Saturday, May 7, 2011

Most widely used climate computer model exaggerates global warming by 67%

A paper published today in the Journal of Climate announces a new version of the computer climate model most widely used by climate scientists and the IPCC, called the Community Climate System Model (CCSM) version 4. The creators claim their program is
 "a fully-coupled, global climate model that provides state-of-the-art computer simulations of the Earth’s past, present, and future climate states."
The abstract, however, contains a remarkable admission that the model exaggerates the global warming from 1850 to 2005 by 0.4°C more than observations. The observed global warming from 1850 to 2005 was only 0.6°C, thus the computer model predicted ~ 67% more global warming than actually occurred. This exaggeration alone could account for all of the claimed "heat trapping" from the increase in man-made carbon dioxide over that same 155 year period. IPCC projections for future global warming based upon this model may be similarly greatly exaggerated.

The Community Climate System Model Version 4

Abstract: The fourth version of the Community Climate System Model (CCSM4) was recently completed and released to the climate community. This paper describes developments to all CCSM components, and documents fully coupled pre-industrial control runs compared to the previous version, CCSM3. Using the standard atmosphere and land resolution of 1° results in the sea surface temperature biases in the major upwelling regions being comparable to the 1.4° resolution CCSM3. Two changes to the deep convection scheme in the atmosphere component result in CCSM4 producing El Nino/Southern Oscillation variability with a much more realistic frequency distribution than CCSM3, although the amplitude is too large compared to observations. They also improve the Madden-Julian Oscillation, and the frequency distribution of tropical precipitation. A new overflow parameterization in the ocean component leads to an improved simulation of the Gulf Stream path and the North Atlantic Ocean meridional overturning circulation. Changes to CCSM4 land component lead to a much improved annual cycle of water storage, especially in the tropics. The CCSM4 sea ice component uses much more realistic albedos than CCSM3, and for several reasons the Arctic sea ice concentration is improved in CCSM4. An ensemble of 20th century simulations produces a pretty good match to the observed September Arctic sea ice extent from 1979 to 2005. The CCSM4 ensemble mean increase in globally-averaged surface temperature between 1850 and 2005 is larger than the observed increase by about 0.4°C. This is consistent with the fact that CCSM4 does not include a representation of the indirect effects of aerosols, although other factors may come into play. The CCSM4 still has significant biases, such as the mean precipitation distribution in the tropical Pacific Ocean, too much low cloud in the Arctic, and the latitudinal distributions of short-wave and long-wave cloud forcings.


  1. There is no doubt that global warming DOES exist...however I am very skeptical about the "causes" and just actually HOW much of an effect it is having..

  2. Forecasting experts’ simple model leaves expensive climate models cold

    Modeling problems: The naïve model approach Verses the IPCC model forecasting procedures

    The naïve model approach is confusing to non-forecasters who are aware that temperatures have always varied. Moreover, much has been made of the observation that the temperature series that the IPCC uses shows a broadly upward trend since 1850 and that this coincides with increasing industrialization and associated increases in manmade carbon dioxide gas emissions.

    To test the naive model, we started with the actual global average temperature for the year 1850 and simulated making annual forecasts from one to 100 years after that date – i.e. for every year from 1851 to 1950. We then started with the actual 1851 temperature and made simulated forecasts for each of the next 100 years after that date - i.e. for every year from 1852 to 1951. This process was repeated over and over starting with the actual temperature in each subsequent year, up to 2007, and simulating forecasts for the years that followed (i.e. 100 years of forecasts for each series until after 1908 when the number of years in the temperature record started to diminish as we approached the present).
    This produced 10,750 annual temperature forecasts for all time horizons, one to 100 years, which we then compared with forecasts for the same periods from the IPCC forecasting procedures. It was the first time that the IPCC’s forecasting procedures had been subject to a large-scale test of the accuracy of their forecasts.

    Over all the forecasts, the IPCC error was 7.7 times larger than the error from the naïve model.

  3. The globe has been generally "warming" for about 17,000 years, and will generally continue to do so until the next ice age... which apparently isn't all that far off. But man did not cause it, and man cannot stop it.