How the IPCC buries it’s inconvenient findings


There has been an interesting hearing before the US Senate on Climate Change, Models and the Scientific Method, with testimonies from J. Curry, J. Christy, M. Mann and R. Pielke Jr.. In a later blog I will comment on this hearing (video link ). For the moment I would just write about an astonishing fact given by Prof. Christy from the UAH (University of Alabama in Huntsville). Christy (and Roy Spencer) analyze and maintain the database of global temperature measurements done by the satellites (the other team is RSS).


  1. The absence of a human caused warming finger-print

All climate models agree that human caused global warming should show up as an upper atmospheric warm hot-spot in the tropics. Look at the next figure, which corresponds to the outcome of one model:


The problem is that observations (by balloons, radiosondes etc.) do not find this hot-spot, which is a serious blow to the validity of the CMIP-5 model ensemble. Christy has shown in his testimony that the difference between models and observations can be found even in the IPCC’s own latest report (AR5): but probably you have to be an avid and patient reader to find it, as it is buried away in the Supplementary Material for chapter 10, figure 10.SM.1.; also the graphics are confusing and obscure, and some detective work is needed to clear the fog.

Here is this original figure 10SM.1:

The second from left plot corresponds to the tropics, and it is this sub-plot which we will look into.


2. IPCC’s hidden truth

I made a zoom from the relevant plot, and added some annotations and boxes:


The red band gives the answer of the CMIP-5 ensemble to the question: “what are the warming trends in the tropical atmosphere (up to about 15km) in °C/decade” when the models include human generated greenhouse gases (essentially CO2); the blue band gives the answer when the models do not include (i.e. ignore) human GHG emissions. And finally the thin grey line shows the observations of one radiosonde database (RAOBCORE = Radiosonde Observation Correction using Reanalysis): it can readily be seen that the models including GHGs terribly overstate the real warming: the red band (= region of uncertainty) lies completely above the observations. Now whats nearly hilarious is that when the models do not include human GHGs (the blue band), the result is absolutely acceptable, as the blue band covers most of the observation line.

Christy made this graph still clearer by including all observations (the region limited by the grey lines):

The conclusion is the same.

So the 1 million dollar question is: how can the IPCC claim with great confidence that its model tell us that the observed warming carries a human fingerprint, and is caused with very high certainty by the anthropogenic emissions, when in its own assessment report it shows the failing of these models?


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