Climate model reliability questioned...

A new study in the Royal Meteorological Society's International Journal of Climatology raises new questions about the reliability of climate models...

“The usual discussion is whether the climate model forecasts of Earth’s climate 100 years or so into the future are realistic,” said the lead author, Dr. David H. Douglass from the University of Rochester. “Here we have something more fundamental: Can the models accurately explain the climate from the recent past? “It seems that the answer is no.”

Scientists from Rochester, the University of Alabama in Huntsville (UAH) and the University of Virginia compared the climate change “forecasts” from the 22 most widely-cited global circulation models with tropical temperature data collected by surface, satellite and balloon sensors. The models predicted that the lower atmosphere should warm significantly more than it actually did.

“Models are very consistent in forecasting a significant difference between climate trends at the surface and in the troposphere, the layer of atmosphere between the surface and the stratosphere,” said Dr. John Christy, director of UAH's Earth System Science Center. “The models forecast that the troposphere should be warming more than the surface and that this trend should be especially pronounced in the tropics.

“When we look at actual climate data, however, we do not see accelerated warming in the tropical troposphere. Instead, the lower and middle atmosphere are warming the same or less than the surface. For those layers of the atmosphere, the warming trend we see in the tropics is typically less than half of what the models forecast.”

The 22 climate models used in this study are the same models used by the UN Intergovernmental Panel of Climate Change (IPCC), which recently shared a Nobel Peace Prize with former Vice President Al Gore.

The atmospheric temperature data were from two versions of data collected by sensors aboard NOAA satellites since late 1979, plus several sets of temperature data gathered twice a day at dozens of points in the tropics by thermometers carried into the atmosphere by helium balloons. The surface data were from three datasets.

After years of rigorous analysis and testing, the high degree of agreement between the various atmospheric data sets gives an equally high level of confidence in the basic accuracy of the climate data.

“The last 25 years constitute a period of more complete and accurate observations, and more realistic modeling efforts,” said Dr. Fred Singer from the University of Virginia. “Nonetheless, the models are seen to disagree with the observations. We suggest, therefore, that projections of future climate based on these models should be viewed with much caution.”