Greenhouse gases in the atmosphere, includes water vapour, carbon dioxide, methane, and
nitrous oxide. In simple terms, they absorb heat energy and emit it in all directions (including
downwards), keeping Earth’s surface and lower atmosphere warm.
Look at the picture on the right side. This picture shows how greenhouse effect works.
The atmosphere allows most of the visible light from the Sun to pass through and reach Earth’s
surface. As Earth’s surface is heated by sunlight, it radiates part of this energy back toward
space as infrared radiation. This radiation, unlike visible light, tends to be absorbed by the
greenhouse gases in the atmosphere, raising its temperature. The heated atmosphere in turn
radiates infrared radiation back toward Earth’s surface. Despite its name, the greenhouse effect
is different from the warming in a greenhouse, where panes of glass transmit visible sunlight
but hold heat inside the building by trapping warmed air.
If all heat energy emitted from the surface passed through the atmosphere directly into space,
Earth’s average surface temperature would be tens of degrees colder than today. Adding more
greenhouse gases to the atmosphere makes it even more effective at preventing heat from
escaping into space. When the energy leaving is less than the energy entering, Earth warms
until a new balance is established.
Scientists have determined that carbon dioxide plays a crucial role in maintaining the stability of
Earth's atmosphere. If carbon dioxide were removed, the terrestrial greenhouse effect would
collapse, and Earth's surface temperature would drop significantly, by approximately 33°C and
most people believe that human activities have added a really big amount of greenhouse gases
to the atmosphere.
In the last century, human activities, primarily from burning fossil fuels that have led to the
release of carbon dioxide and other greenhouse gases into the atmosphere, have disrupted
Earth's energy balance. This has led to an increase in carbon dioxide in the atmosphere and
ocean. Just as what you can see in the second picture on the right that I’ve given you. The level
of carbon dioxide in Earth’s atmosphere has been rising consistently for decades and traps
extra heat near Earth's surface, causing temperatures to rise.