7. Calculate the height of the bar representing carbon dioxide from human activity. 8. How important are volcanoes in adding carbon dioxide to the atmosphere? 9. What effect do the sulfate aerosols formed by volcanoes have on global temperatures? 10. Which contributes more carbon dioxide per year to the atmosphere: volcanic eruptions or human activity? 11. Does a volcanic eruption cause a warming or cooling effect? 12. What is the major cause of cooling after a volcanic eruption? 13. Please explain how your ideas and thinking about greenhouse gases has changed.