Technically, Singer is no longer a denier of warming. He gave that up finally, like he gave up denying that the ozone layer was being attacked by fluorocarbons and gave up denying that second-hand smoke is dangerous. But he is still desperately denying the contribution of man-made CO2 to warming.
Poor old Fred and his band of deniers have a new paper out, which tries to poke a hole in one aspect of the science of global warming. That he got it published at all seems to have been a miracle.
It turns out that the radiosonde data used in this paper (version 1.2 of the RAOBCORE data) does not have the full set of adjustments. Subsequent to that dataset being put together (Haimberger, 2007), two newer versions have been developed (v1.3 and v1.4) which do a better, but still not perfect, job, and additionally have much larger amplification with height.
The authors of Douglass et al were given this last version along with the one they used, yet they only decided to show the first (the one with the smallest tropical trend) without any additional comment even though they knew their results would be less clear.
But more egregious by far is the calculation of the model uncertainty itself…..
there is no clear model-data discrepancy in tropical tropospheric trends once you take the systematic uncertainties in data and models seriously. Funnily enough, this is exactly the conclusion reached by a much better paper by P. Thorne and colleagues. Douglass et al’s claim to the contrary is simply unsupportable.