Greenhouse gases are essential to making Earth habitable, but increasing their concentrations strengthens the natural greenhouse effect and causes the planet to warm. This article explains the science behind that process by examining how energy from the Sun enters the Earth system, how the surface emits longwave infrared radiation, and how greenhouse gases absorb and re-emit that energy within the atmosphere. It also explains why additional carbon dioxide changes the altitude from which heat escapes to space, temporarily disrupting Earth’s energy balance and leading to warming. Finally, the article explores the role of water-vapor and ice-albedo feedbacks in amplifying the initial warming caused by increased greenhouse gas concentrations. Read the full report