The NCA Report Series summarizes regional, sectoral, and process-related workshops and discussions being held as a part of the Third National Climate Assessment (NCA) process. Three workshops focusing on monitoring changes in the physical climate system, as well as the impacts of climate change on ecosystems and socio-economic systems were completed in support of the 2013 NCA and the ongoing NCA process. The first of these workshops, on developing indicators for ecosystem responses to climate change and integrating observational networks, was organized by the Ecosystem Interagency Working Group of the U.S. Global Change Research Program. The workshop was held in Washington, DC on November 30-December 1, 2010 and sponsored by the U.S. Environmental Protection Agency. Volume 5a of the NCA Report Series summarizes the discussions and outcomes of this workshop. A list of planned and completed reports in the NCA Report Series can be found online at http: // assessment.globalchange.gov