Are the Models Untestable?

Some global warming deniers assert that the global climate models (GCMs) used to analyze and predict climate change can be ignored because they are "untestable" or "have no predictive ability." In the words of "Mug Wump" on the Science Discussion Forum "Global Warming is Nothing but a Hoax and a Scare Tactic:"

If you had any scientific evidence that human CO2 causes global warming, you would have produced it by now. Ergo, reality eludes you. Don't believe or argue with me. There are many, many scientists who once rubbed shoulders with the AGW idiots like brothers that can't take enough showers now to wash off the stink--they've come clean and have acknowledged that global warming alarmism is nothing but a hoax. Amaze us all and admit that simple fact. While you're at it, why not admit that GCMs have been shown to have zero predictive ability? Oh wait, you can't: that requires an understanding of math. It's a lot easier for you to stick to the a Leftist-libs' kind of 'truth' and continue sticking science and the search for objective truth in the back.
-Posted Tuesday, September 22nd, 2009, at 5:28 PM PDT.

Are the models, in fact, untestable? Are they unable to make valid predictions? Let's review the record. Global Climate Models have successfully predicted:

Seventeen correct predictions? Looks like a pretty good track record to me.

Are there problems with the models, and areas where they haven't gotten it right yet? Sure there are. The double Inter-Tropical Convergence Zone which shows up in some coupled models, ENSO variability, insufficiently sensitive sea ice, diurnal cycles of moist convection, and the exact response of climate to clouds are all areas of ongoing research. But the models are still the best thing we have for climate prediction under different scenarios, and there is no reason at all to think they're getting the overall picture wrong.

Note added 8/04/2010: Lots of people have asked me to document both the predictions and the confirmations. Here they are in a couple of tables. Read 'em and weep, Rush.

References for Predictions and Confirming Observations

Global warmingArrhenius 1896
Callendar 1938
Plass 1956
Sawyer 1972
Broecker 1975
Crowley 2000
Philipona et al. 2004
Evans and Puckrin 2006
Lean and Rind 2008
Mann et al. 2008
Troposphere warms, stratosphere coolsManabe and Wetherald 1967
Manabe and Stouffer 1980
Ramaswamy et al. 1996, 2006
De F. Forster et al. 1999
Langematz et al. 2003
Vinnikov and Grody 2003
Fu et al. 2004
Thompson and Solomon 2005
Nights warm more than daysArrhenius 1896Dai et al. 1999
Sherwood et al. 2005
Winter warms more than summerArrhenius 1896
Manabe and Stouffer 1980
Rind et al. 1989
Balling et al. 1999
Volodin and Galin 1999
Crozier 2003
Polar amplificationArrhenius 1896
Manabe and Stouffer 1980
Polyakov et al. 2001
Holland and Bitz 2003
Arctic warms more than AntarcticArrhenius 1896
Manabe and Stouffer 1980
Doran et al. 2002
Comisa 2003
Turner et al. 2007
Pinatubo effectsHansen et al. 1992Hansen et al. 1996
Soden et al. 2002
Last Glacial Maximum sea surface temperaturesRind and Peteet 1985Farreral et al. 1999
Melanda et al. 2005
Temperature trend versus UAH resultsChristy et al. 2003Santer et al. 2003
Mears and Wentz 2005
Santer et al. 2005
Sherwood et al. 2005
Water vapor feedback from ENSOLau et al. 1996Soden 2000
Dessler and Wong 2009
Ozone hole effect on southern ocean windsFyfe et al. 1999
Kushner et al. 2001
Sexton 2001
Thompson and Solomon 2002
Hadley Cells expandQuan et al. 2002Fu et al. 2006
Hu and Fu 2007
Storm tracks move polewardTrenberth and Stepaniak 2003Yin 2005
Tropopause and radiating altitude riseThuburn and Craig 1997
Kushner et al. 2001
Santer et al. 2003
Seidel and Randel 2006
Tropical "super greenhouse effect"Vonder Haar 1986Lubin 1994
Constant average relative humidityManabe and Wetherall 1967Minschwaner and Dessler 2004
Soden et al. 2005
Gettelman and Fu 2008
Increased coastal upwelling of ocean waterBakun 1990Goes et al. 2005
McGregor et al. 2007


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Last modified:  02/09/2011