Time_Constant 
There is a relationship between climate sensitivity and the planet's time constant (The time of response to a pulse increase in CO2 content)
t= 33.137407378 + 19.888205077 * cs 0.047279468 * cs^2
Example: If the climate sensitivity is 5 and all emissions are stopped, the temperature will roughly estimated continue to rise for 65 years. Temperatures do not stop in the way described by the IPCC in the last report.
cs=5 t= 33.137407378 + 19.888205077 * cs 0.047279468 * cs^2 = about 65 years.
Since Prof. James Hansen has set cs to 6 and three of the heaviest simulations show 5
.....we can say on this basis that NetZero (Zero Emissions 2045 ) is not a workable climate policy. Temperatures will not be halted in the way that is hoped. It is completely impossible to limit warming to +1.5 or to +2C by stopping all emissions today. Any other scenario that uses zero emissions (solar, wind, hydro, electric cars....) is worse.
There is only one goal for future climate discussion: sketch completely different ways out.
The only possible solution is to suck 200 Gt of CO2 and 2 Gt of methane out of the atmosphere per year.
If this starts by 2025, the Paris Agreement can be saved.
Derivation
The starting point is this ordinary differential equation that describes the model where the Earth is in an oven with overtemperature:
This is the symbolic solution of the differential equation Now this can be evaluated numerically:
2.0000000000000000E+00 1.0000000000000000E+01 3.0000000000000000E+00 2.5000000000000000E+01 5.0000000000000000E+00 6.5000000000000000E+01 1.0000000000000000E+01 1.6000000000000000E+02 2.0000000000000000E+01 3.4000000000000000E+02 3.0000000000000000E+01 5.2000000000000000E+02 3.6000000000000000E+01 6.3000000000000000E+02 5.0000000000000000E+01 8.4000000000000000E+02
From there, a regression analysis : Polynomial Regression (degree=2) can be performed
t= 33.137407378 + 19.888205077 * cs 0.047279468 * cs^2
