out of ice ages?
We know that we do.
There are geological
and ice records of this,
but it's been very hard
for people to model
the mathematics of this
in a dependable way.
That's a major challenge.
One of the really serious ones
is the acidification
of the world's oceans.
It'll take a long, long time
before we actually reach a pH of below 7
but the pH has dropped
in a measurable way,
and the sensitivity of marine biology
to these patterns of
acidification around the world
where basically carbon dioxide
is taken into the water
and you tend towards acidity that way.
What are the impacts going to be
on individual species and on ecosystems,
such as shell-making creatures
that depend a lot on the
carbonate and ocean water?
Then the land surface is
involved in all of this
so climate science, as
it gets more important,
is involving understanding
of all of these things.
Are the rates of future wildfires
going to increase as
much as is now projected
due to increased dryness,
increased temperatures,
longer periods with low
soil moisture and so forth?
Measuring how carbon dioxide is released
from soil organic matter
as climate changes,
so that what up till now has been
a measurable greening,
a fertilization of the Earth's biota
due to more carbon dioxide being in air,
how sensitive is that going to be?
And will these other measured increases
in the rate at which
carbon dioxide is released
by the world's biota back into the air,
is that speeding up faster
than the extra uptake
due to photosynthesis?
And then, of course, the
potential for storing more carbon.
So all of these things
have to be investigated
and many more.
It's an exciting field of science.
The implications are great
and probably happening
faster than any of us expected,
so the stakes are very high.
And fortunately, some
progress is being made
but I think the story is pretty compelling
about the measured increases
being due to human activity.
In all realms, it's very hard to find
any set of measurements
that fly in the face
of that original premise.
So with that, I think
I'll stop at thank you
and I think we have some
time for some Q and A.
Alan, yes?
(clapping)
- [Peter] Thank you very much
for this very fine lecture.
My name is Peter Joseph.
I'm with Citizens Climate Lobby.
I want to ask you how
you deal with the people
who think that it's a vast conspiracy,
and don't believe the science,
and think there's nothing wrong?
- Let me try just to answer your question.
How I deal with them is to point out
somewhat how science works.
Scientists don't become rich and famous
by agreeing with what
other people have said.
Scientists make their claim
and a lot of their ambition
is based on showing
what everybody else is saying is wrong.
Now, of course, that statement
gets some disagreement
but I think it's mostly true.
I wake up many mornings saying,
"What the hell could be
wrong with this picture?"
I would love to undercut it but I can't,
and people a lot smarter than I
who spend more time on it than I do
have also failed.
The basic theory was proposed
well over 100 years ago
by (mumbles) in Sweden,
and even before that in Great Britain
and calendar in the US,
so people have had a long time to shoot.
Just at the National Academy of Sciences,
we've produced, I don't
know, 30, 40, 50 reports
on this general subject
in the last 40 years
and the numbers are remarkably
consistent on what we expect,
let's say, the global
average temperature to be.
So I think the solidity of
the science is pretty good
and I tell people that, "You talk to me
"about a conspiracy, it's impossible."
It's absolutely, I think, impossible
for any one of us to have
convinced everybody else
in this general field,
of a phony proposition.
There could be errors,
but it's not a conspiracy.
That's what I tell people.
I have met with resistance
for that statement,
people saying that I'm wrong
but that's what I tell people.
- Oh hi, Larry (mumbles),
Revolution Newspaper, revcom.us.
There was one point in your type,
first, I appreciated your deconstructing
of every possible, at
least as I understood it,
objection to this inexorable
rise of climate change
but at one point in your
talk, you made the point
that we had to basically
get used to the fact
that fossil fuels were going to
be with us for a very long time
and this in producing the vast, vast bulk
of the energy that this planet uses,
I agree with you on further
developing the science.
You were making that point at the end
but I just find that prospect
intolerable and frightening.
In the New York Times today,
they were talking about sea-level rising
three to four feet, and then ultimately
the seas going even a hundred miles,
and so my view is that
this is a political and economic problem
and everything that you have said
calls upon us to do what I would consider
have a radically new
economic and political system
that capitalism isn't capable of resolving
this issue that we need a revolution
and this new (mumbles) all stop.
- I can't disagree with you,
but whatever this solution is--
- If I could just invite people--
- It has to release a lot
of energy, physically.
That's all I'm saying.
- And I just wanted to invite people
to come to the Tilden room Friday at six
to talk about, I know we can't tonight.
Thank you.
- Hi, something I didn't
hear you talk much about
and I'd love to hear you talk
about is feedback effects.
So the possibility of
positive feedback effects
and the possibility of
negative feedback effects
and which are apt to dominate
and over what temperature range,
and in the end, will we be extinct?
(laughing)
- Do you have a particular feedback effect
that you're interested in?
- Well, actually...
Well, moisture is one that
I've heard a lot about
so there's a physicist at
Princeton, for example,
who, you know, points out that, Harper,
that moisture is one of
the biggest warming gases
and maybe he creates more (mumbling).
- Okay.
Well, Will Harper should know better.
The fundamental that I think
makes you have to take--
Okay, the numbers I just showed you,
this radiative forcing,
those things happen in an
active atmosphere in an ocean
and when you warm a body of water,
you release more water into the gas phase.
That's what results.
The current thinking is
it's a positive feedback,
that is, as there's a warming,
the warming will accelerate
due to lofting more water
vapor into the atmosphere
which then becomes
another greenhouse effect.
What Harper is claiming, and
he's right in one respect,
if you simply evaluate
carbon dioxide itself,
you've got a fraction of these numbers
for a change in carbon dioxide,
and you got about double
that fraction of warming
if you include the increased water vapor
that you assume is going
to accompany the warming,
but the reason that assumption is good
is something that in
physics or engineering
is called the vapor pressure
of a liquid at a various temperature,
in this case, the
Clausius-Clapeyron equation,
which describes the equilibrium of a gas
above a warming liquid,
and it's a strong function of temperature.
It's not a smooth rise.
It's a parabolically-shaped
curve that goes like that
so there's a lot of
potential for feedback.
So as you warm the planet,
the bodies of water warm
and the equilibrium water
vapor above in the air
increases more strongly
than the rate of temperature increase.
It's called the Clausius-Clapeyron effect,
and there has been one notable scientist
who said that he doesn't believe
that this feedback effect
will be so positive
and he's tried to find ways
that the atmosphere will become drier
as you warm up bodies of water beneath it,
and he hasn't been successful,
and he won't be successful.
This Clausius-Clapeyron effect,
any of you know the details yourself,
you know that it's pretty fundamental
so that's one feedback.
Now, there's an
interesting aspect of that.
If you put more water vapor in the air,
which is going to happen
as it gets warmer,
you'll probably create more clouds,
and this is a really interesting feedback.
Will the clouds cover the sky more
in terms of cloud cover,
so there will be less fraction of the sky
where you see it's blue
because it's covered by clouds,
or will the clouds
instead grow vertically,
let's say, with the same cover
but they grow deeper vertically?
In the latter case,
it's a positive feedback
on climate warming,
and the previous case where
you get more cloud cover,
you actually then can
reflect more sunlight
back out to space and
you can get a cooling.
The current understanding
of cloud physics is that
the positive feedback
is going to dominate,
so in all of the mathematical calculations
that have attempted to
understand that feedback,
it comes out positive.
But it's not necessarily definitely true.
It probably is.
Looking at data sets from satellites,
you get supporting evidence
for the positive feedback
and there are many other
interesting feedbacks
in this system.
For example, there's a
lot of organic material
stored in peat lands,
and clathrate deposits in ocean margins
where a little bit of warming
can make those release carbon dioxide
and methane explosively.
So you can get sudden
injections of greenhouse gases
with just a little bit of warming.
There's other ones about snow ice.
As the sea ice disappears on the Arctic,
sunlight now sees dark
water instead of white ice
so the sunlight itself is
absorbed more by the water.
That's a positive feedback.
And there's just feedbacks
all over this system.
And are we modeling them all perfectly?
I doubt it,
but the other tendency that's showing up
as a positive or a strong feedback
is the intensity of rainfall events.
I think it's now been
shown on five continents,
if not six, that the frequency
of heavy rainfall effects
has increased, in observations.
This is due to the fact
that there's more moisture in the air
so that when it rains,
it's more likely that it's a heavy rain
but it can still be dry in between,
so all kinds of feedbacks here
and they're tremendously important.
And we don't have all
of them nailed down yet
but the water vapor one,
I think, is pretty solid
because of the Clausius-Clapeyron effect.
Yes, sir.
- Dr. Cicerone,
thank you very much for
a fine presentation.
I'm also interested in your views about
the feedback effects
from the stored carbon
in the permafrost in the Arctic.
You showed that the average temperature
of the Arctic in certain regions
increased by more than
10 degrees centigrade.
I'm wondering, are you
very worried that perhaps
an uncontrollable feedback effect
could be induced in the Arctic
where trillion and a half
tons of carbon are stored.
- Yes, but again, I don't think
we have very good predictive capabilities.
The current thinking is it's going to take
hundreds of years to really
release a lot of carbon
that's now in old
vegetation and permafrost
and buried deep as methane gas
or even coming out as carbon dioxide.
If the permafrost melts and dries up,
we will get carbon dioxide release.
If the permafrost melts
and leaves a pool of water,
we'll get methane release.
But the question is how soon?
This warming of the Arctic
is more than anybody expected
and faster, but there are still lag times
built into the system that
I think will stabilize it.
The difficulty in conducting heat
down even five meters,
it takes a long time
for the thermal conductivity to work,
to conduct the heat down,
so most of what's happening
now is on the surface.
I'm not aware of any indications
that methane releases are
increasing from the Arctic.
There is more carbon dioxide
that's being released
but it's a pretty small amount
compared to other, so far,
compared to all the other
releases of carbon dioxide.
But in principle, yes.
- Hi, Jim (mumbles).
I want ask you on the maps you showed us
of the temperature record
in recent hot years.
There tended to be one cold
spot in the North Atlantic,
around Iceland, and is that
kind of well-understood?
- I don't think so.
I don't think so.
There are some very good meteorologists
and physical oceanographers
who are arguing about it.
For example, if you look at
the geographical patterns
of the winters in the northern hemisphere
in the last few years,
we've had some cold eastern
United States winters
and there's a lot of
argument going on now.
How that's connected with
the loss of Arctic sea ice,
with mechanistic understanding,
there are some oscillations that observed
in the North Atlantic.
Water flows the last 30 or 40 years each,
one of them 70 years each,
so we don't have enough data record
to know exactly where it's coming from.
Or the mechanisms of it,
I think, is a puzzle.
One of the gross indications
that this is an unprecedented
kind of climate change,
not only that the forcing conforms
to what humans are doing
and the numbers are right,
but the fact that the
warming is pretty ubiquitous.
If you average over a
period of a few years,
you cannot find a place on
the Earth that's cooling.
That's more than a micro site
and in previous climate
changes that have been observed
like the European warm period
in the 15th or 16th century and so forth,
there've been regional
patches of warming or cooling
but nothing this global before.
But you're right, there is
that fairly persistent pool
of cool water above the north,
and some of these temperature records
that I told you that people work on,
somewhat in competition with each other,
they have different methods
of sampling the Arctic
and some of them, the British record,
undersamples the Arctic,
so they tend not even
to see that cold period.
And in turn, they get lower measurements
of global average temperature rise
because they're ignoring
the hot spots in the Arctic,
not completely but relatively,
so there are a lot of details like that
that could be important
that are not clear yet.
- [Woman] Thank you very much.
- Thanks a lot.
(clapping)
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