The report describes activities and plans of the Climate Change Science Program (CCSP), highlighting recent progress in each of the program's research and observational elements. The document also describes how observational and predictive capabilities are being improved and used to create tools to support decision making at local, regional, and national scales to cope with environmental variability and change.

This edition of Our Changing Planet includes a review of the Strategic Plan for the U.S. Climate Change Science Program (CCSP) from 2003 and outlines how the CCSP is moving forward to implement the Strategic Plan during FY 2004 and FY 2005. As a part of this implementation, the report announces the production of 21 scientific syntheses and assessments on a range of topics to support informed discussion of climate variability and associated issues by decision makers and the public.

This Synthesis and Assessment Product (SAP 3.1) focuses on the Climate models. Scientists extensively use mathematical models of Earth's climate, executed on the most powerful computers available, to examine hypotheses about past and present-day climates. Development of climate models is fully consistent with approaches being taken in many other fields of science dealing with very complex systems. These climate simulations provide a framework within which enhanced understanding of climate-relevant processes, along with improved observations, are merged into coherent projections of future climate change. This report describes the models and their ability to simulate current climate.