December 11, 2007
New study increases concerns about climate model reliability
http://www.physorg.com/news116592109.html
A new study comparing the composite output of 22 leading global
climate models with actual climate data finds that the models do an
unsatisfactory job of mimicking climate change in key portions of the
atmosphere.
This research, published on-line Wednesday in the Royal Meteorological
Society’s International Journal of Climatology, raises new concerns
about the reliability of models used to forecast global warming.
“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.”
The findings of this study contrast strongly with those of a recent
study that used 19 of the same climate models and similar climate
datasets. That study concluded that any difference between model
forecasts and atmospheric climate data is probably due to errors in
the data.
“The question was, what would the models ‘forecast’ for upper air
climate change over the past 25 years and how would that forecast
compare to reality?” said Christy. “To answer that we needed climate
model results that matched the actual surface temperature changes
during that same time. If the models got the surface trend right but
the tropospheric trend wrong, then we could pinpoint a potential
problem in the models.
“As it turned out, the average of all of the climate models forecasts
came out almost like the actual surface trend in the tropics. That
meant we could do a very robust test of their reproduction of the
lower atmosphere.
“Instead of averaging the model forecasts to get a result whose
surface trends match reality, the earlier study looked at the widely
scattered range of results from all of the model runs combined. Many
of the models had surface trends that were quite different from the
actual trend,” Christy said. “Nonetheless, that study concluded that
since both the surface and upper atmosphere trends were somewhere in
that broad range of model results, any disagreement between the
climate data and the models was probably due to faulty data.
“We think our experiment is more robust and provides more meaningful
results.”
--
If you disagree with the theories and dogmas of Marxism or Scientific Socialism
then you are a tool of Capitalist interests. If you disagree with the theories
or dogmas of Catastrophic Anthropogenic Global Warming then you are a tool of
Capitalistic interests. Notice a pattern here? -- Captain Compassion
The object of life is not to be on the side of the majority but to
escape finding oneself in the ranks of the insane. -- Marcus Aurelius
"...the whole world, including the United States, including all that
we have known and cared for, will sink into the abyss of a new Dark
Age, made more sinister, and perhaps more protracted, by the lights
of perverted science." -- Sir Winston Churchill
Joseph R. Darancette
daranc@NOSPAMcharter.net
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