Peatland restoration is a key climate mitigation strategy due to the high carbon storage capacity of peat soils. In the European Union (EU), more than half of peatlands have been drained - primarily for agriculture and forestry - resulting in significant greenhouse gas (GHG) emissions. Rewetting these areas can substantially reduce emissions and support the EU’s goal of net-zero CO? emissions by 2050. Essential for tracking progress toward mitigation targets is the precise accounting of GHG emissions from peatlands. While EU countries already report peatland emissions under the UNFCCC, comprehensive accounting for managed wetlands (including peatlands) will only become mandatory in 2026. However, comparability is limited: Peatland emissions are reported across diverse (land-use) categories, soil types, and GHGs, resulting in fragmented reporting with incomplete coverage by many countries. Additionally, countries employ diverse methods, datasets, and emission factors, leading to inconsistencies. This study analyses the methods EU countries use to report GHG emissions from peatlands, focusing on Germany and its neighbouring countries. Specifically, it addresses (1) the methodological differences between and within countries, identifying major inconsistencies, and (2) the extent to which these differences affect reported emissions and their comparability. Using a standardized evaluation framework, we quantify the impact of methodological differences on GHG inventories and visualize variations in CO?-equivalent emissions per hectare of peatland. We also apply these methodologies conceptually to peatland sites with varying characteristics to demonstrate how methodological choices shape reporting outcomes. The results provide a detailed quantification of the discrepancies in reporting for peatland emissions and their effects. This study thus contributes to advancing research to harmonize peatland GHG reporting across the EU and improve comparability.

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