Download The Case for Anthropogenic Warming

The Case for Anthropogenic Warming
The Case for Anthropogenic Warming
Richard McGehee
Is the globe warming?
What determines the Earth’s temperature?
Did human activity cause the problem?
How big is the problem?
What’s at stake?
Seminar on the Mathematics of Climate Change
School of Mathematics
September 9, 2009
The Case for Anthropogenic Warming
What’s at stake?
The Case for Anthropogenic Warming
What’s at stake?
The USA in the Ice Free Earth
Computer Simulation, Clarence Lehman, Univ. Mn. 2006
•No ice fishing in Minnesota
•No polar bears in the Arctic
•No ice in Antarctica
•No Florida
The Case for Anthropogenic Warming
The Case for Anthropogenic Warming
What’s at stake?
The Modern Ice Free Earth
Computer Simulation, Clarence Lehman, Univ. Mn. 2006
Is the globe warming?
What determines the Earth’s temperature?
Did human activity cause the problem?
How big is the problem?
What’s at stake?
Sea level rises 63 meters.
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The Case for Anthropogenic Warming
Is the Globe Warming?
The Case for Anthropogenic Warming
Is the Globe Warming?
2007 Polar Sea Ice
Public Perception
National Journal, Feb 3, 2007
http://syndication.nationaljournal.com/images/203Insiderspoll_NJlogo.pdf
Press Release, 1 October 2007, National Snow and Ice Data Center
http://nsidc.org/news/press/2007_seaiceminimum/20071001_pressrelease.html
The Case for Anthropogenic Warming
Is the Globe Warming?
Polar Sea Ice
Press Release, 2 October 2008, National Snow and Ice Data Center
http://nsidc.org/news/press/20081002_seaice_pressrelease.html
The Case for Anthropogenic Warming
Is the Globe Warming?
Northern Hemisphere Data
http://www.ncdc.noaa.gov/paleo/globalwarming/paleolast.html
The Case for Anthropogenic Warming
Is the Globe Warming?
Global Mean Temperature
Technical Summary, IPCC AR4, p.37
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_TS.pdf
The Case for Anthropogenic Warming
Is the Globe Warming?
Lake Vostok
http://www.nsf.gov/news/mmg/media/images/lake_vostok_nsf_h.jpg
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The Case for Anthropogenic Warming
The Case for Anthropogenic Warming
Is the Globe Warming?
Is the Globe Warming?
Core Samples
Lake Vostok
Photographs copyright Reto Stöckli, NASA GSFC
http://svs.gsfc.nasa.gov/vis/a000000/a000900/a000996/index.html
The Case for Anthropogenic Warming
The Case for Anthropogenic Warming
Is the Globe Warming?
Is the Globe Warming?
Antarctic Temperature Data
Antarctic Temperature Data
2
1.5
kiloyear bp
0
-0.5
400
350
300
250
200
150
100
50
0
4
2
0
-2
-4
-6
-8
-10
delta deg C
0.5
450
-1
temperature
1
-1.5
-8000
-7000
-6000
-5000
-4000
-3000
-2000
-1000
0
1000
-2
2000
year
Petit, et al, Nature 399 (June 3 1999), pp.429-436
Petit, et al, Nature 399 (June 3 1999), pp.429-436
The Case for Anthropogenic Warming
The Case for Anthropogenic Warming
Is the Globe Warming?
Is the Globe Warming?
Ocean Temperature Data
2.5
Benthic Data (δ18 O
O)
3
3
3.5
4
4.5
5
5.5
‐4500
‐4000
‐3500
‐3000
‐2500
‐2000
‐1500
‐1000
‐500
0
time (Kyr)
Lisiecki, L. E., and M. E. Raymo (2005), A Pliocene-Pleistocene stack of 57 globally distributed benthic d18O
records, Paleoceanography,20, PA1003, doi:10.1029/2004PA001071.
Hansen, et al, Target atmospheric CO2: Where should humanity aim? Open Atmos. Sci. J. 2 (2008)
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The Case for Anthropogenic Warming
The Case for Anthropogenic Warming
What Determines the Earth’s Temperature?
Is the globe warming?
Heat Balance
T 4 = kS
What determines the Earth’s temperature?
where T = surface temperature (ºK)
Did human activity cause the problem?
S = solar influx ((W/m2)
How big is the problem?
What’s at stake?
k = constant depending on
reflectivity of the surface,
emissivity of the surface, and
the Stefan-Boltzmann constant.
For the current value of k , T = 255° K = −18°C = 0° F
Why isn’t the Earth a Snowball?
C.Lorius, The ice-core record: climate sensitivity and future greenhouse warming, Nature 347 (1990), pp.139-145
The Case for Anthropogenic Warming
The Case for Anthropogenic Warming
What Determines the Earth’s Temperature?
What Determines the Earth’s Temperature?
Heat Balance
Why isn’t the Earth a Snowball?
The Greenhouse Effect!
J
Joseph
hF
Fourier,
i Mémoires
Mé i
d
de l'A
l'Académie
dé i d
des
Sciences de l'Institut de France, t. vii. 1827.
Svante Arrhenius, "On the Influence of Carbonic
Acid in the Air upon the Temperature of the
Ground," Philosophical Magazine and Journal of
Science (Fifth Series) 41, pp. 237-276, 1896.
Historical Overview of Climate Change Science, IPCC AR4, p.96
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_CH01.pdf
The Case for Anthropogenic Warming
The Case for Anthropogenic Warming
What Determines the Earth’s Temperature?
What Determines the Earth’s Temperature?
Radiative Forcing by Greenhouse Gases
Technical Summary, IPCC AR4, p.25
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_TS.pdf
Greenhouse Gases
Technical Summary, IPCC AR4, p.24
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_TS.pdf
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The Case for Anthropogenic Warming
The Case for Anthropogenic Warming
What Determines the Earth’s Temperature?
What Determines the Earth’s Temperature?
Atmospheric CO2 (Vostok data)
400
400
350
350
300
300
atmos CO2 (ppm
m)
atmos CO2 (ppm
m)
Atmospheric CO2 (Vostok data)
250
200
150
200
150
100
‐450
250
100
‐400
‐350
‐300
‐250
‐200
‐150
‐100
‐50
0
‐450
‐400
‐350
‐300
‐250
time (Kyr)
‐150
‐100
‐50
The Case for Anthropogenic Warming
The Case for Anthropogenic Warming
What Determines the Earth’s Temperature?
What Determines the Earth’s Temperature?
Vostok Data
150
4
200
250
0
Vostok Data
CO2 (ppm)
300
CO2 (ppm)
350
400
150
200
250
300
350
400
15
2
10
0
-2
Ice Core
Today
-4
temperature
5
temperature
Current
conditions
are well
outside the
range
recorded in
the ice core
data.
‐200
time (Kyr)
0
Ice Core
trend
imbalance
-5
-6
-10
-8
-15
-10
The Case for Anthropogenic Warming
to be continued ...
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