Sites in this category cover global warming and cooling, sea level and ice pack changes, desertification, and all general discussion on shifts in the earth's climatic zones, particularly as theorized to result from human emissions of carbon dioxide, methane, and other "greenhouse gases." Among the questions raised are whether human activity is responsible for global warming and to what extent, whether climate change is detrimental and if so what measures must be taken to arrest it, and even whether climate change is occurring at all.