The main focus of this course is upon the climatic aspects of environmental change which affect Great Lakes water levels, disappearing glaciers, sea level rise, desertification and dwindling water resources in an ever more populous world. These changes to the earth surface environment are explored in the context of themes and issues which were introduced in first year, with a view to answering an important question: whether policy action on climate change must wait for more science, or whether action is merely delayed by failure to appreciate science.