What Is Global Warming?
Global warming is a trend observed by climatologists and other scientists showing that the average temperature of Earth's atmosphere is increasing. Along with the rise in global temperature are other changes including rising sea levels and increased frequency of severe weather. Climate change creates changes to the atmosphere, resulting in an abnormal greenhouse effect that affects weather patterns.

What is the role of carbon dioxide as a greenhouse gas? What can be done to help stop global warming?

global warming
"an increase in the average temperature of the atmosphere surrounding the earth that is capable of causing a change in climate"

Global warming occurs when carbon dioxide (CO2) and other air pollutants collect in the atmosphere and absorb sunlight and solar radiation that have bounced off the earth's surface. … Curbing dangerous climate change requires very deep cuts in emissions, as well as the use of alternatives to fossil fuels worldwide.

What is global warming?

Global warming is a gradual increase in the earth's temperature generally due to the greenhouse effect caused by increased levels of carbon dioxide, CFCs, and other pollutants.