Climate change poses many challenges that affect society and the natural world. With these challenges, however, come opportunities to respond. By taking steps to adapt to and mitigate climate change, the risks to society and the impacts of continued climate change can be lessened. The National Climate Assessment, coordinated by the U.S. Global Change Research Program, is a mandated report intended to inform response decisions. Required to be developed every four years, these reports provide the most comprehensive and up-to-date evaluation of climate change impacts available for the United States, making them a unique and important climate change document. The draft Fourth National Climate Assessment (NCA4) report reviewed here addresses a wide range of topics of high importance to the United States and society more broadly, extending from human health and community well-being, to the built environment, to businesses and economies, to ecosystems and natural resources. This report evaluates the draft NCA4 to determine if it meets the requirements of the federal mandate, whether it provides accurate information grounded in the scientific literature, and whether it effectively communicates climate science, impacts, and responses for general audiences including the public, decision makers, and other stakeholders.

Since its inception, the U.S. Global Change Research Program has had the policy of full and open data availability. This policy has already been implemented not only through the participating agencies but through many inter-agency mechanisms such as publications, Internet based services, and in many international settings. This fourth of a series of yearly publications represents another important step in this interagency process of making the data and information related to the Global Change Research Program available. It is particularly needed at this time since the users of this data and information have expanded from being primarily researchers to being a full mix that also includes educators, those making assessments of potential effects of global change, the commercial world, and the public as well as policy makers at all levels. One of this publication's objectives is to provide this diverse user community with a concise summary of what data has been cataloged and made newly available each year. This is being done in both this published form and in the Global Change Data and Information System on the Internet(www.gcdis.usgcrp.gov) with links to each data set, where available. Other objectives, however, are also important. These include giving recognition to the individuals and organizations who have done the important job of making the data available and providing a mechanism where the data sets used in a publication or assessment can be cited similarly to the citations now commonly used in publications to reference other publications.

Summarizes the science of climate change and impacts on the United States, for the public and policymakers.