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