This Fiscal Year 2009 edition of Our Changing Planet highlights recent advances and progress supported by CCSP-participating agencies in each of the program's research and observational elements, as called for in the Strategic Plan for the U.S. Climate Change Science Program released in July 2003, and later modified in the 2008 CCSP Revised Research Plan. The document describes a wide range of activities including examples of CCSP's contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change as well as significant progress in understanding Earth system components of the global climate system, how these components interact, and the processes and forces bringing about changes to the Earth system. It provides details on progress towards understanding the ongoing and projected effects of climate change on nature and society, such as the relationship between climate change and shifts in storm tracks and how this may affect water availability in the southwestern United States. The document also describes how observational and predictive capabilities are being improved and used to create tools to support decisionmaking at local, regional, and national scales to cope with environmental variability and change. The report also describes the program's 21 scientific synthesis and assessment products and its recently completed Scientific Assessment of the Effects of Global Change on the United States.