The freshwater ecosystems represent about the half the emissions global from methane. That strong gas greenhouse effect It is the second component responsible for global warming after carbon dioxide.
The rivers and streams They emit significant amounts. So far, however, there is little documentation on the rates of these emissions on a global scale, the mechanisms that control them, and the patterns that result.
Hence the value of the study’s contributions Global methane emissions from rivers and streamspublished in the magazine this week Nature.
An international team of researchers including experts from the Center for Advanced Studies of Blanes (CEAB-CSIC) compiled and analyzed all the data published data on concentrations and emissions of methane in rivers and streams. After compiling more than 20,000 methane concentration data and coupled with high-resolution hydrological logs capturing methane concentration movement and distribution of the water, models of machine learning for predict emissions Methane in all rivers of the world.
Sampling procedure for boiling methane in a Wisconsin river. / Luke Loken
The scientists saw that the emissions this gas in tropical zones Are Similar to those of rivers much colder even from the arctic tundra. They concluded that unlike other water systems (like lakes) the methane emissions in rivers are less dependent on internal factors such as water temperature. Instead, they are heavily influenced by the landscape features that surrounds them, e.g land-water connections.
The The emissions are higher if rivers and streams Drain land rich in organic matter and lack of oxygen (a deficiency that… favors bacteria which produce methane and at the same time decompose organic matter). zones of wetlandsas well as heavily modified habitats by humans often cause these conditions.
“Humans are actively changing river networks around the world, and in general these changes appear to favor methane emissions,” he explains. Gerard Rocher-RosLead author of the study, researchers at CEAB-CSIC and at the Swedish University of Agricultural Sciences.
Heavily modified environments such as streams closed as drain agricultural fieldsthe rivers below sewage treatment plants or the urban canals They also tend to create conditions that are rich in organic matter poor in oxygen which favor a high production and emission of methane.
EmilyStanleyResearcher at the University of Wisconsin-Madison’s Center for Limnology and co-author of the article, points out, “Research shows that from a climate change perspective, we need to look more closely at the systems in which people create.” methane is produced natural production cycles of this gas“.
The information provided in the study confirms that rivers are an important source of methane in the region global atmosphere And by identifying the key processes that lead to emissions, you can help counteract them climate change. The Restoration of river ecosystems that existed man made could be an approach to reduce and contain methane emissions.
The research was made possible by the collaboration of scientists from Umeå University (Sweden), the Swedish University of Agricultural Sciences, the University of Wisconsin-Madison and Yale (USA). Thanks to this work, a new database was also created, which Gloval River Methane Databasewith more than 24,000 records of methane concentrations.
Rocher-Ros, G. et al. Global methane emissions from rivers and streams. Nature (2023)