1. Global trends in CH 4 and N 2 O Matt Rigby, Jin Huang, Ron Prinn, Paul Fraser, Peter Simmonds, Ray Langenfelds, Derek Cunnold, Paul Steele, Paul Krummel, Ray Weiss, Simon O’Doherty, Peter Salameh, Ray Wang, Chris Harth, Jens Mühle, Laurie Porter NACP meeting, October 2008

2. AGAGE network Advanced Global Atmospheric Gases Experiment High frequency (~40 min), high precision measurements > 40 ozone depleting species and non-CO2 GHGs: –CH4 / N2O / CFCs / HFCs / PFCs / SF6... SIO standards (except methane) Data available: –agage.eas.gatech.edu –cdiac.ornl.gov/ftp/ale_gage_Agage/ Matt Rigby, June 2008 Page 2 Cunnold et al., In situ measurements of atmospheric methane at GAGE/AGAGE sites during 1985-2000 and resulting source inferences, JGR, 107(D14) p4225, 2008

3. AGAGE network Matt Rigby, June 2008 Page 3 agage.eas.gatech.edu

4. Renewed CH 4 growth: AGAGE Matt Rigby, October 2008 Page 4 Rigby et al. Renewed Growth of Atmospheric Methane, GRL, in press, 2008

5. CSIRO flask network ~4 flasks per month analysed at CSIRO Independent (but inter-calibrated) network Matt Rigby, June 2008 Page 5 cdiac.ornl.gov

6. Renewed CH 4 growth: CSIRO Matt Rigby, October 2008 Page 6 Rigby et al. Renewed Growth of Atmospheric Methane, GRL, in press, 2008

7. Box model inversion A-priori emission estimates (Cunnold et al. 2002) AGAGE/CSIRO CH 4 observations Kalman filter Box model: mixing ratio sensitivity to monthly emission pulses Monthly emissions Assume 30% error Matt Rigby, October 2008 Page 7 Annual hemispheric running mean

8. CH 4 12-box model inversion ~ 40 Tg/yr increase from 2006 – 2007 (5-6%) ~ 22 Tg /yr NH (5%), ~18 Tg/yr SH (10%) Matt Rigby, October 2008 Page 8 Inter-annually repeating OH Rigby et al. Renewed Growth of Atmospheric Methane, GRL, in press, 2008

9. OH decrease? Methyl chloroform inversion: 4±14% OH drop in 2007 CH 4 increase: 20Tg/yr global, 13Tg/yr NH, 7Tg/yr SH Matt Rigby, October 2008 Page 9 Rigby et al. Renewed Growth of Atmospheric Methane, GRL, in press, 2008

10. Possible CH 4 sources Anomalous high temperatures over Siberia –Increased wetland emission? Permafrost melt?? Matt Rigby, October 2008 Page 10 No significant CO rise (AGAGE) Still looking for a SH source… www.ncdc.noaa.gov/oa/climate/research/2007/ann/global.html

11. Possible reasons for OH decline Increase in SH column Ozone? Matt Rigby, October 2008 Page 11 No significant CO rise

12. N 2 O trends: AGAGE Matt Rigby, October 2008 Page 12

13. N 2 O latitudinal gradient Matt Rigby, October 2008 Page 13 AGAGECSIROGMD/CCGGGMD/HATS * + Huang et al., Estimation of regional emissions of nitrous oxide from 1997 to 2005 using multinetwork measurements, a chemical transport model and an inverse method, JGR, v113 D17313, 2008

14. N 2 O flux: MATCH inversion Matt Rigby, October 2008 Page 14 MATCH: T62 resolution Kalman filter 125±24 year strat. lifetime 12 regions Global 1997 – 2001: 16.3 -1.2 +1.5 Tg/yr Global 2002 – 2005: 15.4 -1.3 +1.7 Tg/yr Huang et al., Estimation of regional emissions of nitrous oxide from 1997 to 2005 using multinetwork measurements, a chemical transport model and an inverse method, JGR, v113 D17313, 2008

15. Conclusions: CH 4 Global growth of methane for first time in a decade Similar growth rate at all AGAGE/CSIRO stations Inter-annually repeating OH: –~ 40TG/yr emissions increase –Substantial contribution from both hemispheres Inter-annually varying OH: –~20TG/yr emissions increase –Increase more biased to Northern hemisphere Matt Rigby, October 2008 Page 15

16. Conclusions: N 2 O Growth continuing at 0.5 – 1 ppbv MATCH inversion: –16.3 -1.2 +1.5 Tg/yr (1997 – 2001) –15.4 -1.3 +1.7 Tg/yr (2002 – 2005) –Lower emissions from high latitude SH than GEIA –Higher emissions from NH tropics Matt Rigby, October 2008 Page 16

17. Sensitivity to regional sources Inversion repeated, “fixing” combinations of hemispheres Matt Rigby, October 2008 Page 17