BOG3 Report –List of data gaps and List of SLCF categories
Third IPCC Expert Meeting on Short-Lived Climate Forcers (SLCFs)
Virtual Meeting
11-15 April 2022

Discussion
BOG3 experts are expected to:1.

Refine the list of data gaps and, where needed, to refine the list of SLCF categories

2.

Prioritize the gaps for future research according to the significance of the sources,
for which methods gaps and/or data gaps are identified

3.

Review the list of allocation issues (cross-sectoral/cross-category), where a further
work or clarification is needed and to refine the list, if neededDiscussion
BOG considered the list of data gaps and discussed the following:-Tier methodology needs to be considered. Sometimes Tier 1 is not sufficient, morevariables for SLCFs than for GHGs
Uncertainty in SLCFs is high, more regional or technology specific EFs need to be
developed
In developing countries, the small industries contribute large amount of SLCFs. It needs
higher tiers and EFs to quantify emissions
Dust is a large source of uncertainty. Need to consider BC/OC content of the dust invarious sources
Gaps on VOCs and speciation from manure, size/magnitude of the source is uncertain due
to data paucity, same for VOCs from pesticides
Burning. Wildfires, burning of crops and manure – allocation issue, focus on anthropogenicemissions. Biological treatment of Waste – N in feedstock (NH3) or manure is a source ofdata gaps and allocation issue

Discussion
Discussion of priorities in the list of data gaps (1):Potentially Large Sources w/ Limited Data
• Small scale stationary combustion sources (e.g., small industries,cookstoves, etc.) are not well represented in existing SLCFmethodologies and there is a lack of information on AD and EFs.
• Transport off-road combustion: The emissions of SLCFs are highly
dependent on the type of equipment and technology and guidance on
the collection and/or estimation of AD is required as this may
constitute the main challenge in estimating these emissions.
New Sources• There is limited data SLCF emissions from existing non-traditional
fuels (e.g., quality, type, and moisture content of solid fuels may havea large effect on emission factors). There could also be more use of
non-traditional fuels in the future (e.g., biomass, waste, hydrogen) thatwarrant further research.

Discussion
Discussion of priorities in the list of data gaps (2):Missing data
• Availability of BC and OC EFs across all sectors and regions• Solvents AD (various sources of emissions, activity data is difficult tocollect)• Differentiation of technologies and EFs in all sectors
Allocation/uncertainties• Burning in AFOLU, waste in general – high uncertainties andchallenges in allocation to the correct source as a result of complex
and poorly documented transfers between waste, agriculture and usesof feedstocks for energy.
• Manure management – emissions factors are uncertain and datacollection is challenging VOCs and speciation from manure,size/magnitude of the source is uncertain due to data paucity(Also VOCs from pesticides)

Discussion
Discussion of the list of categories.
The list of categories is reviewed by experts and considered to reflect the current statusof SLCF sources and species, future authors will analyse literature for a particular
category and SLCF species in terms of evaluating methods and available EFs.
Other considerations:-Memo item – bunker fuels, not specifically in list of categories-Future transitions: electric vehicles, biofuels, hydrogen, waste-Shale gas and coal fires

Discussion
Discussion of the list of allocation issues (1):• Do we need a different allocation for SLCFs? How to measure andallocate SLCFs on a stack which may include process and energy
emissions? The type of measurement approach used to develop
emission factors should be considered in the allocation approach.
• Control technologies allocation which can include process and energy
emissions. If T1 factors are developed for industries that havecombustion (energy) and process (IPPU) emissions in terms ofproduct output, it will be important to understand allocation and double
counting issues, e.g., if all reported under IPPU the need to subtract
some emissions from energy.
• Can we use Decision tree type approach for allocation?
• Temporal variability needs to be considered• Ammonia production and Iron and Steel production are important
categories in terms of allocation issues

Discussion
Discussion of the list of allocation issues (2):•••••••

Recycling of waste to produce products – nature of emissions andallocation
Dust sources of emissions (which include BC/OC), accounting, mitigation
technologies
Pellet production
Energy balance may not capture all small sources of different
fuels/wastes/bio-sources. There are issues concerning the reconciliationof AD with the energy balance.
Informal combustion in Energy and Waste may be challenging to monitor
The allocation of the emissions in the production of biogas will bechallenging to monitor due to the lack of tracking of the movement andquanitities of feedstocks
Waste, Manure AFOLU, Energy sector - circular nature needs to beconsidered, good description needed to identify pathways for waste andagricultural products, international movement (cross border, e.g. Drax
importing woodchips from Canada/US). Avoiding of double counting.

Conclusions• There are differences between GHG Inventory and SLCF
Inventory, especially in terms of activity datacollection/availability and time dependency of SLCFemissions.
• Sources of SLCF emissions are inherently variable andconsideration of regional and in some cases climatic factors will
be important in developing representative emission factors andmethodologies.
• Higher tiers, or more granular development of Tier 1 emission
factors might therefore be needed to capture SLCF emissions
accurately for some sources across all regions of the globe• Capacities of small/developing countries need to be considered
where information and country specific data is maybe notavailable to accurately estimate SCLF emissions or developing
EI• Sharing of information is important on types of emissions
sources and on relevance of EFs that are developed.

Thank you!

BOG ReportBOG3