Jan 05, 2016
1600
1400
1200
1000
800
Atm. CH
4
(ppbV)
20001950190018501800Calender Years (AD)
360
340
320
300
280
Atm. CO
2
(ppmV)
5
4
3
2
1
x103
310
300
290
280
270
Atm. N
2
O (ppbV)
1
2
3
4
5
World Population (billions)
Atmospheric CH4
Atmospheric CO2
World Population
The Anthropogenic Impact
First Direct Measurements
AtmosphericN2O
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are needed to see this picture.
Before 1950, atm. CO2 values come from ice cores.
Scholander made first measurements of gases in icebergs in Baffin Bay in 1950’s.
The National Ice Core Laboratory in Denver, Colorado
Depth
Bubble Close-Off Region
Free Atmosphere
Glacier Surface
0
115
123
120
100
80
60
40
20
0
Depth (mbs)
1.00.80.60.40.20.0CO2 Diffusivity (m2/day)
0.700.600.500.400.300.200.100.00Open Porosity
S. Pole Firn Properties from Density Measurements
Issues:1) Ice age - gas age2) Trapped gases are ave.3) Gravity and thermal frac.
Depth
Bubble Close-Off Region
Free Atmosphere
Glacier Surface
0
115
123
Convection
Zone
Static-AirColumn
Non-diffusive
Zone
Depth
N (‰)15
0.0
Barometric Equation: Pz = Po(e(mgz/RT))
δ15N=
15N14N
⎛
⎝
⎜ ⎜ ⎜
⎞
⎠
⎟ ⎟ ⎟ sample
15N14N
⎛
⎝
⎜ ⎜ ⎜
⎞
⎠
⎟ ⎟ ⎟ atmN2
-1
⎡
⎣
⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢
⎤
⎦
⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥
103
0.35
0.50
0.35
0.50
0.80
0.83
Bubble close-off region
To Waste
Density (g/cc)
Depth
Rubber Bladder
Firn AirSampling Device
To Inflate bladderTo Flasks
Bender Baffle
120
100
80
60
40
20
0
Depth (mbs)
0.700.600.500.400.300.200.10
15N
15 (‰)N
South Pole Gravitational Signal
Using 15N to assess the depth of bubble close-off in the past
• Bubble close off is primarily a function of temperature (colder temps -> deeper close off depths).
• Gravitational fractionation is also a function of temp.Pz = Po(e(mgz/RT))
• Age difference between bubbles and surrounding ice is proportional to accumulation rate which is also tied to surface temperature
-41
-40
-39
-38
-37
-36
-35
18
Oice
(‰ )SMOW
12.011.811.611.411.211.0 ( ) Age ka BP
0.60
0.55
0.50
0.45
0.40
0.35
15
N
(‰ )air750
700
650
600
550
500
450
CH4
( )ppb
Younger DyrasPreboreal Period
δ18Oice
δ15N (ΔSurface Temp.)
CH4
(Severinghaus et al., Nature vol 391, '98)(Severinghaus et al., Nature vol 391, '98)
T=10.4±2oC
280
260
240
220
200
CO2
(ppm)
100806040200 Gas Age (kry BP)
Vostok
Taylor Dome
Byrd
Dry Extraction technique onlyNumerous labs using different techniquesNumerous Antarctic ice cores drilled differently
300
250
200
150
CO2
(ppm)
100806040200 Gas Age (kry BP)
Vostok
Taylor Dome
Byrd
GISP II (Greenland)
280
240
200
CO2 (ppm)
8007006005004003002001000Gas Age (kyr BP)
800
700
600
500
400
CH4 (ppb)
-440
-420
-400
-380Temp. Proxy
EPICA Ice Core Results
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IPCC 2007 Synthesis report
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Sources of CO2 to atmosphere
Weathering reactions
H2SO4 + CaCO3 → CaSO4 + H2CO3
Fossil Fuel Burning
CH4 + 2 O2 → CO2 + 2 H2O Respiration
C6H12O6 → 2 CO2 + 2 C2H5OH
Volcanoes emit CO2 from subducted oceanic sediment
Sinks of Atmospheric CO2
• Increase Corg reservoir
• Increase CaCO3 reservoir (coral reefs)
• Store CO2 in deep ocean
• Sequestration