Big names like Santer, Sherwood, and Schmidt admit that the models predict more warming 10 km above the equator than what the weather balloons could find. Each time they announce that they’ve resolved the differences, they have to start by admitting there are differences to resolve.
My point here is that some bloggers are variously arguing the nonsensical or irrelevant: that, a/ the hot-spot was always there; b/ it doesn’t matter if it’s not found, and c/ it would occur with all climate forcings. Which disagrees with the top expert supporters of AGW.
The real debate is now about whether the hot-spot has been found or not. The top alarmists argue that we’ve sort of ‘found’ the hot-spot recently with new statistical rehashes or by using wind-gauges instead of thermometers. Note that even when they imply they’ve ‘found it’, after an unfortunate reader wades through the convoluted language, it turns out that they’ve just increased the error bars so they stretch far enough to include the real world results. Thus, it’s no longer ‘statistically different’.
So to state the obvious, from the mouths of the AGW experts themselves… 1/ the discrepancy matters, and 2/ even they agree it was definitely missing.
Climate models and theoretical expectations have predicted that the upper troposphere should be warming faster than the surface. Surprisingly, direct temperature observations from radiosonde and satellite data have often not shown this expected trend.
Sherwood et al 2008. Simple news summary of Sherwood here.
Sherwood reviewed 17 papers in his opening remarks and only one of them showed the expected warming.
Since the late 1960s, scientists have performed experiments in which computer models of the climate system are run with human-caused increases in atmospheric concentrations of greenhouse gases (GHGs). These experiments consistently showed that increases in atmospheric concentrations of GHGs should lead to pronounced warming, both at the Earth’s surface and in the troposphere. The models also predicted that in the tropics, the warming of the troposphere should be larger than the warming of the surface. … Until several years ago, however, most available estimates of tropospheric emperature changes obtained from satellites and weather balloons (radiosondes) implied that the tropical troposphere had actually cooled slightly over the last 20 to 30 years (in sharp contrast to the computer model predictions, which show tropospheric warming). For nearly a decade, this apparent disconnect between models and reality has been used by some scientists and politicians to argue that:
· Human-caused changes in greenhouse gases have no effect on climate;
· Computer models have no skill in simulating the observed temperature changes in the tropics, and therefore cannot be used to predict the climatic “shape of things to come” in response to further increases in greenhouse gases.
Santer 2008 (Real Climate, Fact Sheet)
“On multi-decadal timescales, tropospheric amplification of surface warming is a robust feature of model simulations, but occurs in only one observational dataset. Other observations show weak or even negative amplification.”
Santer et al 2005
“Previously reported discrepancies between the amount of warming near the surface and higher in the atmosphere have been used to challenge the reliability of climate models and the reality of human-induced global warming…..[and while we have sorted out some differences] …discrepancies in the tropics remain to be resolved.”
Karl et al 2006
“A recent report of the U.S. Climate Change Science Program (CCSP) identified a ‘potentially serious inconsistency’ between modelled and observed trends in tropical lapse rates”
Santer et al 2008 (including Gavin Schmidt and Sherwood)
How much of a discrepancy is there?
“Model results and observed temperature trends are in disagreement in most of the tropical troposphere, being separated by more than twice the uncertainty of the model mean. In layers near 5 km, the modelled trend is 100 to 300% higher than observed, and, above 8 km, modelled and observed trends have opposite signs.”