A significant worldwide study utilizing teabags as a measurement tool indicates that rising temperatures may decrease the carbon storage capacity of wetlands. An international team of scientists concealed 19,000 bags of green tea and rooibos across 180 wetlands in 28 countries to evaluate the wetlands’ ability to sequester carbon in their soil.
A significant worldwide study utilizing teabags as a measurement tool indicates that rising temperatures may decrease the carbon storage capacity of wetlands.
An international group of scientists buried 19,000 green tea and rooibos teabags within 180 wetlands across 28 nations to assess how well these areas can retain carbon in their soil, a process referred to as wetland carbon sequestration.
Although using teabags may initially appear unconventional for measuring this impact, it has proven to be an effective proxy method for assessing carbon release from soil into the atmosphere. This marks the first-time teabags have been utilized in a large-scale, long-term study, providing insights on which wetlands are losing the most carbon.
The research, led by Dr. Stacey Trevathan-Tackett from RMIT University, was published in Environmental Science and Technology as part of her Australian Research Council DECRA Fellowship while she was at Deakin University.
The global study features 110 co-authors and contributions from many others, including undergraduate students and citizen scientists. Key team members included Dr. Martino Malerba and Professor Peter Macreadie from Deakin University and RMIT, Dr. Sebastian Kepfer-Rojas from the University of Copenhagen, and Dr. Ika Djukic from the Swiss Federal Institute for Forest, Snow and Landscape Research WSL.
“This is the first comprehensive long-term study using the teabag technique, which will help us optimize carbon storage in wetlands and play a part in reducing global emissions,” Trevathan-Tackett mentioned, currently part of RMIT’s School of Science.
“Changes in carbon sinks can significantly affect global warming—less decomposition means more carbon is stored and less is released into the atmosphere.”
Analyzing the tea leaves
Teabags offer a straightforward and standardized method to determine how factors like climate, habitat type, and soil characteristics affect carbon breakdown rates in wetlands.
At each site, researchers buried between 40 and 80 teabags approximately 15 cm deep and retrieved them at various intervals over three years, noting their GPS locations. They measured the remaining organic mass to evaluate how much carbon had been preserved in the wetlands.
The study employed two varieties of tea bags (green and rooibos) to represent distinct types of organic materials in soils. Green tea breaks down quickly, while rooibos decomposes more slowly. This dual approach provided researchers with a thorough understanding of the wetlands’ carbon storage capabilities.
“This data helps us find ways to enhance carbon storage in wetlands globally,” Trevathan-Tackett added.
Key findings
The research team examined temperature impacts through two methods: analyzing local weather station data for each site and comparing climatic variations across regions.
“In general, warmer temperatures resulted in quicker decomposition of organic matter, which means less carbon retention in the soil,” Trevathan-Tackett explained.
The two types of tea behaved differently under rising temperatures.
“For the more resistant rooibos tea, the location did not influence decay rates—higher temperatures always increased decay, suggesting that typically long-lasting carbon types are susceptible to heat,” Trevathan-Tackett noted.
“With rising temperatures, green tea bags decomposed at diverse rates based on wetland type—decay was quicker in freshwater wetlands compared to mangrove and seagrass wetlands.
“Increased temperatures may also enhance carbon production and storage in plants, potentially compensating for carbon losses in wetlands caused by warmth, but this needs further investigation,” Trevathan-Tackett stated.
Freshwater wetlands and tidal marshes retained the most teabag mass, indicating they have higher potential for carbon storage.
The insights from this study contribute to a broader understanding of global wetland carbon sequestration. Part of the terrestrial TeaComposition initiative led by Djukic, data on litter decomposition has been gathered at around 500 global sites, leading to numerous peer-reviewed publications.
“Using a consistent metric across aquatic, wetland, marine, and terrestrial ecosystems facilitates a comparative conceptual understanding of the main forces controlling global litter carbon turnover,” Djukic said.
“As we learn which environments are more effective at storing carbon, we can use this knowledge to protect these crucial areas from environmental changes or land-use alterations.”
Future Directions
The researchers plan to integrate findings from this study with data from similar research on land-based carbon sinks, including forests, to contribute to the development of predictive global modeling.
