Rewetting on agricultural peatlands can offer cost effective greenhouse gas reduction at the national level

Highlights • Three scenarios with increasing wet field use on cultivated peatlands in Finland. • The yearly emission reduction ranged from 0.3 to 5.0 Mt CO2 equivalents. • Scenarios had a negative impact on the farmers income, which should be compensated. • The median cost of emission reduction ranged from −4 to 45 € per ton of CO2 equivalents. • Rewetting and paludiculture were the most cost-effective to reduce GHG emissions. Abstract To reach EU’s carbon neutrality target by 2050, emission reductions in the land-use sector are needed. Agricultural peatlands attribute for half of the greenhouse gas emissions of cropland in both in EU and Finland. High greenhouse gas emissions from agricultural peatlands are primarily caused by CO2 emissions following aerobic peat decomposition due to deep drainage, and studies have shown that raising water-table has potential to slow down the decomposition process. Here we studied the emission reduction potential and cost of implementing controlled drainage, paludiculture, peatland restoration and afforestation to current land use on agricultural peatlands in Finland. We created three scenarios with increasing amount of wet field use on cultivated organic soils and estimated their effects on national greenhouse gas emissions and farmers’ income. The yearly emission reduction ranged from 0.3 to 5.0 Mt CO2 equivalents in the different scenarios compared to the current state in Finland. Emission reductive land use had a negative impact on the farmers income, which should be compensated. Assuming the government compensates the lost income for the farmers, the cost of emission reduction ranged from −4 to 45 € per ton of CO2 equivalents. Rewetting provided the most emission reduction per area and was the most cost effective. We conclude that substantial emission reduction is attainable by rewetting agricultural peatlands. The cost of emission reduction is inexpensive compared to average carbon price in European Union emission trading system, or to the costs of technical carbon capture and storage in Finland.