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, 2008
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.
1
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, 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?
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
2
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
The Case for Anthropogenic Warming
Petit, et al, Nature 399 (June 3 1999), pp.429-436
The Case for Anthropogenic Warming
Is the Globe Warming?
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?
Hansen, et al, 2008, p. 7
3
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?
T 4 = kS
The Greenhouse Effect!
where T = surface temperature (ºK)
S = solar influx ((W/m2)
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.
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
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.
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?
Radiative Forcing by Greenhouse Gases
Heat Balance
Historical Overview of Climate Change Science, IPCC AR4, p.96
Technical Summary, IPCC AR4, p.25
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_CH01.pdf
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_TS.pdf
The Case for Anthropogenic Warming
The Case for Anthropogenic Warming
What Determines the Earth’s Temperature?
What Determines the Earth’s Temperature?
Greenhouse Gases
Vostok Data
Atmospheric CO2
800
700
600
gigatons
500
400
300
200
100
Technical Summary, IPCC AR4, p.24
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_TS.pdf
0
-450000
-400000
-350000
-300000
-250000
-200000
-150000
-100000
-50000
0
year (2000 = 0)
4
The Case for Anthropogenic Warming
The Case for Anthropogenic Warming
What Determines the Earth’s Temperature?
What Determines the Earth’s Temperature?
Vostok Data
Vostok Data + Recent History
CO2 (ppm)
Atmospheric CO2
150
4
200
250
300
350
400
800
2
700
400
300
200
100
0
-450000
-400000
-350000
-300000
-250000
-200000
-150000
-100000
-50000
0
-2
Ice Core
Today
-4
-6
-8
0
-10
year (present = 0)
The Case for Anthropogenic Warming
The Case for Anthropogenic Warming
What Determines the Earth’s Temperature?
What Determines the Earth’s Temperature?
Vostok Data
CO2 (ppm)
150
200
250
300
350
400
15
10
5
temperature
gigatons
500
temperature
Current
conditions
are well
outside the
range
recorded in
the ice core
data.
600
Ice Core
trend
imbalance
0
-5
-10
-15
http://www.carleton.edu/departments/geol/DaveSTELLA/Carbon/long_term_carbon.htm
The Case for Anthropogenic Warming
The Case for Anthropogenic Warming
What Determines the Earth’s Temperature?
What Determines the Earth’s Temperature?
The Short-Term Carbon Cycle
Couplings Between Changes in theClimate System and Biogeochemistry, IPCC AR4, p.513
Hansen, et al, 2008, p. 7
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_CH07.pdf
5
The Case for Anthropogenic Warming
The Case for Anthropogenic Warming
What Determines the Earth’s Temperature?
The Earth’s Carbon Cycle
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?
Sigman & Boyle, Nature 207 (2000), p.860
The Case for Anthropogenic Warming
The Case for Anthropogenic Warming
Did human activity cause the problem?
Did human activity cause the problem?
Carbon isotope ratios and
atmospheric oxygen depletion
indicate that the increase in
atmospheric CO2 comes from
burning fossil fuels.
M d l with
Models
ith and
d without
ith t
human activity.
Changes in Atmospheric Constituents and in Radiative
Forcing, IPCC AR4, Chap. 2, p.138
Understanding and Attributing Climate Change, IPCC
AR4, Chap. 9, p.684
http://ipccwg1.ucar.edu/wg1/Report/AR4WG1_Print_CH02.
pdf
http://ipccwg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch09.
pdf
The Case for Anthropogenic Warming
The Case for Anthropogenic Warming
How big is the problem?
IPCC Predictions
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?
Global Climate Projections, IPCC AR4, p.803
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_CH10.pdf
6
The Case for Anthropogenic Warming
The Case for Anthropogenic Warming
How big is the problem?
Surface Temperature Predictions
Summary
Is the globe warming?
Yes, but so far not much.
What determines the Earth’s temperature?
Solar forcing plus the greenhouse effect.
Did human activity cause the problem?
Sure looks like it.
How big is the problem?
So far, not big. But it could become huge.
Global Climate Projections, IPCC AR4, p.766
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_CH10.pdf
7