David H. Douglass (Univ of Rochester) and S. Fred Singer (Univ of Virginia/SEPP)
Climate
Data Disagree with Climate Models:
David H. Douglass (Univ of Rochester) and S. Fred Singer
(Univ of Virginia/SEPP)
(Douglass/Singer AGU meeting Dec 5-9, 2005)
Climate Data Disagree with Climate Models:
Policy Dilemma: Should We Believe in Atmosphere or in Models?
David H. Douglass (Univ of Rochester) and S. Fred Singer (Univ of Virginia/SEPP)
We challenge the substantial greenhouse (GH) warming projected from current
climate models. Incontrovertible differences exist between observed temperature
trends from balloons and satellites and those calculated from GH models.
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A key problem is to establish the extent of the human contribution to climate change, especially in the past 25 years. This task involves the careful comparison of observations of surface (from land and oceans) and troposphere (from radiosondes and satellites) temperatures with climate models that incorporate all relevant forcings, including those from rising levels of greenhouse gases.
Unfortunately, uncertainties are still very large. Modelled climate sensitivities can range from about 1.5 C up to 11.5 C (for a doubling of CO2) depending on details of parameterization of clouds [Stainforth et al, Nature 27 Jan, 2005]. Disparities exist for observed temperature trends from the MSU satellite data by the UAH [Christy and Spencer] and RSS [Mears and Wentz, Science, 2 Sept. 2005] groups. There are ongoing corrections of radiosonde trends [Sherman et al, Science, 2 Sept. 2005], and efforts for their resolution [Thorne et al, BAMS Oct 2005].
A concordance of temperature trends for surface and troposphere is a necessary
but not sufficient condition; it seems to exist for short-term climate fluctuations
but not on a decadal scale [Santer et al, Science, 2 Sept. 2005]. The latitude
variation of temperature trends does not accord with models - esp. in the Arctic
and Antarctic [Douglass, et al, GRL, 9 July 2004].
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The leading climate problem continues to be the disparity between large temperature
trends reported for the Earth's surface and the much smaller trends observed
in the atmosphere --- just the opposite to what climate models predict. This
problem has been highlighted in a National Academy report [1].
More recently, Douglass, Pearson and Singer [2] confirmed the NAS conclusion
and extended the analysis. In addition to the existence of a general disparity
in trends between surface and atmosphere, we demonstrated its detailed dependence
on altitude. It is found to be opposite in sign to what would be expected from
three leading GH models (Fig.1).
Now, a panel of experts convened by the CCSP [3] and using updated analyses of balloon and satellite data, has essentially confirmed these earlier results [1,2]. As can be seen from Fig. 2, the disparity between observations and model results is both real and substantial. The surface is warming faster than the lower troposphere (LT) in 3 out 4 data sets.
It is puzzling therefore that the Executive Summary of the CCSP [3] report
claims agreement ("there is no inconsistency between models and observations
at the global scale") when their own analysis suggests the opposite.
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CONCLUSION: The anthropogenic Greenhouse effect has been greatly exaggerated.
The observational evidence does not support the results of the climate models.
But without such validation, there is little reason to trust model predictions
of future Global Warming or to use them for policy decisions that can have severe
impacts on national economies.
References
1. National Research Council. Reconciling Observations of Global Temperature
Change. National Academy Press, Wash. DC, 2000
2. D.H. Douglass, B. Pearson, S.F. Singer. Geophys Res Ltrs, 9 July 2004
3. US Climate Change Science Program (CCSP). Temperature Trends in the Lower
Atmosphere: Steps for Understanding and Reconciling Differences. Synthesis and
Assessment Product 1.1 http://www.climatescience.gov/Library/sap/sap1-1/public-review-draft/sap1-1prd-exsum-all.pdf
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Figure 1. From Douglass/Pearson/Singer [2]. Leading climate models (dashed
lines) show positive temperature trends (tuned to surface temperatures - CIRCLE)
and increasing with altitude. Balloon radiosondes (two independent data sets
- solid lines) show the opposite and agree with satellite result (MSU-UAH -
shown by SQUARE)
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Figure 2. From CCSP report [3]. The difference between tropical temperature trends (since 1979) of Surface (TS) and Lower Troposphere (T2LT). Model results are shown in the histogram. Two independent radiosonde analyses are shown as Circles; two independent satellite analyses as Squares. The disparity between models and observations is evident and suggests that only a minor contribution towards current warming comes from anthropogenic GH gases.
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