What is the greenhouse effect?
Imagine that Earth has been encircled by a giant glass sphere. The heat of the sun penetrates through the glass. Some of the heat is absorbed by the Earth, and some of it is radiated back towards space. The radiated heat reaches the glass sphere and is prevented from dispersing any further.
Similarly, the earth is surrounded by a blanket of gases. This blanket traps energy in the atmosphere, much the same way as glass traps heat inside a greenhouse. This results in an build up of energy, and the overall warming of the atmosphere. The 'greenhouse effect' is the popular expression for that process.
Global warming and climate change result from the greenhouse effect. Scientifically explained, the greenhouse effect is the rise in temperature that the Earth experiences because certain gases in the atmosphere, i.e. water vapor, carbon dioxide, nitrous oxide, and methane, trap energy from the sun.
Without these gases, heat would escape back into space and Earth’s average temperature would be about 16°C colder. Because of how they warm our the earth these gases are referred to as greenhouse gases.
Have you ever seen a greenhouse though? Most greenhouses look like small glass houses. Greenhouses are used to grow plants, especially during winter where the harsh cold would kill most plants. Greenhouses are used to trap heat from the sun. The glass panels of the greenhouse let in light and keep heat from escaping. The greenhouse heats up just as a car would sitting in direct sunlight all day. The plants are kept warm enough to live during winter.
The Earth’s atmosphere is all around us. It is the air that we breathe. Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse. Sunlight enters the Earth's atmosphere, passing through the blanket of greenhouse gases. As it reaches the Earth's surface, land, water, and biosphere absorb the sunlight’s energy. The biosphere is the part of the earth and it's atmosphere in which living organisms exist or the part that is capable of supporting life so the ecosystem composed of the earth and the living organisms inhabiting it.
So once the energy is absorbed from sunlight, this energy is sent back into the atmosphere. Although some of the energy passes back into space much of it remains trapped in the atmosphere by the greenhouse gases and this causes our world to heat up.
The greenhouse effect is important because without it the Earth would not be warm enough for humans to live. However, if the greenhouse effect becomes stronger, it could make the Earth warmer than usual and that would be very harmful for humans, plants and animals alike.
The consequences of global warming and climate change could well include:
- the eradication of entire ecosystems
- increased frequency and intensity of storms, hurricanes, floods and droughts
- melting glaciers and polar ice
- rising sea levels resulting in the permanent flooding of vast areas of heavily popululated land
- increased frequency of forest fires
- spread of tropical diseases due to insect proliferation
- One wash
- A dishwasher can use up to 35 litres of water per load