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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. Without these greenhouse
gases the earth's average surface temperature would be about 33 degrees Celcius
cooler.
Human activities such as deforestation and the burning of fossil fuels have
increased the concentrations of greenhouse gases in the atmosphere. Scientists are
concerned that higher greenhouse gas concentrations will lead to an "enhanced"
greenhouse effect which may lead to global climate change. The Intergovernmental
Panel on Climate Change (IPCC) is an international group of scientists which advises
policymakers on the latest science of greenhouse climate change. In late
1995, the IPCC concluded that "the balance of evidence suggests a discernible
human influence on global climate."
Research institutes such as the Bureau of Meteorology Research Centre and CSIRO
Division of Atmospheric Research use complex computer model simulations of the climate
system to investigate potential greenhouse climate changes. |
