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I. Physical Principles: The foundation & the toolsNewton's laws: forces, pressure, motionEnergy: Temperature, radiant energy
II. Atmospheric & Ocean Physics: First element of climate and environmental science
Atmospheric structure (T, P in "4-D") Winds, Weather, General Circulation, Climate
III. Atmospheric & Ocean Biogeochemistry: Second element of climate and environmental science
Atmospheric and ocean composition, past and present
Human impact, global change
IV. Intersection: what we know, would like to know, will never know, and what can we contribute to the debate.
BioGEOCHEMICAL CYCLESBioGEOCHEMICAL CYCLES
• Most abundant elements: oxygen (in solid earth!), iron (core), silicon (mantle), hydrogen (oceans), nitrogen, carbon, sulfur…
• The elemental composition of the Earth has remained essentially unchanged over its 4.5 Gyr history
– Extraterrestrial inputs (e.g., from meteorites, cometary material) have been relatively unimportant
– Escape to space has been restricted by gravity
• Biogeochemical cycling of these elements between the different reservoirs of the Earth system determines the composition of the Earth’s atmosphere and oceans, and the evolution of life
THE EARTH: ASSEMBLAGE OF ATOMS OF THE 92 NATURAL ELEMENTSTHE EARTH: ASSEMBLAGE OF ATOMS OF THE 92 NATURAL ELEMENTS
BIOGEOCHEMICAL CYCLING OF ELEMENTS:BIOGEOCHEMICAL CYCLING OF ELEMENTS:examples of major processesexamples of major processes
Physical exchange, redox chemistry, biochemistry are involved
Surfacereservoirs
HISTORY OF EARTH’S ATMOSPHEREHISTORY OF EARTH’S ATMOSPHERE
Outgassing
N2
CO2
H2Ooceans form
CO2
dissolves
Life forms in oceans
Onset ofphotosynthesis
O2 O2 reaches current levels; life invades continents
4.5 GyB.P
4 GyB.P.
3.5 GyB.P.
0.4 GyB.P. present
Source: EARLY EARTH Oxygen for heavy-metal fans: Lyons TW, Reinhard CTNATURE Volume: 461 Issue: 7261 Pages: 179-181 SEP 10 2009
COMPARING THE ATMOSPHERES COMPARING THE ATMOSPHERES OF EARTH, VENUS, AND MARSOF EARTH, VENUS, AND MARS
3x10-41x10-23x10-3H2O (atm, mol/mol)
1.3x10-30.216.9x10-5O2 (mol/mol)
0.007
0.64
1
5.98
91
4.87
Surface pressure (atm)
Mass (1024 kg)
2.7x10-20.783.4x10-2N2 (mol/mol)
0.953x10-40.96CO2 (mol/mol)
340064006100Radius (km)
MarsEarth Venus
H2O (total, bars) 0.3 400 2 x 10 -6
0.1x10-9Carbonyl Sulfide (COS)
3.0x10-9Chlorofluorocarbons
0.03x10-6 to 0.3x10-6Carbon Monoxide (CO)
0.32x10-6Nitrous Oxide (N2O)
0.55x10-6Hydrogen (H2)
1.1x10-6Krypton (Kr)
1.7x10-6Methane (CH4)
5.2x10-6Helium (He)
0.02x10-6 to 10x10 –6Ozone (O3) ¶
18.2x10-6Neon (Ne)
Carbon Dioxide (CO2)
0.0093Argon (Ar)
0.04 to < 5x10-3; 4x10-6 -stratWater (H2O)
0.21Oxygen (O2)
0.78Nitrogen (N2)
Mole fractionGasAtmospheric Atmospheric Composition Composition
(average)(average)
1 ppm= 1x101 ppm= 1x10-6-6
red = increased by red = increased by human activityhuman activity
¶ Ozone has increased in the troposphere, but decreased in the stratosphere.
Arrows indicate El Nino events
Notice:• atmospheric increase is ~50% of fossil fuel emissions• significant interannual variability
NOAA Greenhouse Gas records
Ultra-simplified ("toy") model for atmospheric concentrations of CO2, CH4 and other gases:
A) mass balance B) Inputs or Production ("P"), controlled by biogeochemical processesC) Removal or Loss ("L"), at a rate proportional to the amount that is present in the atmosphere (1st order or linear process, for example: dissolving CO2 in the ocean, reacting CH4 with atmospheric hydroxyl radical. 1/L = "Lifetime").
Quantity: C gas concentration in the atmosphere (Gtons C, or ppm; 1 ppm = 2.1 Gtons C globally)
Ultra-simplified ("toy") model for atmospheric concentrations of CO2, CH4 and other gases:
A) mass balance B) Inputs or Production ("P"), controlled by biogeochemical processesC) Removal or Loss ("L"), at a rate proportional to the amount that is present in the atmosphere (1st order or linear process, for example: dissolving CO2 in the ocean, reacting CH4 with atmospheric hydroxyl radical). 1/L = "Lifetime".
Quantity: C gas concentration in the atmosphere (Gtons C, or ppm; 1 ppm = 2.1 Gtons C globally)
The mass balance equation:
Rate of change in the atmosphere = P - L C (units: Gtons/yr)
dC
dt=P −LC
Impulse Approach Steady State
Accumulation Airborne Fraction
Results from a "Toy Model" of human-caused CO2 change
How is the composition of Earth's atmosphere controlled by geochemical and biological processes ?
FAST OXYGEN CYCLE: ATMOSPHERE-BIOSPHEREFAST OXYGEN CYCLE: ATMOSPHERE-BIOSPHERE
• Source of O2: photosynthesis
nCO2 + nH2O -> (CH2O)n + nO2
• Sink: respiration/decay
(CH2O)n + nO2 -> nCO2 + nH2O
O2
CO2
orgC
orgClitter
Photosynthesisless respiration
decay
O2 lifetime: 10,000 years
PO2 ~120 Pg/yr
LO2 ~ PO2
……however, abundance of organic carbon in however, abundance of organic carbon in biosphere/soil/ocean reservoirs is too small to control biosphere/soil/ocean reservoirs is too small to control
atmospheric Oatmospheric O2 2 levels levels 2.1 Pg C in CO2 = 1 ppm in atm.
PO2 ~ 120 Pg/yr
SLOW OXYGEN CYCLE: ATMOSPHERE-LITHOSPHERESLOW OXYGEN CYCLE: ATMOSPHERE-LITHOSPHERE
O2CO2
Compressionsubduction
Uplift
CONTINENTOCEAN
FeS2orgC
weatheringFe2O3
H2SO4
runoff
O2CO2
Photosynthesisdecay
orgC
burial
SEDIMENTS
microbesFeS2orgC
CO2orgC: 1x107 Pg CFeS2: 5x106 Pg S
O2: 1.2x106 Pg OO2 lifetime: 3 million years
The heavier temperature lines 160,000 BP to present reflect more data points, not necessarily greater variability.
Source: Climate and Atmospheric History of the past 420,000 years from the Vostok Ice Core, Antarctica , by Petit J.R., Jouzel J., Raynaud D., Barkov N.I., Barnola J.M., Basile I., Bender M., Chappellaz J., Davis J. Delaygue G., Delmotte M. Kotlyakov V.M., Legrand M., Lipenkov V.M., Lorius C., Pépin L., Ritz C., Saltzman E., Stievenard M., Nature, 3 June 1999.
Antarctic Ice Core Data
CO2 varies over geologic time, within the range 190 – 280 ppm for the last 420,000 years. The variations correlate with climate: cold low CO2 . Is CO2 driving climate or vice versa?
GLOBAL PREINDUSTRIAL CARBON CYCLEGLOBAL PREINDUSTRIAL CARBON CYCLE
The carbon cycle can be viewed as a set of "reservoirs" or compartments, each characterizing a form of C (e.g. trees; rocks containing calcium carbonate [limestone]).
The cycle of C globally is then represented as a set of transfer rates between compartments.
The total amount of carbon in the atmosphere + ocean + rocks that exchange with the atmosphere/ocean is fixed by very long-term geophysical processes.
Human intervention may be regarded as manipulation of the rates of transfer between important reservoirs.
Inventories in Pg C
Flows in Pg C a-1
1950
1960
1970
1980
1990
Year
History of consumption of fossil fuels.
Emissions have increased by more than 2X since 1970. There rise in the last 5 years has been really dramatic.
But there has not been a corresponding rise in the annual increment of CO2.
In 1970 ~75% of the emitted CO2 stayed in the atmosphere, but only ~40% in 2000.
3800
6500
Global Fuel UseGlobal Fuel Use
7800 in 2005!
8200 in 2007!
Carbon Cycle on Land, Organisms in ocean•Photosynthesis:
CO2 + H2O + light => "H2CO" + O2
•Respiration:
"H2CO" + O2 => CO2 + H2O + energy
Very small fraction of organic matter is stored, on average.
Inorganic Carbon Cycle in the ocean•Dissolution/evasion
CO2 + H2O+CO32− ⇔ 2⋅HCO3
−
Composition of Sea WaterComposition of Sea Water
"alkalinity" defines Σ' Zi [i] : response of H+ and OH- to addition of CO2
Charge balance in the ocean:[HCO3
-] + 2[CO32-] = [Na+] + [K+] + 2[Mg2+] + 2[Ca2+] - [Cl-] – 2[SO4
2-] – [Br-] The alkalinity [Alk] ≈ [HCO3
-] + 2[CO32-] = 2.3x10-3M (2.3 mmol/kg)
AlkalinityAlkalinity
• [alk] = Σi Z+[i+] - Σi Z-[i-] = [HCO3-] + 2 [CO3
=]
• [alk] is a re-arrangement of the charge balance equation. It cannot change when adding or removing an uncharged species like CO2.
• [alk] = 2 x 10-3 M -- only 1 in 1000 of total ions!
( 1 out of 600 Eq/L of negative ions)
UPTAKE OF COUPTAKE OF CO22 BY THE OCEANS BY THE OCEANS
CO2(g)
CO2.H2O
CO2.H2O HCO3
- + H+
HCO3- CO3
2- + H+
KH = 3x10-2 M atm-1
K1 = 9x10-7 M
K2 = 7x10-10 M pK 1
Ocean pH = 8.2
pK 2
CO2.H2O HCO3
- CO32-
OCEAN
ATMOSPHERE
LIMIT ON OCEAN UPTAKE OF COLIMIT ON OCEAN UPTAKE OF CO22::
CONSERVATION OF ALKALINITYCONSERVATION OF ALKALINITY Equilibrium calculation for [Alk] = 2.3x10-3 M
pCO2 , ppm100 200 300 400 500
8.6
8.4
8.2
2
3
41.4
1.6
1.8
1.9
2.0
2.1
Ocean pH
[CO32-],
10-4 M
[HCO3-],
10-3M
[CO2.H2O]+[HCO3
-]
+[CO32-], 10-3M
Charge balance in the ocean:[HCO3
-] + 2[CO32-] = [Na+] + [K+] + 2[Mg2+] +
2[Ca2+] - [Cl-] – 2[SO42-] – [Br-]
The alkalinity [Alk] ≈ [HCO3
-] + 2[CO32-] =
2.3x10-3M is the excess base relative to the CO2-H2O system
It is conserved upon addition of CO2
uptake of CO2 is limited by the existing supply of CO3
2-:
Increasing Alk requires dissolution of sediments:…which takes place over a time scale of thousands of years
CO2(g) + CO32 + H2O 2HCO3
-
Ca2+ + CO32-CaCO3
EQUILIBRIUM PARTITIONING OF COEQUILIBRIUM PARTITIONING OF CO22
BETWEEN ATMOSPHERE AND GLOBAL OCEANBETWEEN ATMOSPHERE AND GLOBAL OCEAN
Equilibrium for present-day ocean:
only 3% of total inorganic carbon is currently in the atmosphere
But CO2(g) [H+] F … positive feedback to increasing CO2
Pose problem differently: how does a CO2 addition dN partition between the atmosphere and ocean at equilibrium?
28% of added CO2 remains in atmosphere!
2
2 2 H 1 1 22
( ) 10.03
( ) ( )1 1
N [H ] [H ]
CO
CO CO oc
a
N gF
N g N aq V PK K K K
2
H 1 22 22+
( ) 10.28
( ) ( ) 1H
CO
ocCO CO
a
dN gf
V PK K KdN g dN aq
N
FURTHER LIMITATION OF COFURTHER LIMITATION OF CO2 2 UPTAKE: UPTAKE:
SLOW OCEAN TURNOVER (~ 200 years)SLOW OCEAN TURNOVER (~ 200 years)
Inventories in 1015 m3 waterFlows in 1015 m3 yr-1
Uptake by oceanic mixed layer only (VOC= 3.6x1016 m3) would give f = 0.94 (94% of added CO2 remains in atmosphere)
Global CO2 cycle
compare to ~300 moles CO3=
Observed uptake of fossil fuel CO2 by the oceans
Global CO2 cycle
NET UPTAKE OF CONET UPTAKE OF CO22 BY TERRESTRIAL BIOSPHERE BY TERRESTRIAL BIOSPHERE
(1.4 Pg C yr(1.4 Pg C yr-1-1 in the 1990s; IPCC [2001]) in the 1990s; IPCC [2001])is a small residual of large atm-bio exchangeis a small residual of large atm-bio exchange
• Gross primary production (GPP):
GPP = CO2 uptake by photosynthesis = 120 PgC yr-1
• Net primary production (NPP):
NPP = GPP – “autotrophic” respiration by green plants = 60 PgC yr-1
• Net ecosystem production (NEP):
NEP = NPP – “heterotrophic” respiration by decomposers = 10 PgC yr-1
• Net biome production (NBP)
NBP = NEP – fires/erosion/harvesting = 1.4 PgC yr-1
Atmospheric CO2 observations show that the net uptake is at northern midlatitudes but cannot resolve American vs. Eurasian contributions
CO2 + H2O "H2CO" + O2 Photosynthesis and Respiration
CYCLING OF CARBON WITH TERRESTRIAL BIOSPHERECYCLING OF CARBON WITH TERRESTRIAL BIOSPHERE
Inventories in PgCFlows in PgC yr-1
Relatively small reservoirs Short time scales net uptake from reforestation is transitory...unless resources are managed to preserve
organic matter
6.3 - 7.3Total
1-2Deforestation
5.3Fossil Fuel+ cement
Global CO2 budget (PgC yr-1 ) 1980 – 1990 1990 –2000
Sources
1-2"Missing Sink"
6.3 - 7.3Total
2.1Ocean uptake
3.2Atmospheric accumulation
Sinks
2.1 Pg C = 1 ppm atmospheric CO2 [source: Cias et al., Science 269, 1098, (1995)]
6.5
.5-1
7-7.5
3.2
1.5-2
1.8-2.8
7-7.5
EVIDENCE FOR LAND UPTAKE EVIDENCE FOR LAND UPTAKE OF COOF CO22 FROM TRENDS IN O FROM TRENDS IN O22,,
1990-20001990-2000
Carbon-Climate FuturesCarbon-Climate Futures
Carbon Flux: Ocean to Air
-10-8-6-4-202468
10
1850 1900 1950 2000 2050 2100
Pg
C/y
r
Cox et al (2000)
Friedlingstein et al (2001)
Carbon Flux: Land to Air
-10-8-6-4-202468
10
1850 1900 1950 2000 2050 2100
Pg
C/y
r
Atmospheric CO2
200300400500600700800900
1000
1850 1900 1950 2000 2050 2100
pp
m
1850 1900 1950 2000 2050 210013
14
15
16
17
18
19
20
Global Mean Temperature
Ce
lsiu
s
Vegetation matters! Different models project dramatically different futures using different ecosystem models.
~ 2º Kin 2100
Coupled simulations of climate and the carbon cycle
1950
1960
1970
1980
1990
Year
History of consumption of fossil fuels.
Emissions have increased by more than 2X since 1970. There rise in the last 5 years has been really dramatic.
But there has not been a corresponding rise in the annual increment of CO2.
In 1970 ~75% of the emitted CO2 stayed in the atmosphere, but only ~40% in 2000.
3800
6500
Global Fuel UseGlobal Fuel Use
7800 in 2005!
8200 in 2007!
2007
1
09 m
etr
ic t
on
s o
f C
/ yr
0
.5
1.
1
.5
(source: CDIAC –Trends –updated)
US fossil fuel use
US per capita fossil fuel use
Metric tons C per person
US and World Per Capita Fossil Fuel Use since 1950
Why don't we see a big upswing due to the emergence of economies in China and India ?
China is projected to have exceed US emissions in 2009.
PROJECTIONS OF FUTURE COPROJECTIONS OF FUTURE CO2 2 CONCENTRATIONSCONCENTRATIONS
[IPCC, 2001][IPCC, 2001]
PROJECTED FUTURE TRENDS IN COPROJECTED FUTURE TRENDS IN CO22 UPTAKE UPTAKE
BY OCEANS AND TERRESTRIAL BIOSPHEREBY OCEANS AND TERRESTRIAL BIOSPHERE
IPCC [2001]
C4MIP:coupled climate-biosphere model comparison
(used in IPCC 2007)
US and World Per Capita Fossil Fuel Use since 1950
Japan and Europe…
HIPPO completed the 1st of 5 global surveys in January, 2009
Ne
t E
xc
ha
ng
e (m
ol
CO
2/m
2/s
)
Time (days)3471 3471.5 3472 3472.5 3473
--
-
2001
NEE
R
GEE
-30
-
20
-
10
0
YR
R,
(-1)
*GE
E M
gC/h
a/yr
1992 1996 2000 2004
1012
1416
18
R- GEE
1998
uptake
emission
A
B
C
NE
E M
gC/h
a/yr
1992 1996 2000 2004
-5-4
-3-2
-10
NEEHarvard Forest
1998
A. Eleven years of hourly data for Net Ecosystem Exchange. B. Two days of hourly data. C. 13 years of respiration (R), GEE, and D. 13 years of NEENEE annual sums.
D
Harvard Forest, Petersham, MA. A "typical" New England forest…an artifact!
YR
R,
(-1)
*GE
E M
gC/h
a/yr
1992 1996 2000 2004
1012
1416
18
R- GEE
1998
AG
WB
MgC
/ha
1994 1996 1998 2000 2002 2004
102
106
110
93-798 99 00 01 02 03 04
0.0
0.5
1.0
1.5
AG
WI M
gC
/ha
/yr
Year
GE
E 1
200-
1500
1992 1996 2000 2004
-28
-26
-24
-22
More Efficient
1998
uptake
emission
“LUE”1200-1500
Live Biomass
NE
E M
gC/h
a/yr
1992 1996 2000 2004
-5-4
-3-2
-10
NEEHarvard Forest
1998
Long-term changes at Harvard Forest
NH
% o
f lan
d ar
ea in
fore
sts
20
4
0
6
0
8
0
1
00
Year
1700 1800 1900 2000
MA
Fitzjarrald et al., 2001
A legacy: land use change in New England
-5
-4
-3
-2
-1
0 NEE = -1.28 - 0.146 x (yr-1990); R2 = 0.337
Year
1992 1994 1996 1998 2000 2002 2004
10
12
14
16
-1 x GEE
Resp
GEE = 11.1 + 0.363 x (yr-1990); R2 = 0.732
R = 9.82 + 0.217 x (yr-1990); R2 = 0.626
NEE
(Mg-
Cha-1
yr-1)
Mg-
C ha
-1yr
-1
0
20
40
60
80
100
120
Abo
vegr
ound
woo
dy b
iom
ass
(MgC
ha-1)
93 94 95 96 97 98 99 00 01 02 03 04 05
oak
other spp
Year
Rates for growth and for carbon uptake are accelerating in this 80-year-old New England Forest…why is that? Will that continue? How big do North American trees grow?
Non-CO2 Greenhouse Gases
• CH4 – dominated by fossil emissions over USA and much of Canada
• N2O – mostly agricultural emissions
• CO – a mix of combustion and hydrocarbon sources
Atmospheric Methane (CHAtmospheric Methane (CH44))
SOURCES OF ATMOSPHERIC METHANE
ANIMALS90
LANDFILLS50
GAS60
COAL40RICE
85
TERMITES25
WETLANDS180
BIOMASSBURNING20
GLOBAL METHANESOURCES (Tg CH4 yr-1)
Year
600
800
700
Scenarios
A1BA1TA1F1A2B1B2IS92a
900
Variations of CH4 Concentration (ppbv) Over the Past 1000 years
[Etheridge et al., 1998]
Year20001000
800
IPCCIPCC [2001] Projections of Future [2001] Projections of Future CHCH44 Emissions (Tg CH Emissions (Tg CH44) to 2050) to 2050
1200
1600
1400
1000
1500 2000 2020 2040
Atmospheric CH4: Past Trends, Future Predictions
COBRA-2003§ flight region and footprints
§a CCE ( LBA !) project
LPDM Model: STILTEmissions: EDGAR-2000Met fields: WRF (AER, 35 km, LPDM outputs, Grell-2)
WRF
June 16, 2003 36.72N,96.94W 609 m AGL
1600
170
0 1
800
190
0 2
000
CH4
0 50 100 150 200 250 300
Flask number
WRF/STILT/EDGAR model vs data, with gray and green.
Errors used in fitting are + 38 ppbv for the model, and + 23 ppbv for the measurements
Slope = 0.9
σslope = 0.1
EDGAR—2000 confirmed ±10% for CH4 !
This result pertains to urban-industrial sources, which dominate the flight region
OXIDATION STATES OF NITROGENOXIDATION STATES OF NITROGENN has 5 electrons in valence shell N has 5 electrons in valence shell 9 oxidation states from –3 to +59 oxidation states from –3 to +5
HNO3
Nitric acid
NO3-
Nitrate
+5
NO2
Nitrogen dioxide
+4
HONO
Nitrous acid
NO2-
Nitrite
NO
Nitric oxide
N2O
Nitrous
oxide
N2NH3
Ammonia
NH4+
Ammonium
R1N(R2)R3
Organic N
+3+2+10-3
Decreasing oxidation number (reduction reactions)
Increasing oxidation number (oxidation reactions)
Nitrogen: Nitrogen is a major component of the atmosphere, but an essential nutrient in short supply to living organisms. Why is "fixed" nitrogen in short supply? Why does it stay
in the atmosphere at all?
free radical free radical
THE THE NITROGEN CYCLENITROGEN CYCLE: MAJOR PROCESSES: MAJOR PROCESSES
ATMOSPHEREN2 NO
HNO3
NH3/NH4+ NO3
-
orgN
BIOSPHERE
LITHOSPHERE
combustionlightning
oxidation
deposition
assimilation
decay
nitrification
denitri-ficationbiofixation
burial weathering
free radical
"fixed" or "odd" N is less stable globally=> N2
(C106H124O36) (NH3)16 (H3PO4) + 150 O2 => 106 CO2 + 16 HNO3 + H3PO4 + 78 H2O + energy
Dissolved NO3
-
mole/kg
Dis
solv
ed O
2 m
ole/
kg
The cycle of organic/inorganic C, solubility of O2 in seawater, and onset of denitrification, limit the amount of nitrate in the deep ocean
Oceanic Nitrogen Processes
Org N
NH4+ NH2OH NO2
- NO3-
N2H4 N2
NO
N2O
N2
-3 -2 -1 0 1 2 3 5
-3 -2 -1 0 1 2 3 5
??
ox state
“There are lies, there are big lies, and then there are…box models.”
• Box models are usually considered linear models. Nature isn’t linear.
It matters how you choose to divide up the problem into boxes.
*
*
***************************************************************************************************
time
C1
or
C2
0 2 4 6 8 10
0.0
0.00
20.
004
0.00
60.
008
0.01
0Box 1 of 2
Box 2 of 2
Box 1
Box 2
kk
Only Box 2
Only Box 1
Box 2 only
k=1; M1=1, M2=10; Co = .01 (M1o)
C1=Co/M1+2{M2 exp(-k(M1+2/(M1M2)t) +M1 } C2=CoM1 /M1+2{1 - exp(-k(M1+2/(M1M2)t ) }
Box 1
Box 2
kk
BOX MODEL OF THE NITROGEN CYCLEBOX MODEL OF THE NITROGEN CYCLE
Inventories in Tg NFlows in Tg N yr-1
NN22O: LOW-YIELD PRODUCT OF BACTERIAL O: LOW-YIELD PRODUCT OF BACTERIAL
NITRIFICATION AND DENITRIFICATIONNITRIFICATION AND DENITRIFICATIONImportant as
• source of NOx radicals in stratosphere• greenhouse gas
IPCC[2001]
NH4
++3/2O2 NO2
+ H2O + 2 H+
NO3
+ Org-C N2 + …
N2O
Constraints on N2O budget changes since pre-industrial time from new firn air
and ice core isotope measurements
S. Bernard, T. R¨ockmann, J. Kaiser, J.-M. Barnola, H. Fischer, T. Blunier, and J. Chappellaz, Atmos. Chem. Phys., 6, 493–503, 2006
time
1980 1985 1990 1995 2000 2005
300
305
310
315
320
N2O (ppb)mean annual increase 0.74 ppb/yr
N2O versus depth in the Greenland Ice sheet.
N2O in the atmosphere
PRESENT-DAY GLOBAL BUDGET OF ATMOSPHERIC N2O
SOURCES (Tg N yr-1) 18 (7 – 37)
Natural 10 (5 – 16)
Ocean 3 (1 - 5)
Tropical soils 4 (3 – 6)
Temperate soils 2 (1 – 4)
Anthropogenic 8 (2 – 21)
Agricultural soils 4 (1 – 15)
Livestock 2 (1 – 3)
Industrial 1 (1 – 2)
SINK (Tg N yr-1)
Photolysis and oxidation in stratosphere
12 (9 – 16)
ACCUMULATION (Tg N yr-1) 4 (3 – 5)
Although a closed budget can be constructed, uncertainties in sources are large! (N2O atm mass = 5.13 1018 kg x 3.1 10-7 x28/29 = 1535 Tg )
IPCC[2001]
Inventories in Tg NFlows in Tg N yr-1
BOX MODEL OF THE NBOX MODEL OF THE N22O CYCLEO CYCLE
36 8
1.53 103 N2O
N2O Observed vs Model (EDGAR—2000 )
COBRA-2003
Observed N2O (ppbv)
Mo
del
ST
ILT
/ N2O
(p
pb
v)
US sources of N2O are ~2.5x higher than EDGAR Kort et al., 2008