Greenhouse Made Easy

What is the Greenhouse Effect?

As any good gardener knows, a greenhouse in your garden is a comfortable place to keep young or tender plants that require shelter from the hot sun. This allows some of the light & warmth from the sun to reach the plants and allows air to move about whilst regulating the temperature.

In the case of the earth, over time the amount of energy sent from the sun to the Earth's surface should be about the same as the amount of energy radiated back into space, leaving the temperature of the Earth's surface roughly constant.

The earth's atmosphere is made up of lots of different chemical compounds and some of these act as "greenhouse gases." These gases allow sunlight to enter the atmosphere freely. When sunlight strikes the Earth's surface, some of it is reflected back towards space as infrared radiation (heat). Greenhouse gases absorb this infrared radiation and trap the heat in the Earth's atmosphere.

As the concentration of these Greenhouse gases increases over time, then the atmosphere is more effective at trapping the heat and holding it close to the Earth's surface. With the growing global population and industrial development over the last 150 years, the level of man-made (Anthropogenic) Greenhouse gases has increased dramatically. Over the last 20 years around about 75% of the man-made emissions were created as a consequence of burning fossil fuels.

Figure 1. Trends in Atmospheric Concentrations and Anthropogenic Emissions of Carbon Dioxide