Measures to reduce land subsidence and greenhouse gas emissions in peatlands: A Dutch case study

Abstract

Worldwide, peatlands suffer from land subsidence and greenhouse gas emissions due to artificial drainage inducing peat decomposition. Under anthropogenic climate change, these issues require measures to reduce the emission of greenhouse gases and protect low-lying areas from increasing flood risk. Tighter control of groundwater levels is required, both within existing agricultural systems and through the development of new agricultural systems suitable for farming under high groundwater levels or inundation. The complexity and value-laden nature of the issue warrants the development of a comprehensive overview of potential and side effects of measures. In this paper such an overview is synthesized based on a mixed-method approach for a special case, The Netherlands. The Dutch peatlands comprise extensive land areas in the low-lying west and north of The Netherlands. The case is exceptional as most of these peatlands lie below sea level, sustain world-class intensive dairy farming and are subject to multiple other environmental, economic and societal challenges. Here, land subsidence increases flood risk, salt-water intrusion and the costs of water management, particularly under global climate change. To mitigate land subsidence, both technical measures and alternative land uses can be envisaged. However, the literature about these is fragmented, complicating a careful identification and selection of measures. To address this knowledge gap, we review 27 technical measures and alternative land use options and synthesize evidence and insights for 15 effects. Technical measures allowing continuation of existing dairy farming provide relatively low-risk interventions for farmers, but will only reduce, not stop land subsidence and greenhouse gas emissions. Alternative land-use options, particularly paludiculture, are in a start-up stage of development and can stop land subsidence. However, more research is required to reduce and control methane and potential nitrous oxide emissions during inundation required for crops such as (narrowleaf) cattail and azolla. Paludiculture can provide ecosystem services related to water management and nutrient status, as well as raw materials for a bio-based economy. Gradual transitions in space and time between farming and nature can be envisaged, providing incentives to diversify land use in the Dutch peatlands. This case study identifies key questions and provides valuable insights for peatland management worldwide. Reducing land subsidence and greenhouse gas emissions from peatlands is feasible, but requires thoughtful interventions that cautiously make and align trade-offs between various interests and uncertainties.