Question

Section 2 Some more questions about climate change. Please explain the meanings of the following terms, and how they relate to one another: • • Radiative forcing (also known as climate forcing) Climate sensitivity Climate response Where necessary, please make sure you specify the units we use to measure these things. Finally, explain what is meant by the "global warming potential (GWP)" of a greenhouse gas, being careful to specify precisely how it's measured. Explain why the GWP of, say, a tonne of methane injected into the atmosphere changes with time.

Answer 1

Radiative forcing:

Radiative forcing is a measure of effect of any cilmatic factor on the downward flux of solar energy. It takes into account the earth directed energy and the outward flow of energy due to the albedo effect and emissivity of the earth. It is measured in units of Watt/m^{​​​​​​2} . A positive value radiative forcing means overall warming of the planet.

Climate Sensitivity:

Climate Sensitivity is the globally averaged change in temperature in response to changes in the radiative forcing. It relates the Change in temperature with the change in radiative forcing.It is a measure of energy that was utilised to raise or decrease the average temperature of earth by a particular amount. It is expressed in units of°C/(W/m​​​​​​^{​​​​​​2} ).

Climate response:

Climate response is the measure of increase in global average temperature if the CO_{​​​​​2} levels were to double at a rate 1% per year. This increase is computed with reference to the pre-industrial levels of CO_{​​​​​2} .

Global warming potential is the measure of how much beat is trapped by a green house gas in a given time interval in the atmosphere as compared to the heat trapped by C​​​​​O_​2 .

The Intergovernmental Panel on Climate Change defined carbon dioxide as the reference gas for this comparison. To measure the GWP, the warning effects of a gas are quantified and then compared with well known effects of carbon dioxide.

The GWP of any gas changes because some of the gas occasionally escapes into space. Methane has a lifetime of 12.4 years in the atmosphere. As it slips away from the atmosphere, it's GWP varies.