Here we find out how close we are to having enough GHGs in the atmosphere to raise the temperature by 2 degrees C. The “climate sensitivity” is how much warmer the earth would get if we doubled the greenhouse gases, and for a long time the best estimate has been 3 degrees C. So if we just increase them 67% we would get a 2 deg C temperature increase. So how are we doing?
From these sources we fill in the following table.
|Greenhouse Gas Impacts|
GWP=1 ⇒ 115.4ppm = 1.88 Forcing, W/m2. So the formula for Forcing is:
F = k × GWP × ppm, where k = (1.88/115.4) = 0.01629
The value 115.4 and 1.88 come from CO2 historic data table in July 2015.