What is ‘Global Warming’?
What does Glacier Ice tell us?

One strong line of evidence that it is comes from an unlikely source – the vast ice sheets of Greenland and Antarctica. As glacier ice is formed by compaction of successive layers of snow, small bubbles of air become trapped. When a sample of ice is drilled out, these air bubbles can be dated quite accurately, and when analysed, provide an archive of past atmospheric composition – including the levels of CO2, CH4 and N2O. sets the current situation in the context of ice-core data that trace variations in the atmospheric concentrations of these three gases over the past millennium.

The Sun is the ultimate source of energy for the Earth's climate. A planet such as the Earth will have a stable temperature as long as there is a balance between the rate at which energy comes in from the Sun and the rate at which it is returned to space by the planet. If the two rates fail to match, the planet will either warm up or cool down until a balance is restored.

There is no dispute about this central conclusion. Increasing the atmospheric concentration of CO2, or any other greenhouse gas, will force the global climate to warm up; it can be refered to as ‘greenhouse forcing’. However, the weighty tomes issued by the IPCC bear witness to the fact that ‘the devil is in the detail’! In particular, there is still major uncertainty about what is perhaps the most fundamental question in the whole climate change debate: how much will the Earth's temperature rise in response to a given amount of greenhouse forcing?

Sources for Global Warming Section

‘Global Warming’. An OpenLearn chunk used/reworked by permission of The Open University copyright © (2007).’ http://creativecommons.org/licenses/by-nc-sa/2.0/uk/

The Pew Centre: http://www.pewclimate.org/global-warming-basics/basic_science/

Global Warming Information Centre: http://www.nationalcenter.org/KyotoQuestionsAnswers.html

Wikipedia- Stern Review: http://en.wikipedia.org/wiki/Stern_Review