Freshwater ecosystems account for half of global emissions of methane, a potent greenhouse gas that contributes to global warming. Rivers and streams, especially, are thought to emit a substantial amount of that methane, but the rates and patterns of these emissions at global scales remain largely undocumented.
An international team of researchers, including University of Wisconsin–Madison freshwater ecologists, has changed that with a new description of the global rates, patterns and drivers of methane emissions from running waters. Their findings, published today in the journal Nature, will improve methane estimates and models of climate change, and point to land-management changes and restoration opportunities that can reduce the amount of methane escaping into the atmosphere.
The new study confirms that rivers and streams do, indeed, produce a lot of methane and play a major role in climate change dynamics. But the study also reveals some surprising results about how—and where—that methane is produced.
“We expected to find the highest methane emissions at the tropics, because the biological production of methane is highly sensitive to temperature,” says Emily Stanley, a professor at UW–Madison’s Center for Limnology and co-author of the Nature report. Instead, she says, their team found that methane emissions in the tropics were comparable to those in the much colder streams and rivers of boreal forests—pine-dominant forests that stretch around the Northern Hemisphere—and Arctic tundra habitats.
Temperature, it turns out, isn’t the primary variable driving aquatic methane emissions. Instead, the study found, “the amount of methane coming out of streams and rivers regardless of their latitude or temperature was primarily controlled by the surrounding habitat connected to them,” Stanley says.
2023-08-17 02:00:04
Link from phys.org