Pathways to sustain atolls under rising sea levels through land claim and island raising

Abstract

Low-lying atoll nations (e.g. the Maldives, Kiribati, Tuvalu, Marshall Islands) are highly vulnerable to climate change, especially sea-level rise (SLR). Stringent climate change mitigation will slow but not stop SLR, which will continue for centuries, mandating additional long-term adaptation. At the same time, urbanisation is concentrating population in a few centres, especially around capital islands which creates additional pressure as most atoll nations are ‘land-poor’. This paper demonstrates how structural adaptation using land claim and island raising can be utilised within an adaptation pathway approach to sustain enough islands and land area above rising sea levels to satisfy societal and economic needs over multiple centuries. This approach is illustrated using the Maldives, especially around the capital and its environs (Greater Malé). Raising, expanding and connecting ‘urban’ islands can provide multiple benefits. Significant developments have already occurred in Greater Malé and further developments there and for other urban centres in the Maldives are expected. Migration to urban centres, especially Malé, is widespread and this adaptation approach assumes this trend continues, implying many other islands are depopulated or abandoned. Tourism is core to the Maldives economy and tourist islands require a different ambience to urban islands. They could be sustained with sympathetic soft engineering reinforcing the natural processes that produce atolls. While land advance and island raising provides a technical solution for SLR, any application must also address the additional policy, human, physical, engineering and economic/financial challenges that are raised. Nonetheless, by aligning adaptation through land advance/raising with existing development trends, atoll nations have the potential to persist and prosper for many centuries even as sea levels inevitably rise. This provides a realistic alternative to widespread assumptions about forced migration and ultimate national abandonment. The lessons here may find wider application to other small island settings and even mainland coasts.

Peripheral: Resilient Hydrological Infrastructures

“…This was already undertaken with landfill construction on Hulhumalé Island, which is raised 2.1 m above sea level, or at least 60 cm higher than existing island formations [101] (p. 393). Land reclamation and land raising are also the transitional pathways suggested as socially feasible and more likely, as noted in parts of recent research [102,103].…”

Illustrative Multi‐Centennial Projections of Global Mean Sea‐Level Rise and Their Application

“…If we consider our projections, the exceedance of 2m of global mean sea‐level rise would be delayed by over 250 years by following the lower of the two scenarios (median estimate of 2249 for SSP2‐4.5, beyond 2500 for SSP1‐2.6), that is, keeping to the upper limit of the Paris Agreement, as can be seen in Figure 7. Although this may not prevent erosion or submergence of small atoll islands, this would grant more time for adaptation efforts such as relocation of communities or artificial island‐raising (Amores et al., 2022; Brown et al., 2023; van der Pol et al., 2023). Besides this mitigation challenge, adaptation requires a range of projections that depends on stakeholders' time horizons and risk aversions (Hinkel et al., 2019).…”

Climate change and human security in coastal regions

“…Some highlight maladaptation of seawalls along island coasts (Nunn et al, 2021a) and the diffusion of hard protection to coastal erosion and flooding along island coasts in the Pacific and Indian Oceans (Klöck et al, 2022). In specific small and low-lying island contexts, also land reclamation and island raising are being implemented (Brown et al, 2023).…”