What is the primary gas responsible for the greenhouse effect?

The primary gas responsible for the greenhouse effect is carbon dioxide (CO2). This is because CO2 has a significant capability to absorb infrared radiation emitted by the Earth's surface. When solar energy reaches the Earth, some of it is reflected back into space, and the rest is absorbed, warming the planet. The Earth then emits this energy back as infrared radiation. However, gases like carbon dioxide trap some of this heat in the atmosphere, which helps maintain the Earth's temperature at a level necessary for life. While other gases, like methane, also contribute to the greenhouse effect, carbon dioxide is the most prevalent and impactful on a global scale due to its abundant presence and long-lasting effects in the atmosphere.