Q.What do you understand by the term 'Greenhouse Gases'? Make a list of greenhouse gases.

Greenhouse gases are the gases in Earth’s atmosphere that trap heat by absorbing infrared radiation given off by the warmed planet, and then re-emitting some of it back toward the surface. This natural process, called the greenhouse effect, keeps the planet warm enough for life. The trouble begins when human activities add extra amounts of these gases, thickening the “blanket” and causing global warming.

The main greenhouse gases are:

• Carbon dioxide (CO₂) — released by burning fossil fuels, deforestation, and industrial processes.
• Methane (CH₄) — from livestock, rice paddies, landfills, and natural gas leaks.
• Nitrous oxide (N₂O) — from fertilisers, burning of biomass, and some industrial activities.
• Water vapour (H₂O) — the most abundant greenhouse gas, but its level is largely controlled by temperature rather than directly by human emissions.
• Chlorofluorocarbons (CFCs) — synthetic gases once used in refrigerants and aerosols; they are potent greenhouse gases and also damage the ozone layer. …

The term “greenhouse gases” comes from a simple analogy. A greenhouse — the glass structure used to grow plants in cold weather — lets sunlight in but traps the warmth inside. The Earth’s atmosphere does something similar, though not through glass. Certain gases in the air allow the Sun’s visible light to reach the ground, but they absorb the infrared (heat) radiation that the Earth sends back out towards space. Instead of letting that heat escape, they re-radiate much of it back down, keeping the planet warmer than it would otherwise be. Without this natural effect, the average surface temperature would be far below freezing, and life as we know it would not exist.

So, greenhouse gases are those atmospheric constituents that have this heat-trapping property. They are not all equally powerful, nor do they all stay in the atmosphere for the same length of time. Some occur naturally, like carbon dioxide from volcanic eruptions and respiration, while others are almost entirely human-made. The concern in modern times is not that these gases exist — they always have — but that human activities have sharply increased their concentrations, strengthening the natural greenhouse effect and driving global warming.

Here is a list of the principal greenhouse gases:

• Carbon dioxide (CO₂) — the most abundant and most discussed. Released by burning fossil fuels, deforestation, and industrial processes. It stays in the atmosphere for a very long time, often centuries.
• Methane (CH₄) — far more potent than CO₂ at trapping heat, though it does not last as long. Comes from livestock digestion, rice paddies, landfills, and natural gas leaks.
• Nitrous oxide (N₂O) — a powerful greenhouse gas emitted mainly from agricultural fertilisers, burning of biomass, and some industrial activities. It also damages the ozone layer.
• Water vapour (H₂O) — the most abundant greenhouse gas of all. It is not directly controlled by human emissions, but it responds to warming: a warmer atmosphere holds more water vapour, which in turn traps more heat, creating a feedback loop.
• Fluorinated gases (F-gases) — a family of synthetic gases including hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulphur hexafluoride (SF₆). They are used in refrigeration, air conditioning, and electronics manufacturing. They are present in tiny amounts but are extraordinarily potent, with some lasting thousands of years. …