New Paper Illustrates Another Failure Of The IPCC Mullti-Decadal Global Model Predictions – “On the Warming In The Tropical Upper Troposphere: Models Versus Observations” By Fu Et Al 2011

There is a new paper [h/t to Willie Soon for alerting us!]

Fu, Q., S. Manabe, and C. Johanson (2011), On the warming in the tropical upper troposphere: Models versus observations, Geophys. Res. Lett., doi:10.1029/2011GL048101, in press. (accepted 24 June 2011)

with the abstract [highlight added]

“IPCC (Intergovernmental Panel on Climate Change) AR4 (Fourth Assessment Report) GCMs (General Circulation Models) predict a tropical tropospheric warming that increases with height, reaches its maximum at ~200 hPa, andeases near the tropical tropopause. This study examines the GCM-predicted maximum warming in the tropical upper troposphere using satellite MSU (microwave sounding unit)-derived deep-layer temperatures in the tropical upper- and lower-middle troposphere for 1979-2010. While satellite MSU/AMSU observations generally support GCM results with tropical deep-layer tropospheric warming faster than surface, it is evident that the AR4 GCMs may exaggerate the increase in static stability between tropical middle and upper troposphere during the last three decades.”

The conclusion reads

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. Here we examine this feature by using satellite MSU/AMSU derived deep-layer temperatures in the tropical upper- (T24) and lower- (T2LT) middle troposphere for 1979-2010. It is shown that T24- T2LT trends from both RSS and UAH are significantly smaller than those from AR4 GCMs. 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.”

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, 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.”

Even though their paper failed to cite already published peer-reviewed papers that show the problem is even more serious than they report (e.g. including that both RSS and NOAA have spurious warming in the 1990s), their new paper is still quite critical of the skill of the IPCC model predictions of upper tropospheric tropical warming. 

 The new Fu et al 2011 paper is also a refutation of the paper

Thorne P. et al, 2010: Tropospheric temperature trends: history of an ongoing controversy. WIREs Climate Change. Published Online: Nov 15 2010 DOI: 10.1002/wcc.80

who write

“With increasing greenhouse gas concentrations, the surface and troposphere are consistently projected to warm, with an enhancement of that warming in the tropical upper troposphere……..It is concluded that there is no reasonable evidence of a fundamental disagreement between tropospheric temperature trends from models and observations when uncertainties in both are treated comprehensively.”

In contrast to the Thorne et al 2010 study, there is a fundamental disagreement between the model predictions and the real world observations.

The papers which Fu et al 2011 ignored in their study include

Christy, J.R., B. Herman, R. Pielke, Sr., P. Klotzbach, R.T. McNider, J.J. Hnilo, R.W. Spencer, T. Chase and D. Douglass, 2010: What do observational datasets say about modeled tropospheric temperature trends since 1979?  Remote Sensing, 2(9), 2148-2169

and

Randall, R. M., and B. M. Herman (2008), Using Limited Time Period Trends as a Means to Determine Attribution of Discrepancies in Microwave Sounding Unit Derived Tropospheric Temperature Time Series, J. Geophys. Res., doi:10.1029/2007JD008864

 This new Fu et al 2011 paper, despite ignoring peer-reviewed papers that show the discrepancy is even larger,  is still another “confession” regarding the failure of the IPCC to accurately simulate the climate system.

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