1. BioGEOCHEMICAL 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 ELEMENTS

2. BIOGEOCHEMICAL CYCLING OF ELEMENTS: examples of major processes Physical exchange, redox chemistry, biochemistry are involved Surface reservoirs

3. HISTORY OF EARTH’S ATMOSPHERE Outgassing N 2 CO 2 H 2 O oceans form CO 2 dissolves Life forms in oceans Onset of photosynthesis O2O2 O 2 reaches current levels; life invades continents 4.5 Gy B.P 4 Gy B.P. 3.5 Gy B.P. 0.4 Gy B.P. present

4. COMPARING THE ATMOSPHERES OF EARTH, VENUS, AND MARS 3x10 -4 1x10 -2 3x10 -3 H 2 O (atm, mol/mol)‏ 1.3x10 -3 0.216.9x10 -5 O 2 (mol/mol)‏ 0.007 0.64 1 5.98 91 4.87 Surface pressure (atm) Mass (10 24 kg)‏ 2.7x10 -2 0.783.4x10 -2 N 2 (mol/mol)‏ 0.953x10 -4 0.96CO 2 (mol/mol)‏ 340064006100Radius (km)‏ MarsEarthVenus H 2 O (total, bars) 0.3 400 2 x 10 -6

5. Source: EARLY EARTH Oxygen for heavy-metal fans: Lyons TW, Reinhard CT NATURE Volume: 461 Issue: 7261 Pages: 179-181 SEP 10 2009

6. 0.1x10 -9 Carbonyl Sulfide (COS)‏ 3.0x10 -9 Chlorofluorocarbons 0.03x10 -6 to 0.3x10 -6 Carbon Monoxide (CO)‏ 0.32x10 -6 Nitrous Oxide (N 2 O)‏ 0.55x10 -6 Hydrogen (H 2 )‏ 1.1x10 -6 Krypton (Kr)‏ 1.7x10 -6 Methane (CH 4 )‏ 5.2x10 -6 Helium (He)‏ 0.02x10 -6 to 10x10 –6 Ozone (O 3 ) ¶ 18.2x10 -6 Neon (Ne)‏ 385 370x10 -6 (date: 2009 2000)‏Carbon Dioxide (CO 2 )‏ 0.0093Argon (Ar)‏ 0.04 to < 5x10 -3 ; 4x10 -6 -stratWater (H 2 O)‏ 0.21Oxygen (O 2 )‏ 0.78Nitrogen (N 2 )‏ Mole fractionGas Atmospheric Composition (average) 1 ppm= 1x10 -6 red = increased by human activity ¶ Ozone has increased in the troposphere, but decreased in the stratosphere.

10. NOAA Greenhouse Gas records

11. OXIDATION STATES OF NITROGEN N has 5 electrons in valence shell  9 oxidation states from –3 to +5 HNO 3 Nitric acid NO 3 - Nitrate +5 NO 2 Nitrogen dioxide +4 HONO Nitrous acid NO 2 - Nitrite NO Nitric oxide N 2 O Nitrous oxide N2N2 NH 3 Ammonia NH 4 + Ammonium R 1 N(R 2 )R 3 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

12. THE NITROGEN CYCLE: MAJOR PROCESSES ATMOSPHERE N2N2 NO HNO 3 NH 3 /NH 4 + NO 3 - orgN BIOSPHERE LITHOSPHERE combustion lightning oxidation deposition assimilation decay nitrification denitri- fication biofixation burial weathering free radical "fixed" or "odd" N is less stable globally=> N 2

13. Oceanic Nitrogen Processes

17. Org N NH 4 + NH 2 OHNO 2 - NO 3 - N2H4N2H4 N2N2 NO N2ON2O N2N2 -3 -2 -1 0 1 2 3 5 ? ? ox state

18. “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. Box 1 Box 2 k k Only Box 2 Only Box 1 Box 2 only k =1; M1=1, M2=10; C o =.01 (M1 o ) ‏ C 1 =C o /M 1+2 {M 2 exp(-k(M 1+2 /(M 1 M 2 )t) +M 1 } C 2 =C o M 1 /M 1+2 {1 - exp(-k(M 1+2 /(M 1 M 2 )t ) } Box 1 Box 2 k k

19. BOX MODEL OF THE NITROGEN CYCLE Inventories in Tg N Flows in Tg N yr -1

20. N 2 O: LOW-YIELD PRODUCT OF BACTERIAL NITRIFICATION AND DENITRIFICATION Important as source of NO x radicals in stratosphere greenhouse gas IPCC [2001] NH 4 + +3/2O 2  NO 2  + H 2 O + 2 H + NO 3  + Org-C  N 2 + … N2ON2O

21. Constraints on N 2 O 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 N 2 O versus depth in the Greenland Ice sheet. N 2 O in the atmosphere

22. PRESENT-DAY GLOBAL BUDGET OF ATMOSPHERIC N 2 O SOURCES (Tg N yr -1 )18 (7 – 37) Natural10 (5 – 16) Ocean3 (1 - 5) Tropical soils4 (3 – 6) Temperate soils2 (1 – 4) Anthropogenic8 (2 – 21) Agricultural soils4 (1 – 15) Livestock2 (1 – 3) Industrial1 (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! (N 2 O atm mass = 5.13 10 18 kg x 3.1 10 -7 x28/29 = 1535 Tg ) IPCC [2001]

23. Inventories in Tg N Flows in Tg N yr -1 BOX MODEL OF THE N 2 O CYCLE 36 8 1.53 10 3 N 2 O

26. FAST OXYGEN CYCLE: ATMOSPHERE-BIOSPHERE Source of O 2 : photosynthesis nCO 2 + nH 2 O -> (CH 2 O) n + nO 2 Sink: respiration/decay (CH 2 O) n + nO 2 -> nCO 2 + nH 2 O O2O2 CO 2 orgC litter Photosynthesis less respiration decay O 2 lifetime: 5000 years

27. …however, abundance of organic carbon in biosphere/soil/ocean reservoirs is too small to control atmospheric O 2 levels

28. SLOW OXYGEN CYCLE: ATMOSPHERE-LITHOSPHERE O2O2 CO 2 Compression subduction Uplift CONTINENT OCEAN FeS 2 orgC weathering Fe 2 O 3 H 2 SO 4 runoff O2O2 CO 2 Photosynthesis decay orgC burial SEDIMENTS microbes FeS 2 orgC CO 2 orgC: 1x10 7 Pg C FeS 2 : 5x10 6 Pg S O 2 : 1.2x10 6 Pg O O 2 lifetime: 3 million years

29. (C 106 H 124 O 36 ) (NH 3 ) 16 (H 3 PO 4 ) + 150 O 2 => 106 CO 2 + 16 HNO 3 + H 3 PO 4 + 78 H 2 O + energy Dissolved NO 3 -  mole/kg Dissolved O 2  mole/kg The cycle of organic/inorganic C, solubility of O 2 in seawater, and onset of denitrification, limit the amount of nitrate in the deep ocean

30. 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 CO 2 varies over geologic time, within the range 190 – 280 ppm for the last 420,000 years. The variations correlate with climate: cold  low CO 2. Is CO 2 driving climate or vice versa?

31. Antarctic ice cores compared with modern data for CO 2

32. CO 2 Airborne Fraction 60626466687072747678808284868890929496980002 Year-to-year change in CO 2 (ppm) (SPO+MLO)/2 Starting year RECENT GROWTH IN ATMOSPHERIC CO 2 CONCENTRATIONS The average annual increase did not change much between 1970 and 2000, despite significant increases in fossil fuel emissions. 1 ppm = 2.1 x 10 9 tons of C (in CO 2 )‏ Average rate of increase per year, 1.5 ppm = 3.25 x 10 9 tons/yr—little change (some variations) since 1975. 0 1 2 3 Airborne fraction, CO 2 (ppm)

33. Arrows indicate El Nino events Notice: atmospheric increase is ~50% of fossil fuel emissions significant interannual variability

34. GLOBAL PREINDUSTRIAL CARBON CYCLE 6 8 PgC/yr 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

35. Carbon Cycle on Land Photosynthesis: CO 2 + H 2 O + light => "H 2 CO" + O 2 Respiration: "H 2 CO" + O 2 => CO 2 + H 2 O + energy Very little organic matter is stored, on average. Carbon Cycle in the ocean Dissolution/evasion CO 2(g) + H 2 O + CO 3(aq) =  2 HCO 3 ¯

36. Global CO 2 cycle

37. 6.3 - 7.3Total 1-2Deforestation 5.3Fossil Fuel+ cement Global CO 2 budget (PgC yr -1 ) 1980 – 1990 1990 –2000 Sources 1-2"Missing Sink" 6.3 - 7.3Total 2.1Ocean uptake 3.2 Atmospheric accumulation Sinks 2.1 Pg C = 1 ppm atmospheric CO 2 [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

38. EVIDENCE FOR LAND UPTAKE OF CO 2 FROM TRENDS IN O 2, 1990-2000

39. Composition of Sea Water "alkalinity" defines Σ' Z i [i] : response of H + and OH - to addition of CO 2 Charge balance in the ocean: [HCO 3 - ] + 2[CO 3 2- ] = [Na + ] + [K + ] + 2[Mg 2+ ] + 2[Ca 2+ ] - [Cl - ] – 2[SO 4 2- ] – [Br - ] The alkalinity [Alk] ≈ [HCO 3 - ] + 2[CO 3 2- ] = 2.3x10 -3 M

40. Alkalinity [alk] =  i Z + [i + ] -  i Z - [i - ] = [HCO 3 - ] + 2 [CO 3 = ] [alk] is a re-arrangement of the charge balance equation. It cannot change when adding or removing an uncharged species like CO 2. [alk] = 2 x 10 -3 M -- only 1 in 1000 of total ions!

41. UPTAKE OF CO 2 BY THE OCEANS CO 2 (g) CO 2. H 2 O HCO 3 - + H + HCO 3 - CO 3 2- + H + K H = 3x10 -2 M atm -1 K 1 = 9x10 -7 M K 2 = 7x10 -10 M pK 1 Ocean pH = 8.2 pK 2 CO 2. H 2 O HCO 3 - CO 3 2- OCEAN ATMOSPHERE

42. LIMIT ON OCEAN UPTAKE OF CO 2 : CONSERVATION OF ALKALINITY Equilibrium calculation for [Alk] = 2.3x10 -3 M pCO 2, ppm 100 200 300 400 500 8.6 8.4 8.2 2 3 4 1.4 1.6 1.8 1.9 2.0 2.1 Ocean pH [CO 3 2- ], 10 -4 M [HCO 3 - ], 10 -3 M [CO 2. H 2 O]+[HCO 3 - ] +[CO 3 2- ], 10 -3 M Charge balance in the ocean: [HCO 3 - ] + 2[CO 3 2- ] = [Na + ] + [K + ] + 2[Mg 2+ ] + 2[Ca 2+ ] - [Cl - ] – 2[SO 4 2- ] – [Br - ] The alkalinity [Alk] ≈ [HCO 3 - ] + 2[CO 3 2- ] = 2.3x10 -3 M is the excess base relative to the CO 2 -H 2 O system It is conserved upon addition of CO 2  uptake of CO 2 is limited by the existing supply of CO 3 2- : Increasing Alk requires dissolution of sediments: …which takes place over a time scale of thousands of years CO 2 (g) + CO 3 2 + H 2 O 2HCO 3 - Ca 2+ + CO 3 2- CaCO 3

43. N CO 2 atm =P CO 2 N A = N atm N CO 2aq = P CO 2 K H V oc (1 + K 1 /[H + ] + K 1 K 2 / [H + ] 2 ) | | | [CO 2 aq ] [HCO 3 − ] [CO 3 = ] 1 : 140 : 16 CO 2  H 2 O  HCO 3 - + H + K 1 = [ HCO 3 - ][ H + ] / [ CO 2  H 2 O ] HCO 3 -  H + + CO 3 = K 2 = [ CO 3 = ][ H + ] / [HCO 3 - ] [ HCO 3 - ] = ( K 1 /[ H + ] ) [ CO 2  H 2 O ] ; [CO 3 = ] = ( K 2 K 1 /[ H + ] 2 ) [ CO 2  H 2 O ]

44. EQUILIBRIUM PARTITIONING OF CO 2 BETWEEN ATMOSPHERE AND GLOBAL OCEAN Equilibrium for present-day ocean:  only 3% of total inorganic carbon is currently in the atmosphere But CO 2 (g)  [H + ]  F  … positive feedback to increasing CO 2 Pose problem differently: how does a CO 2 addition dN partition between the atmosphere and ocean at equilibrium?  28% of added CO 2 remains in atmosphere!

45.  (buffer factor) Sundquist et al. 1979

46. FURTHER LIMITATION OF CO 2 UPTAKE: SLOW OCEAN TURNOVER (~ 200 years)‏ Inventories in 10 15 m 3 water Flows in 10 15 m 3 yr -1 Uptake by oceanic mixed layer only (V OC = 3.6x10 16 m 3 ) would give f = 0.94 (94% of added CO 2 remains in atmosphere)‏

47. compare to ~300  moles CO 3 = Observed uptake of fossil fuel CO 2 by the oceans

50. 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 CO 2. In 1970 ~75% of the emitted CO 2 stayed in the atmosphere, but only ~40% in 2000. 3800 6500 Global Fuel Use 7800 in 2005! 8200 in 2007!

51. 2007

53. 10 9 metric tons of C / yr 0.5 1. 1.5 (source: CDIAC –Trends –updated)‏ US fossil fuel use The US is the largest consumer of fossil fuels. Per capita use is very high, ~5 tons C per person per year. This rate has not changed much in 50 years.

54. US per capita fossil fuel use Metric tons C per person

55. 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 ?

56. China is projected to exceed US emissions in 2009.

57. NET UPTAKE OF CO 2 BY TERRESTRIAL BIOSPHERE (1.4 Pg C yr -1 in the 1990s; IPCC [2001]) is a small residual of large atm-bio exchange Gross primary production (GPP): GPP = CO 2 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 CO 2 observations show that the net uptake is at northern midlatitudes but cannot resolve American vs. Eurasian contributions CO 2 + H 2 O  "H 2 CO" + O 2 Photosynthesis and Respiration

58. CYCLING OF CARBON WITH TERRESTRIAL BIOSPHERE Inventories in PgC Flows in PgC yr -1 Relatively small reservoirs  Short time scales  net uptake from reforestation is transitory...unless resources are managed to preserve organic matter

61. Carbon-Climate Futures Vegetation matters! Different models project dramatically different futures using different ecosystem models. ~ 2º K in 2100 Coupled simulations of climate and the carbon cycle

62. PROJECTIONS OF FUTURE CO 2 CONCENTRATIONS [IPCC, 2001]

63. PROJECTED FUTURE TRENDS IN CO 2 UPTAKE BY OCEANS AND TERRESTRIAL BIOSPHERE IPCC [2001]

64. C4MIP: coupled climate- biosphere model comparison (used in IPCC 2007)

65. US and World Per Capita Fossil Fuel Use since 1950 Japan and Europe…

68. HIPPO completed the 1 st of 5 global surveys in January, 2009

70. Net Exchange (  mol CO 2 /m 2 /s)‏ -30 -20 -10 0 YR R, (-1)*GEE MgC/ha/yr 1992199620002004 10 12 14 16 18 R - GEE 1998 uptake emission A B C NEE MgC/ha/yr 1992199620002004 -5 -4 -3 -2 0 NEE Harvard 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

71. Harvard Forest, Petersham, MA. A "typical" New England forest…an artifact!

72. YR R, (-1)*GEE MgC/ha/yr 1992199620002004 10 12 14 16 18 R - GEE 1998 AGWB MgC/ha 199419961998200020022004 102 106 110 93-798990001020304 0.0 0.5 1.0 1.5 AGWI MgC/ha/yr Year GEE 1200-1500 1992199620002004 -28 -26 -24 -22 More Efficient 1998 uptake emission “LUE” 1200-1500 Live Biomass NEE MgC/ha/yr 1992199620002004 -5 -4 -3 -2 0 NEE Harvard Forest 1998 Long-term changes at Harvard Forest

73. NH % of land area in forests 20 40 60 80 100 Year 1700 1800 1900 2000 MA Fitzjarrald et al., 2001 A legacy: land use change in New England

74. 0 20 40 60 80 100 120 Aboveground woody biomass (MgCha -1 )‏ 93949596979899000102030405 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?

75. Non-CO 2 Greenhouse Gases CH 4 – dominated by fossil emissions over USA and much of Canada N 2 O – mostly agricultural emissions CO – a mix of combustion and hydrocarbon sources

76. Atmospheric Methane (CH 4 )‏

78. SOURCES OF ATMOSPHERIC METHANE ANIMALS 90 LANDFILLS 50 GAS 60 COAL 40 RICE 85 TERMITES 25 WETLANDS 180 BIOMASS BURNING 20 GLOBAL METHANE SOURCES (Tg CH 4 yr -1 )

79. Year 600 800 700 Scenarios A1B A1T A1F1 A2 B1 B2 IS92a 900 Variations of CH 4 Concentration (ppbv) Over the Past 1000 years [Etheridge et al., 1998] Year 20001000 800 IPCC [2001] Projections of Future CH 4 Emissions (Tg CH 4 ) to 2050 1200 1600 1400 1000 1500 2000 2020 2040 Atmospheric CH 4 : Past Trends, Future Predictions

81. COBRA-2003 § flight region and footprints § a CCE ( LBA !) project

82. LPDM Model: STILT Emissions: EDGAR-2000 Met fields: WRF (AER, 35 km, LPDM outputs, Grell-2)‏ WRF June 16, 2003 36.72N,96.94W 609 m AGL 1600 1700 1800 1900 2000 CH 4 0 50 100 150 200 250 300 Flask number

84. 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  slope =  0.1 EDGAR—2000 confirmed ±10% for CH 4 ! This result pertains to urban-industrial sources, which dominate the flight region

85. N 2 O Observed vs Model (EDGAR—2000 )‏ COBRA-2003 Observed N 2 O (ppbv)‏ Model STILT/ N 2 O (ppbv)‏ US sources of N 2 O are ~2.5x higher than EDGAR Kort et al., 2008

86. Carbon Monoxide

87. EPA Inventory  3! CO,  3!