Greenhouse Effect

The Impact of Greenhouse Gases

The concentration of greenhouse gases has a significant effect on the temperature of the lower atmosphere.
A higher concentration of greenhouse gases means the atmosphere keeps more of the heat it receives from the sun than it loses, causing warmer temperatures.
Vice versa, a lesser concentration of greenhouse gases leads to higher losses of heat and thus lower temperatures.

Global warming, or anthropogenic climate change, is mainly due people altering the biosphere's natural carbon cycle by releasing carbon into the atmosphere from long-term carbon stocks in the Earth's crust.

These stocks are formed from dead organic matter. Thus they have lots of carbon within them (as all living organisms on Earth are carbon-based).
They are generally called fossil fuels, as their combustible nature makes them an efficient fuel source.
Oil, natural gas, coal and peat are all fossil fuels that are extracted from the Earth's crust.

When organic matter is burned, odorless and colorless carbon dioxide is formed.
Its concentration in the atmosphere has increased due to the use of fossil fuels and is now around 425 ppm (parts per million), or 0.0425 % of all gas in the atmosphere.
While this may seem very little it's effect is extremely noticeable.
The amount of carbon dioxide in the atmosphere is now about 150% of what it was back in the 1750s.
Unfortunately carbon dioxide emissions are still increasing, even today.

Methane gas is produced when organic matter rots in anoxic (non-oxygenous) conditions, for example in wetlands and rice fields.
It is mainly released into the atmosphere by cattle used in livestock production, by the decay of dead plant biomass in rice cultivation and by the more intensive decay processes in tropical wetlands caused by rising temperatures.
Methane is also released when oil and natural gas (which is mainly methane) are refined and transported through pipelines.
It is a very potent greenhouse gas, but only remains in the atmosphere for about 12 years.
Methane is 250% more common in the atmosphere now than it was in 1750.

Nitrous oxide is a major greenhouse gas.
Agriculture is the world's largest producer of nitrous oxide emissions.
Nitrous oxide is approximately 300 times more potent as a greenhouse gas than carbon dioxide.
Carbon dioxide accounts for more than half of the human contribution to global warming.
The rest is mainly due to methane released in agriculture and power plants as well as nitrous oxides released by vehicles.
CFCs and other man-made gases that destroy the ozone layer potent greenhouse gases, even at low concentrations.

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