With the review of the amended Protocol to Abate Acidification, Eutrophication and Ground-Level Ozone (Gothenburg Protocol) under the UNECE Convention on Long-range Transboundary Air Pollution well underway, experts further discussed the sufficiency and effectiveness of current measures at the 60th session of the Working Group on Strategies and Review (11-14 April 2022).
The amended Protocol establishes legally binding emissions reduction commitments for 2020 and beyond for the major air pollutants: sulphur dioxide (SO2), nitrogen oxides (NOx), ammonia (NH3), volatile organic compounds (VOCs) and fine Particulate Matter (PM2.5). Entering into force in 2019 and with 26 Parties to date, the amended Protocol is already supporting action for clean air in a number of countries.
At the Working Group session, experts discussed the draft review report, along with reports on flexibilities and barriers to ratification, synergies with other policy areas, air pollution control scenarios, technical annexes and policy implications of reporting of the condensable part in particulate matter.
According to the draft review report, emissions of sulphur dioxide and nitrogen oxides declined significantly from the 1990s onward, based on concentrations in air measured at EMEP monitoring sites. Since 2000, there has been significant reductions in concentrations in PM10 and PM2.5 (46 per cent between 2000 and 2019 at EMEP long-term observational sites). However, there are still large exceedances of the WHO Air Quality Guidelines for PM10 and PM2.5 and of the critical loads of eutrophication in most parts of the region. Eutrophication describes the process of nitrogen loading of soils or waters, which often leads to a cascade of negative effects, such as algae blooms in waters.
While ground-level ozone peaks have declined systematically, annual mean background concentrations of ozone have increased over the 2000-2018 period. Meeting the emission reduction obligations for ammonia appears to be most challenging and will require additional measures.
There are still risks of eutrophication as a result of nitrogen deposition for more than 60% of Europe’s ecosystems. Therefore, greater nitrogen emission reductions are needed to allow ecosystems’ recovery and to prevent, among other issues, effects of nutrient imbalances on surface and groundwater quality, on biodiversity, on trees and on the resilience of forests to stress factors such as drought or insect infestation.
Methane proves to be the main driver behind increasing background ozone levels. Increases in global methane are expected to more than offset projected reductions of nitrogen oxides (NOx) and volatile organic compounds (VOCs) emissions – precursors of ground-level ozone – in Europe and at least partially offset reductions of NOx and VOC emissions in North America.
Experts discussed possible mitigation strategies for methane emissions in different regions. In Europe, measures in the waste sector have the largest potential. In Eastern Europe and Central Asia, measures in oil and gas sector, and in the US measures in gas production can deliver most of the abatement potential. Possible options to inform consideration of methane in a future instrument under the Convention were also presented.
The draft review report of the Gothenburg Protocol will be further developed, based on comments at the Working Group session and newly available information, together with other accompanying documents, and will be presented to the Executive Body at its 42nd session (12-16 December 2022).