Keeping above the waves? The response of coastal freshwater peatlands to sea-level rise

Global mean sea-level rise (SLR) is accelerating and is projected to continue for centuries across all emissions scenarios. With high emissions, we cannot rule out a rise of 15 m by 2300. Understanding coastal response to SLR is a priority for policymakers and land managers, but limited attention has been focused on the impacts of SLR on coastal freshwater systems such as peatlands. Peatlands are significant ecosystem service providers: storing carbon, attenuating floods, improving water quality, and enhancing biodiversity. This thesis aims to improve our understanding of peatland responses to SLR. Adopting a past-present-future approach, this research combines techniques in palaeoecology, contemporary monitoring, and cutting-edge sea level projections. The methodology includes several analytical techniques: radiocarbon dating, 210Pb dating, loss on ignition, bulk density, testate amoebae, diatoms, foraminifera, peat macrofossil components, ecohydrological monitoring, sea level projections, and mapping. Two UK sites are investigated: Cors Fochno, a coastal raised bog in mid-Wales, and Wheatfen, an estuarine floodplain fen in Norfolk. Localised sea level projections for two storylines to the year 2300 are applied at these sites, as well as at Cors Crymlyn in south Wales, and South Solway Mosses in northern England. Multi-proxy records from Cors Fochno show a spatial pattern which is consistent through the Holocene, with marine influence confined to the bog margins while the central peatland maintained resilient freshwater conditions. Palaeoecological results indicate that through the late Holocene, Wheatfen has remained a predominantly freshwater system punctuated by episodic marine influence while contemporary monitoring reveals spatially variable, intermittent saline incursions driven by both marine and climatic processes, highlighting an increasingly constrained elevation buffer and growing vulnerability. Combining mapped peatland elevation and extent with sea-level rise scenarios provide first-order estimates of future vulnerability across Britain: projections for 2300 show that under a moderate emissions scenario, 3.8% of British peatlands may lie below relative sea level, increasing to 9.7% under a high emissions scenario. Under a high-end scenario, nearly half of England’s peatland area may be risk of 1-in-100-year storm surges by 2300. The results contribute to our understanding of how peatlands can respond to SLR, offering valuable insights for future peatland conservation and management.<p></p>

Author dc:creator

• Madeleine Timmins (21052667)

• Peatlands
• Sea-level rise
• Palaeoecology
• Testate amoebae
• Diatoms
• Foraminifera
• Radiocarbon
• 210Pb
• Coasts
• Wetlands
• Monitoring
• Projections
• GIS
• Multiproxy

Statement dc:rights

• All rights reserved
• Open Access after 2027-05-11

Identifier

10779/exe.32186118.v1

OAI identifier oai:identifier

oai:figshare.com:article/32186118