I hope the Climate Activists are proud of the effect their lies are having on the younger generation

Roger Bryant: 
 

In the 60 years of CO2 measurements at Mauna Loa the CO2 content of the atmosphere has risen by around 100ppm from just over 300ppm to just over 400ppm. If this rate is constant, which it probably isn’t, 

It manifestly isn't. The slope is continually increasing. If you extrapolate the recent slope back, it crosses the 310ppm scale at 1985, not at 1958. If you take that slope as constant, (which is a very conservative assumption), you get 100ppm increase in 36 years, which would mean a further 200ppm in 72 years from now.

But that is not a particularly good extrapolation. If you extrapolate the early years linearly, you come to about 380ppm in 2020, that is, 70ppm in 60 years or 1.17 ppm/yr. Whereas the rate close to now is 100ppm in 35 years or 2.86 ppm/yr. So the rate has doubled in, shall we say, 50 years. If the trend continues, we'll be up to 5.72ppm/yr in 2070, or 100ppm in 17+years. A reasonable rule of thumb would be to take 36 years for the next 100ppm rise and 18 years for the next 100ppm after that. That is 54 years from now, 2074.

In contrast, you suggest

 

 doubling of CO2 from the 1960 level will take 180 years from 1960 or 120 years from now. 

Isn't it interesting how very different estimates are when one uses different approximation techniques? (Mine is better than yours, BTW). 

What is the effect of this doubling? The AR6 assessed best estimate is 3°C with a likely range of 2.5°C to 4°C (high confidence), 

So that's 3° with 80% CI 2.5° to 4°.

I will take their best estimate of 3°C for the ECS. This suggests the with rising emissions we may get a 3°C Global increase by 2100. 

By 2074 if you take my estimate above.

With steady or falling emissions 3°C may be reached by the middle of the next century or beyond. As I have stated many times before we have a climate problem, not a climate emergency.

So what we conclude about how urgent this is is very dependent on our extrapolation techniques. 

Roger Bryant: 
 

In the 60 years of CO2 measurements at Mauna Loa the CO2 content of the atmosphere has risen by around 100ppm from just over 300ppm to just over 400ppm. If this rate is constant, which it probably isn’t, 

It manifestly isn't. The slope is continually increasing. If you extrapolate the recent slope back, it crosses the 310ppm scale at 1985, not at 1958. If you take that slope as constant, (which is a very conservative assumption), you get 100ppm increase in 36 years, which would mean a further 200ppm in 72 years from now.

But that is not a particularly good extrapolation. If you extrapolate the early years linearly, you come to about 380ppm in 2020, that is, 70ppm in 60 years or 1.17 ppm/yr. Whereas the rate close to now is 100ppm in 35 years or 2.86 ppm/yr. So the rate has doubled in, shall we say, 50 years. If the trend continues, we'll be up to 5.72ppm/yr in 2070, or 100ppm in 17+years. A reasonable rule of thumb would be to take 36 years for the next 100ppm rise and 18 years for the next 100ppm after that. That is 54 years from now, 2074.

In contrast, you suggest

 

 doubling of CO2 from the 1960 level will take 180 years from 1960 or 120 years from now. 

Isn't it interesting how very different estimates are when one uses different approximation techniques? (Mine is better than yours, BTW). 

What is the effect of this doubling? The AR6 assessed best estimate is 3°C with a likely range of 2.5°C to 4°C (high confidence), 

So that's 3° with 80% CI 2.5° to 4°.

I will take their best estimate of 3°C for the ECS. This suggests the with rising emissions we may get a 3°C Global increase by 2100. 

By 2074 if you take my estimate above.

With steady or falling emissions 3°C may be reached by the middle of the next century or beyond. As I have stated many times before we have a climate problem, not a climate emergency.

So what we conclude about how urgent this is is very dependent on our extrapolation techniques.