One common factor of the five mass extinctions A. An increase in carbon dioxide B. A decrease in carbon dioxide C. An increase in oxygen D. A decrease in oxygen Which greenhouse gas is more potent than CO_2 A. Ethanol B. Gasoline C. Oxygen D. Methane What causes more greenhouse gases than all the direct emissions form the entire transportation sector? A. Factories B. Single family homes C. Livestock D. None of the above Which extinction was the biggest in the history of the planet when almost all of life disappeared? A. The Permian extinction B. The KT extinction C. The anthropocene D. The Devonian What will contribute to vast amounts of methane entering the atmosphere as a result of global warming? A. Sea level rise B. Arctic ice melting C. Hydrothermal vents erupting D. Acid rain