UNs IPCC Reports https://www.ipcc.ch/site/assets/uploads/2018/03/Chapter-5-Hydropower-1.pdf See fig 5.15. The outliers are the concern (and yes, it's pretty much methane)
Edit: I reread the parent comment, the above won't address what you asked for, but is interesting nonetheless so I'll leave it
UNs IPCC Reports https://www.ipcc.ch/site/assets/uploads/2018/03/Chapter-5-Hydropower-1.pdf See fig 5.15. The outliers are the concern (and yes, it's pretty much methane)
Edit: I reread the parent comment, the above won't address what you asked for, but is interesting nonetheless so I'll leave it