For each of these graphical monthly outputs, I do a scale-match blink
comparison for any changes in the earlier data, this was the first time
to show such data revisionism, pushing earlier data lower, so derating
the earlier such results here.

For Mauna Loa data output 06 Sep 2023 at
https://gml.noaa.gov/webdata/ccgg/trends/co2_trend_mlo.png

Using the off-line javascript curve-fitter at statpages.info
Of curve types , linear=no acceleration, exponential=increasing
acceleration, quadratic=fixed acceleration, indicial= falling
acceleration; indicial was best fit by R^2 factor again, but only
marginally over the quadratic and exponential forms.

then adding yearly sine component,
y= a + b*x^c + d*sin(e*x+f)*(1+g*x)

where x is year minus 2000 for start year of 2003 to
avoid the decade of post-Pinatubo geodata recovery, 6
figures retained for anyone else repeating/checking this exercise
For Sep 2023 output
a= 371.123935
b= 1.105181
c= 1.209881
d= 3.051727
e= 6.270042
f= 6.356776
g= -0.003249

For Aug 2023 output
a= 371.156091
b= 1.096609
c= 1.212332
d= 3.052406
e= 6.269709
f= 6.359984
g= -0.003293

To 2050 , ignoring the sine component,for Sep 2023 output= 496.7226ppm
(-0.26 but data revisionism, so arbitrarily comparing with July output
then +0.08)
previous history for the sine form of indicial curve type

To 2050, for Aug 2023 output= 496.981ppm (+0.35 )
To 2050, for Jul 2023 output= 496.638ppm (+0.46 )
To 2050, for Jun 2023 output= 496.18 ppm ( +0.27 )
To 2050, for May 2023 output =495.91 ppm (-0.10)
To 2050, for Apr 2023 output =496.01 ppm (-0.80)
To 2050, for Mar 2023 output =496.81 ppm (-0.79)
To 2050, for Feb 2023 output =497.60 ppm (-0.67)
To 2050, for Jan 2023 output =498.27 ppm (-0.28)
To 2050, for Dec 2022 output =498.55 ppm (-0.27)
To 2050, for Nov output =498.82 ppm ( -0.49)
To 2050 ,for Oct output=499.31 ppm (-0.32)
To 2050 ,for Sept output=499.63 ppm (-0.04)
To 2050 , for August output= 499.67 ppm (+0.20)
July 2022 output data , to 2050 , 499.47 ppm (+0.04)
June 2022 output data , to 2050 , 498.43 ppm (+0.15)
May 2022 output To 2050 , 498.28 ppm (-0.39)
April output to 2050, 498.67 ppm (-0.83)
March output to 2050, 499.5 ppm (-0.20)
Feb output was 499.7 (-15.55)
Jan 2022 output was 515.25

--
Global sea level rise to 2100 from curve-fitted existing altimetry data
<http://diverse.4mg.com/slr.htm>