Will wetlands help us cope?
Wetlands, as we know, are picturesque locations with lush green paddy fields and beckoning backwaters with gorgeous slender birds and mighty mangroves. Well, these beautiful places on earth are also amongst the biggest sinks of Carbon. Unbelievable Right?
Found in trace amounts, Carbon dioxide or CO2 is famous for its global warming potential. Right now, as we write this article, atmospheric CO2 is at ~410.25ppm (ideal - 350ppm). To limit the warming of planet earth by 1.5 Degree, we need to reduce emissions but most importantly sequester or catch and store CO2.
Carbon sequestration generally occurs across all biomes above and below the ground naturally. Yet below the ground storage of Carbon is the most efficient and wetlands are undeniably the best after ocean (which are the biggest carbon sinks).
It’s simple; we are emitting a lot. We talk about planting more trees to capture carbon.
But the potential of wetlands to catch all that CO2 is much higher than what trees can do.
What is carbon sequestration in wetlands?
Like numerous ecosystem services (benefits obtained to people from ecosystems), carbon sequestration potential of wetlands is inevitable and probably the most crucial need of the hour. It refers to the transference of CO2 from the atmosphere into wetlands’ soil carbon pool as soil organic matter.
However, for every activity, trade-offs are apparent; the sequestered carbon overtime shall remain in the soil and benefit living organisms only with an input-output balance of carbon/forms. The chances are high, the organic matter gets disintegrated into soluble inorganic matter, through a process called mineralization.
This eventually can lead to emission of CO2 and methane , which might hinder the capacity of wetlands to act as a net carbon sink. Global methane emissions from fresh or comparatively less saline wetlands range between 150 - 42g m-2 y-1 however in coastal wetlands its hardly 1g m-2 y-1.
In simple terms, if wetlands are not protected and used wisely, it can backfire by being a carbon source
Terrestrial biomes like forest and tundra consist of enormous carbon above ground, while wetlands, on the other hand, stock carbon underground and holds its largest reserve till date despite its lesser area worldwide.
With just around 8 million km2, wetlands sequester more than 500 Pg C (1Pg C= 1000000000000000g ) underground alone, when with more than 18 million km2, forest sequester just around 300 Pg C above and underground combined.
Vembanad wetlands as an effective carbon sink for Peninsular India
Vembanad wetland covers an area of ~2033.02km2 with coastal wetlands alone holding at least 65-70% of the area. Considering the total land area of Kerala, which is roughly 38,863 km², Vembanad covers almost 5% of it, making latter the most significant blue Carbon (Carbon stored in marine and coastal ecosystems) sink in India.
With an overall carbon emission of over 2,299 million tonnes in 2018, Indian emissions are on the rise by almost 4.8%. At present India, is the fourth largest carbon emitter after China, US and the EU. Places like Vembanad had been under constant threat of reclamation owing to developmental pressures and have lost around 63.62 km2 of water spread since 1970.
Being the largest wetland and Ramsar site (wetland site designated to be of international importance under the Ramsar Convention), Vembanad holds massive potential as an effective blue carbon sink.
Experts say "the cost of preserving wetlands and thus increasing its carbon sequestration potential would cost much less compared to the losses incurred after a disaster strikes".
ATREE's Community Environmental Resource Centre (CERC) has been working at Vembanad on integrated participatory management of Vembanad wetlands.
CERC, in its decade long work in the system has identified and is still in the process of deciphering critical threats affecting the wetland in getting reclaimed at a much faster rate.
Despite, strong legislation in the country, wetlands are getting reclaimed at alarming rates. The main culprit to be blamed is science itself. Understandings about the services that wetlands provide are still unknown to the majority of the masses.
With a global hunger index at 103, India’s clear need of the hour is survival, any conservation effort forgetting this fact is a definite doom.
Wetland conservation proves not just to be a mere climate action, more than a carbon sink; it is also a nutrient sink.
It distributes organic as well as inorganic matter to nearby lands via the water bodies within the vicinity. Coastal wetlands tend to mitigate radiative forcing of climate change.
However, studies believe that change in the hydrology of wetlands mainly due to reclamation's could increase the amount of methane and CO2 in the soil leading to “priming effect”. Subsequently, they start emitting CO2 and methane. BACKFIRE!
Words of Caution
UN Intergovernmental Panel on Climate Change (IPCC) in 2018 through its SR15 report, had warned a 12-year cap for acting against climate change to keep the rising temperature below 1.5°C since the pre-industrial era. To stabilize or at worst lower global temperature, we have to attain a balance in sources and sinks (2S’s) of Carbon.
With a net-zero between the 2S’s, at carbon neutrality, the CO2 emissions shall decline and reach a new equilibrium, stabilizing the global temperature for centuries ahead. By prioritizing wetland restoration, we can enhance climate adaptation and resilience.
A fair percentage of the global population has already started facing the heat of climate change at various level. Water scarcity, between the 2000s and 1900s, there had been a whopping 44% increase in a global population facing this threat. Extreme hydrological events have already started hitting, and Kerala is the best example to spot, with respect to 2018 floods, following drought, and subsequent flood in 2019.
Floods could go up anywhere from 150% to ~580% rise, followed by soil erosion and drought in the coming years globally. Protecting wetlands could reduce this risk.