The Sundarbans, located within the Ganges–Brahmaputra–Meghna delta and spanning nearly 10,000 km², is the world’s largest continuous mangrove forest and a UNESCO World Heritage Site as well as a Ramsar wetland of international importance. It serves as a natural buffer against cyclones, storm surges, and sea-level rise, while supporting rich biodiversity, including the Royal Bengal tiger, estuarine crocodiles, river dolphins, and over 300 bird species. Millions of people in both Bangladesh and India depend on its fisheries, forestry resources, and ecosystem services for their livelihoods, making the Sundarbans an ecological and socio-economic lifeline for the region. However, the Sundarbans is undergoing rapid ecological deterioration driven largely by climate change. Rising sea levels in the Bay of Bengal, intensifying cyclones, saline intrusion, and widespread erosion have caused significant habitat loss—estimated at over 210 km² since the 1960s. Severe storms such as Cyclone Amphan in 2020 caused devastating environmental and economic damage, highlighting the extreme vulnerability of both the ecosystem and surrounding communities. These climatic pressures threaten biodiversity, food security, cultural heritage, and the long-term viability of human settlements across the region.

Compounding these climate-related threats are industrial developments, most notably coal-based thermal power plants situated near the Sundarbans. The 1320 MW Rampal coal-fired power plant in Bangladesh—located only 14 km from the forest—has drawn widespread criticism for its potential to release mercury, coal ash, sulfur and nitrogen oxides, and other pollutants into the air and river systems (Figure 1, Figure 2). Conservation bodies including UNESCO and IUCN have warned that increased dredging, shipping activities, and pollution associated with such projects pose serious risks to the Outstanding Universal Value of the Sundarbans. Despite environmental restrictions in India on establishing coal plants near ecologically sensitive areas, comparable protective frameworks remain weak or absent in Bangladesh.

Figure 1. Rampal power plaint [1].

This situation underscores the significance of international environmental law as a framework for safeguarding vulnerable ecosystems. Bangladesh, as parties to the United Nations Framework Convention on Climate Change (UNFCCC), the Paris Agreement, and the Convention on Biological Diversity (CBD), are obligated to reduce emissions, protect biodiversity, and ensure the sustainable management of critical habitats. Additionally, their commitments under the Ramsar Convention and UNESCO World Heritage regime impose duties to preserve the ecological integrity and Outstanding Universal Value of the Sundarbans. Principles of customary international environmental law—including the no-harm rule, the precautionary principle, and the obligation to conduct environmental impact assessments—further reinforce these responsibilities.

Figure 2. Location of Rampal from Sundarbans area [2].

Against this backdrop, this article examines the legal obligations of Bangladesh under key international environmental agreements in relation to climate impacts and industrial activities near the Sundarbans. It evaluates whether projects such as the Rampal thermal power plant align with these commitments and assesses how international legal standards can guide stronger conservation and regulatory practices. Through this analysis, the paper seeks to clarify the extent to which global environmental norms can—and should—shape national decisions affecting the future of one of the world’s most critical and fragile ecosystems.

This study employs a doctrinal legal research methodology, the primary method for examining the development, interpretation, and application of international environmental law. Doctrinal analysis enables a systematic examination of legal rules, principles, and obligations contained in treaties, case law, and authoritative scholarship. It is particularly suitable for assessing state responsibilities concerning the protection of ecologically sensitive areas such as the Sundarbans.

The research focuses on the international legal commitments of Bangladesh with particular attention to how these obligations apply to climate risks and the establishment of thermal power plants near the Sundarbans. The United Nations Framework Convention on Climate Change (UNFCCC), the Paris Agreement, the Convention on Biological Diversity (CBD), the RamsarConvention, and the World Heritage Convention, have been used as research corpus in this study to identify binding duties relevant to the conservation of the area.

The study also evaluates foundational principles of international environmental law—such as the precautionary principle, the no-harm rule, the obligation to conduct environmental impact assessments, and the principle of sustainable development. Through this approach, the methodology provides a rigorous legal framework for understanding the obligations of Bangladesh in safeguarding the Sundarbans.

The Sundarbans, stretching across coastal Bangladesh and India, is the world’s largest mangrove ecosystem and holds dual recognition as both a UNESCO World Heritage Site and a Ramsar wetland [3]. Home to Bengal tigers, freshwater dolphins, estuarine crocodiles, and countless other species, the forest provides extensive ecological services and substantial carbon storage—an estimated 56 million metric tons valued at USD 280 million annually [4]. More than 3.5 million people in Bangladesh depend directly on its fisheries, timber resources, and ecosystem goods for their livelihoods [5]. The Sundarbans therefore represents both an ecological stronghold and an essential socio-economic resource.

Climate change has sharply intensified risks to the region. Rising sea levels, altered freshwater flows, stronger cyclones, and increasing salinity are accelerating land degradation [6]. Model projections indicate that a sea-level rise of 88 cm could drastically reduce mangrove habitat and significantly diminish forest productivity [7]. The IPCC estimates that a 10 cm sea-level rise alone may result in the loss of 15% of the Bangladesh Sundarbans (approximately 750 km²), with severe consequences for biodiversity, livelihoods, and ecosystem stability [8]. UNESCO assessments further highlight that upstream water withdrawals have reduced freshwater inflow, increasing salinity and siltation and disrupting ecological balance [9]. Combined with repeated cyclones and habitat destruction, these trends pose long-term threats to both wildlife and human communities [10].

These climate threats are compounded by controversial industrial expansion, particularly coal-fired power generation near the forest [11]. Bangladesh is developing two major coal plants—Rampal (Maitree) and Orion—within 15 km of the Sundarbans [11][12]. The 1,320 MW Rampal plant, a Bangladesh–India joint venture, is the most advanced [13]. Scientists, local communities, and UNESCO warn that these developments risk forest destruction, community displacement, and widespread pollution [14]. A 2016 UNESCO–IUCN mission identified Rampal as a critical threat due to coal-ash emissions, wastewater discharge, increased shipping, dredging, and rapid industrialization [15]. Independent studies corroborate these findings: Greenpeace (2016) projects a 25% rise in regional NO₂ and a 50% rise in SO₂, potentially causing thousands of premature deaths and increased low-birth-weight cases. Mercury contamination affecting 70 km² of the Sundarbans watershed may render fish unsafe for consumption [16]. Overall, the Rampal project poses significant risks to air quality, water systems, and public health [17]. These developments also contradict scientific assessments showing that Bangladesh—one of the world’s most climate-vulnerable nations—is simultaneously planning substantial CO₂ increases by 2030 [18].

Environmental degradation has direct socio-economic consequences. The Sundarbans supports vital fisheries, honey production, timber extraction, and other forest-based livelihoods [13]. Over one million seasonal workers depend on these resources. Pollution and habitat loss threaten these economic activities, exacerbating food insecurity and poverty [19]. Research shows that land acquisition for the Rampal project has disproportionately harmed smallholders and landless workers, leading to displacement and heightened socio-economic vulnerability [20][21]. Communities in the area already experience respiratory illness and toxic exposure from coal-related pollutants [22], compounding existing climate-induced hardships.

These concerns extend beyond national borders. As a World Heritage Site and Ramsar wetland, the Sundarbans enjoys international legal protection due to its global significance [7]. Scholars argue that cross-border pollution from Rampal may violate the non-harm rule under Article 6(3) of the World Heritage Convention, as emissions could affect the Indian Sundarbans [23]. Bangladesh has also been criticized for failing to conduct a comprehensive cumulative impact assessment, as required for managing development affecting heritage values [12]. UNESCO monitoring missions have repeatedly urged Bangladesh to secure adequate freshwater flow for the Sundarbans and undertake strategic environmental assessments for industrial projects [9]. While Bangladesh’s Environmental Conservation Act designates a 10-kilometre Ecologically Critical Area around the forest, numerous industries continue to operate within this zone due to regulatory weaknesses and economic pressures [13].

The crisis confronting the Sundarbans illustrates the complex intersection of environmental protection, human rights, climate justice, and sustainable development. It exemplifies the broader challenge of balancing economic growth with the protection of irreplaceable ecosystems—an issue that resonates globally. As a test case for international environmental governance, the Sundarbans demonstrates how legal, policy, and scientific frameworks must converge to safeguard vulnerable ecological and human communities against both climate and industrial threats.

Multiple international treaties protect the Sundarbans mangrove ecosystem because Bangladesh has joined them to enforce binding conservation obligations [24]. The UN Framework Convention on Climate Change (UNFCCC) and the Paris Agreement, together with the Convention on Biological Diversity (CBD), the Ramsar Convention on Wetlands, and the UNESCO World Heritage Convention, require Bangladesh to fulfill specific duties for Sundarbans protection [25]. The Sundarbans faces customary law restrictions through general principles of international environmental law, including the “no significant harm” obligation and the precautionary principle [26]. The following section outlines each treaty and principle together with Bangladesh’s obligations and implemented measures.

Bangladesh has integrated its international environmental obligations into domestic law and policy [52]. The Constitution explicitly mandates environmental protection and biodiversity conservation [53]. The government has designated the Sundarbans as an Ecologically Critical Area (ECA) with buffer zones, enacted strict forest protection laws, and developed disaster management plans to address cyclone impacts [54].

The Biodiversity Act (2017) operationalizes the obligations of the Convention on Biological Diversity (CBD) and the Nagoya Protocol on access and benefit-sharing [33]. The Sundarbans Reserve Forest is legally protected under the Ramsar and World Heritage Conventions, with Bangladesh submitting regular ecological reports [41]. The National Climate Change Policy, along with the forthcoming National Adaptation Plan, underscores Bangladesh’s climate commitments under the UNFCCC, while the updated Nationally Determined Contribution (NDC) pledges a 15% emissions reduction by 2030 [55]. The Environmental Conservation Act (1995) and its subsequent rules embody the no-harm principle, prohibiting activities that could damage ecologically critical areas through pollution or unsustainable development [56].

Bangladesh is thus legally bound to preserve the Sundarbans’ ecosystems, adapt to climate impacts, and prevent transboundary environmental harm in line with climate, biodiversity, wetlands, and heritage regimes [43]. The interplay of treaty obligations and customary principles forms a robust legal framework for sustainable management [57]. These international commitments also provide clear benchmarks to evaluate national policies and projects, despite ongoing enforcement challenges [58].

Bangladesh is a party to multiple international environmental agreements, including the UNESCO World Heritage Convention (1983), Ramsar Convention (1992), Convention on Biological Diversity (CBD, 1994), and the Paris Agreement (2016), reflecting its formal commitment to protecting the Sundarbans [13]. These agreements impose three principal duties on the state: conserving biodiversity, preventing transboundary harm, and integrating environmental protection into development planning [59].

Despite these formal commitments, significant implementation gaps persist. Bangladesh has established legal and policy instruments, including the Environmental Conservation Rules (2023), the Bangladesh Climate Change Strategy and Action Plan, and landmark judicial decisions recognizing environmental rights [18]. Nevertheless, enforcement remains inconsistent. For example, hundreds of projects were approved within the Sundarbans Ecologically Critical Area (ECA) despite the 2023 Strategic Environmental Management Plan (SEMP). Between 2013 and 2023, 320 industrial facilities were authorized within 10 kilometers of the Sundarbans core, violating UNESCO Article 4 requirements to protect Outstanding Universal Values [9]. Although new industrial approvals were eventually suspended in 2025, existing projects continued without adequate safeguards, demonstrating a clear implementation gap.

The 1,320 MW coal-fired Rampal power plant, located 14 kilometers from the Sundarbans World Heritage site, exemplifies this failure. UNESCO World Heritage Convention Articles 5 and 6(3) require integrated planning and avoidance of transboundary harm. Bangladesh approved Rampal without conducting a comprehensive cumulative-impact assessment, violating Article 5 obligations [9]. Scientific evidence from the 2016 UNESCO-IUCN monitoring mission indicates that Rampal’s emissions, coal ash, wastewater discharges, and increased shipping threaten the entire Sundarbans ecosystem, including areas across the Bangladesh-India border [60]. Despite UNESCO recommendations to cancel or relocate the project, Bangladesh proceeded with construction, breaching the transboundary no-harm rule under Article 6(3) [43].

Enforcement mechanisms under international law remain weak. The World Heritage Committee can list threatened sites on the “Danger List” under Article 11(4), but diplomatic delays have limited effective action [14][26]. UNESCO monitoring missions consistently report “serious and specific dangers” to the Sundarbans due to industrialization and hydrological changes, yet recommendations have largely relied on technical progress reports rather than compulsory measures [41].

Under the Ramsar Convention, Bangladesh similarly falls short. Ramsar requires parties to designate important wetlands and establish management plans through public consultation under the “wise use” principle (Articles 2(1) and 3) [61]. Although the Sundarbans was designated a Ramsar site in 1992, enforcement is weak. Illegal activities—including shrimp farming, sand mining, and palm plantations—continue, indicating non-compliance with both Ramsar obligations and the Environmental Conservation Act (2010) [62][63].

CBD obligations are also inadequately implemented. Article 8(a) mandates protected area systems, while Article 8(j) requires protection of indigenous knowledge, and Article 15, together with the Nagoya Protocol, governs benefit-sharing of genetic resources [64]. Bangladesh has expanded the Sundarbans protected area to 317,949 ha by 2017, yet mangrove canopy coverage declined by 50% from 2000 to 2020 [60]. Article 8(j) remains largely unfulfilled, as 6.5 million residents depend on the Sundarbans for livelihoods, yet there are no formal programs documenting traditional knowledge or ensuring community participation in management [65]. Benefit-sharing under Article 15(7) has not been operationalized, and CBD reporting remains superficial due to insufficient funding and institutional capacity [66].

Overall, Bangladesh demonstrates strong treaty participation on paper but struggles with enforcement in practice [64]. The Rampal plant and hundreds of ECA projects illustrate how development priorities often override treaty commitments, undermining precautionary and preventive principles central to international environmental law [67]. Institutional weaknesses, limited funding, political preferences for industrial development, and inadequate agency capacity further constrain compliance [68]. Domestic environmental courts and constitutional public trust obligations have not yet established a systematic defense mechanism for the Sundarbans [41].

In conclusion, while Bangladesh maintains extensive international commitments, actual implementation is inconsistent. Sustainable development remains a formal principle, yet ongoing industrialization and governance deficits prevent treaty obligations from being effectively realized, leaving the Sundarbans vulnerable to ecological degradation [36].

Our analysis demonstrates that, despite multiple legal frameworks, the Sundarbans region remains poorly protected in practice. Bangladesh has ratified numerous international environmental agreements, yet ongoing deforestation, weak implementation of Ramsar “wise use” policies, and projects such as the Rampal coal plant show a persistent gap between formal commitments and actual outcomes. Rampal violates international standards by producing harmful cross-border pollution and threatening cultural and ecological heritage, despite UNESCO recommendations to halt construction. Weak enforcement, reliance on reputational pressure, and non-binding programs have proven insufficient. Institutional constraints, conflicting policies, limited authority of environmental agencies, and financial shortfalls have hindered the practical realization of conservation goals, often prioritizing industrial development and energy expansion over ecological protection.

To address these challenges, policy interventions must integrate environmental, legal, and socio-economic dimensions:

The Sundarbans is both a national treasure of Bangladesh and a global common, serving as the world’s largest mangrove forest, a UNESCO World Heritage site, a critical carbon sink, and a natural shield for coastal communities. Our research demonstrates that, despite Bangladesh’s ratification of multiple international environmental agreements, the country has repeatedly fallen short in translating these commitments into effective protection. The Rampal coal power project exemplifies this failure, as it proceeded near the Sundarbans in disregard of the precautionary and no-harm principles under the World Heritage Convention, causing substantial environmental and transboundary harm. Similarly, Ramsar recognition has not prevented ongoing mangrove degradation, deforestation, or delays in cross-border cooperation with India. These legal gaps are compounded by institutional weaknesses, underfunded agencies, and expired or inadequate environmental reviews.

The urgency for action is both ethical and legal. International law is not merely advisory: conventions such as UNESCO, Ramsar, CBD, the Paris Agreement, and customary rules like the no-harm principle impose mandatory obligations that require implementation. Bangladesh, as a State Party, has a clear duty to ensure that development in the Sundarbans is sustainable, ecologically responsible, and free from harm to neighboring states. The Sundarbans provides critical habitat for tigers and endangered species, buffers communities against cyclones and storm surges, and sequesters significant carbon. Failure to protect this ecosystem constitutes not only a breach of international obligations but also a violation of intergenerational justice.

Our analysis emphasizes that the survival of the Sundarbans depends on fundamental changes in governance, enforcement, and policy. Sustainable development opportunities—including renewable energy, ecotourism, and nature-based coastal defenses—remain attainable, but only if legal frameworks are implemented with dedication and accountability. The international community and future generations will judge Bangladesh by its compliance with treaty obligations and its ability to safeguard this irreplaceable ecosystem. Immediate and decisive action is essential: further delay risks irreversible damage to the Sundarbans and to the global environmental heritage it represents.

First author MD. MOHAIMINUL ISLAM primarily wrote the manuscript. Second author (Corresponding author) MD. MONJUR HASAN prepared it as a research article. Third author SHIJUN ZHANG provided the suggestion and clarified the concept. Fourth author MD. ABU HANIF reviewed the manuscript along with other authors.

During manuscript preparation, the authors used Claude (Anthropic) solely for limited language editing of selected sentences to improve clarity. No AI tool was used to generate research content, analyze data, interpret results, or prepare references. The ideas, arguments, and intellectual contributions of the paper are entirely original. All AI-assisted suggestions were reviewed, revised where necessary, and approved by the authors, who take full responsibility for the final manuscript.