Comparison of inversions withinventories of CO2, CH4 and N2O fluxes

https://essd.copernicus.org/preprints/essd-2021-235/@ciais_philippe
Philippe.ciais@lsce.ipsl.fr

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Background

Introduction

Reconciliation

Bottom-up and top-down
CO2 emissions and sinks:
by bottom-up inventories : activity data + emission
factors, biomass C and soil C stock change

CO2 sinks : prior fossil emissions
from inventories, concentration
measurements and transport models

Reconciliation

Introduction

Background

Inversions
Information onerror
Coherence

GHG fluxes
a priori+ errors

Meteorology(Winds)Correctionof GHG fluxes
by inversion
Observations+ errors
StationsAircraft
Satellite…

Model gives
Concentration of CO2

Background

Inversions

Introduction

Reconciliation

Background

Introduction

Global Inversions used in this study
CO2 : 6 in-situ inversions up to 2019
Same prescribed fossil fuel emissions ; only the land flux is optimized
Period 1979-2019
Available but not used :[ 2009 - ] GOSAT satellite inversions[ 2015 - ] = OCO2 satellite inversions
CH4 : 17 inversions up to 2017
Separation of sectors in priors in most of them
2000-2017 = 9 in-situ inversions & 2 combined inversions
2009-2017 = 8 satellite inversions (GOSAT)
N2O : 2 inversions up to 2017
2000-2017 = 3 in situ inversions
Data from Global carbon project publications

Reconciliation

Background

Introduction

Reconciliation

Compilation and harmonisation of National Inventories
Submitting national inventories periodically to UNFCCC - commitment of the parties「All Parties, taking into account their common but differentiated responsibilities and their specific nationaland regional development priorities, objectives and circumstances, shall:(a)Develop, periodically update,publish and make available to the Conference of the Parties, in accordance with Article 12, national
inventories of anthropogenic emissions by sources and removals by sinks of all greenhouse gases notcontrolled by the Montreal Protocol, using comparable methodologies to be agreed upon by theConference of the Parties……」

Format: xlsx

Background

Introduction

Number of updates of National Inventories

Numbers of years covered by national inventories reports(NC+BUR) in each non-Annex I country

Reconciliation

Reconciliation

Introduction

Background

Submissionsof NC &National
inventories submittedto BUR
UNFCCC (Non Annex I) July 2021
National Communications (NC) & Biennial Update Report (BUR)
NC cycle

National Communications (Total: 396)
Total
Recent submissions

BUR cycle

Biennial Update Report (Total: 113)
Total
Recent submissions

Equatorial Guinea, 25 October 2019
NC1

NC2

NC3

NC4

154

143

85

11South Sudan, 19 August 2019

2

NC6

1

BUR163Cuba, 23 November 2020

Somalia, 19 January 2019

Honduras, 19 November 2020

Andorra, 11 March 2021

Panama, 27 March 2021

Timor-Leste, 17 November 2020

BUR232Morocco, 31 December 2019

Oman (Sultanate of), 23 December 2019

Costa Rica, 23 December 2019

Vanuatu, 22 March 2021

India, 20 February 2021

Malawi, 10 February 2021

BUR313Malaysia, 31 December 2020

Bhutan, 3 February 2021

Thailand, 25 December 2020

Brazil, 31 December 2020

Andorra, 11 March 2021

Ghana, 3 August 2020
Armenia, 17 May 2020

NC5Zambia, 7 December 2020

Mexico, 6 December 2012
Uruguay, 31 December 2019
Mexico, 28 November 2018

BUR45Namibia, 18 February 2021
Chile,18 January 2021

Background

Introduction

Reconciliation

Harmonization and consistency checks (Non Annex I)
Mongolia_BUR1.pdf, P132-139

Background

Introduction

Selected countries ( top 12 emitters )ReconciliationIntroduction

Background

Reconciliation

Coverage by in-situ networks & (for CH4) by GOSAT soundings

Red = countries studiedBackground

Introduction

Reconciliation

Grouping of sectors from National Inventories to match inversions

Introduction

Background

Reconciliation

Processing of inversions to make them comparable to inventories
CO2
Method 1

Method 2

CH4
Method 3

N2O

Rely on each inversions
solution of anthropogenic
sources and remove
wildfires
Remove from inversions
median of inversion natural
sources for wetlands and rivers
Remove from inversions
median of natural sourcesfrom bottom-up estimates
Remove from inversions
natural sources from bottomup estimates

Background

Introduction

Reconciliation

Removing CO2 fluxes that give no stock change and are not surveyed by inventories
Wood products trade
Crop products trade
Biofuels
Rvers

Background

Reconciliation

Introduction

Restricting gridded inversion fluxes to spatially explicit ‘intact land’ as a proxy of unmanaged
Removal of ( spatially explicit ) un-managed land using remote sensing data
Potapov et al. for intact forests Landscapes and Chang et al. for natural grasslands‘Intact forest’ vs ‘Unamanaged’

Note that Ogle et al. 2018 published spatially explicitmaps of unmanaged land for Canada, USA, Brazil

Introduction

Background

CO2 – LULUCF fluxes ( sink = negative values )TgCO2 y-1

sourcesink

Inventories

Range of CO2 inversions

Reconciliation

Reconciliation

Introduction

Background

CO2 – LULUCF fluxes : global sum
Global land CO2 sink
NGHGI
NGHGI UNFCCC data interface + gap filled
FAOSTAT
Inversions (managed land)
Inversion (unmanaged land)

GtC y-1

GtCO2 y-1

ref.

period

-0.3
-1.5
+0.3
-2.7
+0.2

-1.6
-5.4
+1.1
-9.9
+0.7

Grassi et al. 2021Grassi et al. 2022
Grassi et al. 2022
Deng et al. 2022

2000-2015
2000-2020
2007-2017

FAO – NGHGI difference :Due to a much greater forest sink for non-Annex I countries in the NGHGI database than FAOSTAT.
Inversions – NGHGI difference :Due to a smaller forest sink for Annex I and for some non-Annex-1 countries in the NGHGI database than inversions / indirectly
confirmed by the upward revision of the sink in non Annex 1 countries from Grassi et al. 2022
Even with the latest NGHGI data compilation, inversions find a 80% larger CO2 sink in managed land than inventories
Although unmanaged land area is globally a source, it is a sink in Canada (+40% more than managed land ) and Russia (+16%)

Background

Introduction

Reconciliation

Summary CO2 Emissions and sinks from Top fossil CO2 Emitters

UNFCCC LULUCF
UNFCCC Fossil + cement

Background

Introduction

Reconciliation

CH4 – total anthropogenic emission (in-situ and GOSAT inversions)

Background

Introduction

Reconciliation

Robustness of inversions anthropogenic CH4 emissions to the choice of aseparation method for natural sources

Background

Introduction

CH4 – Fossil emissions (in-situ & GOSAT inversions)

Reconciliation

Reconciliation

Introduction

Background

Inventories from countries in the Middle East (Gulf) and rest of theunderestimate fossil CH4 emissions

2010-2020 average for inversions and various BU inventories

UNFCCC estimatesdeserve a closer look

Globalinversions

Bottom-up
inventories

Fossil < 0.5 Tg yr-1

Background

Introduction

Reconciliation

Different versions of UNFCCC reported emissions havelarger variability than inversions uncertainty
Key changes from Russia CH4 oil and gas emissions

Superimposing the inversion data can tell if the changes goingtowards right direction(shaded region - Purple: SURFACE | Orange: GOSAT inversions).

Background

Introduction

Reconciliation

Different versions of UNFCCC reported emissions havelarger variability than inversions uncertainty
Key changes from USA CH4 oil and gas emissions

Superimposing the inversion data can tell if the changes goingtowards right direction(shaded region - Purple: SURFACE | Orange: GOSAT inversions).

Introduction

Background

Reconciliation

CH4 – Resolving discrepancies using ultra emitters TROPOMI inversion

Frequency distribution(assuming they are seen in the total emissions by global inversions but may be missed by inventories )Flow rate : ton per hour

Background

Introduction

Reconciliation

CH4 – Resolving discrepancies using ultra emitters TROPOMI inversion (> 20 tCH4 per h)(assuming they are seen in the total emissions by global inversions but may be missed by inventories )Ultra emitters as a fraction of national inventories
Lauvaux et al. in press%

Background

Introduction

Reconciliation

Summary of CH4 anthropogenic inversions ( last 5 years )Ultra emitters assumed not captured by UNFCCC inventories / basins emissions assumed as part of inversions fossil emissions

BackgroundIntroduction

Reconciliation

Summary N2O anthropogenic emissions ( last 5 years )• Note the overlooked importance of natural emissions (including fires in BRA and IDN) in tropical countries

Conclusions• Importance of sampling inversions over managed lands• Need to correct CO2 inversions for lateral fluxes• Most northern countries under-estimate LULUCF carbon sinks• UNFCCC fossil CH4 emissions lower than inversions for key O&G extraction countries• N2O emissions < inversions in EU, India, DRC, Australia• Perspectives• Regional higher resolution inversions• Lack of in-situ data in many countries• Assimilate satellite XCO2 concentration data

 Inversions using GOSAT and OCO-2 data Complete global CH4 inversions by ultra emitters and basins-scale regional inversions• Criteria to benchmark inversions ( cross-validation )• Weighed ensembles• Analysis of inversions sources of uncertainties

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Can we hope to beat the proble with data ?

CarboScopeRegional uncertainty reduction maps computed as 1- (σpost / σprior)for 2006 and 2018 using a Monte Carlo approach30

Thank you for your attention@ciais_philippe
Philippe.ciais@lsce.ipsl.fr

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Background

Introduction

Submissionsof NC &BUR (Annex I)
National
inventories submitted
to UNFCCC

Reconciliation

Common Reporting Format (CRF)「At its eighth session, the Conference of the Parties requested the secretariat to publish on its web site theannual inventory submissions consisting of the national inventory report (NIR) and common reporting
format (CRF) of all Parties included in Annex I to the Convention. The NIRs contain detailed descriptive andnumerical information and the CRF tables contain all greenhouse gas (GHG) emissions and removals,implied emission factors and activity data.……」Background

Introduction

Reconciliation

CH4 – Agricultural and waste emissions (in-situ & GOSAT inversions)

Background

Introduction

N2O – anthropogenic emissions

Reconciliation

Current policies lead to a 3°C warming

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Background

Introduction

Reconciliation

LULUCF CO2 sinks decreases with increasing land use ratio in temperate countries

Global stock take in 2023

Perugini et al. 2021••••

The GST shall include information about mitigation and adaptation processes, and the means of implementation and support,
based on the best available science and the equity concept.
The process should inform Parties whether the cumulated efforts of all the Parties is in track with the “well-below 2°C”
trajectory, thus providing indication on how to enhance and update their actions at national level and through cooperation.
The outputs of the GST should, thus, provide indication of opportunities and challenges for enhancing action and support.
The process needs to be transparent, in the light of equity and best available science and it is strictly Party driven, althoughexternal experts are invited to participate to support the process.

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