An uneven greenhouse effect
It’s a first! A harmonisation procedure for observation of the atmosphere has shown that the concentrations of methane and nitrous oxide, two greenhouse gases, showed variable trends from one site to another.
(1) Angelbratt J. et al., A new method to detect long term trends of methane (CH4) and nitrous oxide (N2O) total columns measured within the NDACC ground-based high resolution solar FTIR network. Atmos. Chem. Phys., 11, 6167-6183, 2011.