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Climate Change
Bullshit or Not?
How is such change reliable detected?
How can the agents of change be identified
in a scientifically rigorous manner?
Limiting Factors
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Climate Data is very noisy – hard to
discern “natural” timescales
Past climate data has low time resolution
Climate models do not know all the input
physics
Grid models have too coarse of resolution
to adequately account for the presence of
clouds in the grid cell.
System Lag time!
Assumptions about our
Atmosphere
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Its thin
Its in hydrostatic equilibrium
Its isothermal (where most of its mass is)
Equation of state is that of an ideal gas
These assumptions allow us to treat the
atmosphere as a thin, uniform slab of
material at constant density and
temperature.
Equilibrium Temperature
 Planet radiates as a blackbody in TE with
incoming solar radiation:
A = Albedo; L = 1370 watts per sq meter
T = 278(1-A)4
T = 255K for A=0.32
This is not the right answer compared to
observations
The Role of the Atmosphere
Fo = incident flux
Ts = transmission percentage of
short wavelength incoming radiation
Tt = transmission percentage of
outgoing long wavelength radiation
Fg = Flux from ground
Fa = Flux from the atmosphere.
Fo = Fa + TtFg
; Fg = Fa + TsFo
Let Fa = Fo –TtFg
Ultimately get that Fg = Fo
The transmission factors are set by atmospheric chemical
composition which human activities are modifying
Our Atmosphere
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TS = 0.9 (Highly transparent)
Tt = 0.2 (fairly opaque)
Fg = 1.58Fo  Tg = 255*(1.58)1/4 = 287K
(limiting case Tt =0; T=300K )
Fa = 0.68Fo
Ta = 255*(0.68)1/4 = 245K
Net Effect: Surface is warmed above equilibrium temperature due to
flux radiated by our atmosphere. Atmosphere is therefore below the
equilibrium temperature.
Why is Tt Relatively Low?
Methane: Broad absorption from
1.5 to 2.5 and 8-10 Microns
Climate Forcing Terms
Changes in atmospheric composition or
properties that are equivalent to flux
changes (in Watts/m2)
 Changes in Greenhouse gas mixture
 Changes in scattering properties
 Changes in cloud cover, thickness, and
altitude.
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Average Global Energy Balance
(340 Watts/M2 incoming)
• 14 absorbed by
clouds
• 54 absorbed by
atmosphere
• 20 reflected back by
atmospheric
molecules
• 68 reflected back by
mostly high clouds
• 14 reflected by the
service (170 reaches
surface)
• 20 emitted by ground
• 102 emitted by
oceans
• 88 emitted from
clouds
• 130 emitted from
greenhouse gases in
the atmosphere
• 340 in = 340 out
Estimates of Climate Forcing
Aerosols are Important but a very
difficult mixed scattering problem
Pick a Model: 2100 CO2
Doubling
Source of Uncertainties
 Roles of clouds and aerosols in radiative
transfer models? (e.g. scattering!)
 Role of tropical convection and the water
vapor feedback loop?
 How well do observations constrain the
input climate parameters?
 How to weight the inputs for best fit
statistical model?
Water Vapor Feedback
Understanding large scale convection in
the tropics may be crucial  this
determines high cumulonimbus clouds
Effects could be significant
Complete Feedback Models too
Difficult to reliably construct
Those Pesky Swiss
GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L19809, 2005
Anthropogenic greenhouse forcing
and strong water vapor feedback increase
temperature in Europe
Rolf Philipona
Physikalisch-Meteorologisches Observatorium
Davos, World Radiation Center, Davos Dorf, Switzerland
Bruno Dürr
MeteoSwiss, Zürich, Switzerland
Atsumu Ohmura
Institute for Atmospheric and Climate Science,
Swiss Federal Institute of Technology (ETH), Zürich, Switzerland
Christian Ruckstuhl
Institute for Atmospheric and Climate Science,
Swiss Federal Institute of Technolog
Is Water Vapor Increasing?
Very difficult to accurately measure even
with satellites  calibration issues and
strong seasonal variations plus El Nino
fluctuations
But Tropics are everything:
The Potential Role of Methane
Global Warming Potential
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TH = Time Horizon (20 or 100 years)
Ax = increased forcing from X (Watts m^2 kg)
x(t) = decay following some hypothetical
instantaneous release of X
Denominator is relevant quantities for CO2
Methane GWP
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A Methane molecule has an atmospheric
lifetime of 12 +/- 3 years before its broken
down through chemical reactions involving
OH- (Leaving some CO2 as a by product)
On 100 year timescale GWP = 23
But, on 20 year timescale GWP = 62
Note that CO2 has atmospheric lifetime of 50200 years depending on SST.
Sources of Methane Emission
Rice
Cows
Sewage
Oil and
Gas
Production
Methane Tracks Population
A PUZZLE
So There is a Scientifically Plausible
Case to be made for Potential Global
Warming Based on Changing
Atmospheric Composition
Can extant Data support this is
actually happening now?
Poorest Evidence for Warming
Problems with Mean Annual
Temperature as and Indicator
►How
is it defined or measured?
►Role of Urbanization?
►Are measurements equally reliable in
time?
►Does this just reveal small natural
cycles that would be lost in more
distant climate record?
Its not as simple as this
This
is not
the
best
chi^2
fit to
noisy
data
Those Crazy Swiss Again
Better Evidence for Climate Change
Latest Data
It May Even be Getting Wetter
Local Measurements May be the real
smoking guns
Statistics of Extremes
Other Indicators
• Rapid Loss of Arctic
Ice; Larson Ice Shelf
• Rapid retreat/loss of
glaciers
• Increase vector borne
diseases (insects)
• Worldwide coral
bleaching
• Marine life migrations
• Heat Waves
• Earlier
Spring/Snowmelt
• Increase
droughts/wildfires
• Well documented rise
of sea level (from
thermal expansion)
Ice Core Data
Note: Time Resolution is Not
Sufficient to reveal if CO2
Increases Cause Warming or
Follow Warming
Using the Past as a Guide
Do Tipping Points Exist in Climate?
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Does the system have critical phenomena?
Or do the
various and
somewhat
unknown
feedback
mechanisms
serve to
counter this?
Possible Tipping Points
Permafrost Melt In Western Siberia and the
release of vast amounts of stored methane
 As the southern summer limit of Arctic sea ice
cover diminishes, the reflectivity of the earth
decreases and more heat is absorbed
 The strength of the current in the Atlantic Ocean
between Africa and the east coast of America
has slowed by 30 percent from 1993-2005 due
to the sinking of cold, salty, dense waters in the
North Atlantic Ocean.
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Reverse the
Thermohaline?
Methane Burps
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Source of Bermuda Triangle Disappearances
Norwegian Coast landslide 8150 years ago
More tipping
CO2 reaches 400 ppm (in 10 years) 
important to remember that CO2 mixes out
very slowly
 CO2 equivalency = 480 ppm (in 10 years)
 nominal 2 deg C response
 Does this put us in an irrecoverable (on the
50 – 200 year timescale) position?
 Methane is most serious potential feedback
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What About Hurricanes
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Frequency
Intensity
Wind Radius
Tracks
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No connection
Length of time over 83+
degree water
Some measure of total
power but no adequate
temporal baseline
Currently under analysis