The greenhouse effect is a natural process whereby the earths lower atmosphere is warmed because of the gases which trap heat. The sun emits electromagnetic radiation (…Heat), in particular, UV, visible white light, and infa-red radiation. Some of the heat is reflected by the atmosphere, some is absorbed by the gases, and some reaches earth. Some is reflected back from the ocean, and some other radiation is given off from the earth, however not all escapes back out into the big black space, some of it is trapped by the encompassing greenhouse gases. Greenhouse gases include carbon dioxide, methane, ozone, nitrous oxide, water vapour, and halocarbons (Only polar bonds can absorb infa-red radiation, hence diatomic oxygen or nitrogen are not greenhouse gases).
Now us, as humans, are pretty much stuffing up this system because of our excess production of greenhouse gases, causing more heat to be trapped, warming the earth. This is the enhanced greenhouse effect, and it’s what’s been causing all the talk of global warming.
Carbon dioxide is produced for transport, and power, primarily by the combustion of fossil fuels. Methane is produced from the anaerobic breakdown of plant material, and is in excess due to farming of cattle, growing of rice and farming of sheep. Nitrous oxide is produced due to the reduction of nitrates by microbes, and is because of nitrogenous fertilisiers used in agriculture.
The enhanced greenhouse effect has many environmental consequences:
- contraction of area and thickness of sea ice
- contraction of ice sheets
- warming of oceans, rise in sea levels
- changing ocean circulation patterns
- thawing of permafrost (releases methane)
- increase in intensity and frequency of extreme weather events
- retreating of glaciers
- changes in reproduction, growth and migratory cycles of animals
- changing rainfall patterns