A while back I needed an equation to forecast CO2 and after some work playing with equations I found that the equation listed next will predict the level of CO2 as reported by NOAA each month within a few points ppm ignoring the seasonal variation.

CO2 = 270+730/(1+8.75*EXP(0.00175*(4612-M)))

270 is a reasonable guess for the starting value of CO2 in the base year which is 1650 and M represents the number of months from January 1650 to the date a value is need, such that July 2014 would be 4975. Substituting 4975 for M will give a CO2 value of 399.53 the actual NOAA value was 399.0

A plot made from this equation will closely match NOAA’s number’s from 1958 to the present.