Understanding Global Warming Potential (GWP)

We are all aware that CO2 is a critical green house gas. CO2 traps heat in the atmosphere creating a green house effect. OK, so how bad is CO2, is there any value to be measured? What about other gases? Yes, there is and it is called Global Warming Potential or GWP. GWP calculation of a given gas is based on 3 major factors over specific time intervals:

  • the degree of heat (infrared radiation) absoprtion
  • the spectral location of its absorbing wavelengths
  • the atmospheric lifetime

In short, the higher the GWP value of a gas, the more heat it will absorb and the longer it will remain in the atmosphere without being removed. Currently all gases are benchmarked against CO2 so GWP for CO2 is 1. Methane has a 100-year GWP value of  21, which means that if the same mass of methane and carbon dioxide were introduced into the atmosphere, that methane will trap 21 times more heat than the carbon dioxide over the next 100 years. The commonly used refrigerant R143a in vehicles and refrigerators has a 100-year GWP value of  3,800, meaning given the same condition, R143a will trap 3,800 times more heat than CO2. Unlike chlorofluorocarbons (CFCs) , Hydrofluorocarbons (HFCs) are not ozone depleting yet their high chemical stability and infrared absorbency make them one of the potent green house gases in town.

Human activities are contributing towards the rapid build-up of the green house gases. Again, all those chemicals are artificially created by us for our consumption. Hence reduction in consumption and preventive maintenance of equipment utilizing such gases are crucial to slow down climate change. Next time when you replace your refrigerant, read the label and understand more how much the gas can harm the environment.

Want to know more about the green house gases? The following list of green house gas GWP values are taken from the IPCC Fourth Assessment Report will give you a good idea what are the retricted GHGs under the Kyoto Protocol.

GWP of various gases compared to CO2

 

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