Climatic and environmental changes in the 21st century are increasingly impacting the properties and dynamics of different types of physical environments globally, in particular mountains, lowland rivers and coasts. These changes may also then trigger downstream responses by the ecosystem and geosystem resources and services that are provided in these landscapes to human society. Predicting the outcomes of future changes in different physical environments has implications for the sustainable development, resource management and conservation of these environments and their properties. This is particularly the case along coastlines because these lie at the forefront of climate change impacts, at the interface of land and sea (Kron 2013). However, the precise impacts that climate change may have upon any coastline will depend on its physical properties and the nature of the climate forcings that affect it. For example, an increase in coastal storm frequency and associated wind speeds and storm wave height can lead to more extensive coastal flooding and more rapid coastal erosion (Johnson et al. 2015). However, a rocky coastline will respond to coastal storms in a very different way to a sandy one, even if the climate forcing is the same.

Such scenarios of coastal responses to future climate change are not merely hypothetical; they have implications for the effectiveness of coastal management and conservation policies to meet these future needs (Colenbrander 2019). Ensuring that government-led strategic environmental management is fit for purpose is a key challenge. In South Africa, as in many other countries, the existing legislative, policy and administrative frameworks for coastal environmental management were established several decades ago and under different environmental as well as societal and governance structures and values that may be inappropriate for present and future needs (e.g. eds. Fuggle & Rabie 1992; Goble et al. 2014). This means that the purpose of environmental management and its ultimate goals, especially in managing sensitive and rapidly changing environments such as coasts, need to be reassessed in the light of anticipated future environmental management issues and priorities.

The aim of this study is to identify the key environmental issues that coastal management in South Africa needs to focus on in the coming decades under the increasing influence of anthropogenic climate change. This aim is achieved through a horizon-scanning approach that is commonly used in the field of foresight studies, in which future risks can be identified and projected. Horizon scanning can, therefore, inform the development of future policies relevant to environmental decision-making (Bengston, Kubik & Bishop 2012; Vecchiato 2012).

In detail, this article outlines (1) the methodological approach taken to identify the major issues of relevance in this study, (2) the application of coastal biophysical systems to understand the interconnections that exist between these issues and (3) how these lead to the identification of coastal management challenges. Finally, the article identifies some key strategies by which these issues can be addressed. This analysis can inform government, industry, local communities and coastal managers on the most appropriate ways to future-proof the coast and protect its natural resources, assets and services.

This study takes a horizon-scanning approach in which emerging issues affecting the coastal zone in South Africa over the next decades are identified. This is achieved by examining the relevant peer-reviewed literature and other contextual information, such as from the Intergovernmental Panel on Climate Change (IPCC). Once the major coastal challenges have been identified through this process, their impacts on coastal properties and dynamics are then identified. The final step is to consider the implications of any changes in coastal properties and dynamics for future management and conservation; it does not consider the adequacy of existing coastal management strategies to address these issues. This is ultimately an important step because appropriate and timely government and management action can decrease coastal risk and hazard impacts, whereas inappropriate or delayed (or no) action will not achieve this and may actually increase societal and environmental risks. The research approach adopted here is therefore founded on coastal science rather than following previous horizon-scanning studies that use an iterative but subjective Delphi process of expert opinions (e.g. Rudd 2015) or that use a public participatory approach to guide policy (Glavovic 2006). The approach adopted in this study has been previously applied to coastal environments in the Arctic (Gormley et al. 2023) and New Zealand (Macinnis-Ng et al. 2024) and with respect to water systems management (Dunn et al. 2015) and ecological conservation (Kark et al. 2016).

Coastlines can be considered as sedimentary systems through the ways in which sediment moves within coastal or littoral cells by waves, tides and wind (Johnson et al. 2015). The outcomes of sediment movement are spatial and temporal patterns of net erosion and deposition and the distinctive morphometric patterns of coastal landforms that reflect these sediment mass budget changes (Cooper, Hooke & Bray 2001). Although this has been, historically, the fundamental basis on which coastal scientists have considered the sediment dynamics of coasts (Rosati 2005), a better viewpoint of coasts is as integrated biophysical systems, in which there is feedback between coastal geomorphic, sedimentary, biological and chemical properties and processes that interact with each other to influence the development of coastal environments (Knight 2024a). Examples of these interactions include:

This viewpoint of coastal biophysical systems is advantageous because it describes the co-relationships between different coastal properties that, when taken together, better describe coastal morphodynamics and their controls. In addition to these scientific advantages, this understanding can also lead to more effective coastal management; for example, one cannot best conserve coastal biodiversity without understanding how plants and animals are linked to coastal soils, rocks, waves and tides. A biophysical systems approach is also useful in the context of global climate change because it can help describe how different coastal properties respond to climate forcing, e.g. their geomorphological sensitivity (Knight 2024b).

Based on themes that are most commonly identified in the global literature, including the IPCC (Wong et al. 2014), and with specific reference to South Africa, some key challenges for coastal systems, and therefore for management of those systems, can be identified using the horizon-scanning approach adopted in this study (Table 1). Each of these challenges takes place in a specific environmental and societal context; thus, the same ‘challenge’ may be manifested differently in different places.

As indicated in Table 1, these challenges do not take place in isolation but are rather connected to each other, both conceptually and in reality, through a systems framework (Figure 1a). The key drivers of geomorphic change and sensitivity in coastal environments in South Africa are storms and sea-level rise, because these are the main forcing factors that then initiate secondary (downstream) responses in these environments (Rosati 2005). However, the impacts of these drivers will depend on the type and characteristics of the coastline under consideration: sandy and rocky coasts have different sensitivities and will respond in different ways to climate forcing and will give rise to different societal and environmental risks (Knight 2024a). In addition, the relationships shown in Figure 1a are not exhaustive and other factors such as population change and socioeconomic priorities may also change how coastal systems work or are perceived and managed.

A heat index of environmental risks (Figure 1b) can be used to indicate the most significant drivers of coastal change in South Africa, as expressed by the degree to which these drivers pose risks to the workings and dynamics of coastal systems. This qualitative analysis is based on the driving factors and morphodynamic behaviours of different coastlines, as described in the literature, and through an understanding of the biophysical systems context in which specific coastlines operate. For example, sandy beaches in KwaZulu-Natal Province are highly sensitive to coastal storms (Corbella & Stretch 2012); thus, they are at high risk with respect to increased storm frequency (Figure 1b). However, different beaches recover from storm erosion over different timescales, and this is strongly influenced by management practices and the degree of urbanisation at that beach (Corbella & Stretch 2012). Apart from the major physical and climatic forcing factors, human factors such as tourism are also significant. This is because tourism (overpopulation) goes alongside coastal engineering and urbanisation as tourist infrastructure is developed, but, while the latter two are strongly framed today in the context of sustainability (Malan & Swart 1997), tourist presence can lead to significant unanticipated environmental and ecological impacts even in locations away from hotels, car parks, restaurants and other tourist facilities (Goliath, Mxunyelwa & Timla 2018). This highlights the importance yet also the uncertainty of direct and indirect human activities on coastal risk. In addition, some of these major coastal challenges operate on a global scale, are effectively irreversible and cannot be easily mitigated (e.g. sea-level rise), whereas others are because of human agency alone and therefore can be better managed or mitigated by appropriate policies (e.g. sand mining).

Coastal landscape management and conservation is based on identifying and then protecting specific geographical areas that are demarcated with rigid and fixed boundaries. This approach, while bureaucratically easier and the conventional approach taken for spatial management, commonly fails to adequately mitigate against conservation and environmental threats because this approach does not view or manage landscapes as biophysical systems (Knight & Grab 2024). Treating landscapes as integrated biophysical systems can help understand how they may respond to these ongoing changes. This is because this approach can consider how the biological (ecological and biogeochemical) as well as physical (geomorphic and hydrologic) elements of landscapes interact with each other and may experience change through feedback processes. Thus, understanding landscapes as systems can yield a better understanding of their net responses to forcing, such as from anthropogenic climate change in the 21st century. Some previous studies have identified problems with existing coastal policy and legislation to manage these changes (e.g. Colenbrander 2019; Dube, Nhamo & Chikodzi 2022; Goble et al. 2014; Palmer et al. 2011).

Some recommendations on how to future-proof coastal management and conservation under climate change in South Africa can be identified:

Studies are already identifying the threats posed by coastal change on protected areas (e.g. Knight & Grab 2024), and these impacts are likely increasing. However, moving forward, landscape management and conservation in all types of environmental settings in South Africa need to consider not only the role of climate change in landscape processes and properties but also how they influence each other in a biophysical systems context. It is this approach that is best able to future-proof valued landscapes against ongoing climate and environmental changes.

Coastlines globally can be considered as biophysical as well as human systems, and the spatial and temporal evolution of coastlines can be considered as the outcomes of these systems in operation. Significant challenges face the South African coast as a result of ongoing climate change as well as socioeconomic, infrastructural and planning development issues. Together, these give rise to increased risk of negative impacts on coastal systems. In the context of sustainable development in South Africa, minimising the impacts of climate change risks on sensitive environments such as coastlines is a critical management priority (Dube et al. 2022). However, this requires an understanding of the interconnected climatic and anthropogenic drivers and their varied impacts upon coastal systems, but this knowledge is often lacking. A result is that coastal managers and other decision-makers commonly lack the datasets or knowledge necessary to develop appropriate policies or to enact these in a suitable way in different coastal settings or in addressing different coastal risks (Colenbrander 2019). In addition, coastal systems are not static or at equilibrium: they will continue to evolve in possibly unanticipated ways over the coming decades under ongoing change and in response to changing socioeconomic and political conditions. Despite being areas of higher overall risk, in South Africa, coastal population growth, tourism development and future enhanced heating and lack of water inland may push more people towards the coast in coming decades. This also has to be considered in assessing future risk and coastal management priorities.