C6.3 Interpreting and interacting with Earth systems Links Sketch a pie chart showing the gases present in the air today. Describe how the earths atmosphere has changed and what has caused this change. C6.3 Interpreting and interacting with Earth systems Links  C6.2 Organic Chemistry What are particulates? What problems do they cause? How can salt water be turned into usable water? How is acid rain caused? How is carbon monoxide formed? What problems does it cause? What is global warming? Where do we get drinking water from? Describe the stages of water purification What is the greenhouse effect? What can be done to reduce global warming? Keywords