Large-scale survey of aquatic greenhouse gas dynamics in rewetted and restored peatlands across the UK and Sweden.

Globally peatlands have a history of being drained for agriculture, forestry and grazing, leading to large emissions of carbon dioxide (CO2) to the atmosphere. In recent years there has been a positive shift towards peatland rewetting. However, there is concern that this might sometimes lead to large emissions of methane (CH4). Many rewetting studies focus only on terrestrial emissions and fail to account for aquatic emissions from bog pools and remnant ditches. This is particularly the case of rewetting projects in both the UK and Sweden, where these waterbodies are frequently unaccounted for and poorly understood. Here, we report the results of a synoptic survey of measured greenhouse gas (GHG) emissions from 42 rewetted peatlands over two consecutive summers (May-August 2024 and 2025); 22 UK sites and 20 Swedish sites. Sites were spread over a gradient from 50.7°N to 60.4°N, from temperate-oceanic to hemi-boreal climate zones and were under different land uses (conservation-managed, arable, grassland, forestry). At each site, we measured water chemistry, dissolved GHGs (CO2, CH4 and nitrous oxide (N2O)) and ebullitive CH4 emissions, which are frequently not measured. Our findings will help quantify the magnitudes and drivers of aquatic emissions following rewetting, with implications for management and improved GHG accounting. During this presentation we present the full analysis of results and discuss their implications for peatland rewetting and aquatic GHG emission accounting.