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| Lowland tropical rivers emit large quantities of greenhouse gases, with rates influenced by seasonal flooding. Photo Credit: Jenny Davis |
Tropical inland waters don’t produce as many greenhouse gas emissions as previously estimated, according to the results of an international study, led by Charles Darwin University and involving researchers from Umeå University.
The study, published in Nature Water, aimed to better understand greenhouse gas emissions in tropical rivers, lakes and reservoirs by collating the growing amount of observations from across the world’s tropics – including many systems that were previously less represented in global datasets.
Researchers from Umeå University played a key role in the work, estimating the surface area of rivers and contributing to the data analysis that underpins the study’s findings.
Up to 79 per cent less emissions
The results found that while these waters still produce significant amounts of greenhouse gas emissions, it is 29 to 79 per cent less than previously thought. Tropical flowing waters (streams and rivers) contributed to an estimated 46 per cent of emissions from global inland waters, and tropical standing waters (lakes, reservoirs, ponds) an estimated 8 per cent.
About greenhouse gases
Greenhouse gases are the gases in the atmosphere which trap heat, with the main three being carbon dioxide, methane and nitrous oxide. They are released naturally from inland waters, but human activities can greatly increase these emissions.
Lead author and Senior Research Fellow at Charles Darwin University in Australia, Clément Duvert, says by expanding the dataset, greater accuracy in emissions could be gleaned and thus inform approaches to management and conservation.
“We found the tropics cannot really be considered as one big emissions hotspot because of its complexity and the mosaic of different ecosystems, landscapes, morphologies and levels of human activity,” says Clément Duvert.
New insights into tropical river systems
Assistant Professor Gerard Rocher-Ros from Umeå University, one of the paper’s co-authors, highlights the new insights the study provides into tropical rivers systems.
“The large contribution of rivers in the tropics to greenhouse gas emissions stands in contrast with what we know about their drivers. This study really opens the door on next challenges to better predict carbon cycling in rivers,” he says.
Clément Duvert says the next frontier of this research could be to better quantify what portions of these emissions are natural and what are due to human activities:
“We found in this paper that human activities are a strong driver of greenhouse gas emissions. Where you have more activities such as agriculture, you will have higher inputs of organic matter and nutrients into streams, rivers, lakes and reservoirs, then a higher release of greenhouse gases. Understanding when and how human activities impact these emissions is important to inform management.”
Authors: Clément Duvert, Alberto V. Borges, Elisa Calamita, Gerard Rocher-Ros, Annika Linkhorst, Judith A. Rosentreter, Shaoda Liu, Pierre Taillardat, Katrin Attermeyer, Tonya DelSontro, Loris Deirmendjian, Alicia A. Dixon, Charlotte Grasset, Allison M. Herreid, Luke C. Jeffrey, Lediane Marcon, Ricky M. Mwanake, José R. Paranaíba, Lishan Ran, Adam T. Rexroade, Vanessa Solano, Francesco Ulloa-Cedamanos, Jilong Wang, Keridwen M. Whitmore, Liwei Zhang, Carla López-Lloreda, Marcia N. Macedo, Diana Oviedo-Vargas, Diego A. Riveros-Iregui, and Nicholas S. Marzolf
Source/Credit: Umeå University | Sara-Lena Brännström
Reference Number: env102125_02
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