Why is the US Department of Energy still struggling to understand so much science that's allegedly already settled?

Department of Energy - Climate Change

Through DOE's Climate Change Sciences Program, the Office of Science approaches the problems associated with climate change through research and modeling efforts to:(1) improve the understanding of factors affecting the Earth's radiant-energy balance; (2) predict accurately any global and regional climate change induced by increasing atmospheric concentrations of aerosols and greenhouse gases; (3) quantify sources and sinks of energy-related greenhouse gases, especially carbon dioxide; and (4) improve the scientific basis for assessing both the potential consequences of climatic changes.