Discover the scientific facts on greenhouse effect

What is the greenhouse effect?
The greenhouse effect is a natural warming process of the earth. When the sun's energy reaches the earth some of it is reflected back to space and the rest is absorbed. The absorbed energy warms the earth's surface which then emits heat energy back toward space as longwave radiation. This outgoing longwave radiation is partially trapped by greenhouse gases such as carbon dioxide, methane and water vapour which then radiate the energy in all directions, warming the earth's surface and atmosphere. This is the greenhouse effect. More...

Variation of the Earth's surface temperature
for the past 140 years

The Earths annual and global mean energy balance and the greenhouse effect

Of the incoming solar radiation, 49% (168 Wm-2) is absorbed by the surface. That heat is returned to the atmosphere as sensible heat, as evapotranspiration (latent heat) and as thermal infrared radiation. Most of this radiation is absorbed by the atmosphere, which in turn emits radiation both up and down. The radiation lost to space comes from cloud tops and atmospheric regions much colder than the surface. This causes a greenhouse effect.

Increasing the amount of greenhouse gases intensifies the greenhouse effect. Higher concentrations of CO2 and other greenhouse gases trap more infrared energy in the atmosphere than occurs naturally. The additional heat further warms the atmosphere and Earth’s surface.

Climate models suggest this natural warming is being enhanced by human activities that increase concentrations of greenhouse gases in the atmosphere and greenhouse effect. The increase in atmospheric concentration of greenhouse gases, accentuating the natural greenhouse effect globally, is also called the enhanced greenhouse effect or Global Warming. More...

read the GreenFacts Digest on the greenhouse effect


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