The United Kingdom’s Blue Carbon Inventory: assessment of marine carbon storage and sequestration potential in the Irish Sea and Welsh Coast Region (including within Marine Protected Areas)

This report was commissioned by WWF, The Wildlife Trusts and the RSPB to assess the extent, scale, distribution and potential of the current blue carbon sinks in the region of water known as the Irish Sea and Welsh Coast Region, which has coastlines in Wales, Northern Ireland and parts of the English coast ending at the Solway Firth. This report forms part of the UK’s Blue Carbon Inventory alongside regional reports that focus on the English North Sea (Burrows et al., 2021), the English Channel and Western Approaches Region (Burrows et al., 2024a) and Scotland(Burrows et al., 2024b). As in the other reports, the main objective was to assess the present extent and distribution of habitats, with emphasis on those that are identified as blue carbon habitats. Further aims were to evaluate the blue carbon potential of the Region by (1) estimating the quantity of carbon currently stored within blue carbon habitats, (2) establishing the average net sequestration rate (in g C m²/yr), (3) estimating the potential net total sequestration (in g C/yr) for each blue carbon habitat, (4) estimating the carbon stored and potential sequestration in Irish Sea and Welsh Coast Region marine protected areas (MPAs), and (5) further developing methods and approaches to this analysis that can be refined for future studies. The focus of this series of reports has been on stores and accumulations of organic carbon (OC) as particulate material rather than inorganic carbon (IC), given the likely net production of CO₂ through the production of IC as shell material. Carbon store densities and rates of production and storage have been combined with measures of habitat area to give estimates of total carbon stored in blue carbon ecosystems, their associated sediment stores, and the top 10 cm of sublittoral seabed sediment stores. The results are intended to inform management decisions and identify opportunities to protect blue carbon ecosystems, the habitats they provide and their carbon sequestration potential. Evidence of this nature will contribute to exploration of the potential of the UK’s marine protected area (MPA) network to help mitigate against the effects of climate change. The extents of blue carbon habitats for the Irish Sea and Welsh Coast Region were derived from available open sources, including the EUNIS level 3 combined map from the Joint Nature Conservation Committee (JNCC), Natural England Marine Habitats and Species Open Data, and recently published estimates of OC and IC long-term stores in surface sediments (Smeaton et al., 2021).