Transcript Climate Change - Day 2

1955
She sells sea shells
by the sea shore.
Cesare Emiliani (1922-1995),
Geochemist
He used the newly established technique of
investigating different isotopes of oxygen
(Oxygen-18 vs. Oxygen-16). By measuring
how much of these two different isotopes
there is, one can determine the temperature
at which sea shells (like a clam) grew.
(Photo: Archives of the Rosenstiel School of Marine and
Atmospheric Science, University of Miami) From Wikipedia.
1
Looking at fossil shells in a core,
he looked back over 1,000,000
years of geologic time and
realized that there are lots of ice
ages, that they happened every
100,000 years.
1955
This meant that Milankovic was
right about variations in Earth’s
orbits causing major climate
changes, but wrong about which
orbital variation was the most
important.
Drat.
(Photo: Archives of the Rosenstiel School of Marine and
Atmospheric Science, University of Miami) From Wikipedia.
2
Portrait by Paja Jovanovic
1955
Drat.
It turns out that Emiliani was also wrong in
detail. He was completely sure that the
Oxygen isotope record provided
temperatures. It turns out that it does not – it
provides an estimate of the evaporation from
the ocean, because the heavier Oxygen-18
sticks around in the ocean when there are
large ice sheets.
Another great example of how scientists can
be wrong in detail, but very useful.
(Photo: Archives of the Rosenstiel School of Marine and
Atmospheric Science, University of Miami) From Wikipedia.
3
"The young specialist in English Lit ... lectured me
severely on the fact that in every century people
have thought they understood the Universe at
last, and in every century they were proved to be
wrong. It follows that the one thing we can say
about our modern 'knowledge' is that it is wrong.
... My answer to him was, '... When people
thought the Earth was flat, they were wrong.
When people thought the Earth was spherical
they were wrong. But if you think that thinking
the Earth is spherical is just as wrong as thinking
the Earth is flat, then your view is wronger than
both of them put together.”
- Isaac Asimov
1956
Ewing and Donn explain the connection of feedbacks
on the Earth’s globe. This includes the single most
important feedback: Solar radiation and albedo.
Maurice Ewing
Did someone
say libido?
No! Albedo,
albedo, you
psychologist.
Image from LIFE photo Archive
Photo from Columbia University
A random Freud
appearance 5
Albedo
Albedo - extent to which an object reflects
light (the ratio of reflected to incident
electromagnetic radiation)
In short, white objects reflect a lot (absorb a
little) and black objects reflect little (absorb
a lot). This was figured out a long time
ago by……
6
I’m back.
Benjamin Franklin, again.
The year, about 1729.
Image from Wikimedia Commons.
". . . AS to our other subject, the different degrees of heat imbibed from the sun's
rays by cloths of different colors, since I cannot find the notes of my experiment
to send you I must give it as well as I can from memory…
My experiment was this. I took a number of little square pieces of broad cloth
from a tailor's pattern-card, of various colors. There were black, deep blue,
lighter blue, green, purple, red, yellow, white, and other colors, or shades of
colors. I laid them all out upon the snow in a bright sunshiny morning. In a few
hours (I cannot now be exact as to the time) the black, being warmed most by
the sun, was sunk so low as to be below the stroke of the sun's rays; the dark
blue almost as low, the lighter blue not quite so much as the dark, the other
colors less as they were lighter; and the quite white remained on the surface of
the snow, not having entered it at all.”
7
Image from Wikipedia
Although, in 1761, it is Johann Heinrich Lambert in
Germany who introduces the term "albedo" in order to
describe the differing reflective properties of planets
Image from NASA
Planets
Lambert
9
Credit: Steve Ackerman and Tom Whittaker
1957
Source: Air Force photo, from Wikipedia
1957
Sputnik satellite, launched by
the Russians (the old USSR).
The political response was to
allocate an enormous
amount of money for basic
science research in the US
for the next ~30 years.
Science became a priority.
Source: Air Force photo, from Wikipedia
11
Image from Wikipedia.
Promising students were
encouraged to become
scientists, with the highest
form of scientists being a
physicists (this will come up
later). Hence the term…
Source: Air Force photo, from Wikipedia
She’s so smart that
she’ll grow up to be a
rocket scientist.
Image: Wikipedia, from Bronisław Duda
1957
-The first GCM (Global Climate
Model)
Phillips and Charney (atmospheric
scientists) run the first GCM, in an
attempt to model the Earth’s
atmosphere. It was amazing for its
time.
Source: AIP Emilio Segrè Visual Archives
Charney
Phillips
Although, in the simulation, after 20
days of model time it started to look a
little funky and after 30 days it looked
like nothing that ever happened on
Earth.
For the first time scientists could see, for example, how giant eddies spinning
through the atmosphere played a key role in moving energy and momentum from
place to place. Philips's and Charney’s model was quickly hailed as the first true
General Circulation Model (GCM).
13
What is a GCM (General Circulation Models)?
These models consist of connected sub-modules that deal with radiative
transfer, the circulation of the atmosphere and oceans, the physics of moist
convection and cloud formation, sea ice, soil moisture, etc..
14
Source: Australian Bureau of Meteorology
1957
CO2 in the atmosphere:
~312 ppm
CO2 Concentration (ppm)
324
322
320
318
316
314
312
310
308
1940 1945 1950 1955 1960 1965 1970 1975 1980
Year
2 major events
-Launching of Sputnik
-The first GCM (Global Climate Model)
15
1960
The Breakthrough
The Place
T
h
e
Keeling
(atmospheric scientist)
Source: NOAA
Image: NSF, from Wikipedia
P
e
r
s
o
n
Mauna Loa, Hawaii
16
1960
Image from Wikipedia
The Keeling curve is first published.
17
BBC World News
Sunday, 2 December 2007, 20:13 GMT
50 years on: The Keeling Curve legacy
It is a scientific icon, which belongs, some claim, alongside
E=mc2 and the double helix
Its name - the Keeling Curve - may be scarcely known outside scientific circles, but
the jagged upward slope showing rising carbon dioxide (CO2) levels in the
atmosphere has become one of the most famous graphs in science, and a potent
symbol of our times.
It was 50 years ago that a young American scientist, Charles David Keeling, began
tracking CO2 in the Earth's atmosphere at two of the world's last wildernesses - the
South Pole and the summit of the Mauna Loa volcano in Hawaii.
His very precise measurements produced a remarkable data set, which first
sounded alarm bells over the build-up of the gas in the atmosphere, and eventually
led to the tracking of greenhouse gases worldwide.
"Without this curve, and Professor Keeling's tireless work, there is no question that
our understanding and acceptance of human-induced global warming would be 1020 years less advanced than it is today," adds Dr Manning.
18
"Keeling's data put the capstone on the
structure built by Tyndall, Arrhenius,
Callendar, Plass, and Revelle and Seus.
This was not quite the discovery of global
warming. It was the discovery of the
possibility of global warming".
- Weart
Human-induced addition of CO2 to the
atmosphere becomes a legitimate scientific
theory.
.
19
CO2 in the atmosphere:
~315 ppm
324
CO2 Concentration (ppm)
1960
322
320
318
316
314
312
310
308
1940 1945 1950 1955 1960 1965 1970 1975 1980
Year
The concentration is finally being measured
in the atmosphere.
It is now clear that CO2 concentration is
going up.
Human-induced global climate change
become a research focus.
20
Image from Wikipedia.
1968
Beginning of the
Source: National Digital Library
Environmental
movement.
Source: The Climate Community
Rachel Carson
Image from Wikipedia.
A simple, but elegant, book that starts the environmental movement. Carson
was a science writer.
21
1970
John McConnell first introduced the
idea of a global holiday called
"Earth Day" at a UNESCO
Conference on the Environment in
1969. Responding to widespread
environmental degradation,
Gaylord Nelson, a United States
Senator from Wisconsin, called for
an environmental teach-in, or Earth
Day, to be held on April 22, 1970.
Image from Wikipedia
22
Image from Wikipedia.
United States Congress image at Wikipedia
CO2 in the atmosphere:
~ 328 ppm
340
CO2 Concentration (ppm)
1970
335
330
325
320
315
310
305
1940 1945 1950 1955 1960 1965 1970 1975 1980
Year
23
On October 24, 2009, environmental
activists around the world gathered in
support of a geophysical data point.
With their bodies, banners, and balloons,
they formed the numeral 350, advocating
that governments should adopt 350 ppm
as a target for atmospheric carbon
dioxide concentration (some climate
scientists suggest that this is the highest
amount of CO2 possible not cause
significant climate change).
Image from Wikipedia
Source: The Standard
Source: The Standard
The 450 number came from the various
graphs and tables of the 2007 report of
the Intergovernmental Panel on Climate
Change—but Rajendra Pachauri, who
chairs the IPCC, has said repeatedly in
the last year that that science is out of
date.
Recently, asked why he’d endorsed a
350 target instead, he said: “As a human
being, I just couldn’t keep quiet in the
face of all this overwhelming evidence. I
know it’s probably not right for me to
take a position such as this, but on the
other hand, I think it would be totally
immoral on my part not to take a
position, so I came out and said so.”
The Atmosphere
Bryson’s chapter: Into the Troposphere
Source: NASA
Source: NASA
Source: National Business Aviation Association
Aftern 1975, it is all about Global
Climate Models
• 1956 – first GCM (Phillips)
• 1975 – model of 2xCO2 predicts several
degree warming (Manabe)
• 1981 – models show sulfate aerosols =
cooling (Hansen)
• 1991-1995 – model predicts cooling via
Pinnatubo. Verified in 1995. (Hansen)
• 1998 – models can recreate ice-age
climates
1988
The community acceptance that that humaninduced global warming is likely accurate,
results in the formation of a group - the
IPCC (or Intergovernmental Panel on
Climate Change) - that meets every 5 years
to discuss the state of the Earth’s climate.
IPCC
-Consists of more than 2500 scientific and
technical experts from more than 60 countries all
over the world.
-The scientists are from widely divergent research
fields including climatology, ecology, economics,
medicine, and oceanography.
-The IPCC is the largest peer-reviewed scientific
cooperation project in history.
-It has issued 4 reports:1992, 1996, 2001, and
2007.
Images from IPCC report
Images from IPCC report
IPCC
1992: Still trying to sort out effects of natural variation and
human impacts
1996: “The balance of evidence suggests a discernible
human influence on global climate”
2001: Humans are “likely” to cause global warming
2007: Humans are “very likely” to cause global warming.
Two notes: 1) In scientific talk, it does not get much more
certain than “very likely”; and 2) The IPCC is inherently
conservative and often supports minimum possible
climate change (rather than maximum possible change).
Why the change?
• More research
• Better Global Climate models
• More available data: 1998 is globally the
warmest year on record, followed by 2002,
2003, 2001 and 1997. The 10 warmest
years on record have all occurred since
1990.
Images from IPCC report
Radiative Forcing
To compare different variables, you need a
common unit (to compare apples with apples, as
the saying goes).
Radiative forcing is the difference between the
incoming radiation energy and the outgoing
radiation energy in a given climate system.
A positive forcing (more incoming energy)
tends to warm the system, while a negative
forcing (more outgoing energy) tends to cool it.
36
37
Credit: Steve Ackerman and Tom Whittaker
A Watt (as in James)
A unit of power = Work / time
(Your standard household bulb uses 60 Watts)
Because we care about the Earth’s surface,
we use Watts/meters2
I like steam engines. A lot.
38
Image from Thinkquest
So, what causes radiative
forcing?
Solar input - relatively constant, but can be
slightly higher or lower than usual
Chinese records of sunspots go back to Book of Changes
(800 B.C.E.): "A dou is seen in the Sun" and "A mei is seen
in the Sun". ”Dou" and "mei" are taken to mean darkening
or obscuration.
Image from nasa.gov
Sunspots
Author: Hans Bernhard
So, what causes radiative
forcing?
Solar input - relatively constant, but can be
slightly higher or lower than usual
CO2 (& other greenhouse gases) - increases
radiative forcing
Aerosols - decreases radiative forcing
2.5
CO2
2.0
W/m2
1.5
1.0
Solar
0.5
0.0
Temperature
-0.5
-1.0
1800
Aerosols
1850
1900
Year AD
1950
2000
Components of a fully coupled general circulation model
Removed image due to
copywright. It can be found at
the Australian Department of
Meteorology.
GCMs contain our best current understanding for how the physical processes
interact (for instance, how evaporation depends on the wind and surface
temperature, or how clouds depend on the humidity and vertical motion) while
conserving basic quantities like energy, mass and momentum. These estimates
are based on physical theories and empirical observations made around the world.
Development of climate models over time
IPCC, adopted by Australian Department of Climate Change and
Energy Efficiancy
Models
We cannot predict how one variable will inherently
influence another. Therefore, we have to make
models. Models lead to “emergent” properties,
which is large scale behavior that is not a priori
predictable from the small scale interactions that
make up the system.
Models are inherently theoretical. As such, they
are often very quantitative.
Models (con’t)
All models are wrong; some models are useful.
-G.E. Box (UW Professor)
These models are all simplifications of the actual phenomena. But
these models can still be valuable.
Image removed due to
copyright; available at Data
Analysis Australia
The problem with models (or any theoretical approach) lie in the assumptions.
IPCC: Critical aspects
Validation - assessment of the accuracy of
the model
Attribution - the ability to assign causes to
effects (distinguish causation from
correlation)
Prediction - specification, in advance, of
events or changes in a system
Validation
Validation reflects an assessment of the
accuracy (not precision) of the model.
This is done by attempting to duplicate
current climate data, or “backcasting” (as
opposed to forecasting) past climates when
the Earth was very different (such as 18,000
years ago, during the maximum extent of the
ice age).
Image from IPCC
Science is the investigation of
the natural world, based on
the rules of reason and logic.
Science is testable and/or
predictable.
How do you test a model,
particularly of a GCM (Global
Climate Model)?
1981
Image from USGS
Image source: New York Times
We can test our GCM!
1963 Mount Agung (Indonesia)
volcanic eruption
(ok, really, this is a picture of the
1991 Mount Pinatubo eruption)
Jim Hanson
They found that the changes calculated by their simple model
corresponded in all essential respects — including timing and
approximate magnitude — to the observed global temperature
changes. The GCM worked!
But, more importantly, the the results also showed that volcanic
aerosols could significantly cool the surface.
Image source: New York Times
Hot dog! It works!
Attribution
The ability to assign causes to
effects.
This is a problem inherent in
systems with multiple variables.
The simplest approach is
“sensitivity analysis”, in which
each variable is tested for its
possible effect. The IPCC report
is all about attribution.
Is CO2 the only greenhouse gas
that is important?
It turns out (unfortunately), no.
1) Methane (CH4) - From rice paddies and cows.
2) N2O - from agriculture, including fertilizer
3) Ozone (O3) - not anthropogenic
and…
4) CFCs (Chloroflorocarbons) - From refrigeration
and spray (and fire retardant)
The big problem is that these gases could be much more potent than CO2.
But, an even bigger problem was,……
Image from NOAA
Image from NASA
Despite the fact that these gases are much less abundant, they are much
more potent than CO2. But, for the case of CFCs, there was an even bigger
problem…..
The Ozone hole
In addition to being
greenhouse gases, CFCs
destroy ozone (O3).
Consequently, they cause
an ozone hole over the
South Pole.
Note that the ozone hole
has no effect on global
warming (except that the
presence of CFCs both
destroys the ozone AND
causes global warming).
Source: NASA
The Ozone hole
CFC’s in the
stratosphere =
Ozone hole.
CFC’s in the
troposphere =
global warming
Source: NASA
The Ozone hole
This ozone debate plays out like this:
1. Scientists report that CFCs are causing problems
with ozone layer.
2. Industry denies that this is a problem.
3. Scientists confirm this problem.
4. Industry maintains that it is too expensive to
switch to other propellants in spray bottles.
5. Under international pressure, CFCs are
outlawed* in the 1997 Montreal accords.
6. Industry finds new propellants (there is no major
loss in the spray industry and some indications
that there is some economic gain by switching
away from CFCs).
*CFCs are still being produced in some third world countries.
Source: NASA
IPCC
Prediction
Specification, in advance, of events or
changes in a system.
Again, the IPCC includes many predictions,
based on the outcomes of the GCMs.
IPCC & GCMs
The IPCC reports are
based on the composite
results of a variety of
different GCMs.
It is important to realize
that the GCMs just act to
quantifiy (“put numbers
on”) the effects that are
already occurring.
Source: Wikipedia
National Center for Atmospheric
Research laboratory in Boulder,
Colorado
IPCC 2007
Image from NASA
Image from NASA
Image by Robert A. Rohde for Global Warming Art
GCMs are a different approach to
science:
Although we can separate the variables
and treat each individually, they
interact with each other.
This type of interaction requires that
you do science in a different way
than has been done in the past:
Integrated and with a systems
approach. This is sometimes
known as holistic. This approach
must be done IN ADDITION to the
reductionist approach.
Source: Robert A. Rohde
This is the second of the major
divisions in science:
1) Empirical-theoretical
2) Reductionistic-holistic
Holistic science
An analogy
(Image of
doctor and
patient)
The doctor can help a patient who has cancer. But, this
solves a symptom, not the cause. Society is usually
willing to solve a symptom.
But, if you want to really solve the problem, you have to
study the system. This requires a systematic
approach, looking at environmental, genetic
predisposition, and individual facts (the field of
epidemiology) as well as basic understanding of cell
processes (molecular biology).
(Image of
scientists studying
a town)
The medical community has been extremely successful at getting both
funded. This is less true for the scientific community.
Holistic science & Science of
the future
Problem based
Interdisciplinary
Problems of society, not problems of
science (such as, How do we maintain a
habitable Earth?)
Emphasis on predictive power of science
Systems with multiple
variables
1) Sensitivities
2) Positive feedbacks
3) Negative feedbacks
4) Thresholds (“Tipping points”)
5) Complexity (non-linear
feedbacks)
Thresholds
Source: Wikimedia Commons, Bart de Goeij
Side view
Source: Wikimedia Commons, Gertjan R.
Back view
Aftern 1975, it is all about Global
Climate Models
• 1956 – first GCM (Phillips)
• 1975 – model of 2xCO2 predicts several
degree warming (Manabe)
• 1981 – models show sulfate aerosols =
cooling (Hansen)
• 1991-1995 – model predicts cooling via
Pinnatubo. Verified in 1995. (Hansen)
• 1998 – models can recreate ice-age
climates