UPSC DAW Mains Answer Writing 2025 1st September
Question
Analyse the implications of sea level rise for coastal ecosystems and evaluate its socio-economic consequences for small island nations. (15 marks, 250 words)
Model Answer
Introduction:
Global mean sea level is rising at an unprecedented rate due to thermal expansion and ice melt; the Intergovernmental Panel on Climate Change projects further rise this century under all emissions pathways. Regionally, the North Indian Ocean has risen ~3.3 mm/yr in recent decades and a new 90-year coral microatoll reconstruction (1930–2019) from the central Indian Ocean records ~0.30 m rise with acceleration beginning in the late 1950s.
Impact of sea level changes on coastal ecosystem
Mangrove Migration and Coastal Buffer Loss:
Rising seas force mangroves landward, but in many areas "coastal squeeze" (urbanisation, embankments) blocks this migration, leading to mangrove dieback.
E.g. The Sundarban contain 45 mangrove species and 21 species of under-canopy vegetation which experienced an annual degradation rate of about 0.114% from 2005 to 2023.
Saltwater Intrusion into Estuaries:
Higher sea levels push saline water upstream into estuaries and freshwater zones, altering the species mix and reducing yields of freshwater/brackish species.
E.g. About 7% of the Indian coast has been affected by saltwater intrusion, and the Chennai coast (14 km) has reported the maximum intrusion.
Vertical growth limitation of reef corals and microatolls:
Rising mean sea level reduces the low-tide exposure window that enables upward skeletal accretion; many microatolls therefore shift to lateral growth or stagnate.
E.g. A 90-year Porites microatoll record from Maldives shows successive growth bands and elevations consistent with progressive upward limitation and a ~0.3 m rise since 1930.
Changes to lagoon and sediment:
Sea-level rise modifies currents and sediment transport within lagoons, causing some islets to erode while others accrete or migrate laterally.
E.g. Satellite-based analyses of Lakshadweep shorelines show decadal shoreline evolution linked to changing sediment dynamics and sea conditions around coral islands.
Local tectonics and heterogeneity:
Where land is tectonically stable, coral records track true sea-level changes; where uplift/subsidence occur, island responses differ markedly.
Impact of rise in sea level on island nations:
Loss of land area and infrastructure exposure:
Narrow, low-elevation islands lose usable land to chronic inundation and coastal retreat, threatening housing, airports and other critical infrastructure.
Freshwater salinization and water insecurity:
Saltwater intrusion into shallow aquifers and wells reduces potable water availability, raising health and livelihood risks.
E.g. Human Rights Watch and national reports note acute freshwater stress in the Maldives, where groundwater and community access to safe water are already strained by sea-level impacts.
Undermines natural coastal protection and fisheries:
Coral bleaching and reef loss reduce fish habitat and the reef buffering capacity, causing reduced catches and higher shoreline vulnerability.
E.g. The Fourth Global Coral Bleaching Event (2023–May 2024) caused severe damage in Lakshadweep, with about 98% bleaching reported on Kadmat, Kavaratti, and Kiltan islands.
Economic disruption of tourism and livelihoods:
Beach loss, reef degradation and repeated flooding degrade tourist appeal and fishery productivity, threatening GDP and employment in island economies.
E.g. Without effective adaptation, 10-year floods by 2050 could damage up to 3.3% of the Maldives’ total assets, causing losses of US$0.7–1.1 billion of GDP.
Rising adaptation costs and fiscal strain:
Small island states face very high per-capita adaptation costs (sea walls, elevation, water systems), often exceeding domestic fiscal capacity.
E.g. The World Bank estimates that adapting to a 0.5-meter sea level rise will cost Kiribati, Tuvalu, and the Marshall Islands a combined $10 billion, a figure equivalent to about 20 years of their combined GDP.
Conclusion:
Policy must combine science, ecosystem restoration, engineering and social safeguards. First, expand monitoring of tide gauges, satellite altimetry calibration and coral microatoll chronologies to refine local projections and early warning. Second, prioritise nature-based solutions like coral reef protection, mangrove/seagrass restoration where feasible, supplemented by targeted, resilient engineering for critical assets. Finally, mobilise scaled finance and international cooperation for climate funds, concessional loans, bilateral support to enable small island states and Indian island territories to implement these measures