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Useful Climate Definitions

Climate Science

Carbon Equalivance - Greenhouse gas in the atmosphere is often refered to only in terms of pert per millions of carbon dioxide, for example 280 ppm CO2. This however ignores the other green house gases that are in the atmoshpere such as Nitrosoxide, Methane and CFC's.

Inder to have a better measure of Greenhouse gases in the atmosphere scientists have devised a number of systems to better represent the effects of the total pool of greenhouse gases, Carbon Equivalance is one such system, and is written CO2-e.

The Carbon Equivalance system existimates different greenhouse gases' warming effect over 100 years and compares these to the number of CO2 molecules it would take to produce the same effect. This is call global warming potential (GWP).

For example The Intergovernmental Pannel on Climate Change's (IPCC) Guidelines for GHG Inventory Reporting calculate global warming potential of methane as being 25 times the level of carbon dioxide (as defined in the IPCC Fourth Assessment Report (AR4)).

It should be noted that Carbon Equilivance is only an estatemate and can distort the actually effects of the other greenhouse gases. For example Methane only exists in the atmosphere an average of 12 years before it breaks down into carbon dioxide and water vapour, hence the GWP figure of 25 seriously under estimates the actual impact of methane on global warming in the short term. A more realistic GWP for methane is the 20 year figure of 72 GWP (AR4).

Also different sets of rules are used to calculte different resultes for Carbon Equivalance. For example the Australian Greenhouse Office uses a GWP for methane of 21 and not 25 for their greenhouse gas inventory calculations. This is due to the UNFCCC having agreed that the revised figures of GWP for different gases will not apply to greenhouse gas reporting until the second commitment period (2013-2017).

Carbon Equivalance is written X ppm CO2-e

Climate maintenance systems - the climate is a incredibly complex system made up inputs that range from the heat of the sun, concentration of greenhouse gases, the role of clouds, and function of the earth's biota just to name a few. Some of these systems are critical to maintaining a stable climate. One such system is the North Pole's summer ice. Without this ice the Arctic will heat up to such an extent that a number of other positive feedback loops will be triggered and any chance of maintaining a stable climate suitable for the majority of the world humans and species will be lost.

Positive feedback loops - some systems respond to global warming and can further increase or decrease global warming. If the response speeds up climate change is called a positive feedback loop. Examples include the melting of the North Pole summer ice. As the North Pole summer ice melts and exposes more ocean surface, less sunlight is reflected and more heat enters the Arctic system, this in turn melts more ice and so on.

Point of no return - the point at which human effort can no longer reverse climate heating and through positive feed back loops the climate system continues to heat out of our control.

Organisational

The Intergovernmental Pannel on Climate Change (IPCC) - ...

United Nation Framework Convention on Climate Change (UNFCCC) - ...

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300 ppm CO2 or below is the stabilisation target for a safe climate.