The impacts of climate change on coastal and intertidal habitats in the UK

In the United Kingdom, coastal, intertidal, and shallow nearshore ecosystems are under increasingly severe pressure from a multitude of climate change and human-induced drivers, including:
• Relative sea-level rise (RSLR)
• Changes in the frequency and intensity of storms
• Storm surge events
• Changes in the frequency, amount and seasonal distribution of precipitation
• Changes in wave action
• Warming seawater and air temperature
• Increased frequency and duration of heatwaves and marine heat waves (MHWs)
• Ocean acidification
• Coastal erosion
• Saline intrusion
• Coastal development and changes in land-use practises
• Coastal and marine pollution, nutrient enrichment.

Ecosystem processes and functions fundamental for healthy coastal, intertidal and shallow nearshore habitats are dependent on biotic and abiotic factors such as tides, waves, winds, flora, fauna, food web interactions and
sediment dynamics. These factors are susceptible to climatic change while being vulnerable to, and often negatively affected by, human activities. These pressures can lead to changes in ecosystem processes and functions as well as habitat extent and condition; they can significantly alter species distribution patterns. Important ecosystem services provided by coastal, intertidal and shallow nearshore habitats such as flood alleviation, carbon storage, water filtration, sediment stabilisation, and provision of food and nursery grounds to associated species, can also be fundamentally affected by the combined impacts of climate change and human pressures.

Coastal, intertidal and shallow nearshore ecosystems tend to be highly diverse and variable at local, regional and global scales and the impacts of anthropogenic activities and climate change are highly complex, cumulative and interlinked. Therefore, quantifying habitat-specific responses to changes in climate can be extremely challenging (Zimmerman, 2021).

Climate change impacts vary regionally across the UK coasts. Risks from extreme water levels are increasing across the UK, driven by rising sea levels, with the net rate of sea-level rise is slightly higher in the south of England and lower in some parts of Scotland (Haigh et al., 2022). Coastal erosion is expected to increase, in part due to sea-level rise, with low-lying and soft-sediment coasts in the east of England most vulnerable (Masselink et al., 2020), whereas the sediment supply and transport characteristics may continue to make some coastal habitats in the north more resilient to RSLR (Ladd et al., 2019).

Seasonal rainfall patterns across the UK are expected to change significantly, with increased winter rainfall particularly in the north-west, and reduced summer rainfall, albeit with the possibility of an increase in episodic summer storms1. Air temperatures are rising, particularly in the south, and warming sea temperatures are most pronounced in the North Sea. While Marine Heatwaves (MHW) have so far been short-lived in UK seas they are likely to intensify, and seabed ecosystems within southern North Sea and the English Channel have been predicted to become most impacted (Jacobs et al., 2024). Measurements of anthropogenic CO2 in the North Atlantic are higher than for any other ocean basin (Stoker et al., 2020).

This MCCIP evidence update provides a review of climate change impacts on coastal, intertidal, and shallow nearshore habitats from across the UK listed below, drawing out new local and regional examples and evidence that has emerged since the separate MCCIP evidence reviews on coastal2
and intertidal3 habitats were published in 2020. The habitats covered in this review include:
• Saltmarsh
• Sand dunes
• Machair
• Maritime cliff and slopes
• Rocky intertidal habitats
• Intertidal soft sediments
• Intertidal and subtidal seagrass beds (Zostera noltii and Zostera marina).

Intertidal and subtidal seagrass beds were not covered in any of the 2020 MCCIP reviews and as such, a more detailed section is included here. Vegetated shingle and coastal saline lagoon habitats have not been included in this review as no new evidence or studies on climate change impacts were
found for these habitats since the last MCCIP reviews in 2020. Shallow subtidal biogenic reefs are not covered in this review, as they will be addressed in the ‘Shallow, shelf and deep-sea habitats’ MCCIP review (Hill et al., 2026).