I. Physical Principles: The foundation & the tools Newton's laws: forces, pressure, motion Energy: 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 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

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

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

Source: EARLY EARTH Oxygen for heavy-metal fans: Lyons TW, Reinhard CT NATURE Volume: 461 Issue: 7261 Pages: SEP

COMPARING THE ATMOSPHERES OF EARTH, VENUS, AND MARS 3x x x10 -3 H 2 O (atm, mol/mol) 1.3x x10 -5 O 2 (mol/mol) Surface pressure (atm) Mass (10 24 kg) 2.7x x10 -2 N 2 (mol/mol) 0.953x CO 2 (mol/mol) Radius (km) MarsEarthVenus H 2 O (total, bars) x 10 -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) x10 -6 (date: )‏Carbon Dioxide (CO 2 ) Argon (Ar) 0.04 to < 5x10 -3 ; 4x 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.

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 CO 2, CH 4 and other gases: A) mass balance B) Inputs or Production ("P"), controlled by biogeochemical processes C) Removal or Loss ("L"), at a rate proportional to the amount that is present in the atmosphere (1 st order or linear process, for example: dissolving CO 2 in the ocean, reacting CH 4 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 CO 2, CH 4 and other gases: A) mass balance B) Inputs or Production ("P"), controlled by biogeochemical processes C) Removal or Loss ("L"), at a rate proportional to the amount that is present in the atmosphere (1 st order or linear process, for example: dissolving CO 2 in the ocean, reacting CH 4 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)

Impulse Approach Steady State Accumulation Airborne Fraction Results from a "Toy Model" of human- caused CO 2 change

How is the composition of Earth's atmosphere controlled by geochemical and biological processes ?

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: 10,000 years P O2 ~120 Pg/yr L O2 ~ P O2

…however, abundance of organic carbon in biosphere/soil/ocean reservoirs is too small to control atmospheric O 2 levels 2.1 Pg C in CO 2 = 1 ppm in atm. P O2 ~ 120 Pg/yr

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

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 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?

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

Year History of consumption of fossil fuels. Emissions have increased by more than 2X since 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 Global Fuel Use 7800 in 2005! 8200 in 2007!

Carbon Cycle on Land, Organisms in ocean 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 small fraction of organic matter is stored, on average. Inorganic Carbon Cycle in the ocean Dissolution/evasion

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 (2.3 mmol/kg)

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 M -- only 1 in 1000 of total ions! ( 1 out of 600 Eq/L of negative ions)

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

LIMIT ON OCEAN UPTAKE OF CO 2 : CONSERVATION OF ALKALINITY Equilibrium calculation for [Alk] = 2.3x10 -3 M pCO 2, ppm Ocean pH [CO 3 2- ], M [HCO 3 - ], M [CO 2. H 2 O]+[HCO 3 - ] +[CO 3 2- ], 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 H 2 O 2HCO 3 - Ca 2+ + CO 3 2- CaCO 3

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!

FURTHER LIMITATION OF CO 2 UPTAKE: SLOW OCEAN TURNOVER (~ 200 years)‏ Inventories in m 3 water Flows in 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)‏

Global CO 2 cycle

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

Global CO 2 cycle

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

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

Total 1-2Deforestation 5.3Fossil Fuel+ cement Global CO 2 budget (PgC yr -1 ) 1980 – –2000 Sources 1-2"Missing Sink" Total 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)]

EVIDENCE FOR LAND UPTAKE OF CO 2 FROM TRENDS IN O 2,

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

Year History of consumption of fossil fuels. Emissions have increased by more than 2X since 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 Global Fuel Use 7800 in 2005! 8200 in 2007!

2007

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

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 CO 2 CONCENTRATIONS [IPCC, 2001]

PROJECTED FUTURE TRENDS IN CO 2 UPTAKE BY 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 1 st of 5 global surveys in January, 2009

Net Exchange (  mol CO 2 /m 2 /s)‏ YR R, (-1)*GEE MgC/ha/yr R - GEE 1998 uptake emission A B C NEE MgC/ha/yr 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

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

YR R, (-1)*GEE MgC/ha/yr R - GEE 1998 AGWB MgC/ha AGWI MgC/ha/yr Year GEE More Efficient 1998 uptake emission “LUE” Live Biomass NEE MgC/ha/yr NEE Harvard Forest 1998 Long-term changes at Harvard Forest

NH % of land area in forests Year MA Fitzjarrald et al., 2001 A legacy: land use change in New England

Aboveground woody biomass (MgCha -1 )‏ 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-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

Atmospheric Methane (CH 4 )‏

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 )

Year 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 IPCC [2001] Projections of Future CH 4 Emissions (Tg CH 4 ) to Atmospheric CH 4 : Past Trends, Future Predictions

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

LPDM Model: STILT Emissions: EDGAR-2000 Met fields: WRF (AER, 35 km, LPDM outputs, Grell-2)‏ WRF June 16, N,96.94W 609 m AGL CH 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  slope =  0.1 EDGAR—2000 confirmed ±10% for CH 4 ! This result pertains to urban-industrial sources, which dominate the flight region

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 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

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

(C 106 H 124 O 36 ) (NH 3 ) 16 (H 3 PO 4 ) O 2 => 106 CO HNO 3 + H 3 PO 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

Oceanic Nitrogen Processes

Org N NH 4 + NH 2 OHNO 2 - NO 3 - N2H4N2H4 N2N2 NO N2ON2O N2N ? ? 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. 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

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

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 /2O 2  NO 2  + H 2 O + 2 H + NO 3  + Org-C  N 2 + … N2ON2O

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

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 = kg x x28/29 = 1535 Tg ) IPCC [2001]

Inventories in Tg N Flows in Tg N yr -1 BOX MODEL OF THE N 2 O CYCLE N 2 O

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