The greenhouse effect is the process by which certain gases in Earth’s atmosphere trap some of the heat from the Sun, keeping the planet warmer than it would be otherwise. What happens in brief
- Solar radiation from the Sun heats Earth’s surface.
- The surface emits heat (infrared radiation) back toward space.
- Greenhouse gases in the atmosphere (like water vapor, carbon dioxide, methane, nitrous oxide, and ozone) absorb much of this infrared heat.
- The absorbed heat is then re-radiated in all directions, including back toward the surface, which traps heat in the lower atmosphere and at the surface.
- This natural warming makes Earth's average surface temperature roughly 33°C warmer than it would be otherwise, creating a stable climate conducive to life.
Human impact
- Human activities (notably burning fossil fuels, deforestation, and industrial processes) have raised concentrations of these greenhouse gases.
- Higher concentrations enhance the natural greenhouse effect, trapping more heat and leading to an overall increase in Earth's average temperature, known as anthropogenic (human-caused) warming.
Key gases
- Water vapor (H2O)
- Carbon dioxide (CO2)
- Methane (CH4)
- Nitrous oxide (N2O)
- Ozone (O3)
- CFCs and related chemicals (in smaller but impactful amounts)
Notes
- Water vapor amplifies warming as the atmosphere becomes warmer, acting as a feedback rather than a primary forcing.
- The natural greenhouse effect is essential for maintaining a climate that supports life; the current concern is the human-driven enhancement of this effect.