Quantifying methane emissions from North America Daniel Jacob with Alex Turner, Bram Maasakkers, Jianxiong Sheng, Melissa Sulprizio

The Paris Climate Conference (December 2015) Countries pledge to keep global warming to less than 2 o C above pre-industrial; aim for climate neutrality by Voluntary measures by individual countries to reduce greenhouse gas emissions; developed nations are “expected”, developing nations are “encouraged” $100B/year aid from developed to developing nations to promote decarbonisation, remediation of climate change impacts

Global rise in surface air temperature GISTEMP [2016]

Radiative equilibrium of the Earth Solar constant F s = 1,370 W m  m Surface T o Atmosphere T 1 IR absorptivity f (greenhouse effect) blackbody flux σT o 4 (1-f)σT o 4 fσT14fσT14 fσT14fσT  m Albedo A Radiative equilibrium: Increase greenhouse effect by  f:

Rising atmospheric CO 2 and methane The last 50 years (remote sites) CO 2 Methane CO 2 The last 1000 years (ice cores) Radiative forcing since 1750 is 1.7 W m -2 for CO 2, 1.0 W m -2 for methane

Global atmospheric methane budget Wetlands: 160 Fires: 20 Livestock: 110 Rice: 40 Oil/Gas: 70 Coal: 50 Waste: 60 Other: EDGAR inventory (Tg a -1 ): Emission rate = (Activity rate)  (Emission factor) CH 4 Atmospheric oxidation Lifetime 9 years Global distribution of emissions Emission 550  60 Tg/year

US methane emissions from EPA national inventory (2012) enteric fermentation (6.7) rice (0.4) onshore (0.9) offshore (0.6) Natural gas 6.2 production (2.0) processing (0.9) transmission (2.1) distribution (1.2) Oil 1.5 Coal mines 3.2 Agriculture 9.6 landfills (4.9) wastewater (0.6) Waste 5.5 Other 1.4 US EPA [2014]

Gridded EPA inventory of methane emissions (2012) Maasakkers et al., in prep.

EDGARv4.2 inventory

Using satellite observations of atmospheric methane to improve emission inventories EDGAR emission inventory atmospheric transport model simulated concentrations observed concentrations compare Bayesian optimization Improved emissions

Observing methane from space in the near infrared CH 4 H2OH2O CO 2 N2ON2O CO surface solar backscatter Retrieval of the backscattered spectrum  mean methane mixing ratio (mole fraction) in atmospheric column 1.65 µm 2.3 µm Atmospheric optical depths CH 4

Methane observed by GOSAT satellite instrument Turner et al. [2015]

Correction to EDGAR methane emissions using GOSAT data GOSAT observations, Optimization at coarse resolution Dynamic boundary conditions Optimization at fine resolution Turner et al. [2015] correction factors to EDGAR v4.2 + LPJ prior

Correction factors for North America CONUS anthropogenic emission of Tg a -1 vs. EPA value of 27 Tg a -1 Is the underestimate in livestock or oil/gas emissions or both? Turner et al. [2015]

Optimized top-down inventory CONUS anthropogenic emission of Tg a -1 vs. EPA value of 27 Tg a -1 Is the underestimate in livestock or oil/gas emissions or both? Turner et al. [2015]

16 EPA EDGARv4.2 Livestock Oil & Gas Waste Maasakkers et al., in prep. Attribution of emission correction to oil/gas or livestock requires reliable information on source patterns Eagle Ford Shale, Texas Source-resolved emissions in the South-Central US

2002-present NOAA data from Oklahoma show rise in US methane vs. background Turner et al., submitted Implies 3.6%/year rise in US methane emissions affecting Oklahoma… but EPA says that emissions have stayed flat during that time!

GOSAT shows rising methane emissions across midwestern US trend in difference between nadir (land) and glint (Pacific) methane columns; black dots indicate significant (>95%) trends on 4 o x4 o grid Implies rise of 7.0% /year in CONUS emissions – but cause is unclear Turner et al., submitted

Global implications of rise in US methane emissions Trend in global atmospheric methane E. Dlugokencky, NOAA Global methane trend since 2006 implies an emission increase of Tg/year [Kirschke et al., 2013] We find that US emissions during that period grew by 3-7% a -1 or Tg/year Rising US emissions could account for 30-60% of the global rise in methane Turner et al., submitted

Building a North American methane monitoring system CalNex INTEX-A SEAC 4 RS EPA national inventory 2016 satellite launches: TROPOMI global daily mapping with 7  7 km 2 pixels GHGSat targeted sampling with 50  50 m 2 pixels Integrate satellite data with surface, aircraft observations Improved understanding of emissions to serve climate policy

Working with IBM: application to oil/gas fields Oil/gas production field IBM surface monitors How can we best combine surface and satellite data to monitor emissions at device level. detect super-emitters? TO BE CONTINUED!