Remote sensing of peatland degradation – a review on gaps and hotspots of research across the northern hemisphere

While mapping peatlands worldwide remains an important task, capturing their status using earth observation technologies has received less attention. Approximately 500,000 km² of degraded peatland worldwide contribute an excessive 5% of global greenhouse gas emissions. Most human use of peatlands remains unsustainable and can disrupt the balance of peat, water, and vegetation that maintain a stable or even growing peatland. With growing threats like the climate crisis and a need for safe water supplies and other ecosystem services, the restoration of degraded areas becomes ever more eminent. Standardized degradation classifications and land cover mapping techniques that address the severe outcomes of degraded peatlands are important tools but lacking. The temperate and boreal zones of Northern America, Europe and Asia host a large proportion of the worlds’ peatland area. While temperate regions are often densely populated, causing high pressures on peatlands, the far north is facing increasing challenges such as permafrost melt, intensification of fire, mining, and wood harvesting. Based on a Web of Science literature search, this review identified and analyzed articles with a focus on peatland degradation research using remote sensing. 115 articles with study areas across the northern hemisphere were identified. Using a new approach to cluster this research based on a three-dimensional cube, each study’s degradation foci were evaluated along three directions of peatland degradation that build the three directions of the cube: peat, hydrology, and vegetation. Five clusters of different weights emerge from this concept, including two-dimensional and three-dimensional research. Vegetation-focused research dominates, while there are only few holistic approaches (12 of 115) that address peatland degradation along all three dimensions. Almost 80% of all research papers between 1981 and 2023 were published on eight hotspot regions across the northern hemisphere. While there is a general increase in article numbers over the last years, publications from other countries decrease. Restoring peatland ecosystem functions after degradation presents a significant challenge. With this review, we aim to highlight cold- and hotspots of research with regard to geography, research topics and used remote sensing tools to help improving peatland degradation research using remote sensing.