CAESAR

Global warming is based on a very simple hypothesis. Anthropogenic (human caused) emissions of greenhouse gasses (GHGs) contribute a layer of gasses around earth's atmoshpere. The accumulation of GHGs then blocks some of earth's emanating heat from escaping to space, causing a general heating or global warming pattern.

• carbon dioxide (CO₂)
• methane (CH₄)
• nitrous oxide (N₂O)
• hydroflurocarbons (HFCs)
• perflourocarbons (PFCs)
• sulphur hexaflouride (SF6)

Considerations about the degree to which GHGs influence climate change deal with two sets of issues.

Aggregate emissions trends estimate the volume of each of the six GHGs released into the atmosphere per year.

Of equal importance is the relative power of the various GHGs to act as atmospheric road blocks that keep heat in the atmosphere.

Scientists call this road blocking ability the Global Warming Potential (GWP) of a gas. The standard measurement unit is 1 for Carbon, and it turns out Carbon is the least effective of the GHGs in trapping earth's heat.

For comparative purposes, over a twenty year time span, Methane's GWP=56, Nitrorus Oxide's GWP=310 and the GWP of the engineered chemicals varies from 460-16,000 (see UNFCCC Global Warming Potential.

Each GHG also has a life span, or time it remains stable in the atmosphere. Whereas the numbers for carbon look somewhat benign in terms of its GWP, they start to look a bit more daunting when considered in terms of life span.

Scientists estimate that CO₂ remains stable in the atmosphere for anywhere from 50-200 years. Methane, on the other hand, remains stable only about 12 years. Nitrous Oxide's life span reaches the 120 year mark.

Finally the engineered chemicals may remain stable for anywhere from 2 to 50,000 years for Perfluoromethane.