Kevin Trenberth of NCAR told this nonsense to the Washington Post :
Methane is a substantial contributor to global warming
The radiative transfer model used by Trenberth’s NCAR is RRTM. That model shows that even a 500% increase in methane (CH4) would have almost no impact on Earth’s radiative balance in the mid-latitudes, where almost all of the world’s population lives.
Methane is an unstable gas which oxides quickly in the atmosphere. It occupies less than two parts per million of the atmosphere, and its absorption bands almost completely overlap with H2O . Even a very large increase in CH4 would have almost no impact on the climate.