Mangroves of Sunderbans to be Drowned by 2100

Gautam Kumar Das

Sunderbans, the largest mangroves forests in the world covering areas of India and Bangladesh for more than 80 km in forming Sunderbans National Park, is declared a World Heritage Site by UNESCO in 1987. The present mangroves forest areas of its Indian part is 2108.11 sq km recorded by Indian State of Forest Report, 2019. Other than the Sunderbans, mangroves forests are found in 118 counties and territories in the tropical and subtropical regions of the world. The largest percentage of mangroves can be found between 50N and 50S latitudes. Approximately 75% of world’s mangroves are found in just 15 countries, though over the past two decades alone, almost 100,000 hectares, or 6% of the world’s mangrove forests have been lost due to deforestation either for agricultural purposes or for aquaculture practices. Other than such anthropogenic interference for loss of mangrove forests, scientists have found that the mangrove cannot exist in seas rising faster than about 7 mm/year according to a paper published in Science, 5 June, 2020 related to the mangroves, climate change and sea level rise.

The Intergovernmental Panel on Climate Change (IPCC) states that the present rate of global sea rise is 3.4 mm/year, but this rate of sea level rise is projected to 5 mm/year by 2030 and 10 mm/year after a few decades and up to 2100 as depicted in the published paper. And that’s the reason for which the salt-tolerant mangroves forests known for managed to keep pace with rising sea level could drown by 2100 due to rapid sea level rise globally.

Mangroves forests provide a valuable buffer to the communities inhabiting in the coastal stretch against ravaged storm surges due to cyclonic storms off and on, safe nursery ground for estuarine and coastal fin fish and shell fishes and helps declining the carbon dioxide level of the atmosphere by storing it as blue carbon in its substrate sediments. Blue carbon refers to carbon dioxide removed from the atmosphere by the world’s estuarine and coastal ecosystems, mostly mangroves, salt marshes, sea grasses and potentially macro-algae, through plant growth and the accumulation and burial of organic matter in soils. Blue carbon is the carbon captured and stored in ocean and coastal ecosystems. It’s blue because it is formed underwater. Mangroves can store up to five times the carbon of trees on land, provide habitats for wildlife, and boost fisheries at its surroundings.

The blue carbon in these unique ecosystems is vital for tackling climate break down, but they are under threat. Mangroves forest serves as the blue carbon storage since its appearance on a time period in between 10000 - 7000 years before present (BP) when the rate of sea level rise has become gradually slower. Before than that the sea level rise was at the rate of 12 mm/year due to melting of ice just after the peak period of ice age in between 26000 - 20000 years before present (BP). Mangroves are found to be abundantly occurred in between 8600 - 6000 years BP and are in rapid expansion globally since then - the scientists stated in their paper. The researchers predict that the mangroves could not grow if the rate of sea level rise is declined to an average 6.1 mm/year globally. In next 30 years, the rate of sea level rise will be accelerated to 6 to 7 mm/year if the present rate of greenhouse gas emissions continues.

Even in May, 2020, the amount of carbon dioxide in the air hit an average of slightly greater than 417 ppm. This is the highest monthly value ever recorded, and is up from 414.7 ppm in May of 2019 as per readings from the Scrips Institution of Oceanography and the National Oceanic and Atmospheric Administration (NOAA). Earth’s carbon dioxide levels hit record high, despite corona virus-related emissions drop in recent times. At present, the average concentration of carbon dioxide in the atmosphere is 417 ppm. The average concentration of carbon dioxide has been accelerated in every decade recorded by the United Nations Climate Change, a branch of the United Nations.

2000 - 369 ppm
2010 - 388 ppm
2020 - 417 ppm
2030 - ?

The existence of mangroves in the world’s coastal and estuarine ecosystems including the Sunderbans depends on the rate of sea level rise due to global warming that causes ice sheets to melt and sea water to rise rapidly. Again, global warming depends on the rates of the greenhouse gas emissions. If it is not cutting of the emissions of greenhouse gases, and rapid expansion of sea level, mangroves of the Sunderbans could drown and unable to keep its existence by 2100. This planet earth is like our mother, mother loves us, let’s love her back protecting mangroves forests, its biodiversity, species diversity and ecosystem services. Mangrove ecosystem is the only place on the earth where trees thrive in ocean water. It’s really an enchanting forest and love it. Mangrove forests stand by the sea beyond the blue, a guide to the philanthropists and change-makers which is well described by the Global Mangrove Alliance.

When I look in the water all I see is trees
When I look at the trees all I see is water

Jun 18, 2020

 Gautam Kumar Das

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