Here are my calculations. This time I have included the
formulas, not just the numerical values.
Rows 2 through 6 are numbers from the literature.
Row 7 is my chosen scenario.
Rows 9 through 13 are calculated.
The meaning is discussed in my prior email.
row value formula units remark
2 280 =co2_prior ppm
3 400 =co2_now ppm
4 4.4 =sensitivity °C/ppm
5 0.5 =env_per_Gt
6 0.5 =air_per_env
7 504 =added_mass Gt CO2 scenario
8
9 252 =B7*env_per_Gt
10 126 =B9*air_per_env ppm added
11 526 =B10+B3 ppm future total
12 0.910 =log2(B11/B2) doublings
13 4.00 =B12*sensitivity °C temperature rise
The only halfway tricky thing is that I used a
sensitivity number from the high end of the distribution.
That is well justified because that's where the main
contribution to the /expected/ cost comes from, as
previously discussed.
On 10/09/2014 11:14 PM, Craig Lucanus wrote:
I've assumed (526-275)/275 = 0.91
I don't know where that calculation comes from.
I don't see the physical significance of the formula.
Contrast it with row 12 above.
The value 0.91 seems to be a numerological coincidence.
the 504 GT question
I cooked up the 504 by working backwards from a round
number (4 °C) for the final temperature rise. You could
equally well choose a round number (500 Gt) for the input
without significantly changing the conclusions.
There are eeenormous error bars on all these numbers,
and this is only the sketchy outline of a calculation.
Let's not worry about insignificant digits, such as
504 versus 500.
Just because it is insignificant does NOT mean I am
required to round it off. In a properly designed
experiment or calculation, roundoff error is never
the dominant contribution to the overall error.
In general, you should never assume you can determine
the level of significance by counting digits. I don't
care how many high-school chemistry books tell you to
do this; it has never worked and never will. For
details on this, see https://www.av8n.com/physics//uncertainty.htm