Reducing Greenhouse Gas Emissions from Lowland Peat Agriculture: A Rapid Evidence Synthesis

Abstract The estimated conversion of 25 million hectares of peatlands for agriculture worldwide (5% of total global peatlands) has resulted in their large-scale degradation and drainage and poses a risk to the climate by enhancing greenhouse gas (GHG) emissions. We conducted a rapid evidence synthesis of GHG emissions from lowland peatlands under agricultural and natural land uses at the global scale. A total of 513 records were identified, of which 51 met our criteria, from Southeast Asia (88%), Europe (6%), and the Americas (6%). Perennial crops were most frequently studied (43%), followed by drained/degraded peatlands (21%), intact peatlands (16%), annual crops (13%), and secondary forests (7%). The majority of studies reported higher GHG emissions from agricultural peatlands compared to intact or secondary peatlands. Moreover, land preparation itself was a significant driver of GHG emissions, highlighting that further conversion of peatlands for agriculture should be avoided. Rewetting was frequently reported as an effective emission reduction method, with intercropping, fertiliser avoidance, and planting on shallow (instead of deep) peats also cited. Key research gaps related to: (1) geography - peatlands in Africa, Eastern Europe, and Oceania were not represented; (2) methods - excluding GHG measurements from ditches and canals leads to underestimation of the full impacts of drainage for agricultural land use conversion; and (3) definitions - inconsistent naming conventions between regions and peatland types, and the uncommon use of the term ‘lowland’ likely led to the exclusion of many relevant studies. Ensuring that peatland definitions, GHG quantification methods, and research efforts across regions are consistent globally will help ensure that we can understand and protect these ecosystems in a changing climate.