The gas most commonly associated with climate change is carbon dioxide (CO2). It is a greenhouse gas that traps heat in the Earth's atmosphere, contributing to the greenhouse effect. Human activities, particularly the burning of fossil fuels (such as coal, oil, and natural gas) and deforestation, have significantly increased CO2 levels. This rise in greenhouse gases leads to global warming and climate alterations, resulting in severe weather patterns, melting ice caps, and rising sea levels. Efforts to reduce CO2 emissions are crucial for mitigating climate change and its impacts on the planet.