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The Earth’s atmosphere and climate change
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Although both nitrogen and oxygen make up most of the atmosphere and are the most essential to human life on the planet, they have little effect on weather and other atmospheric processes.
The variable gases, which actually make up less than 1% of the atmosphere, have a much greater influence on the climate. Water vapour, carbon dioxide, methane, nitrous and sulphur oxides all have an important property: they absorb heat emitted by the earth and thus warm the atmosphere, creating what is known as the "greenhouse effect."
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In addition to gases, the atmosphere also contains particulate matter in the form of dust, volcanic ash, rain, and snow. Although the amounts of particulate matter varies and are generally less persistent than gas concentrations, they can sometimes remain in the atmosphere for relatively long periods of time. The Icelandic volcano which grounded many flights during 2010 was one such example. Volcanic ash from the 1991 eruption of Mt. Pinatubo in the Philippines, also darkened skies around the globe for over a year.
Most of the greenhouse gases currently being released into the atmosphere come from fossil fuel power stations. There are now many renewable energy providers that offer electricity from wind energy, without costing you a penny more, helping to cut your carbon footprint. Find out more
Remember the ozone hole? Have we learned anything?
The scientist responsible for leading the team which discovered the ozone hole over Antarctica in 1985 has spoken out about the lack of co-ordinated effort to tackle global warming.
When Dr Farman's team at the British Antarctic Survey reported the ozone hole in 1985, it highlighted the earth's fragility and catalysed the environmental movement into action.
In an interview with the BBC on the 25th anniversary of the reporting of the ozone hole, Dr Joe Farman said the environment was still being damaged in many ways.
Dr Farman was particularly critical of politicians who he claimed had failed to show leadership on combating climate change, saying it was "damned stupid" to keep increasing carbon emissions when we know it is a warming gas.
But, in a nod to climate sceptics, he also blamed the scientific establishment for failing to take specific criticisms of detailed climate science seriously enough.
As with the relationship between carbon emissions and warming, it was found that the ozone layer was being stripped away by chemicals known as chlorofluorocarbons (CFCs), which were mostly used in aerosols and refrigerators. Although resisted at the time by some manufacturers, the making of ozone-depleting chemicals was controlled within two years under the Montreal Protocol.
Dr Farman says that governments have failed to learn the lesson that they need to move swiftly and act decisively on global threats to the environment. "You ought to be able to convince people it's a damned stupid thing to increase CO2 - clearly that must trap more energy," he says.
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