The Earth's mangroves could end up emitting 500 times more carbon by the end of the century, study warns

The Ocean Agency — a nonprofit aimed at protecting the oceans — has coronated our mighty mangroves with the title of the world’s most important trees. And while this might seem like a very hefty title to bear, the trees are quite excellent at tirelessly living up to it.

Despite covering a mere 0.1% of Earth's surface, mangrove forests play a critical role in regulating pretty much everything you can think of. These unique ecosystems nurse three-quarters of the world’s tropical fish and provide a safe haven for many critically endangered species, including our national animal, the Bengal Tiger. In addition, our stilted hard-workers are up to ten times better than other land-based forests in skimming atmospheric carbon!

However, their ability to act as vital and massive carbon sinks, particularly in their soil, has led to some unfortunate consequences. A recent study predicts that as these forests degrade, they could release a staggering 500 times extra carbon annually by the end of the century. This means that the current levels of 7 teragrams of mangrove-related carbon emissions could spike to 3,392 teragrams — or 3,392 crore tonnes — by 2100.

As usual, this alarming rise can be attributed to human activities like agriculture, aquaculture, and urbanisation, which have led to the conversion of 158.4 million tons of global mangrove carbon stocks over the past two decades. This loss is equivalent to the carbon emissions from flying the current entire US population from New York to London, the researchers explain.

To delve more into the influence of human settlements on these wetlands, the study examined the link between human population density and soil carbon storage in urban mangrove forests. They found that mangroves near highly populated areas (similar to or more than the current average population density of Gujarat or Andhra Pradesh) store less than two-thirds of soil carbon storage compared to isolated forests.

This is a clear indicator that human activity has significantly altered their ability to sequester carbon. Further, considering mangrove soils contain 3-4 times the mass of carbon usually found in boreal, temperate or tropical forests, and play a gargantuan role in regulating global carbon cycling, something needs to be done to check this emission trend as soon as possible.

The research emphasises the urgent need to protect existing mangroves, especially in densely populated areas like South India, southeastern China, Singapore, and eastern Australia, which are experiencing significant degradation. By acknowledging the impact of human activities on these ecosystems, we can take crucial steps towards safeguarding these irreplaceable carbon stores and ensuring a healthier planet for all.

The findings of this research have been published in Environmental Research Letters.