The primary gas that contributes to the greenhouse effect is carbon dioxide (CO2). This gas is emitted from various sources, including the burning of fossil fuels, deforestation, and industrial processes. Carbon dioxide traps heat in the Earth's atmosphere, creating a "greenhouse" effect that leads to global warming and climate change. Although CO2 is a natural part of the atmosphere, human activities have significantly increased its concentration, amplifying its impact on the climate and leading to severe environmental consequences.