1. SETTING THE STAGE FOR: BIOSPHERE, CHEMISTRY, CLIMATE INTERACTIONS

2. TOPICS FOR TODAY 1.Intro to atmospheric chemistry concepts 2.Atmosphere-biosphere connections 3.Climate change observed & predicted 4.How chemistry may amplify/dampen climate change 5.How climate change may change atmospheric composition

3. STRATOSPHERIC CHEMISTRY…BASIC MECHANISM Chapman Mechanism: Source of ozone (O 2 + hv) Sink of ozone (O+O 3 )  predicts too much ozone! Other ozone sinks: catalytic loss cycles: 1. HOx: from H 2 O 2. NOx: from N 2 O / lightning 3. ClOx: from CFCs H2OH2O slow fast OH HO 2 Antarctic ozone depletion involves special case of ClOx catalyzed O 3 -destruction where (cold) PSCs return Cl from reservoir to catalyst

4. TROPOSPHERIC CHEMISTRY O3O3 OHHO 2 h, H 2 O NO H2O2H2O2 CO, CH 4, RH NO 2 h HNO 3 OH, M VOC limited NOx limited CO, HC, NOx O3O3 O2O2 h Deposition STRATOSPHERE TROPOSPHERE 8-18 km

5. PARTICULATE MATTER (PM, AEROSOLS) SOURCES AND PROCESSES SO 2 H 2 SO 4 NH 3 VOCs NO x RCO… HNO 3 nucleation coagulation condensation carbonaceous combustion particles soil dust sea salt...... oxidation cycling ultra-fine (<0.01  m) fine (0.01-1  m) cloud (1-100  m) combustion biosphere volcanoes agriculture biosphere coarse (1-10  m) scavenging precursor gases

6. TOPICS FOR TODAY 1.Intro to atmospheric chemistry concepts 2.Atmosphere-biosphere connections 3.Climate change observed & predicted 4.How chemistry may amplify/dampen climate change 5.How climate change may change atmospheric composition

7. TERRESTRIAL BIOSPHERE / ATMOSPHERE INTERFACE Monson and Holland, 2001

8. OCEAN-ATMOSPHERE INTERFACE Monson and Holland, 2001

9. TOPICS FOR TODAY 1.Intro to atmospheric chemistry concepts 2.Atmosphere-biosphere connections 3.Climate change observed & predicted 4.How chemistry may amplify/dampen climate change 5.How climate change may change atmospheric composition

10. OBSERVED TEMPERATURE TREND 100-year trend (1906–2005): 0.74°C ± 0.18°C  rate of warming doubled in later half of century  Land warming faster than ocean IPCC, 2007

11. OBSERVED TREND IN WATER VAPOUR IPCC, 2007 ocean global UT Total column water vapour has increased over the global oceans by 1.2 ± 0.3% per decade (1988 to 2004)  UT water vapour also increasing, where of radiative importance

12. OBSERVED TREND IN PRECIPITATION IPCC, 2007 Long-term trends in precipitation amounts from 1900 to 2005 have been observed in many large regions: ↑ eastern North and South America, northern Europe and northern and central Asia ↓ Sahel, the Mediterranean, southern Africa and parts of southern Asia Also evidence for an increase of intense tropical cyclone activity in the N Atlantic since about 1970, correlated with increases in tropical SSTs.

13. OBSERVED CHANGES IN SNOW COVER, SEA ICE AND SEA LEVEL IPCC, 2007 1961 to 2003 global mean sea level rise: 1.8 ± 0.5 mm yr –1  thermal expansion contribution: 0.42 ± 0.12 mm yr –1  melting of glaciers, ice caps and ice sheets: 0.7 ± 0.5 mm yr –1

14. EXTREME WEATHER AND CLIMATE: TRENDS AND PREDICTIONS IPCC, 2007

15. PREDICTED TEMPERATURE TREND IPCC, 2007

16. PREDICTED PRECIPITATION TREND Increases in the amount of precipitation are very likely at high latitudes while decreases are likely in most subtropical land regions IPCC, 2007

17. UNCERTAINTY IN CLIMATE SENSITIVITY “equilibrium climate sensitivity is likely to be in the range 2°C to 4.5°C, with a best estimate value of about 3°C.” Climate Sensitivity: the warming to be expected if CO 2 concentrations were sustained at double PI (~ 550ppm) IPCC, 2007

18. TOPICS FOR TODAY 1.Intro to atmospheric chemistry concepts 2.Atmosphere-biosphere connections 3.Climate change observed & predicted 4.How chemistry may amplify/dampen climate change 5.How climate change may change atmospheric composition

19. DIRECT RADIATIVE FORCING AGENTS IPCC, 2007

20. AEROSOL “INDIRECT EFFECT” FROM CLOUD CHANGES Clouds form by condensation on pre-existing aerosol particles (“cloud condensation nuclei”) when RH>100% clean cloud (few particles): large cloud droplets low albedo efficient precipitation polluted cloud (many particles): small cloud droplets high albedo (1 st indirect) suppressed precipitation (2 nd indirect)

21. SCATTERING vs. ABSORBING AEROSOLS Scattering sulfate and organic aerosol over Massachusetts Partly absorbing dust aerosol downwind of Sahara Absorbing aerosols (black carbon, dust) warm the climate by absorbing solar radiation

22. AEROSOL RADIATIVE FORCING: UNCERTAINTIES IGAC, 2006 Forward calculations: models of aerosol physics and chemistry Inverse calculations: forcing to match model simulations with observed T changes

23. TOPICS FOR TODAY 1.Intro to atmospheric chemistry concepts 2.Atmosphere-biosphere connections 3.Climate change observed & predicted 4.How chemistry may amplify/dampen climate change 5.How climate change may change atmospheric composition

24. HOW WILL CLIMATE CHANGE AFFECT STRATOSPHERIC CHEMISTRY? Chapman Mechanism: Source of ozone (O 2 + hv) Sink of ozone (O+O 3 )  predicts too much ozone! Other ozone sinks: catalytic loss cycles: 1. HOx: from H 2 O 2. NOx: from N 2 O / lightning 3. ClOx: from CFCs H2OH2O slow fast OH HO 2 Antarctic ozone depletion involves special case of ClOx catalyzed O 3 -destruction where (cold) PSCs return Cl from reservoir to catalyst

25. Nitrogen oxide radicals; NO x = NO + NO 2 combustion, soils, lightning Methane wetlands, livestock, natural gas Nonmethane volatile organic compounds (NMVOCs) vegetation, combustion, industry CO (carbon monoxide) combustion, VOC oxidation O3O3 O2O2 h O3O3 OH HO 2 h, H 2 O Deposition NO H2O2H2O2 CO, VOC NO 2 h STRATOSPHERE TROPOSPHERE 8-18 km Tropospheric ozone precursors HOW WILL CLIMATE CHANGE AFFECT TROPOSPHERIC CHEMISTRY?

26. HOW WILL CLIMATE CHANGE AFFECT PM? SO 2 H 2 SO 4 NH 3 VOCs NO x RCO… HNO 3 nucleation coagulation condensation carbonaceous combustion particles soil dust sea salt...... oxidation cycling ultra-fine (<0.01  m) fine (0.01-1  m) cloud (1-100  m) combustion biosphere volcanoes agriculture biosphere coarse (1-10  m) scavenging precursor gases

27. EFFECTS OF CLIMATE CHANGE ON BIOSPHERE- ATMOSPHERE SYSTEM Zepp et al., 2003