Various government agencies, academic institutions, and other organizations contribute data critical to the development of the indicators. All of the indicators in this report are based on peerreviewed data that have been collected and compiled according to protocols accepted by the scientific community. The indicators were chosen using a standard set of criteria that considered usefulness, objectivity, data quality, transparency, ability to meaningfully communicate, and relevance to climate change.Each indicator features five elements: (1) one or more graphics depicting changes in the indicator over time, ( 2) key points about what the indicator shows, (3) background on how the indicator relates to climate change, (4) information about how the indicator was developed, and (5) factors that influence one's ability to draw valid conclusions from the indicator.Accompanying the report is a technical support document which describes detailed information about each indicator, including data sources, data collection methods, calculations, and statistical considerations. This document also describes EPA's approach and criteria for selecting indicators for the report (www.epa.gov/climatechange/science/indicators).
USA National Phenology NetworkThe USA National Phenology Network (USA-NPN; www.usanpn.org), established in 2007 as a partnership-driven program with leadership by the USGS and with funding from the National Science Foundation, USGS, and several other organizations, is a national science and monitoring network that organizes and facilitates the collection and integration of phenological observations across space and time (Jones et al., 2010). Partners include scientists, resource managers, educators, and policy-makers from a diversity of organizations including governmental and nongovernmental organizations, American Indian tribes, specialized networks, and academic institutions.