Deep seam and minesoil carbon sequestration potential of the South Wales Coalfield, UK

Combustion of coal for energy generation has been a significant contributor to increased concentrations of atmospheric carbon dioxide. It is of interest to evaluate the potential of former coalfields for mitigating these increases by carbon sequestration and to compare different options to achieving this end. Here, carbon sequestration in residual coal seams and through reclamation of spoil tips is compared, and their carbon dioxide storage potential in the South Wales Coalfield estimated. Coal seam sequestration estimates come from an established methodology and consider the total unmined coal resource below 500 m deep with potential for carbon sequestration. The most likely effective deep seam storage capacity is 104.9 Mt carbon dioxide, taking account of reservoir conditions and engineering factors. Whilst many spoil tips in South Wales have been reclaimed, the focus has not been on carbon sequestration potential. Estimates of minesoil restoration sequestration capacity were based on a survey of restored minesoil and vegetation carbon stocks, mainly on sites 20–30 years after restoration; data from this survey were then extrapolated to the coalfield as a whole. Minesoil storage is estimated at 1.5 or 2.5 Mt (+2.2 Mt in tree biomass) carbon dioxide based on average grassland or woodland measurements, respectively; modelled data predicted equilibrium values of 2.9 and 2.6 Mt carbon dioxide respectively in grassland or woodland minesoils. If all sites achieved close to the maximum capacity in their land use class, minesoil storage capacity would increase to 2.1 or 3.9 Mt carbon dioxide, respectively. Combining the best woodland minesoil and standing biomass values, sequestration capacity increases to 7.2 Mt carbon dioxide. The wider social, economic, environmental and regulatory constraints to achieving this sequestration for each approach are discussed. Coal seam sequestration has a much higher capacity but sequestration in mine sites is less costly and has fewer regulatory constraints. Findings indicate a significant combined potential for carbon sequestration in the South Wales Coalfield and highlight challenges in achieving this potential. On a global scale, ex-coalfield sequestration could contribute to broader efforts to mitigate emissions

Spatial co-localisation of extreme weather events: a clear and present danger

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordExtreme weather events have become a dominant feature of the narrative surrounding changes in global climate. with large impacts on ecosystem stability, functioning and resilience, however, understanding of their risk of co-occurrence at the regional scale is lacking. Based on the UK Met Office’s long-term temperature and rainfall records, we present the first evidence demonstrating significant increases in the magnitude, direction of change and spatial co-localization of extreme weather events since 1961. Combining this new understanding with land use datasets allowed us to assess the likely consequences on future agricultural production and conservation priority areas. All land uses are impacted by the increasing risk of at least one extreme event and conservation areas were identified as hotspots of risk for the cooccurrence of multiple event types. Our findings provide a basis to regionally guide land use optimisation, land management practices and regulatory actions preserving ecosystem services against multiple climate threats.Welsh GovernmentHigher Education Funding Council for Wale

Vegetation and edaphic factors influence rapid establishment of distinct fungal communities on former coal-spoil sites

We investigated re-establishment of fungal communities on eight former colliery sites in South Wales following revegetation 22–27 y earlier. Regraded bare coal-spoil was seeded to sheep-grazed grasslands, with saplings planted into coal-spoil for woodlands. Metabarcoding (28S rRNA, D1 region) of soil fungal populations showed that woodland and grassland habitats were clearly divergent but edaphic variables only weakly affected fungal community structure. Root-associated basidiomycetes dominated all habitats, with ectomycorrhizal fungi more abundant in woodlands and Clavariaceae/Hygrophoraceae (‘CHEG’ fungi) in grasslands. The composition of coal-spoil grassland communities resembled that of a typical upland grassland site, suggesting that propagule immigration was not a limiting factor. However, fungal biomass (ergosterol) was 3-fold lower, reflecting high bulk density and poor structure. Re-establishment of fungal communities in coal-spoil soils represents an important barometer of restoration success. From a fungal conservation perspective, such sites represent important refugia for waxcap fungi subject to habitat loss from agricultural intensificatio