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SETTING THE STAGE FOR: BIOSPHERE, CHEMISTRY, CLIMATE INTERACTIONS

SETTING THE STAGE FOR: BIOSPHERE, CHEMISTRY, CLIMATE INTERACTIONS. TOPICS FOR TODAY. Intro to atmospheric chemistry concepts Atmosphere-biosphere connections Climate change observed & predicted How chemistry may amplify/dampen climate change

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SETTING THE STAGE FOR: BIOSPHERE, CHEMISTRY, CLIMATE INTERACTIONS

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

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

  3. Chapman Mechanism: Source of ozone (O2 + hv) Sink of ozone (O+O3)  predicts too much ozone! STRATOSPHERIC CHEMISTRY…BASIC MECHANISM Other ozone sinks: catalytic loss cycles: 1. HOx: from H2O 2. NOx: from N2O / lightning 3. ClOx: from CFCs slow H2O OH HO2 fast slow Antarctic ozone depletion involves special case of ClOx catalyzed O3-destruction where (cold) PSCs return Cl from reservoir to catalyst

  4. O2 TROPOSPHERIC CHEMISTRY hn O3 STRATOSPHERE 8-18 km TROPOSPHERE OH, M VOC limited HNO3 hn NO2 NO O3 hn, H2O NOx limited OH HO2 H2O2 CO, CH4, RH Deposition CO, HC, NOx

  5. . . . . . . PARTICULATE MATTER (PM, AEROSOLS) SOURCES AND PROCESSES ultra-fine (<0.01 mm) fine (0.01-1 mm) cloud (1-100 mm) precursor gases oxidation nucleation cycling coagulation H2SO4 SO2 condensation RCO… VOCs coarse (1-10 mm) scavenging NOx HNO3 NH3 carbonaceous combustion particles combustion biosphere volcanoes agriculture biosphere soil dust sea salt

  6. TOPICS FOR TODAY • Intro to atmospheric chemistry concepts • Atmosphere-biosphere connections • Climate change observed & predicted • How chemistry may amplify/dampen climate change • 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 • Intro to atmospheric chemistry concepts • Atmosphere-biosphere connections • Climate change observed & predicted • How chemistry may amplify/dampen climate change • 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 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 ocean global UT IPCC, 2007

  12. OBSERVED TREND IN PRECIPITATION 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. IPCC, 2007

  13. OBSERVED CHANGES IN SNOW COVER, SEA ICE AND SEA LEVEL 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 IPCC, 2007

  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 Climate Sensitivity: the warming to be expected if CO2 concentrations were sustained at double PI (~ 550ppm) “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.” IPCC, 2007

  18. TOPICS FOR TODAY • Intro to atmospheric chemistry concepts • Atmosphere-biosphere connections • Climate change observed & predicted • How chemistry may amplify/dampen climate change • 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 (1st indirect) • suppressed precipitation (2nd 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 Forward calculations: models of aerosol physics and chemistry Inverse calculations: forcing to match model simulations with observed T changes IGAC, 2006

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

  24. Chapman Mechanism: Source of ozone (O2 + hv) Sink of ozone (O+O3)  predicts too much ozone! HOW WILL CLIMATE CHANGE AFFECT STRATOSPHERIC CHEMISTRY? Other ozone sinks: catalytic loss cycles: 1. HOx: from H2O 2. NOx: from N2O / lightning 3. ClOx: from CFCs slow H2O OH HO2 fast slow Antarctic ozone depletion involves special case of ClOx catalyzed O3-destruction where (cold) PSCs return Cl from reservoir to catalyst

  25. O2 hn HOW WILL CLIMATE CHANGE AFFECT TROPOSPHERIC CHEMISTRY? O3 STRATOSPHERE 8-18 km TROPOSPHERE hn NO2 NO O3 hn, H2O OH HO2 H2O2 Deposition CO, VOC Nitrogen oxide radicals; NOx = NO + NO2 combustion, soils, lightning Methane wetlands, livestock, natural gas Nonmethane volatile organic compounds (NMVOCs) vegetation, combustion, industry CO (carbon monoxide) combustion, VOC oxidation Tropospheric ozone precursors

  26. . . . . . . HOW WILL CLIMATE CHANGE AFFECT PM? ultra-fine (<0.01 mm) fine (0.01-1 mm) cloud (1-100 mm) precursor gases oxidation nucleation cycling coagulation H2SO4 SO2 condensation RCO… VOCs coarse (1-10 mm) scavenging NOx HNO3 NH3 carbonaceous combustion particles combustion biosphere volcanoes agriculture biosphere soil dust sea salt

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

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