Greenhouse gas

A greenhouse gas (GHG) is any atmospheric compound that absorbs and re-emits infrared radiation, trapping heat in Earth's atmosphere and contributing to global warming. These gases allow solar radiation to pass through but prevent thermal radiation from escaping back to space—mimicking the physics of a garden greenhouse.

The most abundant greenhouse gases are carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), and various fluorinated compounds. While some occur naturally and are essential for maintaining habitable temperatures, anthropogenic emissions from fossil fuel combustion, agriculture, and industrial processes have dramatically accelerated atmospheric concentrations since industrialization.

Carbon dioxide accounts for roughly 75% of human-caused warming. Methane, released from livestock farming, wetlands, and fossil fuel extraction, is far more potent per molecule but shorter-lived. Understanding GHG concentrations is central to climate science, environmental policy, and strategies like carbon capture, renewable energy, and reforestation.

The concept gained scientific prominence through work on radiative forcing and became a cornerstone of frameworks like the Kyoto Protocol and Paris Agreement.

Related

Climate change, Carbon cycle, Atmosphere, Anthropogenic, Energy transition