Climate change-induced sea level rise has exacerbated coastal change putting millions of people at risk from coastal hazards, such as flooding and coastal erosion. Nature-based solutions have been recognised as an opportunity to simultaneously address the coastal hazard risks and achieve biodiversity goals. While such solutions are included in climate adaptation strategies, “hard” engineered solutions are still often preferred by those implementing the schemes. We sought to explore the diverse perspectives on UK coastal flood risk management among interested and/or affected groups by utilising the Q-methodology. We identified five perspectives: (1) The Pro-Green Practitioners; (2) The Future-Planning Relocators; (3) The Case-by-Case Thinkers; (4) The Cautious Practitioners and (5) The Climate Change Concerned. All five perspectives strongly valued the co-benefits of nature-based solutions and their role in coastal risk reduction. None of the perspectives prioritised hard-engineered solutions as the primary flood protection strategy in the UK, though they recognised their role in protecting essential infrastructure. The main disagreements between perspectives were (1) on the need for relocation strategies, and (2) whether nature-based solutions could cause social inequalities. The Q-methodology does not identify how prevalent such perspectives are, thus further research is needed to assess the social acceptance of nature-based solutions.

Coastal morphological changes can be assessed using shoreline position observations from space. However, satellite-derived waterline (SDW) and shoreline (SDS; SDW corrected for hydrodynamic contributions and outliers) detection methods are subject to several sources of uncertainty and inaccuracy. We extracted high-spatiotemporal-resolution (~50 m-monthly) time series of mean high water shoreline position along the Columbia River Littoral Cell (CRLC), located on the US Pacific Northwest coast, from Landsat missions (1984–2021). We examined the accuracy of the SDS time series along the mesotidal, mildly sloping, high-energy wave climate and dissipative beaches of the CRLC by validating them against 20 years of quarterly in situ beach elevation profiles. We found that the accuracy of the SDS time series heavily depends on the capability to identify and remove outliers and correct the biases stemming from tides and wave runup. However, we show that only correcting the SDW data for outliers is sufficient to accurately measure shoreline change trends along the CRLC. Ultimately, the SDS change trends show strong agreement with in situ data, facilitating the spatiotemporal analysis of coastal change and highlighting an overall accretion signal along the CRLC during the past four decades.

Sea-level science has seen many recent developments in observations and modelling of the different contributions and the total mean sea-level change. In this overview, we discuss (1) the evolution of the Intergovernmental Panel on Climate Change (IPCC) projections, (2) how the projections compare to observations and (3) the outlook for further improving projections. We start by discussing how the model projections of 21st century sea-level change have changed from the IPCC AR5 report (2013) to SROCC (2019) and AR6 (2021), highlighting similarities and differences in the methodologies and comparing the global mean and regional projections. This shows that there is good agreement in the median values, but also highlights some differences. In addition, we discuss how the different reports included high-end projections. We then show how the AR5 projections (from 2007 onwards) compare against the observations and find that they are highly consistent with each other. Finally, we discuss how to further improve sea-level projections using high-resolution ocean modelling and recent vertical land motion estimates.

Ongoing sea-level rise has brought renewed focus on terrestrial sediment supply to the coast because of its strong influence on whether and how long beaches, marshes and other coastal landforms may persist into the future. Here, we summarise findings of sediment discharge from several coastal rivers, revealing that infrequent, large-magnitude events have disproportionate influence on the morphodynamics of coastal landforms and littoral cells. These event-dominated effects are most pronounced for small, steep mountainous rivers that supply beach and wetland sediment along the world’s active tectonic margins, although infrequent events are important drivers of sediment discharge for rivers worldwide. Additionally, extreme events (recurrence intervals of decades to centuries) that follow wildfires, earthquakes, volcanic eruptions, extreme precipitation or – most notably – combinations of these factors can redefine coastal sediment budgets and morphology. Some of these extreme events (e.g., wildfires plus rainfall) are increasing in magnitude and frequency under modern climate warming, with the likely result of increasing sediment flux to affected coastlines. Climate change is also altering watershed processes in both high latitudes and high altitudes, resulting in increased sediment supply to downstream catchments. We conclude that sediment inputs to coastal systems are highly variable with time, and that the variability and trends in sediment input are as important to characterise as long-term averages.

Small islands can guide visualization of the diverse information requirements of future context-relevant coastal governance. On small marine islands (<20 000 km2), negative effects of coastal challenges (e.g., related to population growth, unsustainable resource use or climate change) can develop rapidly, with high intensity and extreme impacts. The smallest and most remote islands within small-island states and small islands in larger states can be threatened by intrinsic governance factors, typically resulting in access to fewer resources than larger islands or administrative centres. For these reasons, efforts to support coastal change governance are critical and need to be targeted. We propose a conceptual framework that distinguishes key governance-related components of small-island social–ecological systems (SESs). To prioritize areas of vulnerability and opportunity, physical, ecological, social, economic and governance attributes are visualized to help show the ability of different types of small-island SESs to adapt, or be transformed, in the face of global and local change. Application of the framework to an Indonesian archipelago illustrates examples of local rule enforcement supporting local self-organized marine governance. Visualization of complex and interconnected social, environmental and economic changes in small-island SESs provides a better understanding of the vulnerabilities and opportunities related to context-specific governance.

It is widely accepted that between the beginning of the Early Neolithic period and the end of the Early Bronze Age different regions of Britain were connected to one another by sea, but little is known about the nature of maritime contacts before plank-built boats developed during the 2nd millennium bc. This paper considers a series of coastal sites, some of which were first settled from Mesolithic times. From the early 4th millennium they were also associated with artefact production and the use of imported objects and raw materials. Their distribution focuses on the region of isostatic uplift in northern Britain where the ancient shoreline still survives. It is considered in relation to a new model of coastal change which suggests that these locations were characterised by natural havens sheltered behind islands or bars. The sites can be compared with the ‘landing places’ and ‘beach markets’ discussed by historical archaeologists in recent years.

The Lapita expansion took Austronesian seafaring peoples with distinctive pottery eastward from the Bismarck Archipelago to western Polynesia during the late second millennium BC, marking the first stage in the settlement of Oceania. Here it is shown that a parallel process also carried Lapita pottery and people many hundreds of kilometres westward along the southern shore of Papua New Guinea. The key site is Hopo, now 4.5km inland owing to the progradation of coastal sand dunes, but originally on the sea edge. Pottery and radiocarbon dates indicate Lapita settlement in this location c. 600 BC, and suggest that the long-distance maritime networks linking the entire southern coast of Papua New Guinea in historical times may trace their origin to this period.

Coastal distributions such as that of the Neolithic chambered tombs of Brittany raise important questions about prehistoric beliefs and understandings relating to sea and shoreline. Concepts of liminality come particularly to the fore where headlands and islands are selected as places for the disposal of human remains. The density of chambered tombs recorded by Du Châtellier on the islands of the Molène archipelago, with its rocks, inlets and small islands exposed and covered by the tides, provides a prominent example of this coastal emphasis. The analysis presented here includes assessment of the reliability of the Du Châtellier inventory and of the topographic changes resulting from sea-level rise. It is argued that the dramatic transformative effect of the tides on the shallow waters of this archipelago will have enhanced the liminality of the setting and may have endowed the islands with special mythological or symbolic associations that may explain the density of the monuments. Ethnographic accounts of coastal beliefs from North America and northern Europe provide additional indications of the likely symbolic importance of such shoreline settings for Breton Neolithic communities.