Rivers and streams, as a vital part of freshwater ecosystems, play a substantial role in the worldwide methane emissions, shifting previous beliefs about the influence of temperature on this process. The new research demonstrates that both human-altered and natural surroundings heavily impact methane production. This finding opens opportunities for diminishing methane emissions through dedicated conservation and restoration efforts.
Accounting for around half of global methane discharges, freshwater ecosystems are key contributors to this potent greenhouse gas that amplifies global warming. There has been an apparent void in thorough data regarding global emission rates and patterns, particularly from rivers and streams.
A multinational research group, inclusive of freshwater ecologists from the University of Wisconsin–Madison, has furnished significant insights into global trends, rates, and reasons behind methane emissions from flowing water bodies. Published in the journal Nature, their work broadens our grasp of methane predictions and climate models and proposes potential adjustments to land-management and restoration endeavors to reduce atmospheric methane.
The recent study validates that rivers and streams are indeed substantial methane producers, significantly affecting climate change dynamics. However, the research also brings to light astonishing discoveries about the locations and methods of methane creation.
Although higher methane emissions were expected in tropical areas due to temperature-sensitive biological methane production, the study revealed that tropical methane emissions were akin to those in colder streams and rivers of boreal forests – predominantly pine forests that encircle the Northern Hemisphere – and the Arctic tundra landscapes.
The research showed that temperature isn’t the chief factor governing aquatic methane emissions. Rather, according to Emily Stanley, a co-author of the Nature report, emissions from streams and rivers are mainly dictated by the adjacent habitat linked to them, irrespective of latitude or temperature.
High-latitude rivers and streams in boreal forests and polar regions often interconnect with peatlands and wetlands, and waters in dense forests such as the Amazon and Congo River basins contain organic matter-rich soils. These systems frequently yield large methane amounts due to low-oxygen conditions favorable for methane-producing microbes.
Nevertheless, not all high methane rivers and streams generate emissions naturally. In some regions, human actions in urban and rural settings predominantly govern freshwater methane emissions.
Human modifications of river networks generally appear to boost methane emissions, says Gerard Rocher, the report’s lead author. Habitats heavily altered by humans, such as drainage ditches in agricultural fields or concrete stormwater canals, often create conditions conducive to high methane production.
Rocher points out the positive potential of this human influence, as conservation and restoration of freshwater could decrease methane emissions. Limiting pollutants like fertilizers, human and animal waste, or excess topsoil in rivers and streams could restrain high methane production.
Emily Stanley emphasizes the need to focus on human-induced methane production rather than natural methane production cycles, considering climate change.
The study highlights the necessity of collaborative scientific efforts to understand the breadth of climate change. The extensive results were achieved through multi-year collaboration between various global institutions and involved complex computer modeling and machine learning to expand datasets initially begun by Stanley in 2015.
Now, with greater confidence in methane estimates, the researchers anticipate that their findings will augment the comprehension of the scale and geographical patterns of methane sources in Earth’s atmosphere and refine the large-scale models employed to decipher global climate and predict its trajectory.
Reference: “Global methane emissions from rivers and streams” by Gerard Rocher-Ros, Emily H. Stanley, Luke C. Loken, Nora J. Casson, Peter A. Raymond, Shaoda Liu, Giuseppe Amatulli and Ryan A. Sponseller, 16 August 2023, Nature.
DOI: 10.1038/s41586-023-06344-6
Funding for the study was provided by the National Science Foundation, the National Key Research and Development Program of China, and the Swedish Research Council.
Table of Contents
Frequently Asked Questions (FAQs) about methane emissions
What are the surprising findings regarding methane emissions in the new research?
The new research reveals that rivers and streams, particularly in freshwater ecosystems, are significant contributors to global methane emissions. Contrary to previous assumptions about the role of temperature, the study found that surrounding habitats, both human-modified and natural, are key in methane production. Even in colder regions such as boreal forests and the Arctic tundra, methane emissions were found to be comparable to those in the tropics.
How might these findings affect conservation and restoration efforts?
These findings open up opportunities for reducing methane emissions through targeted conservation and restoration efforts. By understanding how and where methane is produced, measures can be implemented to control the contributing factors in various habitats. Human-modified systems, in particular, can be managed to mitigate emissions.
What role do humans play in methane emissions according to the study?
According to the study, human activity in both urban and rural communities significantly controls freshwater methane emissions in some parts of the world. Human modifications to river networks and habitats that have been highly altered by human activities, like agricultural fields and concrete stormwater canals, often result in conditions that promote high methane production. The research suggests that human-led conservation and restoration efforts could lead to a reduction in methane emissions.
How does this study contribute to our understanding of global climate and methane projections?
The study enhances our understanding of methane projections and climate change models by providing detailed insights into global rates, tendencies, and causes of methane emissions from flowing waters. The researchers used state-of-the-art computer modeling and machine learning to expand datasets, offering more confidence in methane estimates. This information can be used to refine large-scale models that predict global climate trends.
What institutions were involved in the research, and where was it published?
The research involved a collaboration between the University of Wisconsin–Madison, Swedish University of Agricultural Sciences, Umeå University, and other institutions worldwide. It was published in the scientific journal Nature.
Who funded the research?
The study was funded by the National Science Foundation, the National Key Research and Development Program of China, and the Swedish Research Council.
More about methane emissions
- Nature
- University of Wisconsin–Madison Center for Limnology
- Swedish University of Agricultural Sciences
- National Science Foundation
- National Key Research and Development Program of China
- Swedish Research Council
5 comments
Seems like a game changer in climate change understanding. hats off to the researchers! Need more studies like this.
This article really opend my eyes! Never knew that rivers and streams were such a big source of methane. Conservation efforts must focus on this ASAP.
Human influence again. why am i not surprised? We keep messing with nature and this is the result. Glad that there’s research showing how to maybe fix it.
im really impressed with the research but confused. Thought temperature was the key to methane, now it’s more about surroundings? Need to dig deeper on this.
Big fan of the University of Wisconsin team, their studies always push boundaries, This one too! We’ve gotta take action on these findings.