Mangroves and Climate Resilience in India: Bio-Shields, Carbon and Coastal Livelihoods

Mangroves and climate resilience are tightly linked in India’s coastal story. India holds roughly 4,992 square kilometres of mangrove cover according to the India State of Forest Report 2023 — concentrated in the Sundarbans, the Bhitarkanika delta of Odisha, the Godavari–Krishna estuaries of Andhra Pradesh, the Pichavaram of Tamil Nadu, the Gulf of Kachchh and the Andaman and Nicobar islands. These salt-tolerant forests stand at the boundary of land and sea, take the first blow of cyclones, store extraordinary quantities of carbon in waterlogged soils, and underwrite the lives of millions of coastal fisher households. Understanding mangroves and climate resilience accurately means understanding three things they do — bio-shielding, livelihood support, and biomass carbon storage — and three things they do not do.

A prelims question on mangroves and climate resilience usually tests whether you can separate the genuine ecosystem services from popular misconceptions.

What Mangroves Are — and Where They Grow

Mangroves are halophytic (salt-tolerant) trees and shrubs that grow in intertidal zones of tropical and subtropical coastlines. They tolerate flooding by saline water twice a day, anaerobic muddy substrate, and high salinity that would kill most other plants. India’s mangroves include genera such as Rhizophora, Avicennia, Sonneratia, Bruguiera and Heritiera. The Sundarbans, shared with Bangladesh, is the world’s largest single mangrove tract and the only one that hosts a population of Royal Bengal tigers.

Specialised adaptations

Mangroves have evolved striking root and reproductive adaptations:

• Pneumatophores — pencil-shaped breathing roots that emerge from the mud to access oxygen.
• Stilt roots — looping prop roots that anchor the tree in soft sediment and dissipate wave energy.
• Vivipary — germination of seeds while still attached to the parent tree, producing dart-shaped propagules that float to new mudflats.
• Salt-secreting leaves — that excrete excess salt through specialised glands.

These adaptations are why mangroves can exist in environments no terrestrial forest can.

Three Genuine Functions: Why Mangroves Build Climate Resilience

1. Bio-shield against cyclones, storm surges and tsunamis

The dense, multi-layered root network of a mangrove forest dissipates wave energy and reduces the height and inland reach of storm surges. After the 1999 Odisha super cyclone and the 2004 Indian Ocean tsunami, evidence accumulated that villages behind intact mangrove belts suffered substantially lower damage to life and property than villages with degraded or absent mangroves. Studies of the Bhitarkanika–Kendrapara belt show that mangrove vegetation can reduce wave energy by up to 70 per cent over 100 metres of forest.

This is the most direct way that mangroves and climate resilience operate together — and it is the function being intensified by climate change as cyclone frequency and surge heights rise.

2. Livelihood support for coastal communities

Mangroves underwrite a large fisheries and non-fishery economy. They are nursery habitats for fish, prawns, crabs and molluscs; they support honey collection, fuelwood, fodder, thatch, and medicinal plants; and they are critical to the eco-tourism economy of Sundarbans, Bhitarkanika and Pichavaram. Estimates by the World Bank and IUCN place the value of mangrove ecosystem services in the Indian context at thousands of dollars per hectare per year, far above the value of converted shrimp ponds or paddy fields over the same period.

3. Blue carbon storage in biomass and sediment

Mangroves are one of the most carbon-dense terrestrial ecosystems on the planet. They store carbon in living biomass (above and below ground) and, more dramatically, in waterlogged anaerobic sediments that can hold organic carbon for centuries. Per hectare, mangrove carbon stocks can exceed those of tropical rainforests by a factor of three to four. This is the original meaning of “blue carbon” — coastal carbon held by mangroves, salt marshes and seagrass meadows.

What Mangroves Are NOT

A clear common confusion is to attribute to mangroves the services of other ecosystems.

Mangroves are not freshwater storage systems

Mangroves grow in saline-brackish water; they tolerate it but do not desalinate or store fresh water for drinking, irrigation or aquifer recharge. That function belongs to inland wetlands such as lakes, ponds, oxbows and floodplain marshes.

Mangroves are not paddy fields

Rice cultivation needs fresh water; mangroves grow in inundated saline mudflats. Some coastal communities have, historically, attempted to convert mangroves to paddy by building bunds — almost always with poor agricultural outcomes and significant ecological damage, particularly in the Sundarbans.

Mangroves do not support freshwater aquaculture

Freshwater aquaculture — for species such as rohu, catla or freshwater prawns — requires non-saline water. Mangroves support brackish-water fisheries (mud crabs, mullets, milkfish, tiger prawns). The popular confusion between “aquaculture in mangrove zones” and “freshwater aquaculture” is exactly the kind of trap UPSC sets in multi-statement questions.

When a question lists “freshwater storage, paddy cultivation and freshwater aquaculture” as mangrove functions, the correct answer is that none of those are mangrove functions — only the bio-shield, livelihood and biomass-carbon roles are.

Threats to Indian Mangroves

• Conversion to shrimp aquaculture, salt pans and ports. The most damaging driver in the past three decades.
• Sea-level rise and salinity intrusion that exceed the natural migration rate of mangrove forests inland.
• Cyclone damage that, when superimposed on degraded forests, prevents recovery.
• Pollution from industrial effluents and untreated urban sewage.
• Reduced freshwater and sediment supply from upstream dams and barrages, particularly affecting the Sundarbans.

Policy Architecture

• Coastal Regulation Zone (CRZ) notifications classify mangroves under CRZ-IA, the most restrictive category.
• MISHTI (Mangrove Initiative for Shoreline Habitats and Tangible Incomes) was announced in the Union Budget 2023–24 to restore mangroves on 540 sq km across nine coastal states and three UTs by 2027–28, blending CAMPA, MGNREGS and other funds.
• Mangrove Alliance for Climate, launched at COP27 by the UAE with India as a partner, mobilises international finance and knowledge-sharing for mangrove protection.
• State-level mangrove cells in Maharashtra, Gujarat and Odisha drive on-ground action.
• Wildlife (Protection) Act, 1972 protects mangrove flora and fauna inside notified sanctuaries and national parks.

Frequently Asked Questions