I superimposed two horizontal red lines on the below graph of lower stratosphere temperature (via the SkS website) which shows a flatlining for about a decade, before the graph conveniently stops in 2005:
A more up to date graph shows this temperature flatline lasts about 21 years:
21 years is not too dissimilar from 19 years: the amount of time satellite Temperature Lower Troposphere temperatures have also flatlined.
I took RSS data for lower troposphere and lower stratosphere and inverted one graph and superimposed them:
As the troposphere warms the stratosphere cools.
SkS says the sun can't be the cause of this because the stratosphere and troposphere would warm simultaneously. Perhaps there's merit to this argument but this still doesn't rule out other natural causes.
Even the basic premise that CO2 IR trapping can cool the stratosphere is doubtful. Just because a bit of IR is withheld by CO2 why wouldn't the increase in emission of other frequencies of light through the atmospheric window warm the stratosphere, thus cancelling the warming effect?
Furthermore despite the tropopause consisting of very sparse air with minimal convection there would still be a little bit of heat by physical conduction going to the lower stratosphere from the troposphere, which would prevent it from cooling.
In any case the lower stratosphere has been warming since about 2007 according to RSS satellite:
|Fingerprint fail: stratosphere not cooling last few years as predicted|
Stratospheric cooling's actually more related to the depletion of ozone than CO2-induced global warming. The IPCC recognises this fact but the folks at SkS struggle to, often downplaying ozone's role and up-playing carbon dioxide's role.
The following graph shows there's a better link of stratospheric temperature to ozone depletion than CO2. As stratospheric ozone depletes it absorbs less UV and gets cooler.
And as the stratosphere absorbs less UV, more is let through to the surface to warm it:
Global warming is caused by ozone depletion, not greenhouse gases
It seems ozone depletion could cause at least some of the 20th-century global warming often attributed solely to carbon dioxide.
SkS attempts a vague rebuttal of the idea of ozone-induced warming (here) by claiming that ozone depletion has stopped yet temperature keeps rising. That's a pretty lame explanation considering the satellites show temperature has flatlined for 19 years.