The ‘Hotspot’ is crucial to the climate debate.
If greenhouses gases are warming the planet that warming will happen first in the cold blob of air 8-12 km above the tropics. It’s freezing cold up there, but it ought to be slightly less freezing cold thanks to greenhouse gases. All 20-odd climate models predict warming there first—it’s the fingerprint of greenhouse gas warming, as opposed to warming by some other cause, like solar magnetic effects, volcanic eruptions, solar irradiance, or ozone depletion etc etc.
Look at A above, the greenhouse gas fingerprint is markedly different from the rest and dominates the overall predicted pattern in graph F. The big problem for the believers of AGW is that years of radiosonde measurements can’t find any warming, as shown in part E of Figure 5.7 in section 5.5 on page 116 of the US CCSP 2006 report
(A) Predicted changes 1958-1999. Synthesis and Assessment Report 1.1, 2006, CCSP, Chapter 1, p 25, based on Santer et al. 2000;
(B) Hadley Radiosonde record: Synthesis and Assessment Report 1.1, 2006, CCSP, Chapter 5, p 116, recorded change/decade, Hadley Centre weather balloons 1979-1999, p. 116 , fig. 5.7E, from Thorne et al., 2005.
UPDATE 2022: The former links are broken (why do government departments do that?) All original CCSP Chapters are stored at the Wayback Machine. See Wayback Machine copies of (Chapter 1) Specifically download the PDF. and Wayback Machine Copies of (Chapter 5) Specifically download the PDF. If they disappear there is a back up copies here of Chapter 1 SAP and Chapter 5 SAP 1.
Is there any way the missing hot-spot doesn’t fatally kill the greenhouse theory?
Perhaps we’re looking in the wrong spot and the hot-spot is lurking somewhere else?
If we are, that gets us right back to square one. The theory of greenhouse gas warming depends on finding a hotter spot of air above the equator… if that hot spot is somewhere else, the greenhouse theory itself collapses in a heap. It means either the greenhouse effect is not causing much of the recent warming, or the greenhouse theory is just plain wrong. AGW supporters are not asking this question because they can’t win either way.
Possibly we just can’t measure the air temperatures accurately enough to find the hot-spot?
Maybe, but we’ve been recording temperatures up there repeatedly for decades, and it’s not that the hot-spot is weak—it’s absent. There is no sign at all.
AGW says: Santer and Sherwood have found the missing hot spot.
Skeptics say: Santer uses statistics to show that the hot spot might be hidden under the noise. He hasn’t found any sign of warming–just the sign of fog in the results. Sherwood ignores the thermometers altogether and uses wind gauges to tell us the temperature. (Who’d a thought?!)
On my blog there’s more answers to the claims that the hot spot is not missing here.
See all posts tagged “Missing Hot Spot”
The bottom line is that either the thermometers are wrong or the theory is.
On David Evans site there’s a full definitive explanation of the missing hot spot and all the common attempts to rebut it on one pdf here (25 pages). If you can’t open it in Mozilla try Explorer.