Ultraviolet rays from the Sun drive Earth's climate. Some of this incoming radiation is absorbed by the atmosphere, and some passes through to the Earth's surface, causing the atmosphere to warm.
Greenhouse gases in the atmosphere absorb most of the Earth's infrared radiation, which heats the lower atmosphere. In turn, the warmed atmosphere emits radiation, some of which radiates toward the Earth's surface, keeping our planet warm. But increasing concentrations of greenhouse gases such as carbon dioxide and methane increase the temperature by restricting the outward flow of radiation, resulting in "global warming," or, more broadly, global climate change.