Fu and Manabe agree the hot spot is missing
GRL June 2011.
Yet another study hunted for a form of the missing hot spot– and again the results show the models are unable to make useful predictions.
The upward rising trend predicted in the models is of critical importance. The models assume that the 1.1 degrees of warming directly due to CO2 will be tripled by feedbacks from humidity and water vapor. Studies like Fu and Manabe are looking to see if the assumptions built into the models are right. If relative humidity stays constant above the tropics throughout the troposphere, we should see the upper troposphere warm faster than the surface.
Fu and Manabe used satellite data rather than weather balloons, and compared the tropical upper troposphere to the lower middle troposphere during 1979 – 2010. (Other papers I’ve written about compared the upper troposphere to the surface, and mainly used weather balloons.)
“One of the striking features in GCM‐predicted climate
change due to the increase of greenhouse gases is the much
enhanced warming in the tropical upper troposphere”
Satellites cannot separate out the altitudes at narrow resolutions, as the radiosondes can, but they produce reliable data around the entire globe. In this test of the models predictive ability, we should have seen the upper troposphere warm faster than we did. Indeed while the difference in trends was positive, it was so weakly positive as to be not significantly different. In other words, we can’t be sure that the upper troposphere is warming faster than the lower-middle area, though it might be. Even if it is warming, it just isn’t doing it enough to verify the models.
Given that the IPCC don’t seem to be in a rush to acknowledge the discrepancies between models and observations (heck, they were discovered by the mid-90’s), this is what “90% likely to be right” looks like:
The trends of T24‐T2LT from both observations and models are all positive (Figure 2, below), indicating that the tropical upper‐middle troposphere is warming faster than lower middle troposphere [Fu and Johanson, 2005]. But the positive trends are only about 0.014 ± 0.017 K/decade from RSS and 0.005 ± 0.016 K/decade from UAH, which are not significantly different from zero. In contrast, the T24‐T2LT trend from multi‐model ensemble mean is 0.051 ± 0.007 K/decade, which is significantly larger than zero. The trends from observations and multi‐model ensemble mean do not fall within each other’s 95% confidence intervals…
Maybe the satellites are wrong and not the models:
This indicates possible common errors among GCMs although we cannot exclude the possibility that the discrepancy
between models and observations is partly caused by biases in satellite data.
But remember that 28 million radiosondes have found similar discrepancies with the models in the tropical upper troposphere.
If millions of radiosondes and 30 years of satellite data are both biased, then the models could be right.
IPCC AR4 GCMs overestimate the warming in the tropics for 1979–2010, which is partly responsible for the
larger T24‐T2LT trends in GCMs. It is found that the discrepancy between model and observations is also caused by
the trend ratio of T24 to T2LT, which is ∼1.2 from models but ∼1.1 from observations. While strong observational evidence
indicates that tropical deep‐layer troposphere warms faster than surface, [note we don’t name any…] this study suggests that the AR4 GCMs may exaggerate the increase in static stability between tropical middle and upper troposphere in the last three
decades. In view of the importance of the enhanced tropical upper tropospheric warming to the climate sensitivity and to
the change of atmospheric circulations, it is critically important to understand the causes responsible for the discrepancy
between the models and observations.
The post that will put this in perspective best is The models are wrong (but only by 400%). (McKitrick et al 2010)
The missing hotspot (What they expected to find, and what the weatherballoons didn’t show)
Found: the hot spot? Not (This has been a long running search).
Other useful posts are: Thorne 2010: A very incomplete history of the missing hot spot
For other perspectives:
Fu, Q., S. Manabe, and C. Johanson (2011), On the warming in the tropical upper troposphere: Models versus observations, Geophys. Res. Lett., 38, L15704, doi:10.1029/2011GL048101. [PDF]