In 2012, spring came earlier for the contiguous United States than in any year since 1900, according to recent research by a team of scientists with the USA National Phenology Network (USA-NPN). This research used the USA-NPN suite of “spring indices”—or algorithms based on the accumulated warmth needed to initiate growth in temperature-sensitive plants, which are validated by nationwide historical
Since 1989, the U.S. Global Change Research Program (USGCRP) has submitted annual reports to Congress called Our Changing Planet. The reports describe the status of USGCRP research activities, provide progress updates, and document recent accomplishments
In particular, Our Changing Planet highlights progress and accomplishments in interagency activities. These highlights represent the broad spectrum of USGCRP activities that extend from Earth system observations, modeling, and fundamental research through synthesis and assessment, decision support, education, and public engagement. Highlights describe the state of science at the time of publication of each yearly report, and may not reflect more recent advances in understanding. The date of publication of the source report is noted on each highlight page.