- Teal carbon is sequestered in vegetation, microbial biomass and in dissolved or particulate organic matter in wetlands.
- This is in contrast to “blue carbon” which is carbon stored in coastal and marine ecosystems.
- To conserve teal carbon ecosystems, it’s also important to build awareness and connections with wetlands and their role as carbon stocks.
Teal carbon, which refers to carbon stored in freshwater wetlands, is a lesser-known concept in carbon-related terminology. Most discussions about carbon storage focus on “blue carbon” which is carbon stored in coastal and marine ecosystems like mangroves, seagrasses, and salt marshes or “green carbon” which is carbon stored in land, primarily grasslands, croplands, and forests. Other colours are also used to describe properties of carbon sinks. Teal carbon, in particular, highlights the importance of inland, non-tidal freshwater ecosystems in capturing and storing atmospheric carbon.
Priya Ranganathan, wetland ecologist and researcher, came across the term, teal carbon, in a pre-print on the potential of teal carbon to mitigate climate change. “Wetlands are a mix of land and water — green and blue spaces — so using ‘teal’ is an interesting approach,” says Ranganathan, who is pursuing her doctoral degree at Ashoka Trust for Research in Ecology and the Environment (ATREE).
This research was led by Laxmi Kant Sharma of Central University of Rajasthan (CURAJ) and brings to focus inland wetlands and their significance in climate mitigation. Conducted at Keoladeo National Park (KNP) in Rajasthan’s Bharatpur district, the preliminary findings emphasise the need to develop nature-based solutions to enhance teal carbon ecosystems’ efficiency in carbon sequestration and tap into their potential as carbon sinks.
For a long time, teal carbon was considered as part of blue carbon and not as a separate component. In a 2016 research paper published in Nature, researchers Amanda Nahlik and Professor Siobhan Fennessy highlighted the term. “They used the term ‘teal carbon’ independently for the first time in a study which was hugely important,” Sharma adds. Now, about eight years later, Sharma is collaborating with Nahlik and Fennessy to further the research on teal carbon. The authors aim to publish the complete study later this year.
“There have been studies on inland wetlands and the carbon stored in them so this not the first to do that, but the use of the term ‘teal carbon’ is innovative,” says Ritesh Kumar, director of Wetlands International South Asia.

What is teal carbon?
A colour-based terminology is used to describe organic carbon, its properties and distribution. This approach enhances the understanding of the carbon cycle by linking carbon types to their specific functions and locations.
Some of the colours, blue, green, and teal, highlight the role of carbon in climate change mitigation through sequestration while black, brown, and red impact Earth’s heat balance or promote cryospheric melting.
Teal carbon, a newer addition to the carbon colour nomenclature, is sequestered in vegetation, microbial biomass, and in dissolved or particulate organic matter in the wetlands, Sharma explains. “Inland wetlands are a major source of carbon sequestration, if not polluted,” he says.
What is the significance of teal carbon?
According to the United Nation’s Intergovernmental Panel on Climate Change’s 2018 report, carbon dioxide (CO2) emissions need to be reduced by 45% by 2030 to limit global warming to around 1.5°C (2.7°F). One of the important ways to achieve this goal is by improving carbon sequestration efficiency of existing ecosystems, particularly that of the often-ignored ones such as inland wetlands.
Inland wetland ecosystems are critical carbon reservoirs storing 30% of global soil organic carbon (SOC) within 6% of the land surface.
According to Sharma’s research, the global storage of teal carbon across these ecosystems is approximately 500.21 Pg C. Peatlands, freshwater swamps, and natural freshwater marshes account for about 448.85 Pg C, 36.72 Pg C, and 14.89 Pg C, respectively, while ponds store an estimated 0.24 Pg C.
“Although only certain types of wetlands can sequester and store carbon, those are very efficient. For example, peatlands can store up to 40 times more carbon than what a tropical forest. The world is also catching up to mangroves’ efficiency of carbon storage, which is very high,” says Kumar. “According to our estimates, two to three gigatons of carbon stored in Indian wetlands is susceptible to be released if the wetlands are degraded,” he adds.
However, the use of the term ‘teal carbon’ is still rare in research. Wetlands are also methane producers so often they are seen through the narrow lens of greenhouse gas emitters. “The paper [led by Sharma] shifts this perspective of inland freshwater wetlands to that of carbon storage sites, which is very important”, Kumar explains.
What are the challenges faced by teal carbon ecosystems?
Inland wetlands are fragile ecosystems that are constantly threatened by anthropogenic activities such as contamination from sewage plant systems, construction activities, and other types of pollution.
Wetlands are places in the landscape where water and land meet. “People understand land, people understand water. But these are transitional systems which have been neglected for quite some time,” says Kumar. For instance, wetlands in India’s “Silicon City”, Bengaluru, have been converted into IT parks and floodplains in Delhi have been replaced with infrastructure or roads, he adds.
Inland wetlands are natural depressions in our landscapes. Whenever the rain falls, it accumulates in these parts of the landscape. It’s how the water goes down and the groundwater is recharged.
The most significant factors that impact wetlands are pollution, use of biological resource, natural system modification, and agriculture and aquaculture. Their land area and the health of ecosystems are most at risk from these factors. For instance, in her initial findings, Ranganathan, who studies Myristica swamps in Uttara Karnataka, observed that even the isolated Myristica swamps have been impacted by chemical pollution through fertilisers and herbicides that flow into them. “It’s an acidic ecosystem. The chemical pollution neutralises the soil pH value which hinders the growth and survival of new saplings,” Ranganathan says.
Another major challenge in tapping inland wetlands’ potential as carbon stores is their methane emissions. About a third of total methane emissions comes from wetlands. Methane emissions from wetlands have increased faster this century than in the most pessimistic climate scenarios.
Sharma and colleagues’ preliminary findings also showed elevated methane emissions in KNP. Interestingly, it was lesser than other wetland ecosystems such as urban polluted and non-forested degraded ecosystems. “KNP is comparatively less polluted. This shows how pollution can increase methane emissions and reduce a wetland’s capacity to act as a carbon sink,” Sharma says.

How can teal carbon ecosystems be used for climate action?
To tap into the potential of teal carbon ecosystems as carbon store, a crucial step is to reduce the methane emissions. One way is to develop a specialised biochar, Sharma says. Biochar is black carbon produced from biomass sources such as plant residues, manure, or other agricultural waste.
“Using nature-based solutions such as biochar can avoid any chemical input into these ecosystems. This specialized type of biochar must be collaboratively developed to keep the teal carbon active in these wetlands while trapping the methane released by them. This could be a game changer,” Sharma says.
The research by Sharma and colleagues emphasised that the development of nature-based solutions is important to control pollution in freshwater inland wetlands and enhance the efficiency of this biochar.
“If you pollute a wetland, the methane emissions increase four to five times,” warns Kumar.
However, about 30% of natural wetlands have declined in last three decades, Kumar says. “It would be an understatement if I say that natural wetlands are in quite a bit of stress,” he adds. “They are hydrologically fragmented and wetlands, especially inland wetlands are becoming ephemeral.”
To conserve teal carbon ecosystems, it’s also important to build awareness and connections with wetlands and their role as carbon stocks. For instance, India also announced the Amrit Dharodhar scheme in the 2023-2024 budget, which has brought focus to wetland carbon as a component, says Kumar.
“People subconsciously interact with wetlands without really understanding the connections. For instance, a lot of birders will take photos of birds that are actually wetland birds and often don’t know that their presence means there’s a wetland nearby,” Ranganathan says, adding on using communication tools such as social media to build awareness through unexpected connections.
“If people feel like a wetland is theirs, they will want to conserve it,” she adds.
Banner image: Kole wetland in Thrissur. Image by Manojk via Wikimedia Commons (CC BY SA 4.0).