The leaders of the U.S. Navy, Coast Guard, and Marine Corps have recognized the potential impact of climate change on naval forces' missions and have positioned their organizations to make adaptive changes. This report is the first component of a study to assess the implications of climate change for the U.S. Naval Services. Specifically, this report highlights issues that could have potential near-term impacts, impose a need for near-term awareness, or require near-term planning to ensure that longer-term naval capabilities are protected. The final report of this study will address all of the elements in the study's terms of reference and explore many potential implications of climate change not covered in this letter report.