Case studies from Germany and Scotland indicate climate change mitigation potential of riverine and coastal wetlands

Wetlands help to regulate the climate by sequestering and storing carbon from the atmosphere into their biomass and soils. Although wetlands can provide valuable ecosystem services such as carbon sequestration, there is a lack of quantifiable data for different types of wetlands. Teal-green carbon in floodplain forests and blue carbon in coastal and marine environments are the focus of this study. We use two contrasting wetland habitats and explore carbon sequestration and storage mechanisms, current evidence and data gaps, and their potential opportunities to contribute to climate change mitigation. Using a case study of hardwood floodplain forests in Germany, we find that age, structure and hydrological conditions are important factors in carbon sequestration while the evidence shows that sequestration is higher in young forests compared to old ones. Soil carbon stocks are found to be larger in the low elevated active floodplain compared to the higher elevated floodplain highlighting the importance of connectivity between the river and the floodplain. In a second case-study exploring carbon storage in Scottish saltmarshes, similar factors driving carbon storage are seen, including, position in the tidal frame, sediment supply, and sediment type. The policy landscape is used to highlight opportunities to increase the potential contribution of Scottish saltmarshes for climate change mitigation. Although data are limited and gaps exist for other greenhouse gas fluxes, overall, we argue that it is crucial to conserve all remaining riverine and coastal wetlands for their biodiversity and carbon storage function. Where possible and practical, these valuable ecosystems should be restored to increase their potential in this regard. Highlights Blue and teal-green carbon habitats can make an important contribution to carbon sequestration and storage. Blue and teal-green carbon habitats offer multiple ecosystem services in addition to carbon sequestration. Protection and restoration of blue and teal-green carbon habitats provide opportunities for improved climate change mitigation potential.