Atmospheric methane growth stalled in 2000 and started increasing again in 2006 \cite{ref:kirschke2013}.\cite{ref:rigby2017} suggest that from 2004 to 2014, global OH concentrations decreased by 8% (11%), with a 70% (64%) chance of a negative trend since 2007 given the uncertainties when using the AGAGE (NOAA) data. Similarly, \cite{ref:turner2017} suggest a 5% decrease in global OH from 2005 to 2015. This corresponds to an increase in methane lifetime over that period from 8.8 years to 9.4 years. Both of these studies are consistent with previous analyses using MCF measurements to determine OH variability \cite{ref:mcnorton2016}.\cite{ref:dalsoren2016} use a multilinear regression to derive an empirical relationship between the methane lifetime inferred from surface observations over a 40 year period and several factors that drive OH variation. \cite{ref:murray2014} derive a similar empirical relationship and show that it holds for chemistry-climate simulations in the preindustrial and LGM.Trends in stratospheric ozone over the past decade are well-studied by a suite of satellite instruments \cite{ref:harris2015}. Ozone in the upper stratosphere (35-45km) exhibits a positive trend since 2000, with central estimates of the trend of 3.9 ± 1.3 % per decade in the northern mid-latitudes, +1.9 ± 1.2 % per decade in the tropics, and +3.0 ± 1.2 % per decade in the southern midlatitudes.IPCC AR5 estimates a rise in tropospheric humidity of about 0.1 g/kg per decade from 1973 to 2012.
