Global warming is the gradual increase in the average temperature of Earth’s atmosphere and oceans, which is caused by the emission of greenhouse gases, such as carbon dioxide (CO2). CO2 is one of the primary contributors to global warming, and is produced through the burning of fossil fuels such as coal, oil and natural gas for electricity, heating, and transportation. As CO2 levels rise, the atmosphere traps more of the sun’s heat, causing the planet to warm. The resulting climate change can have significant impacts on ecosystems and human communities.