Taking the equations from
Radiative forcing - Wikipedia, the free encyclopedia
dF=5.35*Ln(C/Co)
dT = 0.8*dF
dF = change in forcing
C = current concentration CO2 (I'm using 2005) 315ppm
Co = orriginal concentration CO2 (I'm using 1958) 380ppm
dT = change in temperature (using 1958 to 2005) 0.64C
I am hoping they made an actual physical measurement and didn't just run that through a model and call it good. This shows that for a doubling of CO2 we get a change of forcing of 3.39w/m^2, which is different from the IPCC value of 3.7w/m^2.
Using the "measured" value changes the equation to
dF = 4.89 * Ln(C/Co)
Filling in for CO2
dF = 4.89*LN(380/315) = .91w/m^2 for the measured 1958-2005 change in CO2.
That should give us a change in temperature of
dT = .8*0.91 = 0.73C which is 0.09C higher than observed.
Correcting for observed gives us a climate sensitivity of 0.696
Now we can calculate for future warming.
Forcasting a rise to 600pmm.
dF = 4.89*Ln(600/315) = 3.15w/m^2
dT = .696*3.15 = 2.19C
That is assuming all warming is due to CO2 with no influence from the sun.
Neil: A lot of the changes that are happening faster than we expected are because they are in the colder climates. One of the things the equations above do not take into account is the fact that in the colder climates a small change in the energy ballance causes a greater change in temperature than it does in warmer climates. The warmer climates will hardly change at all, while the coldest climates will warm by probably 10C or more.