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Integrated air quality scenarios will support further emissions reductions under UNECE Air Convention

Integrated air quality scenarios will support further emissions reductions under UNECE Air Convention

Air pollution Madrid

To address the conclusions of the review of the amended Protocol to Abate Acidification, Eutrophication and Ground-Level Ozone (Gothenburg Protocol), as adopted by the Executive Body to the UNECE Convention on Long-range Transboundary Air Pollution in December 2022, further work is currently being undertaken, most notably by an ad-hoc group of experts to develop policy options.  

The review report, analysing the sufficiency and effectiveness of the amended Gothenburg Protocol finds that current commitments and legislation will not be sufficient to achieve the long-term objectives of the Protocol, which is to not exceed the target thresholds for ecosystems and health (critical loads and levels), which could cause long-term damage. The report therefore calls for further targeted emission reduction measures across sectors including in the agricultural sector (NH3 and the ground-level ozone precursor methane (CH4)), the energy sector (NOx), road transport (NOx, VOCs, black carbon (BC) and non-exhaust PM), (international) shipping (NOx), solvent use (VOCs), domestic wood burning (PM2.5, BC and VOCs), agricultural residue burning (PM2.5 and BC), gas flaring (BC and CH4) and landfills (CH4).  

Available scenarios show that even if the current legislation is fully implemented, more needs to be done to be able to achieve the long-term objectives of the Protocol. In particular, the rising concentrations of methane, which are not regulated under the Protocol, raise concern, as this pollutant increasingly contributes to the formation of ground-level ozone, with impacts on health, crops and ecosystems. 

While technical measures will remain part of the solution to reduce emissions, non-technical and structural measures, including behavioural change, synergies with other policy fields, as well as additional efforts outside the region (e.g. methane and in international shipping), will also be needed.   

Having been instrumental in developing scenarios in the Greenhouse Gas Air Pollution Interactions and Synergies (GAINS) model that have supported negotiations and the recent review of the Protocol, the Convention’s Task Force on Integrated Assessment Modelling (TFIAM) met last week for its 52nd meeting (Utrecht, the Netherlands, 24-26 May 2023) to discuss the status of the updated model. TFIAM brings together the best available science within the Convention on emissions, air quality, health and ecosystem impacts, and cost-effectiveness of abatement measures. Scenarios using the GAINS model show future developments in air quality up to 2050 with current policies and with additional policy measures.  

At its meeting, TFIAM agreed that the GAINS model is fit to be used in further policy work following the review of the Protocol. However, the quality of modelling results remains highly dependent on the quality of data reported by countries (e.g. on emissions, air quality polices adopted and implemented). Including the impacts of climate and energy measures on air quality and being able to zoom in from the continental to the city level, the model is highly comprehensive. The model can now clearly show that urban concentrations of air pollution are to a large extent influenced by sources outside the city, often even from sources in other countries. The model also clearly shows that measures are needed at all political levels (multi-level governance) to meet WHO air quality guideline values.  

Following discussions at the meeting and in follow-up to the review of the Protocol, TFIAM decided to develop and present a number of policy scenarios to the policy bodies of the Convention, including scenarios aimed at a 50% reduction of air quality-related health impacts; scenarios aimed at the protection (of e.g. 30%) of nitrogen-sensitive ecosystems; and scenarios that illustrate the impact of successive sectoral control policies. These scenarios are intended to further support the policymaking process under the Air Convention. 

TFIAM also discussed national integrated assessment studies. While there is overall consistency with the GAINS analyses, the inclusion of climate and energy measures in the current policy scenario differs among parties, with some climate and energy measures involving lower emissions of NOx and PM, while others, such as wood burning, leading to an increase in emissions. The impacts of emerging measures, such as carbon capture and storage, or hydrogen and the use of ammonia as an energy carrier, would require additional attention from the integrated assessment community. Further methodological discussions with national experts will be carried out to improve scenarios. 

At the meeting, France took over the co-lead of the task force following its guidance by co-chair Rob Maas (the Netherlands) since 1994. Simone Schucht (France) will co-chair TFIAM together with Stefan Åström (Sweden), who has co-chaired the task force since 2013.