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Global methane budget : The 2006-2012 period

Global methane budget : The 2006-2012 period. Philippe Bousquet 1 , Robin Locatelli 1 , Shushi Peng 1 , and Marielle Saunois 1 1 LSCE-CEA-UVSQ-CNRS, IPSL France,. GEO CARBON. Atmospheric methane is … different than carbon dioxide. Outline. 2010 Budget

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Global methane budget : The 2006-2012 period

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  1. Global methane budget : The 2006-2012 period Philippe Bousquet1, Robin Locatelli1, Shushi Peng1, and Marielle Saunois1 1LSCE-CEA-UVSQ-CNRS, IPSL France, GEOCARBON

  2. Atmospheric methane is … different than carbon dioxide

  3. Outline • 2010 Budget • Inter-annual variability (IAV) of emissions 2006-2012 • Trends

  4. Inversions performed • Variational system (PYVAR-LMDZ-SACS) • 3 versions of the LMDZ model (different PBL schemes & different convection schemes) : LMDZ-TD, LMDZ-SP, LMDZ-NP • 3 set of observations : surface background (BG), surface extended (EXT), satellite (GOSAT) • Time period 2006-2012 (surface), 2009-2011 (GOSAT-LEIcester) Locatelli, PhD

  5. 2010 methane budget • Global emissions : 534 Tg/yr • Range = [528-540] • Chineseemissionsreducedcompared to the prior and to a former inversion (EDGAR42) : 68 Tg/yrcompared to 80 Tg/yr (-16%) EPA=44, EDGAR=80 • 1 inversion onlygives a total above the prior in China (LMDZ-NP withextended network) • S. Am. Trop flux consistentlylargerthan former inversion • Africa : stay close to the prior in bothpresent and former inv. Important influence of transport atregionalscale ! Blackline: former inversion Red line : prior flux Red Bar : global flux (right scale) Blue bar : regional flux (leftscale) Locatelli, PhD

  6. IAV of emissions : global & hemisphericscale • 2 large anomalies : • 2007-08 : Tropics + High Nlats • 2010-11 : Tropics + MidNlats • Largeremission changes in 2010-11 whenusing satellite data Locatelli, PhD

  7. IAV of emissions : Regional & country scales Locatelli, PhD • Robust and fast changes in Tropical South America end 2009 with positive trend • Lessrobust changes in South eastAsia & China (more transport dependant)

  8. IAV of emissions : Link with ENSO Locatelli, PhD

  9. IAV of emissions : Link with ENSO Locatelli, PhD

  10. IAV of emissions : comparaison with ORCHIDEE Tropical South America GLOBAL • 2 versions of ORCHIDEE : old version (blue), new version (red) • Goog agreement at global scale, • Phasingdifferences in South America Locatelli, PhD; S. Peng, pers. comm

  11. Trends of emissions : 2006-2012 • +1.4 Tg/yr2at global scale • +1.9 Tg/yr2from the tropics • +0.9 Tg/yr2from China • 1/3 of EDGAR trend • 2 times EPA trend • +0.6 Tg/yr2 in Trop. south Am. • Not consistent with ORCHIDEE wetl. model • -0.3 Tg/yr2fromNorthAmericatemperate • Negative trend in ORCHIDEE model but large IAV Locatelli, PhD; S. Peng pers. Comm.

  12. Paths to uncertaintyreduction in the methane cycle • Large uncertainties in natural wetland emissions • ---> Improved parametrisations, remote sensed flooded areas, WETCHIMP-II • Other natural emissions are also highly uncertain (geological, fresh waters) • ---> proxy tracers, field measurements • Emission partition in space and time with atmospheric inversions • ---> Use of isotopes, other proxy tracers (e.g. ethane), improved inventories • Regionalisation of methane fluxes using inversions has to be improved • ---> Satellite data, continuous measurements • Large uncertainties in the OH meanvalues (less on IAV after 2000) • ---> proxy methods& isotopes • Uncertainty on transport modellingis significant • ---> Refine models, Use/Compare models (TRANSCOM) • Global methane budget needs consolidation • ---> Produce regular updates through Global Carbon Project (GCP)

  13. Additionnalslides

  14. Atmospheric methane is important because … • After carbon dioxide (CO2), methane (CH4) is the second most important well-mixed greenhouse gas contributing to human-induced climate change. • In a time horizon of 100 years, CH4 has a Global Warming Potential >30 times larger than CO2. • It is responsible for 20% of the global warming produced by all well-mixed greenhouse gases. • The concentration of CH4 in the atmosphere is above 150% from the levels prior to the Industrial Era (cf. 1750). • The atmospheric life time of CH4 is approximate 10±2 years making it a good target for Climate change mitigation Kirschke et al. 2013, IPCC 2013 ; Voulgarakis et al., 2013 Updated to 2012 • Methane also contributes to ozone production in the troposphere, which is a pollutant with negative impacts on human health and ecosystems. • Increasing emissions of methane are transformed into water in the stratosphere by chemical reactions.

  15. 1-box model for CH4 and 13CH4 : Observations Observations DIFFERENCE (Tg/yr) (2009-2011)–(2004-2006) + 24 ppb -0.12 ‰ ~ +5.3 ppb/yr ~ -0.04‰/yr

  16. 1-box model for CH4 and 13CH4 : Setup • 1-box model, 2 equations for mass conservation of CH4 and 13CH4 • 3 emission types, one sink : • Anthropogenic, prior : 280 to 350 Tg/yr, -52.8 to -51.3‰ (IAV from EDGAR4.2), or flat with time. • Natural, prior : 180 Tg/yr, -60‰, No IAV • Biomass & biofuel Burning, prior : 35 Tg/yr, -20‰, No IAV • Sink, prior : 540 Tg/yr, IAV from atmospheric concentrations • Annual optimization for the period 2000-2012 • Larger relative prior errors on emissions than on isotopic signatures and total sink

  17. 1-box model for CH4 and 13CH4 : Observations Observations Optimized model Prior model DIFFERENCE (Tg/yr) (2009-2011)–(2004-2006) + 24 ppb -0.12 ‰ ~ +5.3 ppb/yr ~ -0.04‰/yr

  18. 1-box model for CH4 and 13CH4 : Fluxes DIFFERENCE (Tg/yr) (2009-2011)–(2004-2006) Anthrop Anthopogenicemissions (-52‰) Natural emissions (-60‰) Natural BiomassBurning (-20‰) BBG Chemicalsink (KIE -5‰) Chem. loss Prior = EDGAR

  19. 1-box model for CH4 and 13CH4 : Fluxes Anthrop Between 2000 and 2008 : Anthopogenicemissions (-52‰) Natural emissions (-60‰) EDGAR4.2 : Increase of coalemissions of +60% 1-Box model : Increase of coalemissions Of ~ 20 % Natural BiomassBurning (-20‰) BBG Chemicalsink (KIE -5‰) Chem. loss

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