Sandro Federici (Head of IPCC TFI TSU)

1. Estimating GHG emissions and removals
The IPCC Guidelines approach for NGHGIs under the UNFCCC
IPCC event on: Estimating GHG Emissions - Reconciling Different Approaches
IPCC TFI TSU - Sandro Federici
IPCC pavilion - UNFCCC COP27
Sharm el-Sheikh - November 2022

2. Outline
 The UNFCCC National Greenhouse Gas Inventories
 Identifying/Quantifying anthropogenic emissions & removals from land
 Rationale and assumptions to identify anthropogenic emissions and removals
 Natural vs Anthropogenic emissions and removals
 Drivers of emissions and removals
 The managed land proxy - MLP
 MLP’s GHG emissions and removals
 Tiered approach
 Actual GHG fluxes included in the NGHGI

3. The UNFCCC National Greenhouse Gas Inventories
Scope of the National GHG Inventories
UNFCCC text, Art 12, par 1(a)
“A national inventory of anthropogenic emissions by sources and removals by sinks of all greenhouse gases
not controlled by the Montreal Protocol….”
Methodological approaches for the National GHG Inventories
UNFCCC text, Art 12, para 1(a)
“….using comparable methodologies to be promoted and agreed upon by the Conference of the Parties”
UNFCCC Decision 18/CMA.1, para 20 (Annex)
“Each Party [to the Paris Agreement] shall use the 2006 IPCC Guidelines…”

4. Identifying/Quantifying anthropogenic emissions & removals from land
Rationale and assumptions (2002 IPCC Expert meeting on Factoring Out Direct Human-Induced Changes; 2003 IPCC GPG for
LULUCF, 2006 IPCC Guidelines; 2009 IPCC Expert Meeting on the MLP)
The distinction between anthropogenic and natural emissions is clear in most sectors apart from land; where
human activities act as a perturbation to the natural dynamic of ecosystems and its associated GHG
fluxes.
Estimating all carbon stock changes in land would capture management, all disturbances, indirect
anthropogenic effects and natural processes.
Although the effects of particular factors may be estimated, and the IPCC guidelines provides appropriate
details on how to estimate these stock changes e.g. wildfires, Interactions among drivers are generally so
complex that it is not possible through direct observation to apportion the total carbon stock change
uniquely to individual drivers (e.g. biomass increases or decreases driven by differing management
regimes, age distribution of forests, natural disturbances (and the impact of climate change on those), CO2
and N fertilisation etc.).

5. Identifying/Quantifying anthropogenic emissions & removals from land
Natural vs Anthropogenic
Natural and anthropogenic (direct and indirect human induced) drivers that concur in determining current
losses of C stocks similarly concur in determining subsequent gains of C stock, so that symmetry in the
attribution of current and future CO2 fluxes is required
Forest C stocks
C stock losses
Forest C stocks
Manged Forest where distribution
and composition of C stocks is
determined by growth and decay
processes as influenced by
management activities
C stock gain
Natural variables (humidity/temperature/biodiversity, etc),
associated interannual variability and disturbances (drought, wildfires, etc)
Indirect human-induced effects (CO2 & N fertilization, global warming)

6. Identifying/Quantifying anthropogenic emissions & removals from land
Direct-human induced drivers
 Land use change
 Harvest and other management
Indirect-human induced drivers
 Climate change induced change in temperature, precipitation, length of growing season
 Atmospheric CO2 fertilisation and N deposition, other impacts of air pollution
 Changes in natural disturbances regime
Natural drivers
 Temperature, precipitation, length of growing season and associated natural interannual variability
 Natural disturbances and associated natural interannual variability

7. Identifying/Quantifying anthropogenic emissions & removals from land
The managed land proxy - MLP
Therefore, the IPCC guidelines recommend using emissions and removals from managed land as a proxy
for anthropogenic emissions and removals.
Managed land is land where human interventions and practices have been applied to perform production,
ecological or social functions.
The key rationale is that the preponderance of anthropogenic effects occurs on managed lands.
By definition, all direct human-induced effects on GHG fluxes occur on managed lands only. While it is
recognized that no area of the Earth’s surface is entirely free of human influence, many indirect human
influences on GHG fluxes will be manifested predominately on managed lands*, where human activities are
concentrated. Finally, the natural ‘background’ of GHG fluxes tends to average out over time and space, while
local and short-term variability in emissions and removals due to natural causes can be substantial.
This leaves the GHG fluxes from managed lands as the dominant result of human activity
* faster C dynamic because of activities/disturbances

8. MLP’s GHG emissions and removals
Thus, applying the managed land proxy, inventory compilers under the UNFCCC shall report emissions and
removals from all sources/sinks on managed land for which IPCC Guidelines explicitly provide
methodological guidance. For instance:
IPCC methodological guidance covers:
 all C stock changes (and associated net CO2 emissions) from perennial C stocks in C pools,
 All man-made sources of GHG directly associated with agricultural activities (e.g. N2O emissions from fertilizers, CH4
and N2O emissions from livestock, GHG emissions from burning, CO2 emissions from liming and carbonate-fertilizers)
 Perturbation to natural GHG fluxes associated with human activities, where clearly identifiable, (e.g. additional
N2O emissions from SOM mineralization associated with SOC losses; GHG fluxes from drained and rewetted land)
IPCC methodological guidance do not cover:
- CO2 fluxes from non-perennial C stocks
- Geological CO2 emissions, as well as CO2 emissions from weathering of mineral C in soils
- Natural CH4 sink and Natural N2O source in mineral soils
- GHG emissions from Permafrost thawing
- All emissions from non-livestock animals

9. Tiered approach
IPCC methodological guidance is provided according to tier levels of complexity (from 1 to 3)
Although the methodological tier is not expected to impact the estimated total net C stock change across time, it
does however impact the annual net C stock change estimate, and the tier-sensitivity to the annual variability of
indirect human-induced drivers and of natural drivers differ.
For instance, in forest land remaining forest land:
- Applying Tier 1 in DOM and SOM C pools means assuming no net change in the long term average C stock,
so no emissions/removals are annually estimated (this approach can be extended to Belowground biomass)
- Applying collected growth data, e.g. derived from yield tables, at Tier 2 or 3, means to include in the estimated C
stock gain the effects of climate and of indirect human-induced drivers, as well as of variability of those as
occurred in the time period from which growth data are sourced; i.e. effects of current trends of those drivers
may not be included
- Applying an inventory-based Tier 3 means to report annual data, averaged across the time period of subsequent
measurements, that capture the effects of all drivers, with highest accuracy and precision for the total across the
time period, so with sensitivity for trends in natural and indirect human-induced drivers but with no sensitivity
for the interannual variability of those

10. Actual GHG fluxes included in the NGHGI
A diagram of anthropogenic emissions and removals included in UNFCCC NGHGIs can
 support comparison efforts with alternative estimates
 Guide the further evolution of models applied to design mitigation pathways applied to the IPCC work
 Clarify possible refinements of the MLP, e.g. the disaggregation of the natural disturbances components from
the emissions and removals estimated according to the MLP

11. Thank you
https://www.ipcc-nggip.iges.or.jp/index.html