This event is open to:
Abstract:
Freshwaters are among the largest global sources of methane (CH4) to the atmosphere. There is evidence that global warming has increased CH4 emissions from freshwater ecosystems, providing positive feedback to the global climate. Yet for rivers and streams, the controls and the magnitude of CH4 emissions remain highly uncertain.In this talk I will show our recent work on the global estimate of CH4 emissions from running waters, based on a new global database of river methane concentrations and emissions. Estimated emissions of CH4 account for 27.9 (16.7–39.7) Tg CH4 per year and roughly equal in magnitude to those of other freshwater systems. Riverine CH4 emissions are not strongly temperature dependent, with low average activation energy compared with that of lakes and wetlands. By contrast, global patterns of emissions are characterized by large fluxes in high- and low-latitude settings as well as in human-dominated environments. These patterns are explained by edaphic and climate features that are linked to anoxia in and near fluvial habitats, including a high supply of organic matter and water saturation in hydrologically connected soils. Our results highlight the importance of land–water connections in regulating CH4 supply to running waters, which is vulnerable not only to direct human modifications but also to several climate change responses on land.
Bio:
Gerard Rocher-Ros is a catchment ecologist, currently a postdoctoral researcher at the Swedish University of Agricultural Sciences. His research has focused on the role of rivers processing organic matter, and how biological processes can affect the river carbon cycle and emissions of carbon dioxide and methane to the atmosphere.