The proposed project will assemble NASA remote sensing data products to provide a pilot land cover indicator for the U.S. National Climate Assessment (NCA). A land cover indicator for the NCA will track changes in land cover due to human activities and as a result of climate change, making it a synthetic indicator of influences on climate, climate change impacts, and the consequences of adaptation or mitigation measures involving land management. The project will combine moderate resolution (MODIS) land cover data products with higher resolution (Landsat) data. Land cover maps will serve as an important component of the indicator, but charts depicting attributes such as composition by land cover class, statistical indicators of landscape characteristics such as fragmentation, and tabular data summaries are all indispensable for communicating the status and trends of U.S. land cover to planners, decision makers, and a variety of stakeholders relying on NCA products. We will combine these representations of land cover at national, regional, and state scales. We will investigate the error and uncertainty imposed by combining remote sensing data at multiple spatial resolutions, and in the case of Landsat data at irregular temporal intervals, and incorporate measures of uncertainty into land cover indicators. We expect to visualize the land cover indicator in a spatially nested manor from the national to NCA regions to individual states within a region. Charts and tabular data will correspond to the spatial units of adjacent maps and aggregate accordingly. The project will develop several prototype land cover indicators based on remote sensing data. We will interact with those involved directly in the NCA (e.g., the Federal Advisory Committee), users within Agencies and other institutions, and stakeholders (e.g., through NCAnet) to evaluate the utility of alternative prototypes. Adopting the most promising aspects of different prototypes, the project will develop a pilot indicator and provide access by the general public through the Web. We expect experience with this pilot indicator to provide clearer definition of the requirements of a land cover indicator for the NCA, the best uses of remote sensing data in meeting those requirements, and the basis for further indicator development involving remote sensing data.