How Relevant are Freshwater Ecosystems for the Global Methane Budget

Lakes have a controversial climate footprint. In fact, they are a sink of CO2 but at the same time they can be an important source of CH4. Indeed, a global synthesis of methane emission data (Bastviken et al., 2011) suggests that freshwater ecosystems - in particular lakes - may be much larger sources of methane than previously thought, questioning current methane budgets and the general role of freshwater ecosystems in the greenhouse gas balance. The main objective of this study is to improve data availability and quality regarding methane emissions from lakes in the Alpine region - a region that presently is heavily under-represented in global data sets - in order to allow a robust assessment of their role in the global greenhouse gas balance. This is of fundamental importance for the assessment of CH4 emissions from regions particularly sensitive to an increasing climatic variability. Aiming at spatial and temporal representativeness of flux measurements, we made use of an innovative mobile eddy covari...