'Methane demands exceed methane available' error

[robbert02]

What version of the code are you using?
cesm3_0_beta06-0-g637b593 with the compset I2000Clm50Fates (long name = 2000_DATM%GSWP3v1_CLM50%FATES_SICE_SOCN_MOSART_SGLC_SWAV_SESP) on f09g17 resolution.

Have you made any changes to files in the source tree?
None

Describe every step you took leading up to the problem:
I am attempting to spin up FATES using the standard GSWP forcing data. I am running from 1700 to hopefully reach equilibrium at the present. Upon submission, the case crashes after a certain time period (some history is already written), with the following error:

Note: sink > source in ch4_tran, sources are changing  quickly relative to diff
 usion timestep, and/or diffusion is rapid.
 Latdeg,Londeg=  -76.8062827225131        148.750000000000
 This typically occurs when there is a larger than normal  diffusive flux.
 If this occurs frequently, consider reducing land model (or  methane model) tim
 estep, or reducing the max. sink per timestep in the methane model.
 Negative conc. in ch4tran. c,j,deficit (mol):           3           2
   14.6853939123955
 cbalance warning at c =           3  5.215406417846680E-008
  -34482989.2558107
 cbalance warning at c =           3  5.960464477539062E-008
  -396872224.669351
 Methane demands exceed methane available. Error in methane competition (mol/m^3
 /s), c,j: -7.275957614183426E-012           3           2
 Latdeg,Londeg=  -76.8062827225131        148.750000000000
iam = 1250: local  column   index = 3
iam = 1250: global column   index = 11204
iam = 1250: global landunit index = 8283
iam = 1250: global gridcell index = 4147
iam = 1250: gridcell longitude    =  148.7500000
iam = 1250: gridcell latitude     =  -76.8062827
iam = 1250: column   type         = 1
iam = 1250: landunit type         = 1
 ENDRUN:
  ERROR: Methane demands exceed methane available.ERROR in ch4Mod.F90 at line 36
 93

I tried to decrease the number of timesteps, by increasing LND_NCPL and ATM_NCPL to 144 and in a third attempt even to 288, but this didn't resolve the issue.

Any ideas how to solve this issue?

 

[oleson]

The methane model doesn't interact with the rest of the model, it is essentially diagnostic, so simplest thing to do is to turn it off (use_lch4=.false. in your user_nl_clm).