Blue Carbon: Offsetting Carbon Emission by Conserving Coastal Vegetative Ecosystems

 / Research / In-House /FTR/ Blue Carbon: Offsetting Carbon Emission by Conserving Coastal Vegetative Ecosystems

The Project

Coastal vegetated ecosystems namely marshes, mangroves, and seagrass, termed “blue carbon”, are well known for their effective high rates of annual carbon sequestration and the storage of the sequestered C on longer time scales. Coastal ecosystems are well known for the efficient C sequestration and storage capacity and could effectively mitigate the increase in atmospheric greenhouse gas(GHG) concentration.

The need of a comprehensive database on blue carbon sequestration and GHG emission from the ecologically important coastal ecosystems in India was felt while developing the climate change adaptation and mitigation strategies. While creating a national GHG database from published literatures, an inconsistency in the methodology for quantification of GHG fluxes from the coastal wetlands were observed which were difficult to compare. Furthermore, the mangroves of East coast of India was well studied as compared to West Coast. There were no reported studies from Indian seagrass ecosystems related to GHG emissions.

Hence, the project was conceived with dire need to assess the GHG source/sink potential of coastal wetlands using a universal methodology. This would lead to development of a national database on GHG emissions from blue carbon ecosystems underlying their significance towards their role in mitigating regional/ global climate change.

Keywords

Blue carbon ecosystem

Greenhouse gas flux

Carbon stock

Mangroves

Seagrass

National GHG Inventory

Total sediment carbon stock (top 1 m) in mangroves of

India is ____ Mg/ha

Aim

Developing a comprehensive database on GHG emissions and carbon stocks from the ecologically important coastal (mangroves, seagrass) ecosystems of India and determine their source-sink characteristics.

Objectives

  • Quantifying GHGs fluxes from blue carbon ecosystems (Mangroves, Seagrass)

  • Understanding the factors inducing GHG release from these ecosystems

  • Determining the species-specific GHG emissions

  • Quantification of sediment organic carbon stocks from Blue carbon ecosystems

  • Preparation of a National Inventory of GHG emissions from Blue carbon ecosystems using a uniform methodology

Key Findings

State-wise % contribution of CO2 fluxes from mangrove ecosystems

Annual mean CO2 fluxes varied from 11 to 101 mol m-2 y-1 in the mangroves of West coast and 5 to 84 mol m-2 y-1 in the East coast mangroves. Relatively higher annual mean flux was found in the east coast mangroves (53 mol m-2 y-1) than west coast mangroves (34 mol m-2 y-1), Highest GHG fluxes were observed from thane mangroves (101 mol m-2 y-1).

Total CO2 emission (in terms of CO2 equivalents) from Indian mangroves was ~5020 Gg CO2e y-1 with more than 60% contribution from east coast.

State-wise % contribution of CH4 fluxes from mangrove ecosystems

The annual mean dissolved CH4 concentrations in the east and west coast, mangrove waters ranged between ~18 to 108 nmol L-1 and ~14 to 104 nmol L-1, respectively.. The annual CH4 fluxes from Indian mangrove waters ranged between ~0.01 to 0.12 mol m-2 y-1, with an average of 0.05 mol m-2 y-1. Total CH4 emission (in terms of CO2 equivalents) was ~88 Gg CO2e y-1 with more than 60% contribution from east coast.

Total Sediment Carbon Stocks (Mg C ha-1) from Indian Mangrove Ecosystems

For Indian mangroves, the total sediment carbon stock is estimated as ~ 41.5 Tg C. Andaman mangroves were estimated to contain 13.8 Tg C whereas in mainland coast, Sundarbans ( 8.7 Tg C) in east coast and Gujarat Mangroves (7.7 Tg C) in the west coast has the highest sediment carbon stock. In addition, the mean sediment carbon content per unit area is high in mangroves of west coast as compared to east coast of India, which can be attributed to degree of anthropogenic influences.

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