Measuring Sources and Sinks of Greenhouse Gases at The "Missing Scales: Ecosystem to Continent, Weeks to Decades (Invited Keynote Presentation)

Increases in the concentrations of methane (CH4) and carbon dioxide (CO2) are powerful drivers of global change and climate warming. In order to understand the underlying causes and to design mitigation strategies, the emissions of these gases must be quantified, and the response to the driving biological, physical, and human processes must be understood. The key spatial scales for this analysis range from ecosystems, landscapes, urban, regional, to continental, and the temporal scales range from seasonal to decadal. Direct observations of sources and sinks are very challenging on these scales. In this talk, case studies focusing on emission of CH4, in the Arctic and the Continental US, will be presented illustrating why these spatial and temporal scales are so important, and showing how new approaches that combine direct observations with model-data assimilation methods provide the means to determine greenhouse gas fluxes at the "missing" scales with growing confidence and accuracy.