Transcript CH217 Climate Change 2008.ppt

Solar Luminosity- How Bright the star
Twinkles
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Hotter temperature = more light flux
•
Increases in Luminosity seems to be linked to sunspot activity (sunspots are a little
dimmer counter intuitive, but brighter spots make up for dimmer spots)
Sunspot activity: cycles every 11 years or so…
Total luminosity of sun is ~.036% higher in 1996 than in 1986  could suggest that
each sunspot cycle results in higher total irradiance
Each cycle has little effect, but over centuries… it adds up especially on the time
scales that are being talked about
Geological Timescale
– Since sun formed ~4.6 Billion years ago, luminosity has increased ~30%, but in
the past million years, the change has been less than 3%.
– Raises questions: 25% decrease in luminosity= oceans freeze..
“Contemporary Time Scale”
In 1645-1705 lack of sunspot activity = “little ice age” temp drop of ~1 deg C
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Eric Roy
http://www.xs4all.nl/~carlkop/solar.html (Columbia Prof)
Black Body Radiation

2hc 
1
M 
 hc / kT 
5
 e
1
2
max
5000
3000
2.88x103

(meters)
T
 M  F  T
2000
1000
500
300
4
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Wikipedia.org
Flux from a “black body”
S= kT4 , k=5.67x10-8 watts/m2K4
(Wien’s law)
6000 K
Sun
279 K
1370 Watts/m2
1.5x1011 m
EARTH
342 Watts/m2
6378 km = r
max (nm) = 2.9x106/T
278
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Tavg. = 288 K !!
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World Carbon Dioxide Emissions
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North America: 27.2%
Central and South
America: 4.1%
Europe (including all
Russia): 27.7%
Middle East (petroleum
producing nations): 4.7%
Africa: 3.8%
Asia and Oceania: 32.5%
www.eia.doe.gov/iea/carbon.html
www.volker-quaschuning.de
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Keeling, C.D. and T.P. Whorf. 2005. Atmospheric CO2 records from sites in the SIO air sampling network. In Trends: A Compendium of Data on
Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn.,
U.S.A.
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The Role of Water Vapor and Clouds on
Climate
Water Vapor : The main heat-trapping gas in the lower atmosphere
Clouds : Formed when water vapor in the air condenses
~ Clouds cool Earth by reflecting incident sunlight into space
~ Clouds warm Earth by absorbing the heat released from the ground
and reradiating this heat back down to the planet
The mean distribution of total atmospheric
water vapor above the Earth’s surface
(1992).
http://okfirst.ocs.ou.edu/train/meteorology/EnergyBudget2.html
http://www.agu.org/sci_soc/mockler.html
Albedo Effect
- reflectance of incident sunlight by clouds, ice, snow, and
light colored surfaces
- strongly correlated to the color of the surface
- feedback effects
31% of light reflected
Back into space
Ice/Snow
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Methane Sources and
Sinks
Sources (Mt/year)
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–
–
–
–
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Wetlands
150
Other Sources
Oceans, lakes 35
Cattle
120
Rice Paddies 95
Other Sources150
Natural Gas Leaks??? Rice Paddies
• Sinks
– CH4 + OH ----> CH3 + H2O
Wetlands
Oceans, lakes
Cattle
• Sources > Sinks resulting in about a 1-2%
annual increase
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Methane Clathrites
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What are Methane Clathrites
– Methane Hydrates in ice.
– Contains high concentration of
C-12
55 Million years ago and the
PETM.
Methane-burp theory
– Escape and formation of CO2
• Evidence
• What caused it?
Why does it have a big impact?
– Positive feedback loop.
How was it reversed?
www.newsfromrussia.com
Sources
Schiermeier, Quirin. 2003. The mechanisms that helped bring down temperatures in
the past are still active today. Nature. Vol 423. Pages 681-682.
Methane Hydrates
It is estimated that the energy locked up in methane
hydrate deposits is more than twice the global reserves
of all conventional gas, oil, and coal deposits combined.
In order to form and remain stable, methane hydrates need some very specific
conditions to be met. If the conditions are not met, the hydrate will dissociate into
water and methane gas.
The three factors what control stability are an adequate supply of water and methane, suitable temperature and pressure,
geochemical conditions, suitable temperatures and pressures, and geochemical conditions.
A hydrate will form if 70% of the cavities within the hydrate lattice are filled. Obviously water is always abundant, as it
saturates most of the sediment on earth. Methane formation occurs in two ways. Biogenic methane is a by product of bacterial
ingestion and is also produced in swamps, landfills, and rice paddies. Thermogenic methane is produced by the combination
of heat, pressure, and time on a buried organic material. Both forms of methane are trapped in the sea floor and the gas will
combine with water to form the hydrate.
There are a few geochemical processes that restrict or increase stability and formation of a hydrate. A high salinity will restrict
the formation of methane hydrate. The presence of natural gasses like carbon dioxide, hydrogen sulfide, and larger
hydrocarbons, will increase the stability of hydrates.
Matt Aschaffenburg
http://www.llnl.gov/str/Durham.html
http://www.ornl.gov/info/reporter/no16/methane.htm
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Gas
Carbon dioxide (CO2)
Methane (CH4)
Nitrous oxide (N2O)
Hydrofluorocarbon
HFC-32
HFC-41
HFC-43-10mee
HFC-125
HFC-134
HFC-134a
HFC-143
HFC-143a
HFC-152a
GWP
1
21
310
11,700
650
150
1,300
2,800
1,000
1,300
300
3,800
140
Global Circulation
•Warm air olds more moisure than cold air, and moist air retains heat
longer than dry air.
•The sun warms air at the equator, as the air gets warmer it rises,
spreads out, and cools (adiabatic cooling)
•This cooled air then goes poleward and drops at 30°
•Air warms as it drops, so it picks up moisture, deserts occur at 30°
•Equatorial air is replaced by winds coming in from the 30°s
(tradewinds)
•Wind moves poleward along the earths surface between 30 and 60
•Coriolis Force causes the “westerlies”
•Water has a higher specific heat than air
•Air coming off the water in Northern areas(California,
• England) will be warmer than the land, so as it goes over the land
and cools it drops moisture.
•During the summer, the land may be warmer than the water, so the air
picks up moisture as it moves over the land creating wet winters and
dry summers.
Overall patterns
2.00x1017
Integrated CO2 Production (moles)
1200
1.50x1017
1000
800
1.00x1017
Atmospheric CO2 Concentration
600
400
5.00x1016
Integrated CO2 Production
0.00x100
1850
1900
1950
2000
2050
200
Atmospheric CO2 Concentration (p.p.m.)
1400
0
2100
Year
1) Historical and predicted integrated CO2 production and resultant
atmospheric CO2 concentration assuming no interaction with the ocean.
CO2 SOLUBILITY IN THE WORLD’S OCEANS
Gas
Molecular
Weight (g/mol)
He
Ne
N2
O2
Ar
Kr
Xe
Rn
CO2
N2O
4
20
28
32
40
84
131
222
44
44
Diffusion Coefficient (x10^-5 cm2/sec) SxD (gas)
0˚C
24˚C
SxD (O2)
2.0
1.4
1.1
1.2
0.8
0.7
0.7
0.7
1.0
1.0
4.0
2.8
2.1
2.3
1.5
1.4
1.4
1.4
1.9
2.0
0.54
0.44
0.45
1.00
0.72
1.2
2.5
4.8
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Molecular diffusion rates of various gases in seawater (35% salinity)
CO2 (g)  H2O(l)  H2CO3 (l)
H2CO3 (l)  H  (aq)  HCO3 (aq)
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COs (g)  H 2O(l)  H  (aq)  HCO3 (aq)
HCO3 (aq)  H  (aq)  CO32 (aq)

K1'
K 2'
H 2O(l)  CO2 (g)  CO32 (aq)  2HCO3 (aq)
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Broecker, W.S., Peng, T.-H. Tracers in the Sea. New York: Eldigio Press, 1982.
http://www.ssec.wisc.edu/data/sst/latest_sst.gif
http://oceanworld.tamu.edu/resources/ocng_textbook/chapter13/chapter13_03.htm
Ocean circulation model
• mixing time is 1000 years!
1000
Atmospheric CO2 Concentration (p.p.m.)
900
800
No Ocean
700
600
10% Ocean
500
20% Ocean
400
X
100% Ocean
300
200
1850
1900
1950
2000
2050
Year
Predicted atmospheric CO2 concentrations for four different
ocean mixing scenarios. The current atmospheric CO2
concentration is marked with an X.
2100
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FAQ 8.1, Figure 1
Figure 10.1
Figure 11.11
Figure 11.12
Figure 11.13
FAQ 9.2, Figure 1
Figure 10.4
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Figure 10.12
Ocean Currents:
By Tom Reznick
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Forces Affecting Ocean Currents:
– Wind
– Solar Heating
– Gravity
– Coriolis Force
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5/31/2016
Effect of Current on Global
Climate:
– Ocean Current Warming
• Heats High
Northern Latitudes
– Europe
– Gulf Stream
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Temperature of the Earth over Geologic Time
Past 120 Years
Methods for Determining Past Climates
End of Little Ice Age
Geochemical (18O/16O, CaCO3)
Sedimentary Rocks (evaporites, glacial deposits)
Fossils (organisms that lived in limited climates)
NASA, Goddard Institute for Space Studies
http://data.giss.nasa.gov/gistemp/graphs/Fig.A_lrg.gif
Past 1,000 Years
http://arjournals.annualreviews.org/doi/pdf/
10.1146/annurev.ea.05.050177.001535
Past 18,000 Years
Medieval
Warming
Holocene
Max
Medieval Warming
Little Ice
Age
Little Ice Age
Australian Government, Bureau of Meteorology
http://www.bom.gov.au/info/climate/change/gallery/50.shtml
GE131 Lecture by Jennifer Shosa, Colby College Geology Department
Historical Evidence of Abrupt Climate Change
• Throughout the past century, various models and hypothesis
(many erroneous and chaos-theory oriented)
• Scandinavian lakes and bogs. 14C and biological evidence.
Oscillation of temperatures 12,000 years ago. Younger Dryas
• Hans Suess. 1˚C/1000 years
• O isotopes in ice. Saw tooth pattern. 90,000 year glacial build up
• Early ‘90’s-Greenland. 7˚C warming, 50 years. Evidence around
globe. Younger Dryas confirmed.
• Clatharates-particular era of warm. 55 million years ago
• Intergalcial, 14˚C drop in 10 years. Lasted for 70 years.
• Ice core-Vostok Antarctica; currently in an unusually sustained
period of warmth. CO2 and greenhouse production?
http://www.aip.org/history/climate/rapid.htm#a_Bryson
Abrupt Climate Change
Ice core evidence of abrupt climate change
http://www.pnas.org/cgi/content/full/97/4/1331?ijkey=JifxlJJnHUR2Q
Climate Engineering
• Change radiative flux
• Increase outgoing solar
radiation via CO2
reduction
• Decrease absorbed solar
radiation
• Albedo: aerosols,
space-based
technology
• Carbon capture
• Forests, oceans
Sources: Matthews, B. 1996. A critical review of proposals, their scientific and political context, and possible impacts.
Scienctists for Global Responsibilty. http://www.chooseclimate.org
Keith, D.W. 2000. Geoengineering the climate: History and prospect. Annual review of energy and the environment
25:245-284