Space Monitoring of Wetlands for Climate Solutions – the Global Wetland Center initiative

Although covering a small fraction of Earth’s surface, wetlands play an important role in the global carbon cycle. They store about 35 percent of terrestrial carbon and have a high capacity for carbon sequestration and long-term retention. However, because the high water table in wetlands often creates anaerobic conditions, they can also emit greenhouse gases (GHG) such as methane and nitrous oxide. When drained, cleared or otherwise disturbed, large amounts of stored organic carbon can be released into the atmosphere as carbon dioxide.

Recent Earth Observation satellite systems such as Sentinels, SWOT or Planet provide new ways to map and capture wetland dynamics at high spatial and temporal resolutions. In combination with earlier missions (e.g., Landsat, PALSAR), they can provide essential information in support of modelling wetland hydrology and biochemistry. At the Global Wetland Center we leverage these multiple satellite systems and sensors to improve global accounting of GHG emissions for wetlands. Our vision is to extend wetland mapping based on categorizations relevant for GHG estimation with continuous priority variables and drivers that can inform about the spatial and temporal dynamics of GHG emissions. Furthermore, making use of differential programming, modern computer vision and knowledge-guided machine learning forced by EO and in-situ observation, we also work towards a better understanding of how management and disturbances (e.g., land conversion, fire, restoration) affect GHG dynamics.

Reducing the uncertainty of the global greenhouse gas budget of wetlands is an ambitious endeavour. The Global Wetland Center started contributing to this grand objective by leveraging methods for large-scale high-resolution mapping of wetland types and of flooded forest extent and inundation frequency. We used machine learning with Sentinel-1, Sentinel-2, and ancillary data to produce a 10-m wetland-type map across Europe, supporting wetland restoration. We also mapped seasonal dynamics of water beneath the forest canopy in the Amazon and Congo basins taking advantage of multi-year SAR data and virtual altimetry stations. Other activities at the GWC focus on using EO to calibrate catchment scale hydrological models in tropical wetlands where in situ data is scarce.

Together, these research activities aim to deliver new observation-driven insights into wetland processes that can directly support improved modelling of greenhouse gas emissions, reducing uncertainties in emission estimates and strengthening the scientific basis for wetland management and climate change mitigation.

 

More information: https://globalwetlandcenter.ku.dk

Acknowledgement: The Global Wetland Center is funded by the Novo Nordisk Foundation (grant NNF23OC0081089).