Enhancing the resilience of high-vulnerability, low-elevation coastal zones

Highlights

• Complex socio-environmental connectivity in relation to climate change pressures.

• Large areas of low-lying land so coastal dune ridge has high protective function.

• High natural and social capital justifies particular focus.

• High community awareness/engagement confers likely success of resilience planning.

• Introduction and context.

Abstract

This paper aims to explore how resilience to climate change can be achieved and optimised within an example of a complex, high-vulnerability and low-elevation coastal zone. In Uist, Outer Hebrides, Scotland, a completed INTERREG project provided a framework for resilience planning in a complex, multifaceted environment, where official bodies, NGOs, academics and the community already work together productively. A range of approaches to coping with climate change in Uist is reviewed, some of these originating from within the community, and the local situation is discussed in the context of the extent to which resilience theory and national policy intertwine. These approaches identify and combine nature-based solutions and compatible engineering-based solutions, demonstrating how resilience can be achieved and enhanced in a vulnerable area via sustained engagement with local communities backed by peer-reviewed research and complying with the policy context.

Introduction

This paper aims to identify how resilience to climate change can be achieved and optimised within high-vulnerability and low-elevation coastal zones, such as occur in the Outer Hebrides (Western Isles) of Scotland. Low Elevation Coastal Zones (LECZs) (defined as coastal land below 10 m elevation) are identified to be at particular risk to climate change impacts by the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) on coastal systems (Wong et al., 2014). In Scotland, such vulnerable LECZ coastlines include many islands characterised by soft sedimentary coasts that are exposed to high wave energies and backed by an extensive and low-lying hinterland, such as Sanday (Orkney), Uist (Outer Hebrides) and Tiree (Inner Hebrides). All lie within areas of the North Atlantic seaboard that are impacted by high wave energies and sea level rise, with some areas compounded by isostatic land subsidence.

The study area was selected partly because it has a wide range of complex inter-related features that allow for onward use in other LECZs but also because of concerns raised by residents and their Local Authority. Other LECZs could include not only coasts in Orkney and the Inner Hebrides in Scotland (see above) but internationally, given that 2% of the world's land area has been classified as LECZ. This imparts this topic with a sense of urgency, not only in the context of global climate change, but also in relation to the fact that Least Developed Countries have a higher proportion (14%) of their populations in LECZs than OECD countries (10%) (McGranahan et al., 2007; Vafeidis et al., 2011).

The inherent vulnerability to climate change impact in Scottish LECZs is manifest in high rates of coastal erosion, especially on the extensive sandy beach and dune coasts that are common to these islands as well as impacting coastal habitats. Scottish Natural Heritage (SNH, now rebranded as NatureScot), as the statutory advisory body on natural heritage in Scotland, has targeted research on the vulnerability of the low-lying areas of Uist to climate impacts as an exemplar of how any research outcomes might be applied more widely. These studies (Angus and Hansom 2004; Angus et al., 2011; Angus 2014, 2017a, 2018a, 2018b; Angus and Rennie 2014) have been developed and discussed with local communities in meetings and presentations, initially within the INTERREG CoastAdapt project (Muir et al., 2014) and subsequently via meetings convened by local organisations, all of which generated useful and practical feedback. Community awareness of the implications of climate change for Uist is extremely high, particularly following the experience of a severe storm in 2005 (Dawson et al., 2007; Angus and Rennie 2014). Subsequent frequent interaction with academics has helped enhance this community awareness, accompanied by a high level of realism, that provides an effective template for the local development and adoption of resilience strategies.

National studies on coastal change and related coastal risk in Scotland feature detailed reports on the Outer Hebrides within the Dynamic Coast project (Hansom et al. 2017a, 2017b) while the Local Authority (LA), Comhairle nan Eilean Siar (2016), has clear obligations under the Coast Protection Act 1949 and Flood Risk Management (Scotland) Act 2009 (Scottish Government 2009). These national and local approaches concentrate on the dynamics of the coastal edge and civil liability respectively. However, there is a need for both approaches to integrate the entirety of the coastal ecosystem and its function within LECZs. Angus (2018a) identifies a multi-faceted meta-ecosystem in Uist that embraces the coastal edge, near offshore, and habitat function of the hinterland, including wetlands and their management history.

The key habitat component of the Uist hinterland is machair, an extensive plain of dune grassland lying between the dune ridge and the main chain of wetlands (Angus 2006). Machair has multiple conservation interest in terms of habitat, species, landform, landscape and archaeology, reflected in a high proportion of the habitat complex having national and international conservation designations. The habitat has developed and evolved in tandem with human settlement and management, yet has high nature conservation interest, a key element of which is the cultivation of sections of machair for fodder crops for cattle. This contrasts with the typical situation, where arable agriculture is often regarded as having a negative impact on the environment. The main Uist crops are rye and oats, with small amounts of bere (a form of barley). This arable land use is unusual in that no herbicides or pesticides are used, and though some artificial fertiliser is applied, much of the fertiliser is organic, in the form of beach-cast kelp. This low input system, using locally grown seed, allows the prolific growth of wild flowers among the crop, with each of the adjacent small patches having slightly different flora, varying with timing, fertiliser use and seed source. Cropping is rotational, and variety persists in the fallow areas, which have their own characteristic flora. This complex of crop and fallow has a wide range of wild plants, promoting a range of invertebrates, in turn attracting large numbers of ground-nesting birds including a range of waders (lapwing, oystercatcher, redshank, dunlin and ringed plover) with other noteworthy species including corncrake. This form of agriculture that promotes biodiversity is increasingly rare and is dependent on skilled, active management (Angus 2001). Conservationists recognise not only the biodiversity contribution made by this land use, but also its fragile socio-economic setting: agriculture here is mostly a part-time occupation on tenanted smallholdings (crofts) and dependent on additional employment for viability. The other attribute of this multi-faceted meta-ecosystem is the extreme level of interconnectivity between: abiotic processes and habitats; the habitats themselves; the optimal management of machair and its socio-economic context (Angus 2018a). The motivation for a conservation body (such as NatureScot) to invest scarce resources in strategic resilience planning is based on the protection of key designated habitats locally, and the importance of continuation of the arable machair system and its socio-economic context, with a view to applying the results more widely.

If science has identified the extent of the present-day hazard (Table 1) and Local Authorities are aware that well-planned adaptation to cope with these hazards is essential, the emphasis moves to the need to deliver adaptation based on effective resilience enhancement. The aim of this paper is to identify how resilience can be optimised for the Uist environment and community, addressing the issues identified by previous work. The overarching context is the Scottish Climate Change Adaptation Programme (Scottish Government 2014; Scottish Government 2019; Committee on Climate Change 2019).

Achieving coastal resilience to climate change is now recognised as a desirable outcome, with both management policy and practice increasingly moving towards maximising some form of resilience. However, in management contexts the term resilience remains ambiguous, poorly defined, and has a wide range of definitions (Masselink and Lazarus, 2019). Cahoon and Guntenspergen (2010) suggest resilience is the “capacity of an ecosystem to respond to disturbance and maintain its capacity to function normally”. Cole's (2012) definition is similar with “the ability of future ecosystems to absorb change and persist without undergoing a fundamental loss of character” using this as one of four components of a wider concept, the others being nature's autonomy, historical fidelity, and ecological integrity. Masselink and Lazarus (2019) offer coastal resilience as holistic with an emphasis on systemic functionality: “Coastal resilience is the capacity of the socioeconomic and natural systems in the coastal environment to cope with disturbances, induced by factors such as sea level rise, extreme events and human impacts, by adapting whilst maintaining their essential functions.”. The last definition is adopted here as it includes coping with socio-economic and environmental disturbance resulting from natural and human impacts as well as an acknowledgement that adaptational behaviour may occur.

Uist provides a particularly valuable study area in respect of wider LECZ issues in that it has a range of hazards acting together in a complex ecological environment with a complex social infrastructure (Table 1). Rapid rates of relative sea level rise (RSLR), increasing precipitation and land altitudes that are not merely low, but below the level of high tide, give the dune ridge a critically important protective role (Angus 2018a). Uist is thus an ideal environment to test the effectiveness of resilience planning, having a high level of local natural capital where habitat function and high biodiversity have coexisted with, and have had a high reliance on, active human management over the centuries. The existence of a high proportion of land with national or international conservation designations and with a long history of traditional management techniques that boost biodiversity, has aided the resourcing of climate change vulnerability research, enabling NatureScot to become one of the key players in local resilience planning. This symbiotic interrelationship of human management, environment and habitat is key since change in any of these systems triggers change in the others, so that if active management is prevented or discouraged in any way then negative impacts on biodiversity may follow. Trade-offs in management aims, objectives and costs often result in the enhancement of socio-economic resilience at the expense of natural resilience, and vice versa (Masselink and Lazarus, 2019) but here the two are symbiotic. For example, any negative impact on socio-economic resilience in Uist that results in local population decline may create a domino effect: population loss in low-density, traditional agricultural environments has the potential to trigger reduction or even closure of some community provision with consequent adverse impacts on aspects of biodiversity and ecosystem service provision.