Rising sea to swallow 50% of Tamil Nadu's mangroves by 2100
The estimated carbon storage of Muthupet mangrove region at present is 4.74 Tg C (teragrams of carbon), which may be reduced to 2.46 Tg C under the high emission scenario.
Loss of mangroves can threaten coasts with flooding, storm surges, etc.
CHENNAI: Pichavaram and Muthupet, the two largest and most important mangrove ecosystems in Tamil Nadu - will lose more than 50 per cent of their present extent by 2100 under the high emission scenario, leaving the coastal areas vulnerable to coastal floods, storm surges, and cyclones.
According to a study conducted by researchers from various institutions, including IIT-Delhi, the total area of mangroves in 2022 was 4,959.45 hectares in Muthupet mangrove region and 708.48 hectares in Pichavaram. But this is projected to shrink to 2,577.78 hectares and 295.20 hectares by 2100 - 48.02 per cent and 58.33 per cent loss, respectively.
"Between 2022 and 2100, an estimated 413.28 hectares and 2,381.67 hectares of mangrove forest (of Pichavaram and Muthupet) will be degraded or lost through different natural and anthropogenic causes. However, sea level rise (SLR) due to increasing temperature and melting glaciers is perhaps the fundamental issue in determining the survival of the mangroves in tidal environments," the study said.
Apart from putting coastal areas at risk, the loss of mangrove cover will also negatively affect carbon fluxes in the regions due to damages to above-ground biomass (AGB - the total amount of living and dead plant matter above the ground).
The estimated carbon storage of Muthupet mangrove region at present is 4.74 Tg C (teragrams of carbon), which may be reduced to 2.46 Tg C under the high emission scenario. The figure for Pichavaram mangrove region is an estimated 0.67 Tg C presently, which may decline up to 0.28 Tg C.
Losing this storage from these major two mangrove regions due to sea level rise will further accelerate the local climate change, the study warned.
"The reduction of mangrove patches not only increases the coastal exposure of this region but also reduces the habitat for many endangered species, directly or indirectly impacting the livelihood opportunities of the local forest-dependent communities," the study added.
Overall, more than half of the coastal area in Tamil Nadu is under high to very high exposure to vulnerability, while approximately 10 per cent of the area is under very low exposure. The remaining coastal stretch has been recorded as a medium to high exposure index.