On July 29, 2025 the Environmental Protection Agency issued a proposal for “Reconsideration of 2009 Endangerment Finding and Greenhouse Gas Vehicle Standards.”  At the same time, the Department of Energy issued a report entitled “Critical Review of Impacts of Greenhouse Gas Emissions on U.S. Climate” prepared by five members of the DoE Climate Working Group (CWG) appointed by the Secretary of Energy.  This report is intended to provide a scientific basis for the proposed EPA action.  Shortly afterwards I joined an interdisciplinary group of about 85 scientists who worked to provide a detailed review of the CWG report within the month-long comment period. In my talk I will review the state of our knowledge of climate science, the relationship between scientific knowledge and policy making, and the character and content of the CWG report.