Committee
on EarthObservation
Satellites
Committee
on Earth
Observation
Satellites

Space-based Atmospheric CO2and CH4 Inventories to Support
the Global StocktakeDavid Crisp
Jet Propulsion Laboratory, California Institute of Technology
CEOS/CGMS WGClimate Greenhouse Gas Task Team
5 December 2019
Copyright 2019 California Institute of Technology.
Government sponsorship acknowledged.
UNFCCC/COP25 Japan Pavilion SeminarAtmospheric Inventories of CO2 and CH4• Ground-based, airborne, and space-based atmospheric CO2 and CH4
measurements are now being assimilated into atmospheric transport models toestimate emissions on scales spanning individual large power plants to nations• The objective is to develop top-down global inventories for these two gases that:o reduce uncertainties in national emission inventory reportso identify additional emission reduction opportunities
o provide nations with timely and quantified guidance on progress towards theiremission reduction targets and pledges (Nationally Determined Contributions,NDCs), ando track changes in the natural carbon cycle caused by human activities(deforestation, degradation of ecosystems, fire) and climate change.
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National Statistical Inventories Provide theBasis for the Stocktakes

CDIACODIACEDGARv4.3.2• National statistical and scientific inventories provide source-specific estimates
CO2 and CH4 emissions into the atmosphere for most, but not allanthropogenic sources.
• They provide less insight into the natural carbon cycle or its changes due toanthropogenic activities and climate change.
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A Role for Atmospheric CO2 and CH4 Inventories• Ground and space-based atmosphericmeasurements of CO2 and CH4 complement
Statistical Inventory methods by providing anintegral constraint on the net amount ofthese gases that are added to or removed
from the atmosphere by all processes.
• Ground-based measurements from theWMO Global Atmospheric Watch (GAW)
Network and its partners provide the mostaccurate available estimates of atmospheric
CO2 and CH4 concentrations and their trends
on global scales, but their spatial coverage
and resolution are limited.
UNFCCC/COP25 Japan Pavilion Seminar4Collecting GHG Measurements from Space:
the Evolving Fleet
Space agencies have supported several pioneering space-based
GHG sensors:•German-Dutch-Belgian SCIAMACHY on ESA’s ENVISAT•

Japan’s GOSAT TANSO-FTS, NASA’s OCO-2, China’s TanSat AGCS, FengYun-3D GAS and Gaofen-5 GMI, Copernicus Sentinel 5 Precursor TROPOMI.

Other sensors just added to the fleet:•Japan’s GOSAT-2 TANSO-FTS-2 and NASA’s ISS OCO-3

Others are under development:•CNES MicroCarb, CNES/DLR MERLIN, NASA’s GeoCarb, Japan’s GOSAT
Follow-on, and the Copernicus CO2M

These spacecraft demonstrate the measurement approach, but more
resolution, coverage, and resiliency are needed for an operationalsystem.
UNFCCC/COP25 Japan Pavilion Seminar

5Space-based CO2 and CH4 Measurements
Provide Increased Coverage and Resolution

GOSAT

380

390

400410420

OCO-2

Spatially-resolved estimates of the column-averaged CO2 and CH4 dry air mole
fractions, XCO2 and XCH4, like those from NASA’s Orbiting Carbon Observatory-2(OCO-2) and Japan’s Greenhouse gases Observing SATellite (GOSAT) are lessprecise and accurate than ground-based in situ data but provide high spatial andtemporal resolution and greater coverage of the globe.
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Space-based Measurements provide maps ofnatural and anthropogenic CO2 emissions
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Hakkarainen et al., 2019
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Gridded Atmospheric CO2 Inventories
Net Biospheric Exchange (NBE)

Uncertainty

J. Liu et al., CMS Flux Project, 2019

Flux Inversion models that assimilate space-based CO2 estimates as well as
ground based in situ measurements describe some aspects of the atmospheric
CO2 emissions and uptake better than conventional, bottom-up statisticalinventories – such as the total Net Biospheric Exchange (NBE). They also provide
UNFCCC/COP25Japan Pavilion
Seminarestimatesof uncertainty.

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A System Approach for Atmospheric Inventories

Measurements
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Models

Products9Implementing Space-Based AtmosphericInventories for Informing Stocktakes
1. Refine requirements and implementation plans for atmospheric flux inventories.
• Foster collaboration between the space-based and ground-based GHG measurement and modelingcommunities and the bottom-up inventory and policy communities.

2. Produce a prototype atmospheric CO2 and CH4 flux inventory that is available intime to inform the bottom-up inventories for the 2023 global Stocktake.
• Exploit capabilities of CEOS), Coordination Group on Meteorological Satellites (CGMS) and theWMO Integrated Global Greenhouse Gas Information System (IG3IS).

3. Use lessons learned from the prototype flux product to refine requirements for a
future, purpose-built, operational, atmospheric constellation that better addresses
the inventory process in time to support the 2028 global Stocktake.

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