Keynote abstracts
Keynote: Ronny Lauerwald
The role of inland waters in the global carbon cycle and greenhouse gas budgets
The network of inland waters – including streams, rivers, lakes and reservoirs – connects terrestrial and marine ecosystems through the transport of carbon and nutrients. Along the way, inland waters act as biogeochemical reactors, transforming the material they receive from their catchments and emitting substantial amounts of greenhouse gases. The terrestrial inputs of carbon makes inland waters important net sources of carbon dioxide (CO2) to the atmosphere. Oxygen-poor conditions also favor methane (CH4) production, while transitions between oxygen-rich and oxygen-poor environments promote nitrous oxide (N2O) production. Despite their recognized importance, inland water greenhouse gas emissions remain poorly quantified globally, largely because measurements are scarce and unevenly distributed.
Similarly, the amount of carbon transferred from terrestrial ecosystems to inland waters remains uncertain, but is likely comparable in magnitude to the land carbon sink - the net uptake of atmospheric CO2 by terrestrial ecosystems that partly offsets fossil fuel emissions. Changes in these lateral carbon transfers, driven by climate or land use, can therefore enhance or weaken the strength of the land carbon sink.
This presentation explores how inland waters influence global carbon and greenhouse gas budgets, and how their role is changing under the combined pressures of climate change, land use and river damming. Drawing on examples from tropical, temperate to Arctic regions, it illustrates how water flows, vegetation and permafrost thaw shape connections between land, water and atmosphere. It also discusses how observations and models can help address key uncertainties and improve our understanding of the role of inland waters in the carbon cycle and greenhouse gas budgets.