Highest projected 2050 figure for this metric but increases are slowing.
Best fit indicial very marginally over quadratic again , but for
continuity, going with quadratic .
Further such month with marginally better indicial fit,
if going with indicial then increased projection to 2050 of 2608.057
ppb, with no added sine components,
so staying with conservative quadratic as well as continuity of results
y= 1776.364047 +(a)*x + b*x*x + c*sin(d*x+e) + f*sin(g*x+ h)
y in ppb and x = year -2000,
6 figure values retained for anyone else checking/confirming all this
For Sep 2023 output (data to May 2023)
a= -1.569778
b= 0.328930
c= 0.997363
d= 1.739532
e= 6.072061
f= 3.458929
g= 0.964274
h= 4.721378

For Aug 2023 output (data to Apr 2023)
a= -1.561854
b= 0.328694
c= 0.998391
d= 1.737290
e= 6.096702
f= 3.462558
g= 0.964285
h= 4.719351

Ignoring the SH and NH sine components
From 06 Sep 2023 output (data up to May 2023) for 2050 projection
forwards, 2520.200 ppb global CH4 (increase about 0.3 ppb, to highest
projection of this metric)
From 08 Aug 2023 output (data up to Apr 2023) for 2050 projection
forwards, 2519.949 ppb global CH4 (increase about 1 ppb)
From 05 July 2023 output (data up to Mar 2023) for 2050 projection
forwards, 2519.166 ppb global CH4
From 05 June 2023 output (data up to Feb 2023) for 2050 projection
forwards, 2518.408 ppb global CH4 (increase 1 ppb)
From 09 May 2023 output (data up to jan 2023) for 2050 projection
forwards, 2517.873 ppb global CH4 (increase 2 ppb)
From 05 Apr 2023 output (data up to dec 2022) for 2050 projection
forwards, 2515.77 ppb global CH4 (increase 3 ppb )
From 06 Mar 2023 output (data up to nov 2022) for 2050 projection
forwards, 2512.28 ppb global CH4 (increase 5 ppb )
From 06 Feb 2023 output (data up to oct 2022) for 2050 projection
forwards, 2507.56 ppb global CH4 ( increase 4 ppb)
From 06 Jan 2023 data, for 2050 projection forwards, 2503.47 ppb global
CH4 (increase +3ppb, back to Oct 2022 projected level)
From 07 Dec 2022 data, for 2050 projection forwards, 2500.31 ppb global
CH4 (decrease -2ppb)
From 07 Nov data, for 2050 projection forwards, 2502.32 ppb global CH4
(decrease -3ppb)
From 06 Oct data, for 2050 projection forwards, 2505.15 ppb global CH4
(increase +26 ppb)
From 06 Sep data, for 2050 projection forwards, 2478.72 ppb global CH4
(decrease -27ppb)
from 06 Aug data, 2506.16 ppb global CH4 (increase +1ppb)
from 11 July data, 2505.27 ppb global CH4 (increase +5ppb)
from 06 June data, 2500.61 ppb global CH4 (increase +4ppb)
from 05 May data, 2496.26 ppb global CH4 (increase +5ppb)
from 07 Apr data, 2491.42 ppb global CH4 (increase +7ppb)
from 08 Mar 2022 output gives 2484.94 ppb global CH4 (increase +4)
from 07 Feb 2022 output gives 2480.69 ppb global CH4 ( increase +11)
from 06 Jan 2022 output gave 2469.27 ppb global CH4 ( increase +4)
Dec 2021 output gave 2465.43 ppb (slight decrease -1, lowest
projection for this metric with up to july 2021 data, 6 months after
minimum of ENSO ONI)
Nov 2021 output gave 2466.0 ppb (first such determination)

data update at
https://gml.noaa.gov/webdata/ccgg/trends/ch4/ch4_mm_gl.txt

Subset of 245 datapoints from 2003.0
to avoid the decade post-Pinatubo recovery in geodata
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.

history of the annual semi-amplitude fits, c and f,
For Sep 2023 output
both falling
c= 0.997363
f= 3.458929

For August 2023 output
one rising, one falling
c= 0.998391
f= 3.462558

For July 2023 output
one rising, one falling
c= 0.983487
f= 3.475663

For Jun 2023 output
both rising
c= 0.980033
f= 3.480589

For May 2023 output
both rising
c= 0.977262
f= 3.479937

For Apr 2023 output
both rising
c= 0.969287
f= 3.467247

For Mar 2023 output
both rising
c= 0.965349
f= 3.408772

output in Feb 2023
both rising
c= 0.938541
f= 3.364805

output in Jan 2023
both rising
c= 0.915613
f= 3.353881

both NH and SH ones still continuously falling since Sep 2022 ,
(output in Dec) 2022
c= 0.891852
f= 3.319105

(output in Nov) 2022
c= 0.912050
f= 3.344683

(output in Oct) 2022
c= 1.022339
f= 3.508251

(output in Sept) 2022
c= 1.074210
f= 3.576829

up to July (output in August) 2022
c= 1.028145
f= 3.478293

up to June (output in July) 2022
c= 1.013330
f= 3.473744

May 2022
c= 0.966767
f= 3.445663

April 2022
c = 0.938531
f = 3.438794

March 2022
c = 0.896438
f = 3.370038

Feb 2022
c = 0.873589
f = 3.300138

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