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Ref: D. Fahey, adapted from IPCC 4th Assessment, Summary for Policymakers, Feb. 2, 2007

WHAT ARE THE MAJOR HUMAN & NATURAL ACTIVITIES FORCING CLIMATE CHANGE IN THE INDUSTRIAL ERA (1750-2005)?. Ref: D. Fahey, adapted from IPCC 4th Assessment, Summary for Policymakers, Feb. 2, 2007.

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Ref: D. Fahey, adapted from IPCC 4th Assessment, Summary for Policymakers, Feb. 2, 2007

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  1. WHAT ARE THE MAJOR HUMAN & NATURAL ACTIVITIES FORCING CLIMATE CHANGE IN THE INDUSTRIAL ERA (1750-2005)? Ref: D. Fahey, adapted from IPCC 4th Assessment, Summary for Policymakers, Feb. 2, 2007 1.6 W m-2 x 5.1 x 1014 m2 = 8.16 x 1014 W = 816 TW (about 52 times current global energy consumption)! RON PRINN, MIT-FEN LUNCHEON TALK, 10/14/08

  2. How well do we understand Greenhouse Gas (GHG) Cycles? Global Cycles of Greenhouse Gases are studied using Measurements & Global Circulation models AGAGE measures 45 gases 20-36 times per day at globally distributed stations dating back to 1978 28-level 1.8ox1.8o Model for Atmospheric Transport & Chemistry (MATCH) uses NCEP meteorology

  3. Hateruma (Japan) Mt. Cimone (Italy) AGAGE NETWORK STATIONS Jungfraujoch (Switzerland) Ny-Alesund (Norway)

  4. 1. AGAGE INSTRUMENTATION 1. Medusa GC-MS 2. GC-Multi-detector 3. Calibration 2. 3.

  5. MONTREAL PROTOCOL GASES & THEIR REPLACEMENTS

  6. Radiative Forcing from Carbon Dioxide and other Greenhouse gases CO2 CH4 N2O CFCs others

  7. TRENDS IN METHANE: WHY DO THEY VARY INTERANNUALLY AND WHY HAVE THEY DECELERATED IN RECENT YEARS? AGAGE NOAA QUASI-STEADY STATE: Emissions(CH4) ~ k[OH].Content(CH4) ? Ref: IPCC 4th Assessment, Summary for Policymakers, Feb. 2, 2007

  8. METHANE INVERSE STUDIES USING 3D MATCH MODEL (Chen & Prinn, 2005, 2006) • High-Frequency (13: AGAGE, NOAA, etc.) and Flask (41 comprehensive & 32 more intermittent: NOAA, CSIRO, etc.) monthly mean observations between 1996-2001 • Interannually varying transport (NOAA/NCEP) used in 3D MATCH model (T62, 1.8o x1.8o, 28 levels, 1000-2.9mb) to create the CH4 response of each site to monthly pulses from individual regional processes (sensitivity H(t) matrix) • Kalman Filter used to solve for: (a) 7 Seasonally-varying processes as monthly varying fluxes (b) 2 Pseudo-steady processes as constant fluxes using annually repeating time/space varying MATCH model OH tuned to AGAGE CH3CCl3 observations

  9. MATCH Simulates Effects of ENSO Transport on CH4 AGAGE observationsversusMATCH modelat Samoa El Nino winds MIRROR PLOT La Nina winds MIRROR PLOT Ref: Chen & Prinn, J.G.R., 2005

  10. SUMMARY: AVERAGE SEASONAL CYCLES (SELECTED AND ALL DATA SETS) Reference High Freq. All Best CAPTURES EXPECTED SEASONAL CYCLES (RICE PEAKS EARLIER) Ref: Chen & Prinn, J.G.R., 2006

  11. Summary: Interannual variability (Monthly Anomalies) 32-33 Tg yr-1 Total Emission increase in 1998 with 8-17 Tg yr-1 due to Rice regions Northern/Tropical Wetland and Rice Region Emissions dominate the total variability 1998 wetland Flux Anomalies *wetland model driven by 1998 record temperature and large precipitation anomalies (Dlugokencky et al. (2001)) BUT Boreal Fires in Siberia may have also contributed to our deduced strong Northern wetlands increase

  12. Summary: 5-year averages _ (literature) COMPARED TO PREVIOUS ESTIMATES: (1) ENERGY RELATED EMISSIONS SMALLER (RUSSIAN GAS LEAKS?) (2) RICE RELATED EMISSIONS LARGER (PROXIMAL WETLANDS OR TROPICAL ECOSYSTEMS?)

  13. METHANE IS RISING AGAIN, BUT WHY? (TRENDS AT AGAGE & CSIRO STATIONS) (Rigby et al, 2008)

  14. RESULTS FOR EMISSION ANOMALIES FROM INVERSIONS (Rigby et al, 2008)

  15. The hydroxyl free radical (OH) is the major oxidizing chemical in the global atmosphere It annually removes about 3.7 billion metric tons of trace gases (CO, CH4, higher hydrocarbons, hydro-halocarbons, NOx, SOx, etc.) from the atmosphere.. Are the levels of this dominant cleansing chemical changing? A decrease is dangerous! With a lifetime of only about 1 second it is possible to measure locally, but not possible to measure directly at regional to global scales. Use AGAGE measurements of the industrial chemical CH3CCl3, whose major sink is OH, to indirectly estimate large scale OH variations.

  16. Global weighted average OH inferred from AGAGE CH3CCl3 [OH] (10 5 radicals cm -3) The inferred OH minima generally coincide with strong El Nino’s and/or massive global wildfires (updated from Prinn, Huang, et al, G.R.L.,2005). The 2006-2007 drop is therefore unexpected. Ref: Update of Prinn, Huang et al, G.R.L., 2005

  17. 12.335(U) / 12.835(G)Experimental Atmospheric Chemistry (Fall 2008)Logistics:Lectures: Tuesdays (usually), 12:30-2:30pm, Room 54-1510Lab Periods: Thursdays (usually), 12:30-2:30pm, Room 54-18114 Field Trips: Sun: 9/7, Fri: 10/10, Sat: 11/1, Sat: 11/15Attendance at lectures, labs and especially field trips is mandatory.Instructors:Ronald G. Prinn, 54-1312,rprinn@mit.eduLaura Meredith, 54-1320,predawn@mit.eduKat Potter, 54-1414,kep@mit.eduGrading:10% - Participation20% - Topic 1 - CO2 & Climate20% - Topic 2 - CFCs & Ozone Layer20% - Topic 3 - Air Pollution & Health30% - Topic 4 - Tropospheric Photochemistry - [20% - Lab Report, 10% - Presentation]Each student will focus on a chosen aspect of tropospheric photochemistry for their topic 4 lab report and presentation. A list of possible subjects will be provided mid-semester and student selections are due on Nov. 17th.Credit:2-2-8 Undergraduate or Graduate CreditsStellar website:http://stellar.mit.edu/S/course/12/fa08/12.335/

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