Climate change is increasingly transforming environmental degradation from an ecological concern into a multidimensional security challenge. This is particularly evident in the Indian Sundarbans, where rising climatic pressures intersect with fragile deltaic ecosystems, livelihood dependence, poverty, population vulnerability and strategic coastal considerations. South 24 Parganas, which contains a substantial part of the Indian Sundarbans, is exposed to cyclones, tidal flooding, coastal erosion, saline-water intrusion, sea-level rise and ecosystem degradation. Recent government assessments identify the coastal districts of West Bengal, including South 24 Parganas, as particularly vulnerable to cyclones and flooding. The district administration has also introduced a District Environment Plan 2025, demonstrating the increasing institutional emphasis on environmental management. this article examines the emerging climate-security nexus in South 24 Parganas through the interconnected dimensions of environmental security, human security, livelihood resilience and coastal governance. It analyses how climatic hazards affect agriculture, fisheries, freshwater availability, public infrastructure, migration and vulnerable households. The article further examines the role of mangrove ecosystems as natural protective infrastructure and evaluates the importance of integrated coastal-zone management, early-warning systems, ecosystem restoration and livelihood diversification. Recent initiatives concerning climate-resilient livelihoods and community-based adaptation are also considered. The article argues that environmental security in South 24 Parganas requires a shift from disaster-response-oriented governance towards anticipatory, ecosystem-based and community-centered resilience planning. Strengthening cooperation among government institutions, scientific organisations, local communities and civil society is essential for protecting both ecological integrity and human security in the Indian Sundarbans.