1.1. Climate Change and Atoll Countries

Atoll countries such as Kiribati, Tuvalu, the Marshall Islands, and the Maldives face an unparalleled degree of climate vulnerability due to the interaction of their geomorphological characteristics, regional climate trends, and socioeconomic constraints. These factors jointly undermine long-term habitability and frame the adaptation challenges examined in this study.

1.1.1. Geomorphological Vulnerability of Atoll Systems

Figure 1 shows the geographical locations of the four atoll countries examined in this study. Atolls are low-lying carbonate islands that rarely exceed 2–3 m in elevation above mean sea level ¹. This extremely low topography renders them highly susceptible to even modest increases in sea level. Their porous substrates allow seawater to infiltrate readily, placing the thin freshwater lenses—often their primary source of potable water—under constant threat from salinization and storm-driven overwash ^2,3. The physical stability of atoll islands is inseparable from the health of their surrounding coral reefs, which dissipate up to 97% of incoming wave energy and supply the carbonate sediment essential for island maintenance ⁴. As ocean warming and acidification impair corals’ capacity to survive and accrete, these islands simultaneously lose natural wave protection and sediment supply ⁵. This convergence of factors places atoll systems among the most geomorphologically fragile environments on Earth.

1.2. Artificial Islands as a Transformational Adaptation Strategy

The growing recognition that conventional adaptation measures may be insufficient to preserve long-term habitability in atoll countries has prompted increasing interest in transformational approaches. The Intergovernmental Panel on Climate Change defines transformational adaptation as a fundamental alteration of social–ecological systems in response to climate impacts that exceed the limits of incremental strategies ²⁶. In practice, transformational adaptation requires large-scale, irreversible changes beyond incremental coastal protections, including population-scale land creation and new governance for artificial territory. In atoll countries, where SLR, freshwater salinization, and coral reef degradation threaten the continued viability of natural islands, artificial island development has emerged as a potential means of creating elevated, climate-resilient territory capable of sustaining populations long term. This section describes the conceptual, technical, environmental, legal, and financial considerations that underpin this adaptation pathway and provides a structured framework for evaluating its feasibility.

1.3. Overview of the Four Atoll Countries

Atoll countries exhibit shared vulnerabilities and significant differences in governance, economic capacity, and adaptation trajectories. This section provides essential comparative context for the Maldives, Kiribati, the Marshall Islands, and Tuvalu—the four countries examined in this review. Their common geomorphological characteristics place them at the forefront of climate-related risks. Nonetheless, their institutional structures and development pathways diverge in ways that shape the feasibility of artificial island development.

1.3.1. Rationale for Case Selection: Why These Four Atoll Countries?

Among the 38 SIDS, only a small subset is composed entirely of low-lying atolls without higher volcanic terrain. The Maldives, Kiribati, the Marshall Islands, and Tuvalu share this distinctive geomorphology, with maximum elevations rarely exceeding 3 m above mean sea level ⁴². As no interior upland areas are suitable for internal relocation, climate change directly threatens their territorial integrity and habitability in ways that differ fundamentally from island nations with high islands, such as Fiji and the Solomon Islands.

These four atoll states have also played a significant role in international diplomacy on climate change, coordinating through the Alliance of Small Island States (AOSIS) and, more recently, forming the Coalition of Atoll Nations on Climate Change (CANCC) in 2014 ^42,43,44. Their diplomatic efforts underscore shared concerns regarding SLR, climate mobility, and the continuity of statehood, along with highlighting the political salience of preserving sovereign territory. Simultaneously, these countries differ in their approaches to artificial island development: the Maldives has pursued extensive reclamation for decades; Kiribati and Tuvalu are advancing planning frameworks; and the Marshall Islands is evaluating multiple adaptation pathways without committing to a single strategy ⁴⁵. These contrasting approaches provide a valuable basis for comparative analysis.

2.1. Country Profile and Climate Vulnerability

Often described as the world’s lowest-lying country, the Maldives has an average elevation of approximately 1.5 m above mean sea level and faces a substantial risk of submergence driven by SLR. The capital, Malé, is among the world’s most densely populated urban areas, with approximately 250,000 residents living on the central island of Malé (less than 6.8 km\(^2\)), and acute housing shortages and severe pressure on infrastructure constitute pressing challenges. Under these conditions, the Maldivian government has promoted the creation of new artificial islands with the dual aims of climate change adaptation and decentralization of urban functions ^34,35,67,68.

Key motivations for artificial island development include: (1) securing residential land by creating higher-elevation terrain resilient to SLR, storm surges, and tsunamis ⁶⁷; (2) alleviating congestion in the Greater Malé area and accommodating population growth ⁶⁹; (3) strengthening the economic base by expanding tourism and industrial infrastructure ⁶⁸; and (4) supporting island consolidation under the post-2004 Indian Ocean tsunami “Safer Island” policy by relocating residents from vulnerable small islands to larger disaster-preparedness hubs ⁷⁰. Against this backdrop, the Maldives began large-scale land reclamation and artificial island construction in the late 1990s, positioning this as an “innovative” model for building a disaster-resilient nation and attracting sustained scholarly attention ³⁸.

Taken together, the extreme physical exposure of the Maldives to SLR and its highly centralized population structure have rendered conventional in situ adaptation insufficient. Thus, artificial island development emerged not simply as an engineering response but as a state-led spatial strategy to simultaneously address climate risk, urban congestion, and territorial fragmentation. This framing positions artificial islands as a cornerstone of national adaptation policy rather than as isolated infrastructure projects.

2.2. Artificial Island Projects and Experiences

In the Maldives, land reclamation and expansion have been conducted on more than 50 islands; anthropogenic increases in island area have been confirmed for approximately 93.5% of all inhabited islands, including resort islands. Over the past decade, 59.1% of the inhabited and resort islands in the Maldives have expanded ³⁸.

Among these, the following artificial islands are regarded as strategically significant national projects.

The Maldivian government created Hulhumalé, an artificial island in a lagoon near the capital, as an emblematic climate change adaptation project. To create this island, which is located approximately 8 km northeast of Malé, reclamation began in 1997 and the first residents were accommodated in 2004. The elevation of the island is designed to be approximately 2 m above mean sea level, more than double that of conventional natural islands (generally under 1 m), and it is positioned as a comparatively “safer urban hub,” an adaptation measure against SLR and inundation risks. With an area of approximately 4 km\(^2\), Hulhumalé housed roughly 50,000 residents as of 2019 and is planned to accommodate more than 200,000 in the future. The project is being developed in two phases: Phase 1 (reclamation between 1997 and 2002; 188 ha) advanced housing and basic infrastructure with a target capacity of approximately 88,000 people, while Phase 2 (reclaimed in 2015; 244 ha) added an urban expansion designed for an additional 145,000 people and was completed within nine weeks ^69,71. Completion of the island as a whole is scheduled to proceed in stages through the 2030s.

Hulhumalé is not merely reclaimed land; it incorporates an advanced urban plan that presents itself as “the Maldives’ first sustainable city.” For example, ventilation corridors (“wind corridors”) are integrated along streets to reduce thermal loads on high-rise housing under anticipated future warming; building layouts are oriented along a north–south axis to mitigate solar heat gain. The plan also emphasizes renewable energy deployment; photovoltaic panels are being installed on 1,000 high-rise units in Phase 1, with an ongoing initiative to supply roughly one-third of the island’s energy through solar power. In addition, climate resilience is being pursued through rainwater storage systems for water security and green infrastructure, including urban farms, parks, and wetlands. Through these comprehensive measures, Hulhumalé has been framed as a model case that simultaneously adapts to future SLR and advances sustainability, and it is sometimes referred to as the “City of Hope.” The Director-General of the Global Center on Adaptation (GCA), Patrick Verkooijen, has described Hulhumalé as “probably one of the largest and boldest adaptation projects on the planet” ³⁵.

The development of Hulhumalé is led by the state-owned Housing Development Corporation (HDC). Established by presidential decree in 2001, HDC oversees the island’s development in its entirety, from urban planning and reclamation to housing provision ^72,69. Hulhumalé is positioned as an urban hub that could, in the long run, accommodate approximately two-thirds of the national population ⁶⁹. This large-scale concentration of population on an artificial island is also intended to address inefficiencies arising from the spatial dispersion of the national territory and to enable the provision of advanced infrastructure under severe resource constraints ⁷³.

Gulhifalhu, which is located in a lagoon approximately 2.5 km west of Malé, is another large-scale reclamation project that has attracted attention in recent years. It is an artificial island created by reclaiming shallow waters that were originally a coral reef lagoon and is intended to expand port functions in the Greater Malé area while securing land for housing ⁷⁴. The project proceeded in stages: in the first phase, approximately 30 ha were reclaimed in 2020 using government funding, followed by plans for an additional expansion of roughly 150 ha using international loans ⁷⁴. The contract was awarded to the Dutch dredging firm Boskalis; works began in 2021, and reclamation was completed in July 2024. Total costs amounted to 3 billion Maldivian rufiyaa (approximately USD 195 million). The volume of sand used reached about 18 million m\(^3\), producing a reclaimed area of 150 ha, which corresponds to converting more than half of the lagoon area into land ⁶⁸.

The development rationale is closely linked to capacity constraints at Malé’s commercial port. In response, the relocation of port functions within the Greater Malé region (including the Thilafushi new port concept) and the parallel development of port and industrial functions around Gulhifalhu have been debated and advanced ⁷⁵. The island is also planned to host industrial infrastructure such as warehouses and factory plots, positioning it as a logistics and manufacturing base for the capital region ^75,76. In 2018, then-President Yameen announced a large-scale housing project referred to as “Villimalé 2,” and indicated a policy of conducting residential development on Gulhifalhu as an alternative housing site for the neighboring Villingili Island ^77,78. If realized, Gulhifalhu is expected to become a new city with a population density and urban scale exceeding those of Malé. Gulhifalhu is also scheduled to be connected via road to Malé proper, the nearby Villingili Island, and the industrial island of Thilafushi via the “Sinamalé Bridge Phase 2” (also known as the “Thila-Malé Bridge”), supported by India, with a target completion year of 2026. If completed, together with the existing Sinamalé Bridge, the capital region’s artificial islands would function as an integrated metropolitan area.

In addition to Hulhumalé and Gulhifalhu, Thilafushi is a representative artificial island in the Greater Malé region. Thilafushi began as a reclaimed island created in 1992 to be a waste-disposal site for Malé and is now widely known as a “trash island” where industrial and municipal waste accumulates ^79,80. As the island expanded, large waste mounds formed; however, marine pollution and fires became serious concerns, leading the government to pursue countermeasures, including construction of a waste-to-energy facility on the island ^81,79. More broadly, reclamation for resort development and infrastructure has been undertaken across the country, and resort island expansion, aimed at attracting tourists, has progressed since the 2000s. Research suggests that many resort islands have undergone artificial expansion through reclamation and/or breakwater construction, and that, in light of post-2004 tsunami assessments, the importance of coastal protection and the development of design guidelines has been further emphasized ^38,82. For example, large-scale reclamation within lagoons has recently been implemented in the southern Addu Atoll; however, some stakeholders in the tourism sector have raised concerns that land creation of questionable necessity has damaged the attractiveness of beaches through environmental degradation ^83,84. Collectively, these cases underscore the fact that balancing economic development with environmental protection remains a central challenge in artificial island development.

The experiences of Hulhumalé, Gulhifalhu, and Thilafushi illustrate how artificial islands in the Maldives function as multipurpose urban platforms, simultaneously serving housing, industrial, logistical, and disaster-preparedness roles. While these projects demonstrate the state’s capacity to rapidly create urban land at scale, they also reveal a tendency toward population and infrastructure concentration that may amplify systemic risks. Thus, artificial islands operate as instruments of spatial efficiency and sites of emerging socio-environmental vulnerability.

2.3. Environmental and Social Impacts

In the Maldives, artificial island creation typically relies on dredging sand and gravel from shallow areas within atoll lagoons and hydraulically pumping the material through pipelines to the reclamation site for deposition and land formation ^85,86. Hulhumalé was likewise constructed by pumping and depositing several million cubic meters of dredged seabed sand ²⁹. At Gulhifalhu, large-scale suction and pumping operations were conducted using trailing suction hopper dredgers ⁷⁴. In Phase 2 of Gulhifalhu, approximately 18 million m\(^3\) of fill material was placed, and a perimeter revetment using rock blocks was constructed to attenuate offshore wave energy ⁸⁶. The standard workflow involves first constructing an enclosing bund using sandbags or sandbars and then filling the enclosed area with dredged material to create land. In Gulhifalhu, a 2.2 km-long enclosure bund was installed, and silt curtains were also deployed to mitigate the spread of turbid water generated by reclamation activities ⁷⁴. While these methods enable the rapid creation of large land areas using abundant atoll-derived sand, they raise persistent concerns regarding the impact of suspended sediment on coral reefs and seagrass beds, as well as the potential depletion of borrow-material resources ^87,88.

In the Maldives, most of the reclamation sand is sourced from within local atolls, which can directly disturb valuable coral reef ecosystems. Reclamation may also undermine surrounding natural “reef-protection systems,” potentially increasing vulnerability to storm surges and coastal erosion rather than reducing it ^38,34. For this reason, in Gulhifalhu Phase 2, which was supported by foreign financing, an implementation plan aligned with the International Finance Corporation’s (IFC) environmental and social standards was developed, and protective measures such as coral transplantation and water-quality monitoring were implemented ⁸⁶. Concrete measures include adjusting borrow sites and construction schedules to reduce impacts on corals during spawning periods; setting turbidity thresholds and controlling dredging intensity through real-time monitoring; and conducting advance briefings and consultations with surrounding stakeholders (including fishers and diving operators) ^86,74. Conversely, for smaller-scale reclamation undertaken by domestic firms, such safeguards may be insufficient; environmental degradation has also been raised as a concern in reclamation projects led by the state-owned Maldives Transport and Contracting Company (MTCC) ^89,90. Overall, although advanced technologies enable rapid reclamation, reconciling sand extraction with effective environmental conservation remains a major unresolved challenge ⁹¹.

Because reclaimed land is composed largely of gently sloping coral sand and gravel, shoreline protection infrastructure is indispensable for protecting newly created terrain from wave action and storm surges ³⁸. While traditional approaches may rely on sandbags or stone revetments, large-scale developments typically employ modern methods such as concrete armor units (tetrapods), sheet piles, and rock-block structures ⁹². Cost estimates as of 2011 suggest that tetrapod seawalls can be extremely expensive, at roughly 64,000 Maldivian rufiyaa per meter (approximately USD 4,000), with other approaches also requiring substantial expenditures (around 40,000 rufiyaa per meter). In Malé, shoreline protection has been implemented with support, including Japan’s grant aid. Hulhumalé, conversely, was planned as an artificial island with its ground level raised to approximately 1.8–2.0 m, aiming to reduce risk through elevation gain combined (as needed) with peripheral coastal defenses ⁹². Internal drainage infrastructure is also critical: reclaimed land tends to have low permeability and is prone to inundation during heavy rainfall, making adequate drainage systems and pump stations essential ⁹³. Taken together, artificial islands often entail a trajectory toward “fortification” through hard infrastructure, and their long-term maintenance costs and technical sustainability must be evaluated explicitly from a multi-decadal perspective ³⁸.

The environmental impacts of large-scale reclamation underscore a fundamental tension between engineered adaptation and ecosystem-based coastal protection. Although artificial islands can enhance short-term physical security through elevation and hard defenses, their reliance on extensive dredging risks degrading coral reef systems, which attenuate natural hazards. These dynamics suggest that artificial island development may, under certain conditions, reproduce forms of maladaptation by undermining long-term ecological resilience.

2.4. Governance and Financing

For decades, the government has explored policies to consolidate populations dispersed across the outer islands to improve infrastructure efficiency. As part of this agenda, the post-2004 Indian Ocean tsunami “Safer Islands Programme” institutionalized a plan to relocate residents from vulnerable small islands to larger islands that are elevated and equipped with disaster-prevention infrastructure ³⁸. Hulhumalé represents the most prominent example and is positioned as a disaster-preparedness hub where national human and economic resources are concentrated ⁶⁹. At the same time, maintaining the sustainability of outer-island communities remains a challenge, and consolidation policies have been criticized for potentially severing residents’ cultural attachment and livelihoods ⁹⁴.

Since 1993, development projects have been subject to mandatory EIAs, with the Environmental Protection Agency (EPA) responsible for review and oversight under the environmental protection law ⁹⁵. However, in practice, implementation challenges have been noted. In the Gulhifalhu reclamation project, civil society actors raised concerns about a lack of transparency regarding the sequencing of EIA procedures relative to contracting and project commencement ⁹⁶. Public environmental awareness has also increased in recent years, including moves by civil society groups to seek injunctive relief against reclamation projects ⁹⁷. In one case where the High Court ordered a construction halt, the Supreme Court reportedly overturned the decision on the grounds that continuing suspension would cause “significant losses to the national economy,” illustrating how tensions between development and environmental protection have entered judicial arenas ⁹⁷.

As large-scale reclamation requires substantial capital, the Maldivian government has actively leveraged external loans and aid. For example, Gulhifalhu Phase 2 reportedly secured financing from multiple international financial institutions via export credit provided through the Netherlands-based Atradius, enabling access to funds that would be difficult to mobilize domestically ^74,86. Under the lending conditions, compliance with the World Bank Group’s IFC Environmental and Social Performance Standards and the Equator Principles was required, and international-standard environmental and social impact assessment and monitoring frameworks were introduced. Regional powers have also played a significant role in infrastructure assistance. While external financing enables large-scale projects, attention must also be paid to growing external debt burdens and their potential geopolitical implications ⁹⁶.

The World Bank’s 2024 Country Climate and Development Report has raised concerns regarding the Maldives’ fiscal sustainability, noting that the country’s public debt has risen significantly and that its heavy reliance on external financing from a relatively small number of bilateral and multilateral sources creates fiscal vulnerabilities ⁹⁸. The concentration of development finance among a limited set of donors amplifies exposure to shifting geopolitical priorities and lending conditions. These fiscal pressures are compounded by the ongoing capital requirements for large-scale reclamation projects, raising questions about the long-term financial sustainability of artificial island development as a national adaptation strategy without substantial reform of public fiscal management and diversification of funding sources.

The government has established specialized state-owned enterprises (SOEs) to advance artificial island development ⁹⁹. The HDC has been responsible for Hulhumalé development, spanning master planning through land sales and housing development, while also leveraging domestic and external financing (including borrowing) ⁹⁹. In parallel, the MTCC functions as a key domestic contractor for port dredging and reclamation works, undertaking numerous smaller-scale projects on the outer islands (e.g., fisheries-harbor upgrades and airport expansions) ¹⁰⁰. Although SOE-led development can enable integrated implementation aligned with national strategy, it has also been associated with risks such as non-competitive contracting and corruption. In Gulhifalhu, no-bid contracting and corruption allegations have been raised, highlighting persistent governance challenges ^101,102.

The governance and financing arrangements underpinning artificial-island development reveal the enabling and constraining roles of state-led implementation and external capital. Although SOEs and international financing have facilitated rapid project execution and access to advanced technologies, they have also intensified concerns regarding transparency, debt sustainability, and environmental accountability. Consequently, the long-term viability of artificial islands depends on engineering performance and on institutional capacity to balance development imperatives with environmental and social safeguards.

The governance and financing arrangements examined above illustrate how the Maldives has established itself as a pioneer in artificial island development among atoll countries. The country has demonstrated that large-scale land creation is technically feasible and can proceed rapidly when supported by state-led implementation and international capital. Hulhumalé, in particular, represents a pioneering model of climate-resilient urban development that combines elevated terrain with integrated sustainability features. As this section has shown, realizing the full potential of such projects requires continued attention to balancing development priorities with environmental safeguards, maintaining outer-island community sustainability alongside population consolidation, and ensuring fiscal prudence in the use of external financing. The Maldivian experience offers valuable lessons for other atoll countries considering artificial islands as a climate adaptation pathway.

3.1. Country Profile and Climate Vulnerability

Kiribati is a Central Pacific atoll country comprising 33 coral islands organized into three distinct groups: the Gilbert Islands in the west, the Phoenix Islands in the center, and the Line Islands in the east. The nation’s 811 km\(^2\) of land area is scattered across approximately 3.5 million km\(^2\) of ocean, making it one of the most dispersed territorial configurations in the world ⁵⁵. This extreme spatial distribution creates substantial governance and infrastructure challenges, as the capital atoll of South Tarawa lies over 3,000 km from the easternmost Line Islands. The country’s exclusive economic zone (EEZ) of approximately 3.55 million km\(^2\) represents one of the largest maritime jurisdictions among Pacific Island states, with a land-to-EEZ ratio of approximately \(1:\textrm{4,400}\) (Table 1).

The geomorphological characteristics of Kiribati’s atolls render them exceptionally vulnerable to climate change. All islands are low-lying carbonate formations with mean elevations of approximately 2 m above sea level and maximum elevations rarely exceeding 3–4 m ¹⁰³. The islands rest on porous coral substrates that allow seawater to infiltrate readily, placing the thin freshwater lenses—the primary source of potable water for most communities—under constant threat from salinization and storm-driven overwash ³. The physical stability of these islands depends critically on the health of the surrounding coral reef systems, which dissipate up to 97% of incoming wave energy and supply the carbonate sediment essential for island maintenance ⁴. As ocean warming and acidification impair coral survival and accretion capacity, Kiribati’s islands simultaneously lose natural wave protection and sediment supply ⁵.

Climate projections indicate severe compound risks for Kiribati over the coming decades. SLR in the Central Pacific is expected to exceed the global mean, with regional projections suggesting increases of 0.3–0.6 m under moderate emission scenarios and potentially exceeding 1 m under high-emission pathways by 2100 ⁶. However, scientific evidence suggests that Kiribati’s atolls may become effectively uninhabitable well before permanent submersion occurs. Storlazzi et al. ¹ project that wave-driven flooding will contaminate freshwater resources across most atolls by mid-century, rendering them uninhabitable decades before complete inundation. These trends coincide with intensifying tropical cyclone risks, prolonged drought episodes, and coral bleaching events that have already affected over 75% of regional reef systems during the 2014–2017 marine heatwave ¹⁰⁶.

Kiribati’s socioeconomic profile compounds these physical vulnerabilities. The national population of approximately 131,000 (2023) is heavily concentrated in South Tarawa, which accommodates over half of all residents on just 16 km\(^2\) of land. This concentration yields population densities exceeding 3,500 persons per km\(^2\) on average, with the most congested areas, such as Betio, reaching more than 8,000 persons per km\(^2\) ¹⁰⁴. Such extreme densities place immense pressure on limited freshwater resources, sanitation systems, and housing stock, while severely constraining options for inland retreat from coastal hazards. The nation’s economic capacity to finance adaptation measures remains limited: GDP per capita of approximately USD 2,000 places Kiribati among the lowest-income atoll countries, with the economy heavily dependent on fishing license revenues, remittances, and external development assistance ¹⁰⁷.

Critical national infrastructure faces acute exposure to climate hazards. The international airport, main hospital, government buildings, and port facilities on South Tarawa are situated at elevations of only 1–2 m above sea level, rendering them vulnerable to chronic flooding and extreme storm events ¹⁰⁸. The causeway system connecting the islets of South Tarawa, essential for daily transportation and economic activity, has experienced repeated damage from storm surges and king tides. These infrastructure vulnerabilities interact with freshwater stress: the Bonriki freshwater lens, which supplies drinking water to South Tarawa’s population, has experienced progressive salinization from SLR and overextraction ³.

The convergence of geomorphological fragility, climate hazard exposure, demographic concentration, and limited economic resources has made Kiribati one of the world’s most climate-vulnerable nations. These conditions frame the adaptation challenges examined throughout this section and explain why artificial island development has emerged as a subject of serious policy consideration, despite the significant obstacles to its implementation.

3.2. Artificial Island Development Prospects

Kiribati’s early adaptation documents, such as the National Adaptation Programme of Action (NAPA) published in 2007, do not propose artificial island development as a primary strategy; instead, they portray existing land reclamation efforts in South Tarawa as contributing to coastal vulnerability rather than resilience ¹⁰⁹. The NAPA describes South Tarawa’s shoreline as featuring “seawall protection, land reclamation, accreted land, uprooted coconut trees by shoreline erosion, dilapidated buildings that are undermined through erosion, and sand mining,” highlighting how such uncoordinated interventions exacerbate erosion and accretion processes ¹⁰⁹. Priority projects emphasize upgrading existing seawalls and causeways, community-based coastal zone management, and regulatory enforcement, without explicit endorsement of large-scale reclamation or new artificial islands ¹⁰⁹.

The 2007 First National Consultation under the Kiribati Adaptation Project (KAP) Phase II reveals that artificial island development was not yet conceived as a viable adaptation option; even when participants addressed worst-case scenarios in which all measures fail, discussions focused exclusively on international relocation to Australia, New Zealand, and Canada, despite having visited existing reclaimed structures such as the Parliament House ¹¹⁰.

Earlier documentation from the KAP reinforces this cautious stance. The 2005 Lands Acquisition and Resettlement Policy Framework, prepared for KAP Phase II and later amended for Phase III, identifies ten priority areas for climate adaptation—including water resources, coastal erosion, and overcrowding—but makes no reference to artificial island development ¹¹¹. The framework explicitly states a “preference for adaptation strategies that do not include hard structural solutions such as seawalls or related structures but rather involve preservation or extension of natural protection against climate-related threats” ¹¹¹. Although the Foreshore and Reclamation Ordinance (Cap 35) provides a legal pathway for reclamation projects requiring ministerial approval and public consultation ¹¹¹, such mechanisms were envisioned for protective infrastructure rather than for large-scale land creation.

This cautious stance was reinforced by documented implementation failures during KAP Phase II. Donner and Webber ¹⁰⁵, based on eight years of field research, reported that seawalls constructed under the project experienced serious erosion within months of completion, with experts describing them as “not best practice” due to designs that poorly dissipated wave energy. These experiences underscore the institutional reluctance toward hard structural solutions evident in early adaptation frameworks.

The Kiribati Joint Implementation Plan (KJIP), published in 2019, marks a shift toward transformative prospects, integrating land reclamation into broader coastal resilience under Strategy 6 ¹⁰⁴. It promotes “bold and innovative engineering solutions” such as raising islands to 2 m above sea level, piloting alternatives, and incorporating reclamation into land-use plans while addressing unavoidable impacts ¹⁰⁴. KJIP envisions strategic reclamation in high-risk areas such as South Tarawa and Kiritimati to protect infrastructure, aligned with community-based mangrove management and marine spatial planning ¹⁰⁴. However, prospects hinge on overcoming historical maladaptation, with emphasis on EIA, participatory design, and international partnerships for technical and financial support. This evolving policy trajectory aligns with Kiribati’s long-term development blueprint, Kiribati 20-Year Vision (KV20), published in 2016, which prioritizes improving land use planning and creating additional land for commercial development as part of building national wealth and infrastructure resilience ⁶⁴.

Beyond conventional reclamation, futuristic floating island concepts have also been proposed for Kiribati. In 2013, Shimizu Corporation unveiled the “Green Float” project, a lily-pad-shaped floating city designed to accommodate 40,000 residents, and former President Anote Tong reportedly held discussions with the company about purchasing such structures ¹¹². However, Bryant-Tokalau ¹¹² argues that such externally driven technological solutions often exclude community participation and fail to recognize Pacific Islanders’ centuries-long history of constructing artificial islands. These critiques underscore the importance of participatory design as emphasized in the KJIP framework.

Contrary to earlier policy documents that did not articulate large-scale reclamation or artificial island development, recent engineering studies for the Temaiku Land and Urban Development project propose reclaiming approximately 300 ha of low-lying swampy land in the Temaiku Bight area in South Tarawa and raising it 2–5 m above the highest measured sea level ¹¹³. This initiative aims to create resilient urban space for up to 35,000 people, government facilities, and infrastructure, while addressing overcrowding, SLR, and storm surges through integrated coastal engineering and environmental planning ¹¹³. Site investigations have confirmed limited suitable lagoon sediments for fill, highlighting key technological challenges ¹¹⁴. These constraints must be navigated within Kiribati’s overarching governance framework outlined in the KV20, which emphasizes infrastructure development, anti-corruption measures, and mainstreaming climate adaptation across sectors to support sustainable projects such as Temaiku ⁶⁴.

The Temaiku site has been under consideration for urban development for over two decades. A 2004 feasibility study proposed sustainable urban development of approximately 306 ha, with a projected capacity of 15,000 residents upon completion ¹¹⁵. However, that earlier proposal did not incorporate climate-resilient elevation standards, reflecting the limited emphasis on SLR adaptation at the time. The current proposal’s requirement to elevate land by 2–5 m represents a significant evolution in planning philosophy, although it also substantially increases the material requirements and associated costs.

The Temaiku project represents more than a defensive adaptation measure. By creating an elevated, resilient urban space for up to 35,000 residents, it offers a proactive solution to South Tarawa’s overcrowding while demonstrating that atoll countries can build sustainable futures rather than await displacement. This transformative potential positions Temaiku as a model for climate-resilient development across the Pacific.

Kupferberg ¹¹⁶ offers a positive assessment of the Temaiku Adaptation Project in the short term but expresses skepticism about its viability as a long-term solution. This is because Kiribati’s population is projected to reach approximately 239,000 by the end of this century, and given Temaiku’s capacity of only 35,000 people, approximately seven Temaiku-scale projects would be required for it to succeed as a climate change adaptation measure. However, this argument warrants further investigation. Hulhumalé, an artificial island currently under construction in the Maldives, is expected to have an area of 432 ha and accommodate a population of 240,000 upon completion ^34,117,118. Given that the Temaiku project covers an area of 300 ha, assuming the same population density as Hulhumalé, it could accommodate approximately 167,000 residents. Since Kiribati’s current total population is approximately 131,000, Temaiku alone would have sufficient capacity to house the entire present national population with room to spare—although additional land creation would be required to accommodate the projected population growth. At present, the status of the Temaiku project remains unclear, particularly following the withdrawal of New Zealand government funding in 2021 ¹¹⁹, a constraint examined further in the following section.

3.3. Legal, Technological, and Financial Constraints

Under Kiribati law, the foreshore and seabed are vested in the state, and any land reclaimed through government-authorized projects becomes state property ^120,121. The responsible minister may subsequently enter into agreements for the sale, lease, or granting of other rights over reclaimed land (Sec.10). This legal framework means that large-scale reclamation projects, such as the Temaiku development, would initially create state-owned land, which could then be allocated to residents through leasehold or freehold arrangements under the State Lands Act 2001.

Lister and Muk-Pavic ³³ proposed a modular hexagonal mega-float structure as a sustainable artificial island concept for the Republic of Kiribati, with an estimated cost of approximately GBP 19.2 billion (USD 24 billion) for a 9.15 km\(^2\) island. This study dismissed conventional reclamation on the grounds that sediment cannot be locally sourced on isolated atoll islands. However, this categorical dismissal oversimplifies technical realities. Although site investigations for the Temaiku project have confirmed that suitable lagoon sediments are limited in South Tarawa ¹¹⁴, this finding indicates constrained rather than absent resources. The Hulhumalé experience in the Maldives demonstrates that lagoon dredging can provide sufficient fill material under comparable atoll conditions, although project-specific geological assessments remain essential. The key distinction is between technical challenges requiring adaptive engineering solutions and fundamental impossibility—the former characterizes Kiribati’s situation more accurately than the latter. Notably, South Tarawa itself possesses a lagoon of approximately 20 m deep at the proposed construction site—a resource acknowledged by the authors but not adequately evaluated for dredging potential.

The cost difference between the two approaches is substantial (Table 2). The proposed mega-float would cost approximately USD 2.6 billion per km\(^2\), whereas Hulhumalé’s total development cost, including housing and infrastructure, amounts to USD 230–350 million per km\(^2\)—approximately 8 to 11 times lower. This significant disparity suggests that while floating structures may offer certain advantages in terms of flexibility and tsunami resilience, their economic viability for large-scale permanent settlement remains questionable compared to proven reclamation approaches. The Hulhumalé experience demonstrates that lagoon-based reclamation represents a technically feasible and substantially more cost-effective alternative that warrants serious consideration for atoll countries such as Kiribati.

Kupferberg ¹¹⁶ raises another financial concern specific to the Temaiku project, noting that land reclamation alone would cost approximately USD 273 million—exceeding Kiribati’s annual GDP of approximately USD 194 million—and questioning whether such an investment is feasible for a small island developing state. However, comparative analysis suggests this cost is not unreasonable by international standards. The Temaiku reclamation cost translates to approximately USD 91 million per km\(^2\), whereas Hulhumalé’s total development cost—including reclamation, housing, roads, utilities, and other infrastructure—amounts to USD 230–350 million per square kilometer (Table 2). Thus, Temaiku’s per-unit-area reclamation cost represents only 26%–40% of Hulhumalé’s comprehensive development expenditure. Kupferberg’s critical point is not that the project is too expensive in absolute terms but that it exceeds Kiribati’s domestic financing capacity. However, Hulhumalé itself was not financed solely by the Maldivian government; it relied on international development finance institutions, bilateral aid, public-private partnerships, and reinvestment of housing sales revenues ^122,123. This suggests the relevant question is not whether Temaiku’s costs are prohibitive but whether adequate international climate adaptation funding can be secured. The withdrawal of New Zealand government funding for Temaiku in 2021 ¹¹⁹ underscores the project’s dependence on external support and its vulnerability to shifting donor priorities.

The legal, technological, and financial constraints examined above carry significant implications for Kiribati’s long-term adaptation pathway. Unlike some Pacific Island nations, where land tenure conflicts impede adaptation, Kiribati’s legal framework vesting reclaimed land in state ownership provides a relatively favorable foundation for projects such as Temaiku. Technologically, conventional reclamation remains substantially more cost-effective than alternatives such as floating structures. The critical constraint is financial: projects of the required scale exceed domestic fiscal capacity and depend on sustained international climate finance, as demonstrated by the withdrawal of donor funding for Temaiku. Nevertheless, Kiribati’s policy evolution from cautious resistance toward hard structural solutions to explicit endorsement of “bold and innovative engineering solutions” in the 2019 KJIP reflects growing recognition that incremental measures alone cannot secure long-term habitability.

4.1. Country Profile and Climate Vulnerability

RMI is located in the western Pacific Ocean, north of the equator, and west of the International Date Line. Comprising 29 atolls and five low coral islands, RMI has a landmass of 181 km\(^2\) in total with an exclusive economic zone of 1,990,530 km\(^2\) ¹²⁶. Recent World Bank data show a population of roughly 37,500–38,000 people in 2023, down from approximately 42,000 around 2022, reflecting continued outmigration ¹²⁷. The economy is small and aid-dependent, with key sectors including government services, fisheries, copra, and small-scale commerce, and limited tourism ¹²⁸. Approximately 80%–90% of food consumed in RMI is imported, making food security sensitive to external price and supply shocks ¹²⁹. Limited arable land, poor soil, freshwater scarcity, and increasing climate impacts constrain domestic agriculture and make substantial increases in staple crop production difficult ¹³⁰. The extreme topographic vulnerability exposes RMI to compound climate risks, including SLR, wave-driven flooding, coastal erosion, and saltwater intrusion into freshwater lenses that underpin domestic water supply ³. Recent modeling indicates that even under moderate emissions scenarios, many atolls in the Marshall Islands may experience annual wave-driven flooding sufficient to contaminate freshwater resources by mid-century, rendering large areas effectively uninhabitable well before permanent inundation occurs ¹. RMI often faces repeated typhoons, which cause severe economic losses. For instance, Typhoon Paka in 1997 damaged agricultural areas and destroyed 80% of the houses in the Ailiniglaplap Atoll. This disaster brought significant financial losses to the entire nation, estimated at USD 80 million ¹²⁷. Urban atolls in the Marshall Islands—particularly Majuro (the capital, with more than 20,000 residents) and Kwajalein—face severe inundation risk from SLR ¹²⁷. Without adaptation measures, a 1-m rise in sea level could lead to permanent inundation of 37% of buildings in Majuro and over 50% of buildings in Ebeye, highlighting the urgent need for adaptation planning ¹²⁷.

This section reviews RMI’s broader adaptation strategies before focusing on artificial island development as an emerging option. RMI’s recent adaptation plan highlights a gradual shift toward transformative adaptation pathways, including large-scale land raising, engineered reclamation, and planned internal relocation. In the Marshall Islands, such approaches are most frequently discussed for Majuro Atoll, where population density, infrastructure concentration, and economic activity are highest ¹³¹. In 2018, the Tile Til Eo 2050 Climate Strategy defined four key adaptation pathways for RMI: Protection; Elevation; Consolidation; and Relocation ¹³². Protection focuses on strengthening coastal defenses, climate-proofing infrastructure, and safeguarding community resilience, along with food, water, and health security ¹³². Elevation involves raising all new infrastructure and developing elevated settlements under updated building standards ¹³². Consolidation includes strategies to concentrate population in safer high-ground areas as climate impacts intensify ¹³². Relocation is considered a last-resort option, ensuring the right to remain on the islands and the provision of dignified migration pathways if long-term habitability can no longer be sustained ¹³².

Building seawalls and other physical defenses has been used as a conventional adaptation strategy. RMI has constructed seawalls, mostly via the private sector, particularly along Majuro’s valuable coastline. For example, a 450-m-long seawall near the new stadium on Majuro was built to mitigate the indirect impact of the existing seawall, with a budget of USD 1 million ¹³³. However, recent assessments by the World Bank in 2021 revealed that conventional protection measures alone may be insufficient under high SLR scenarios. In such cases, large-scale land reclamation and engineered land raising are increasingly discussed as unavoidable last-resort adaptation options to maintain the habitability of key atolls such as Majuro, despite their financial, environmental, and technical costs ¹²⁷.

RMI’s NAP identifies land reclamation and land raising as core long-term adaptation measures for maintaining habitability under projected SLR, particularly beyond the 0.5 m SLR threshold (around 2070) and up to 2 m SLR by 2150 ¹³³. In highly urbanized areas such as Majuro and Ebeye, raising land within existing city centers is considered economically and technically impractical because of groundwater salinization, drainage and dewatering requirements, and construction constraints. Consequently, the strategy emphasizes the creation of new elevated land through selective reclamation or raising of less-developed islands, enabling the consolidation of population, government functions, and critical infrastructure into new centers. Cost estimates indicate unit costs of approximately USD 800/m\(^2\) for raising land with rebuilding (1 m SLR) and USD 1,500/m\(^2\) for raising land with revetments (2 m SLR), with higher protection standards substantially reducing the area and population that can be accommodated per dollar invested ¹³³. For example, an investment of USD 500 million could create about 0.63 km\(^2\) of elevated land under a 1 m SLR design, compared with 0.33 km\(^2\) under a 2 m SLR design, accommodating up to approximately 25,000 and 13,000 people, respectively, under high-density assumptions. Island-scale estimates further show that elevating individual islets to withstand long-term SLR typically requires up to several billion USD, making nationwide reclamation infeasible ¹³³. Consequently, the NAP concludes that reclamation and raising land must be applied selectively, at high densities, and in a phased manner, forming part of a broader adaptation pathway that ultimately prioritizes strategic consolidation over the comprehensive protection of all existing atolls.

4.2. Artificial Island Development Prospects

Artificial islands have also emerged as climate adaptation infrastructure; however, they remain a controversial approach. Nakayama et al. identified land reclamation and elevation as one of four major adaptation options for RMI, and more recent work has started to examine the technical feasibility and social acceptability of artificial islands as tools to operationalize the “right to stay” ¹³⁴. In the Pacific, artificial island development faces context-specific technical and cultural challenges that differ markedly from those of land reclamation in continental settings. Atoll-based artificial islands must often be constructed in deeper waters with limited sediment sources, requiring designs that can maintain structural stability during extreme weather, prevent erosion, preserve sufficient elevation above future sea levels, and support essential infrastructure such as freshwater supply, sewage treatment, and renewable energy ¹³⁵. For Marshallese communities, these engineering issues intersect with profound cultural considerations because people–land relationships are deeply rooted in particular atolls and islets, tied to ancestral heritage and matrilineal land-tenure systems. Relocating to “artificial” land that is detached from customary tenure and ancestral sites; therefore, challenges core dimensions of Marshallese identity and social organization ¹³⁶. Existing research on Marshallese views toward artificial islands is mixed. Some studies suggest conditional openness, where such projects allow people to remain within national waters and retain sovereignty, while others highlight strong spiritual and emotional bonds to ancestral lands that may be difficult to reproduce on engineered substrates ¹²⁵. These accounts also point to concerns about losing traditional land connections, doubts about whether culture and community can truly be transplanted to new landforms, and skepticism that artificial islands can replicate the complex ecological and social systems of natural atolls.

4.3. Legal, Technological, and Financial Constraints

RMI faces a key legal constraint in implementing its reclamation-based adaptation strategy, primarily a conflict between its Constitution, which allows government land acquisition for public use, and a domestic law that vests reclaimed land in adjoining private owners ¹³⁷. Sec.105 of the 2008 Public Lands and Resources Amendment Act states that reclaimed land automatically becomes the property of adjoining private owners; however, Art. II, Sec.5 of RMI’s Constitution authorizes the government to acquire land for public use, including through reclamation ¹³⁷. This key legal issue hinders climate adaptation funding tied to public-purpose projects, as the required billions of dollars in funding for the NAP must be donated for public purposes rather than private benefits. According to Bernard Adiniwin (who has worked as the Attorney General since March 2022), uncertainty over whether reclaimed land is public or private directly undermines the ability to structure and justify large-scale adaptation investments. He filed a petition against Speaker Brenson Wase in the High Court at the end of September 2025. However, High Court Judge Anne Bodley ruled against the government in her 18-page decision ¹³⁸. While the judge ordered the deletion of the introductory phrase “notwithstanding the provision of any law to the contrary” from Sec.105 of the 2008 Landfill Act, she upheld the core provision: title to new land created through landfill from marine areas below the ordinary high-water mark shall vest in the owners of the adjoining land. This ruling confirms that reclaimed land funded by the government or donors will automatically become private property, potentially complicating efforts to secure international funding for the NAP because donors typically refuse to fund projects that benefit private entities.

RMI’s land-elevation and reclamation strategy also faces significant technological constraints alongside legal and financial barriers. From geotechnical and engineering design perspectives, the atolls comprise narrow, low-lying coral limestone and sand; hence, raising land by several meters requires a large volume of fill and sophisticated geotechnical design to ensure stability and avoid erosion or settlement ¹³⁹. As the goal is to remain above SLR, storm surge, and wave run-up, designs must consider higher elevations, robust coastal protection, and integrated drainage to prevent chronic flooding from rainfall and overtopping. Densely populated urban atolls such as Majuro and Ebeye need to be raised by up to 3–4 m ¹³⁹, making it difficult to sequence phased construction while maintaining essential services, public facilities, and evacuation routes during implementation. Implementation capacity and long-term operability present additional technological risks. Large dredging vessels, heavy machinery, and specialized engineers are largely sourced from overseas, and RMI’s remoteness and limited port capacity tend to inflate project costs and construction timelines. Moreover, the long-term maintenance of elevated land—addressing settlement, erosion, coastal defense repair, and drainage system upkeep—requires technical expertise and financial resources that are not yet fully available domestically. Consequently, post-construction maintenance and operational sustainability remain critical technological uncertainties in the reclamation-based adaptation strategy.

Further technological constraints involve the need to minimize environmental damage; using technology and optimization to reduce the impact on sand movement and reef ecology for planning seawalls, rising lands, and reclamation is essential but challenging. Xue’s study indicates that coastal erosion is mainly caused by human activities, including sand excavation and the construction of causeways, artificial channels, and landfill, among others ¹⁴⁰. Vertical seawalls, protruding landfills, artificial channels, and large wharves are listed as human-induced causes that either block longshore sediment transport or divert sand offshore—reclamation for cargo wharves and fuel depots has eliminated the space on reef flats where sand could otherwise accumulate ¹⁴⁰. Since World War II, low-cost aggregates have been excavated, mainly from beaches and reef flats along the eastern lagoon coast, to build runways, causeways, wharves, and housing, significantly reducing the supply of sand to the lagoon shore ¹⁴⁰. Further research indicates that the reclamation of reef flats and channels would result in the loss of foraminiferal habitats and create differences in water circulation patterns ¹⁴¹. Osawa et al. show that pier construction and associated human activities on the northeastern reef flat of Majuro degrade communities of large benthic foraminifers, which are key producers of carbonate sand, implying that coastal structures should be designed to minimize disruption to these biological sand factories ¹⁴¹. Additionally, studies on ecosystem-based coastal protection for atoll countries emphasize the role of coral reefs, seagrass, and coastal vegetation as natural buffers, and warn that hard structures such as vertical seawalls can interfere with sediment transport and ecological processes that underpin long-term shoreline stability ¹⁴⁰. Hence, technologies that minimize the risks of coastal erosion and changes to coastal ecology must be considered to reduce existing erosion risks.

RMI’s reclamation plan is constrained by financing challenges. Large-scale land reclamation and elevation projects require extensive capital investment for dredging, material transport, coastal protection structures, and long-term maintenance, which far exceeds the fiscal capacity of the RMI government. The RMI economy is highly dependent on fisheries and external development assistance, particularly grants provided under the Compacts of Free Association. In 2021 (at constant 2021 prices), the RMI received approximately USD 330 million in climate-related development finance in the form of grants, equivalent to approximately 130% of its GDP ¹⁴². According to the Organisation for Economic Co-operation and Development (OECD) data, the World Bank was the largest contributor, accounting for 32% of total financing, followed by the GCF (23%) and Japan (16%) in 2024 ^143,144.

Estimates for implementing the NAP run into several billion USD, making the country heavily dependent on external climate finance and donor support (Table 3). With an investment of USD 250 million, raised land could accommodate approximately 1,300 people under low-density settlement patterns (230 m\(^2\) per person) or up to 12,400 people at high density (25 m\(^2\) per person) ¹³³. Scaling up to USD 2 billion increases the potential capacity to between 10,900 and 100,000 people across the same density range. Land-raising and rebuilding strategies designed to withstand 1 m of SLR, at an estimated cost of USD 800 per m\(^2\), consistently yield approximately twice the usable land area and population capacity compared to designs incorporating revetments for 2 m SLR, which cost around USD 1,500 per m\(^2\) ¹³³. Island-level estimates further underscore the magnitude of financial constraints: elevating individual islets typically requires investments ranging from several hundred million to multiple billions of USD, whereas larger islands may exceed USD 4 billion under higher protection standards ¹³³. These estimates indicate that targeted, high-density consolidation on newly raised land is substantially more cost-effective than the uniform elevation of all existing islands. Nevertheless, even this comparatively efficient approach would depend heavily on sustained external financing and comprehensive long-term planning to ensure economic viability and long-term habitability.

To summarize, the RMI case suggests that conventional seawalls alone are increasingly inadequate as a long-term adaptation strategy in the context of accelerating SLR. While seawalls can provide short-term, site-specific protection, they do not address fundamental constraints such as land scarcity, chronic flooding, freshwater salinization, or the need to sustain urban functions in densely populated atolls such as Majuro. As climate impacts intensify, reliance on piecemeal coastal defenses risks locking the country into escalating maintenance costs, while failing to preserve long-term habitability. Conversely, artificial islands, employing land raising and selective reclamation, offer a more strategic pathway by creating elevated, consolidated spaces that can support housing, infrastructure, and essential services over longer time horizons. These approaches are better aligned with the “right to stay” for Marshallese communities, enabling in-place adaptation rather than displacement. However, their feasibility on the Marshall Islands remains highly constrained due to unresolved land tenure laws, limited technical capacity, ecological risks, and extreme financial requirements. Overall, while engineered land elevation represents a more promising long-term alternative to seawalls, its success depends on substantial governance reform, ecological safeguards, and sustained international financing, rather than engineering solutions alone.

5.1. Country Profile and Climate Vulnerability

Tuvalu is a low-lying atoll country in the central Pacific Ocean, comprising nine inhabited islands with a total land area of approximately 26 km\(^2\) ^145,146. The country is highly vulnerable to SLR, coastal erosion, and flooding ^147,65. Population and infrastructure are heavily concentrated in Funafuti, where land scarcity is a major issue owing to its high population density ^147,65. These geographic and demographic characteristics constrain adaptation options and intensify interest in engineered land-based solutions.

In the case of Tuvalu, “artificial island development” should be understood not as the construction of entirely new, elevated islands akin to Hulhumalé, but rather as a continuum of engineered land interventions, ranging from coastal reclamation and elevation of existing islets to hypothetical future artificial islands.

5.2. Artificial Island Development Prospects

Artificial island construction and land reclamation have emerged within policy discourse as potential long-term adaptation strategies for Tuvalu. Although large-scale, elevated artificial islands designed to host significant population resettlement have not been operationalized, smaller-scale reclamation and elevation initiatives have begun to be implemented. The consideration of engineered land solutions reflects acute constraints faced by this low-lying atoll country, where land scarcity, population concentration, and escalating climate risks intersect to produce profound habitability concerns ⁴⁵. However, it is essential to recognize that discussions of artificial islands in the Tuvaluan context have not progressed to the implementation stage witnessed in other jurisdictions, and their feasibility remains subject to considerable uncertainty.

The rationale for exploring artificial island options in Tuvalu stems from several interrelated factors. With a total land area of approximately 26 km\(^2\) and an average height above sea level of less than 3 m, Tuvalu possesses minimal capacity to accommodate population displacement resulting from coastal erosion, saltwater intrusion, and inundation ^145,146. The capital city, Funafuti, experiences acute land pressure, with more than half of the national population residing on an atoll where habitable land is severely constrained by the surrounding lagoon. Projections of SLR under various emissions scenarios suggest that substantial portions of existing land may become uninhabitable within decades, creating imperatives for adaptation measures that extend beyond conventional coastal protection ⁴².

Land reclamation has been discussed within the government and international development forums as a means of increasing habitable land area, and the TCAP—supported by the World Bank and launched in 2017—represents the most substantial and concrete engagement with engineered land solutions undertaken in Tuvalu to date ¹⁴⁸. TCAP encompasses coastal protection infrastructure, land reclamation, and the elevation of vulnerable areas in Funafuti, with the primary objective of enhancing the resilience of existing settlements rather than creating new artificial island territory ¹⁴⁹. The project involves reclaiming approximately 15 ha of land from the lagoon, raising ground levels to reduce flood vulnerability, and constructing seawalls and revetments to protect critical infrastructure, including government buildings and the hospital ^150,151. TCAP demonstrates that engineered measures, such as reclamation and elevation, can be implemented in Funafuti.

It is important to distinguish Tuvalu’s position from that of nations such as the Maldives, where artificial island construction has advanced considerably through projects such as Hulhumalé ³⁴. The Maldives benefits from greater financial resources, a larger population base, a more developed governance infrastructure, and established tourism revenue streams that have enabled the pursuit of more capital-intensive adaptation strategies ⁶³. Tuvalu lacks comparable economic capacity and institutional resources, rendering large-scale implementation significantly more challenging.

Ecological constraints constitute a key limiting factor in the design of the TCAP, with environmental assessments indicating that lagoon-side reclamation in Funafuti must remain spatially restricted to mitigate unavoidable impacts on marine ecosystems ¹⁵². The financial requirements for creating and maintaining reclaimed land far exceed Tuvalu’s fiscal capacity and would necessitate sustained international support, as evidenced by the TCAP’s multi-million-dollar budget funded primarily through international climate finance ¹⁵³. Furthermore, unresolved questions regarding the status of artificial islands under international maritime law introduce uncertainty about whether such interventions would preserve existing exclusive economic zone entitlements, which constitute a crucial element of national sovereignty and economic viability ¹⁵⁴.

Consequently, while artificial islands and land reclamation remain within the spectrum of discussed adaptation options for Tuvalu, their prospects must be characterized as highly conditional. Implementation would depend upon securing unprecedented levels of climate financing, resolving complex technical and environmental challenges, achieving clarity on legal and sovereignty implications, and maintaining political commitment across extended timeframes. Currently, these engineering solutions represent aspirational possibilities rather than imminent interventions, and their ultimate viability remains uncertain, pending further technical assessments, financial commitments, and international legal development.

5.3. Legal, Technological, and Financial Constraints

As traditional adaptation measures prove insufficient, artificial islands and land reclamation have emerged as potential strategies for maintaining territorial integrity and sustaining habitability. However, these engineering solutions present substantial challenges across financial, governance, technical, and legal dimensions that warrant careful examination.

The financial barriers to implementing artificial island construction and land reclamation in Tuvalu are formidable. Small island developing states (SIDS) typically possess limited fiscal capacity, with narrow revenue bases dependent on fisheries access fees, remittances, and international aid ¹⁵⁵. Land reclamation projects require substantial capital investment, as demonstrated above in TCAP ¹⁵³. For Tuvalu, with a GDP estimated at approximately USD 60 million annually, such expenditure represents an insurmountable burden without extensive external financing ¹⁵⁶.

International climate finance mechanisms, including the GCF and Adaptation Fund, theoretically provide potential funding sources. However, accessing these resources presents considerable obstacles for nations with limited administrative capacity ¹⁵⁷. The competitive nature of funding applications, complex procedural requirements, and lengthy approval processes disadvantage small countries that lack technical expertise in proposal development. Moreover, the prioritization of mitigation over adaptation in global climate finance architecture means that transformative engineering projects may struggle to secure adequate support ¹⁵⁸.

The long-term financial sustainability of reclaimed land presents additional concerns. Maintenance costs for coastal protection structures, ongoing monitoring requirements, and potential reconstruction following extreme weather events create perpetual financial obligations that may exceed the initial construction expenditure over multidecadal timeframes ¹⁵⁹. Without guaranteed sustained funding mechanisms, artificial islands risk becoming stranded assets that further strain national budgets.

These financial constraints intersect with significant governance and institutional challenges. Effective implementation of large-scale land reclamation requires robust institutional frameworks and technical capacity that often exceed the capabilities of small island states. The complexity of designing, tendering, implementing, and overseeing major infrastructure projects demands specialized expertise in coastal engineering, EIA, procurement management, and contract administration—skills that may necessitate extensive international consultancy support, especially in a country with limited economic capacity such as Tuvalu.

Governance challenges also extend to land tenure and customary ownership systems. In many Pacific contexts, including Tuvalu, land is communally held under customary arrangements that complicate state-led development initiatives ¹⁶⁰. Reclamation projects may require negotiation with multiple landholding groups, raising questions about benefit distribution, compensation mechanisms, and decision-making authority. The potential for social conflict over newly created land, particularly regarding ownership rights and access, introduces governance complexities that technical solutions alone cannot resolve.

In parallel with physical adaptation strategies, Tuvalu has begun exploring innovative approaches to sovereignty preservation through digital means. The government’s “digital nation” initiative seeks to establish a virtual presence that could persist even if physical territory becomes uninhabitable, including digitizing government services and cultural heritage and potentially asserting continuing statehood through digital infrastructure ¹⁶¹. However, the governance capacity required to operationalize such novel approaches, including digital infrastructure development, international diplomatic engagement to establish precedents, and coordination with technology partners, represents additional institutional demands on an already constrained public administration. This initiative highlights a divergent adaptation pathway, one that decouples sovereignty from physical territory, implicitly challenging the premise that engineered land solutions are the only means of preserving statehood.

Beyond governance, the technical viability of artificial islands and land reclamation in atoll environments presents equally significant uncertainties. Atolls comprise coral reef structures surrounding lagoons, with limited availability of suitable fill material for reclamation ¹⁶². Extracting sand and aggregate from lagoon floors or reef systems risks damaging critical coastal protection functions and marine ecosystems that provide essential services such as fishery productivity and natural wave attenuation. Importing fill material from external sources escalates costs substantially while introducing additional logistical complexities.

Geotechnical conditions in atoll settings pose engineering challenges for supporting infrastructure and buildings on reclaimed land. The unconsolidated nature of fill material and underlying coral substrates may result in settlement issues, liquefaction risks during seismic events, and limitations on load-bearing capacity for structures ¹⁶³. Ensuring adequate land stability requires careful engineering design, including ground improvement techniques, which further increase project costs.

Coastal dynamics and wave action in exposed atoll environments create ongoing threats to the integrity of reclaimed land. Climate change-induced increases in tropical cyclone intensity, changing wave patterns, and accelerating SLR may overwhelm coastal defense structures designed using historical parameters ¹. The effectiveness of protection measures over 50–100-year timeframes remains uncertain, given the magnitude of projected environmental changes. Furthermore, reclamation that disrupts natural sediment transport processes or alters wave refraction patterns may inadvertently exacerbate erosion elsewhere in these interconnected atoll systems.

Finally, international law and sovereignty considerations introduce additional constraints. The implications of artificial islands for maritime zones and sovereignty under international law present complex challenges. The United Nations Convention on the Law of the Sea (UNCLOS) determines maritime entitlements—including territorial seas, EEZs, and continental shelf rights—based on naturally formed land territory ¹⁹. Art.60, Sec.8 of UNCLOS explicitly states that artificial islands do not possess the status of islands for purposes of generating maritime zones ¹⁶⁴. This provision suggests that constructing artificial islands to replace submerging natural land may not preserve existing EEZ boundaries, potentially resulting in a substantial loss of maritime territory and associated resources.

The question of whether land reclamation on existing natural features maintains maritime entitlements lacks definitive resolution in international law ¹⁶⁵. Although reclamation that augments existing islands may be viewed differently from entirely artificial structures, the proportion of artificial to natural land, changes to baseline determinations, and persistence of habitability remain controversial issues. For Tuvalu, whose EEZ encompasses approximately 750,000 km\(^2\) of ocean containing valuable fishery resources, uncertainty regarding maritime boundary preservation introduces profound concerns about long-term economic viability and sovereignty ¹⁹.

The potential for reclamation to be perceived as illegitimate by neighboring states or the international community presents additional risks. Accounts from disputed maritime regions suggest that alterations to contested maritime features can become politically and diplomatically sensitive, particularly when such actions intersect with unresolved claims under the law of the sea ¹⁶⁶. Although Tuvalu’s circumstances differ fundamentally—as defensive adaptation rather than territorial expansion—establishing international acceptance of reclamation as legitimate climate adaptation requires diplomatic engagement and potentially new legal frameworks.

However, Tuvalu has achieved significant success in securing international financing for land reclamation as an adaptation measure. The TCAP has received substantial funding from the GCF and the World Bank ^148,153, and the 2023 Falepili Union Treaty with Australia provides financial support for adaptation and migration pathways for Tuvaluan citizens ²⁵. In this respect, Tuvalu may be considered more advanced than Kiribati in mobilizing international resources for engineered adaptation, despite its smaller economic base and more constrained institutional capacity. This contrast highlights the significant role of bilateral diplomatic arrangements and successful engagement with multilateral climate funds in enabling adaptation measures that would otherwise be beyond the fiscal reach of small island developing states.

In sum, artificial islands and land reclamation present multifaceted challenges that severely constrain their viability as climate adaptation strategies for Tuvalu. Financial requirements exceed available resources; governance limitations hinder effective implementation; technical feasibility remains uncertain in atoll environments; and international law provides inadequate clarity on the preservation of sovereignty. These interconnected challenges suggest that while engineering solutions may form part of comprehensive adaptation portfolios, they cannot serve as sole solutions to the existential threats faced by low-lying atoll countries.

6.1. Common Challenges and Opportunities

6.1.2. Universal Financial Constraints

The enormous capital requirements for artificial island development represent the most significant shared barrier. As Table 4 illustrates, estimated adaptation costs substantially exceed the fiscal capacities of all four nations. The Maldives faces estimated needs of USD 2–4 billion ⁹⁸, the Marshall Islands requires investments ranging from several hundred million to multiple billions of USD for comprehensive island raising ¹³³, and Tuvalu’s land reclamation projects require resources far exceeding domestic capacity. Even Kiribati’s modest Temaiku proposal would impose a substantial fiscal burden, with reclamation costs alone estimated at approximately USD 273 million, exceeding Kiribati’s annual GDP ¹¹⁶.

The GCF has approved only about USD 1.6 billion for all SIDS combined, representing roughly 12% of its total portfolio, with approximately 44% delivered as debt rather than as grants ⁴⁰. This structural inadequacy in international climate finance constitutes a universal constraint requiring coordinated advocacy and innovative financing mechanisms.

6.1.3. Environmental Trade-Offs

All four nations must navigate the inherent tension between creating climate-resilient territories and protecting the marine ecosystems upon which their economies and cultures depend. Dredging operations physically remove benthic communities and generate sediment plumes that smother corals over wide areas ³⁷. The Maldives’ experience demonstrates that reefs around reclamation sites suffer significantly greater mortality and fourfold increases in sand deposition than undisturbed areas ³⁹. Given that coral reef health directly influences coastal protection and the tourism and fisheries sectors, which are critical to all four economies, this environmental trade-off presents a universal challenge that requires careful site selection and mitigation measures. The Maldives’ experience also reveals governance challenges in environmental protection. Civil society actors have raised concerns about the sequencing of EIA procedures relative to project contracting and commencement, and have sought judicial intervention to halt reclamation projects. In one notable case, the Supreme Court overturned a High Court construction halt order on the grounds that suspension would cause “significant losses to the national economy,” illustrating how tensions between development and environmental protection have entered judicial arenas ^97,83.

6.2. Country-Specific Factors

6.2.1. Governance Structures and Land Tenure

Perhaps the most consequential variation among the four nations lies in their governance frameworks and land-tenure systems, which fundamentally shape the feasibility of implementation (Table 5). The Maldives operates under a highly centralized system in which the state retains ownership of most land ⁵⁷, enabling the government to undertake extensive reclamation without complex negotiations. The 2015 constitutional amendment, which created pathways for foreign investment in reclaimed land, further demonstrates this institutional flexibility ¹⁶⁹.

Conversely, the Pacific atoll countries maintain customary land-tenure systems that require extensive community engagement. Kiribati’s Foreshore and Land Reclamation Ordinance (1969) vests state ownership in the foreshore and seabed, with reclaimed land becoming state property, providing some flexibility for adaptation projects. The Marshall Islands presents the most complex case, with its hierarchical Iroij–Alap–Ri-jerbal system embedded in matrilineal clans ^170,59. A particularly acute governance challenge has emerged: a fundamental legal conflict between the Constitution, which authorizes government land acquisition for public purposes, including reclamation (Art. II, Sec.5), and Sec.105 of the 2008 Public Lands and Resources Amendment Act, which automatically vests reclaimed land in adjacent private landowners. In January 2026, the High Court upheld this statutory provision, ruling that land created through government-funded reclamation becomes private property. This legal uncertainty directly undermines the ability to structure international climate adaptation investments, as donors typically require funded projects to serve public rather than private purposes ^138,171,172. Tuvalu’s Falekaupule system grants traditional assemblies substantial influence over local development decisions ⁶¹, requiring consensus-building processes that may slow but potentially strengthen community ownership of adaptation initiatives.

6.2.4. Population Dynamics and Spatial Constraints

Demographic pressures and migration patterns differ significantly across the four nations. The Maldives faces acute urban concentration, with more than 250,000 residents on the central island of Malé, which is less than 6.8 km\(^2\) ¹⁷⁹ (the administrative area of Malé City is approximately 8.3 km\(^2\); see Section 1.1.3 and Table 1), creating immediate pressure for population dispersal that artificial islands can address. Similarly, South Tarawa in Kiribati experiences densities exceeding 3,500 persons per km\(^2\), with the most congested areas such as Betio reaching over 8,000 persons per km\(^2\) ¹⁰⁴. Majuro in the Marshall Islands also faces severe population concentration with more than 20,000 residents ¹²⁷.

The Marshall Islands presents a unique migration dynamic: approximately one-third of the Marshallese population already resides in the United States under Compact provisions ¹⁸⁰, yet community consultations have revealed strong preferences for territorial preservation, underscoring the political imperative for in situ solutions ¹²⁵. As detailed in Section 6.2.2, Tuvalu’s 2023 Falepili Union Treaty with Australia combines a structured migration pathway with an explicit commitment to supporting in situ adaptation ²⁵. The Tuvaluan government’s policies explicitly emphasize support for residents choosing to remain, reflecting a dual-track approach that balances migration facilitation with territorial preservation. This model merits attention from other atoll countries seeking to provide population security without abandoning sovereign territory.

6.3. Regional Cooperation Potential

6.4. Synthesis: Toward a Comparative Framework

The comparative analysis reveals that artificial island feasibility varies substantially across the four nations based on the interaction of multiple factors (Table 7). The Maldives demonstrates the highest near-term feasibility due to favorable governance structures, established institutional capacity, proven technical experience, and relatively stronger economic capacity. Tuvalu has achieved important early implementation progress and benefits from international partnerships, though financial constraints remain binding. Kiribati possesses some institutional flexibility through state foreshore ownership but faces technical constraints and lacks bilateral support arrangements that benefit other nations. Despite developing the most comprehensive long-term planning framework, the Marshall Islands faces the most significant governance complexity and accordingly envisions the longest implementation timeline.

These variations suggest that no single model is suitable for all atoll countries. Rather, country-specific approaches calibrated to local governance systems, technical conditions, financial access, and community preferences offer the most promising pathway. Regional cooperation can nonetheless enhance collective advocacy, facilitate knowledge transfer, and potentially unlock financing mechanisms that are unavailable to nations acting alone.

7.1. Summary of Key Findings

The Maldives’ experience with Hulhumalé (approximately 430 ha at 2 m elevation) and Tuvalu’s TCAP (approximately 15 ha) demonstrate that artificial island construction is technically achievable in atoll environments. Hydraulic fill methods using lagoon-sourced sediments have proven effective, although sediment availability varies by location. Site investigations for Kiribati’s Temaiku project identified limited suitable lagoon sediments as a constraint.

Governance structures critically determine implementation prospects. The Maldives’ centralized state land ownership enables rapid project execution, as demonstrated by HDC’s management of Hulhumalé. Conversely, customary land-tenure systems in Pacific nations require complex negotiations. The Marshall Islands faces a particularly acute barrier: the legal conflict between constitutional provisions authorizing government land acquisition and the 2008 statute vesting reclaimed land in adjacent private owners directly undermines international climate finance eligibility.

Financial requirements represent the most significant shared barrier. Estimated adaptation costs—USD 2–4 billion for the Maldives, USD 273 million for Kiribati’s Temaiku reclamation alone, and up to several billion of USD for the Marshall Islands’ phased land raising—vastly exceed domestic fiscal capacities. GCF has approved only approximately USD 1.6 billion for all SIDS combined, with 44% delivered as debt rather than as grants. The withdrawal of New Zealand government funding for the Temaiku project in 2021 illustrates the vulnerability of transformative adaptation initiatives to external decision-making.

All four nations must navigate the tension between creating climate-resilient territory and protecting coral reef ecosystems. Dredging operations physically remove benthic communities and generate sediment plumes that damage corals. In the Maldives, reefs around reclamation sites have suffered significantly greater mortality than those in undisturbed areas. This trade-off is particularly consequential, given that coral reefs provide natural coastal protection and support tourism and fisheries sectors, which are critical to all four economies.

UNCLOS Article 60 establishes that artificial islands cannot generate territorial seas or exclusive economic zones. All four nations face uncertainty regarding the long-term status of maritime zones as sea levels rise and natural baselines shift or disappear. These unresolved questions have profound implications for sovereignty and resource access.

7.2. Country-Specific Conclusions

The Maldives has demonstrated the highest implementation capacity, with more than five decades of reclamation experience and approximately 2,500 ha created by 2020. Hulhumalé represents a successful model of climate-resilient urban development, although the environmental impacts on the surrounding reef systems and governance challenges in environmental oversight remain concerning.

Kiribati has evolved from a strong rejection of hard structural solutions in early adaptation frameworks to the endorsement of “bold and innovative engineering solutions” in the 2019 KJIP. The Temaiku project offers transformative potential for South Tarawa’s overcrowding and climate vulnerability but faces technical constraints from limited sediment availability and dependence on external financing.

The Marshall Islands has developed the most comprehensive long-term planning framework through its NAP, with a phased pathway extending to 2150. However, the unresolved legal conflict over reclaimed land ownership presents a fundamental barrier that must be addressed before large-scale implementation can proceed. The NAP envisions transformative interventions beginning only around 2070.

Tuvalu has transitioned from planning to early implementation through TCAP, demonstrating that engineered land solutions can be realized even in the most resource-constrained contexts when international support is secured. The project’s successful reclamation of approximately 15 ha provides proof-of-concept for future phases, although financial and institutional constraints remain binding.

7.3. Overall Assessment

Artificial island development can serve as an effective climate adaptation strategy under specific conditions: clear legal frameworks for land acquisition, availability of suitable sediment sources, access to international climate finance, effective environmental mitigation, and community acceptance. The four nations occupy distinctly different positions along the implementation continuum, with feasibility determined by the interaction between governance capacity, technical conditions, and financial access.

The “right to stay” concept provides the unifying policy foundation across all four nations. Political leaders have consistently rejected external migration as a primary adaptation strategy, emphasizing sovereignty, cultural continuity, and the right to remain in ancestral homelands. Artificial island development, despite its costs and complexities, offers a pathway to honor this commitment.

However, engineering solutions alone cannot address the existential threats faced by atoll countries. Successful implementation requires integrated governance reform, sustained international financing at scales far exceeding current commitments, and careful environmental management to avoid undermining the natural coastal protection systems upon which these nations also depend.

7.4. Limitations and Future Research

This review focuses on technical, financial, legal, and governance dimensions of artificial island development. Several areas warrant further investigation: the long-term social and cultural implications of population relocation to artificial islands; the effectiveness of environmental mitigation measures over decadal timescales; evolving international legal frameworks for climate-affected states; and comparative cost-effectiveness of artificial islands versus other transformational adaptation options.

The question that the international community faces is not primarily whether artificial islands are technically feasible—the Maldives has demonstrated that they are—but whether sufficient resources and political will can be mobilized to support this transformational adaptation at the required scale. For atoll countries that assert their right to stay, the answer has existential implications.

If, however, the international community is unable or unwilling to mobilize the resources required for in situ adaptation at the necessary scale, the consequences will extend beyond the atoll countries themselves. Countries across the Pacific Rim and other regions may ultimately be compelled to determine the number of climate migrants they are willing and able to accept. This question has profound implications for international solidarity, burden-sharing, and the future of climate justice. The Falepili Union Treaty between Tuvalu and Australia may represent an early precedent for such arrangements. However, the potential scale of climate-induced displacement from vulnerable coastal and island communities worldwide would require responses of an entirely different magnitude.