News from the World of Emission Inventories

By the occasion of the Tenth joint meeting of the EMEP (European Monitoring and Evaluation Programme) Steering Body and TFEIP (Task Force on Emission Inventories and Projections), which will take place in Geneva from September 9th to 13th, 2024, three important documents (reports) for national expert reporting teams have been published.

News from the World of Emission Inventories
  1. Report: Reporting the impact of emission inventory adjustments on emission projections

This document describes TFEIP's proposal to revise the guidelines for reporting emission projections under the Convention on Long-range Transboundary Air Pollution (CLRTAP). These revisions were discussed at several working meetings in 2023 and are ready for adoption at upcoming meeting in 2024.

The proposal recommends including estimated future impacts of previously approved revisions in emission projections to enhance transparency and accuracy of future air pollution control measures. The document specifies that although emission projections are not used for compliance assessment, estimated future impacts of already approved revisions can be included for informational purposes along with regular projections based on the best scientific knowledge.

The main goal is to improve consistency between historical emissions trend and future emission projections, which will help countries in providing a more accurate picture of their estimated national emission totals. The proposed changes include minor adjustments to existing reporting guidelines and templates, allowing approved revisions to be optionally included in emission submissions.

  1. Report: The practicalities and processes required for including CH4 in emissions reporting under the Air Convention

This document, to be presented at the 10th Joint TFEIP and EMEP meeting in 2024, evaluates the possibilities of including methane emissions reporting within the framework of CLRTAP emissions inventory submissions. Some possibilities and facts of current methane emissions reporting were considered in this initiative:

Comparison of methane emissions reporting systems:

The UNFCCC requires detailed and comprehensive reporting of greenhouse gas emissions for Annex I countries by providing annual detailed data on CH4 emissions similar to those required by CLRTAP. In contrast, non-Annex I countries report less frequently and in less detail, with data typically submitted every four years with updates every two years. These data are less detailed and less frequent, posing a challenge, as they require the adjustment of reporting formats between the UNFCCC and CLRTAP.

Incorporation of UNFCCC data into CLRTAP:

Using methane emissions data from UNFCCC reporting could simplify reporting under CLRTAP and reduce additional requirements for countries. However, differences in geographical definitions of territory and reporting of emissions from aviation and shipping need to be considered. Integrating methane emissions from non-Annex I countries requires additional resources to collect and adapt data into CLRTAP formats. These circumstances may be improved by the fact that from January 1, 2025, non-Annex I countries are also required to report their greenhouse gas emissions, including methane, annually to the UNFCCC.

Use of data for modelling, recommendations, and next steps:

For air pollution modelling purposes, which focus primarily on ozone formation, less detailed methane emission data may suffice. However, if methane emission data are required for compliance purposes, it will be necessary to ensure more detailed reporting in accordance with the NFR format standards (for reporting under CLRTAP). Therefore, it is important to further explore the needs of air quality modellers to determine the required level of detail. A pilot study to test the integration of methane emissions data reported under the UNFCCC into CLRTAP data sets could also be beneficial, requiring additional funding.

Although the use of methane emissions data under the UNFCCC can meet air quality modelling needs with minimal additional reporting requirements, it is essential to carefully consider data consistency, geographic scope, and the need for more detailed reporting to meet legal and regulatory obligations.

  1. Report: Condensable PM emissions: Reviewing the progress made against user needs, and identifying improvement priorities

This document addresses the assessment of progress and future priorities in the reporting of condensable particulate matter (PM) emissions. The aim of the document is to evaluate what the current reporting lacks and suggest improvements.

The document notes that the 2020 report on the inclusion of condensable PM in emission inventories remains relevant, as no significant progress has been made in understanding them since then. This report proposes a plan to improve emission estimates, particularly for residential combustion, emphasizing the need for better data and methodologies.

Although some progress has been made in incorporating condensable PM into methodologies, particularly for small combustion devices, there is still a need to improve the accuracy and transparency of data. One of the main challenges is the lack of detailed and accurate activity data that would enable more precise emission estimates.

The document identifies several priority areas for improvement. High priorities include emissions from non-road diesel engines, which are a significant source of primary organic aerosol (POA) and condensable POA. A high priority are emissions from shipping, where greater transparency in reporting condensable PM, especially in coastal areas, is needed. Medium priorities include emissions from aviation and uncontrolled fires, for which more accurate methodologies are needed. Low priorities include natural gas combustion and other industrial processes that are less significant sources of condensable PM.

The document also emphasizes the need for better collaboration with the emission measurement community to improve methodologies and to understand the health impacts of condensable PM. Although this research is limited, better information would support the work and goals of the air quality agreement. In the context of developing the EMEP/EEA Guidelines, it is necessary to update and include more sources, improving accuracy and transparency, with an update planned for 2027.

In conclusion, the document states that to improve the transparency, accuracy, and inclusion of condensable PM in national emission inventories, further secure funding to support these improvements, is essential.