Battle of the climate scientists - Gray versus Hansen part 3

February 12, 9:31 AMDenver Weather ExaminerTony Hake

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Hot or not?  Are the global climate models accurate or are
they full of hot air? 

The science behind the theory of anthropogenic global warming (AGW), or manmade climate change, has been said to be ‘settled’.  The United Nation’s Intergovernmental Panel on Climate Change (IPCC), Al Gore, and Dr. James Hansen make up a triumvirate of climate change advocates.  Wielding studies, computer models, and various charts and analyses, they believe man is heading down the road to self-destruction of we do not reverse course immediately and do everything and anything to stop what they believe is an unnaturally warming climate.

Last week we first brought to light a letter by Dr. William Gray, Professor Emeritus of Colorado State University, admonishing the American Meteorological Society’s decision to give its highest award to Dr. James Hansen.  Hansen is head of NASA’s Goddard Institute for Space Studies (GISS), an astronomer, and a very divisive figure in the global warming debate. 

We continue our analysis of not only the battle between Dr. William Gray and Dr. James Hansen but the larger issue of anthropogenic global warming.  In his letter Dr. Gray raises some very interesting arguments about Hansen’s research and about the science behind the theory of AGW.  Today we take a closer look at the science as Dr. Gray sees it.

Hansen previously studied the run-away greenhouse warming of Venus. He appears to think that man’s emittance of CO2 gases, if unchecked, will eventually cause the Earth to follow a similar fate. Hansen’s arrogance and gall over the reality of his model results is breathtaking.
- Dr. William Gray, Professor Emeritus of Colorado State University

A view of the physical process differences between the
global warming for a doubling of CO2 from the GCM climate
models and reality.  (Dr. William Gray)

Perhaps one of the biggest issues Dr. Gray sees is with the computer modeling used by Dr. Hansen and other AGW advocates.  The computer models show a situation where the accumulating carbon dioxide (CO2) in our atmosphere will continue to warm our planet, possibly to the point of being irreversible in the foreseeable future.  However, if the data being used or the assumptions being made are faulty, the conclusions in the end will be wrong and that is what Dr. Gray sees.  To put it in its simplest terms, computer models are fine but the saying, “garbage in, garbage out” certainly applies to these as well as any other computer model. 

A depiction of initial value numerical forecasting. 
This shows that while forecasts can be reasonably
accurate and consistent in the short term, they become
much more chaotic and inaccurate over the long term.
  (Dr. William Gray)

The problem that some see with the Global Climate Model’s (GCM) is that while they forecast these increases in CO2 and temperature, when they are fed historical data they are unable to replicate the warming that has already occurred.  Further, they have not been able to even accurately forecast short term climate of a year or two.  If these models cannot even see what has already happened or on a short term, how accurate can they be at predicting the long term future?  Dr. Gray believes that Hansen’s models use invalid water vapor assumptions, do not accurately reflect the effect of rainfall, and fails to properly take into account ocean circulation.  In essence, the garbage in, garbage out system. 

Dr. Gray sums it up like this: 

“If skillful GCM climate forecasts were possible for a longer period of a season to a few years, we would be eager to track their skill.  Currently, GCMs do not make official seasonal or yearly forecasts.  They dare not issue these forecasts because they know they are not skillful and would quickly lose their credibility if they gave real time forecasts that could actually be verified.  How can we trust GCM climate forecasts 50 and 100 years into the future (that cannot be verified in our lifetime) when these same models are not able to demonstrate shorter range forecast skill of a season or a year or two?”

As we continue looking at Dr. Gray's letter and analysis, we will post more excerpts and thoughts from it.  Be sure to check out our slideshow below with details on Dr. Gray and the other key players in the global warming debate.