methane in the climate system: monitoring emissions from...
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Methane in the climate system: monitoring emissions from space
Daniel J. JacobHarvard University
A 30-year partnership of my group with PKU
Yuhang WangBS, PKU (1990)PhD, HarvardProf., Georgia Tech
Hongyu LiuBS, PKU (1990)PhD, Harvard Scientist, NASA
Qinbin LiBS, PKU (1995)PhD, HarvardProf., UCLA
Tzung-May FuPhD, HarvardProf., PKU
Lin ZhangBS, PKU (2004)PhD,, HarvardProf., PKU
Jintai LinBS, PKU (2003)postdoc, Harvard Prof., PKU
Yaping XiaoBS, PKU (2002)PhD, HarvardSoftware engineer
Xu YueBS, PKU (2003)Postdoc, HarvardProf., NUIST
Qiaoqiao WangBS, PKU (2005)PhD, Harvard Prof., Jinan
Xiao LuPhD, PKU (2019)Postdoc, Harvard
Jiawei ZhuangBS, PKU (2016)PhD, Harvard
Haipeng LinBS, PKU (2019)soon PhD, Harvard
Pengfei LiuBS, PKU (2008)Postdoc, Harvard
Yuzhong ZhangBS, PKU (2010)Postdoc, Harvard
Methane: 2nd anthropogenic greenhouse gas after CO2
CO2 Methane
The last 1000 years (ice cores)
Solar
Terr
estr
ial
0.4-0.7 μm 5-20 μm
Fin Fout
increase greenhouse gasby ΔX
0.4-0.7 μm 5-20 μm
Fin Fout
Climate equilibrium: Fin = Fout
ΔX
Radiative forcing: ΔF = Fin - Fout
Radiative forcing of climate referenced to emissions, 1750-2011
• Methane is 60% as important as CO2 in explaining warming since pre-industrial time
• Climate policy treats methane emissions as 25 CO2 equivalents but in fact the two gases operate on very different time horizons
[IPCC, 2014]
Methane: 2nd anthropogenic greenhouse gas after CO2
Need to recognize duality of short-term (methane) and long-term (CO2) climate goals
Methane is a major greenhouse gas… but where does it come from?
Complexity of methane sources
Wetlands Livestock Oil/gas
Landfills, wastewaterSatellite observations hold the key!
Wetlands: 180
Fires: 15
Livestock: 120Rice: 26
Oil/Gas: 70
Coal: 38
Waste: 68Other: 42
CH4Lifetime 9.1±0.9 years
Emission550 ± 60 Tg a-1
CO2
Global emissions (Tg a-1): EDGAR4.3.2, WetCHARTSFires
Tropospheric OH
Methane fits and starts over past 40 years
MethaneCO2CO2
• Leveling off in the 1990s is not understood
• Renewed growth after 2007 is not understood either
Using atmospheric methane observations to test emission inventories
3-D chemical transport model
predicted concentrations observed atmospheric concentrationscompare
optimize emissions(posterior estimate)
Observing methane from space in the shortwave IR (SWIR)SWIR atmospheric optical depths
solarbackscatter
CH4 column mixing ratio
1.6 1.8 2.0 2.2 2.4 Wavelength [µm]
1.65 µm 2.3 µm
Low-elevation orbit
GOSAT (2010 - )GHGSat (2016 - )
TROPOMI (2017 - )
GOSATTROPOMI
GHGSat
GOSAT methane observations, 2010-2015
1.2 million observations
10 km pixels250 km apart
Use GOSAT methane data to optimize:• mean 2010-2015 methane emissions on 4ox5o grid • 2010-2015 emission trends on same grid• annual global OH concentrations
Maasakkers et al., in press
Global optimization of mean 2010-2015 emissions
Maasakkers et al., in press.
EDGARv4.3USEPAWetCHARTS
Livestock and oil/gas are the dominant anthropogenic sources
GOSAT attribution of global 2010-2015 emission trends
Tropical wetlands account for about half of the methane trend
Maasakkers et al., in press
Improved inversion, updated with GOSAT data to end of 2017
2010-2017 linear trend for non-wetland emissions Wetlands emission trend
prior
posterior
Country Trend (million head per year)
Pakistan 1.4Ethiopia 1.2Tanzania 1.1Brazil 0.9
Countries with largest growth in cattle populations
Wetlands and livestock each contribute half of 2010-2017 growth
Zhang et al., in prep.
New TROPOMI data are providing much higher coverage
May 2018 – January 2019 methane column data
http://www.tropomi.eu/data-products/methane
global daily coverage, 7x7 km2 pixel resolution
Annual mean TROPOMI data for China, 2018Methane columns, ppb
Lu Shen, Harvard
Dominant contributions from rice cultivation, coal mines
GHGSat space-based observation of methane point sources Effective pixel resolution of 50x50 m2 over selected 12x12 km2 scenes
First microsatellitelaunched in June 2016
methane plume
Point source(coal mine, oil/gas field, landfill, farm…)
Unique resource to quantify methane emissionsfrom individual facilities
estimated emission 8 tons h-1
2014
2014
2014: dam under construction
estimated emission 8 tons h-1
2016
2016
2016: dam completed, former vegetation flooded
Hydroelectric dams may be a large unrecognized methane source
Dam
dead organic material
oxicline
CH4
CO2
low CH4
O2
no O2
high CH4
CH4
turbine flow
Lom Pangar damview from top
view from bottom
Discovery of massive source from oil/gas production in western Turkmenistan
Feb 2018- Jan 2019 observations
Korpezhe gas compressor station
Compressor station: 10-42 tons h-1 (steady)Pipeline: 30 tons h-1 (once) Varon et al., submitted
buriedpipeline
buriedpipeline
13 Jan 2019