Greenhouse gases (GHGs) are gases in Earth's atmosphere that trap heat by absorbing infrared radiation emitted from the planet's surface, thereby warming the atmosphere through the greenhouse effect. They allow sunlight to pass through the atmosphere but prevent some of the heat from escaping back into space, which keeps the Earth's average temperature around 15°C (59°F) instead of about -18°C (0°F) without them

. The main greenhouse gases include:

• Water vapor (H2O) : The most abundant greenhouse gas, which increases as the atmosphere warms and acts as a feedback to other gases

• Carbon dioxide (CO2) : Released by burning fossil fuels, deforestation, and certain chemical processes; it is the primary contributor to human-driven climate change due to its abundance and long atmospheric lifetime

• Methane (CH4) : Emitted during fossil fuel production, livestock farming, landfills, and rice cultivation; it is more potent than CO2 but remains in the atmosphere for a shorter time

• Nitrous oxide (N2O) : Produced by agricultural activities, fossil fuel combustion, and industrial processes

• Fluorinated gases : Synthetic gases such as hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6), and nitrogen trifluoride (NF3) used in industrial applications; they have very high global warming potentials despite being present in smaller quantities

These gases occur naturally but their concentrations have increased significantly due to human activities since the Industrial Revolution, intensifying the greenhouse effect and driving global warming and climate change

. In summary, greenhouse gases are heat-trapping gases in the atmosphere essential for maintaining Earth's temperature but are now at elevated levels due to human activity, causing harmful climate impacts