- Aug 10, 2001
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September 11, 2002
Global warming models flawed
AUCKLAND, New Zealand (AFP) ? A discovery that it is much colder over the South Pole than believed has exposed a major flaw in the computer models used to predict global warming, a new scientific paper says.
U.S. scientists based at the Amundsen-Scott South Pole Station say they have measured the temperature of the atmosphere 18 to 68 miles over the pole and found that it is 68 to 86 degrees Fahrenheit lower than computer models showed.
Various models are used to predict global climate, and some assumptions have had to be made, including air temperatures over Antarctica.
Writing in the American Geophysical Union Letters, Chester Gardner, a professor of electrical and computer engineering at the University of Illinois; Weilin Pan, a doctoral student at the university; and Ray Roble of the U.S. National Center for Atmospheric Research say the models are wrong.
"Because of the obvious challenges, until now, the only temperature data we have had from either the North or South Poles has been from surface measurements and weather balloons that don't go any higher than about" 12 to 18 miles, Mr. Gardner said.
The researchers used a laser radar system from the South Pole to make the first measurements of the temperature higher up and found that it was much colder than assumed.
Global warming could be caused by greater concentrations of carbon dioxide, which is a strong absorber of infrared radiation.
In the lower atmosphere ? known as troposphere ? carbon dioxide absorbs the heat. Although carbon dioxide also emits heat, other carbon dioxide absorbs it. In the thinner stratosphere (the second level of the atmosphere from the Earth) and mesosphere (the third level), much of the heat emitted by carbon dioxide is radiated into space. So in the upper atmosphere, the primary effect of carbon dioxide is cooling.
"Thus as CO2 levels continue to rise in the atmosphere, we expect the lower atmosphere to continue warming while the upper atmosphere will cool," the report says.
In the winter, Antarctica receives little sunlight and its atmosphere is sealed off by a vortex of winds preventing warmer air from lower latitudes from traveling to the pole.
"As a consequence, the region cools to very low temperatures in winter, primarily by radiation of heat into space."
In May, June and July, the stratopause ? the boundary between stratosphere and mesosphere ? was considerably colder than model predictions. The greatest difference occurred in July, when the measured stratopause temperature was about 0 degrees Fahrenheit, while the models predicted it to be about 40 degrees Fahrenheit.
The team's measurement is expected to become a baseline for temperature studies. Mr. Gardner said the team's South Pole measurements will help modelers and theoreticians better understand the atmosphere and incorporate that understanding into their models, making their predictions more accurate.
Global warming models flawed
AUCKLAND, New Zealand (AFP) ? A discovery that it is much colder over the South Pole than believed has exposed a major flaw in the computer models used to predict global warming, a new scientific paper says.
U.S. scientists based at the Amundsen-Scott South Pole Station say they have measured the temperature of the atmosphere 18 to 68 miles over the pole and found that it is 68 to 86 degrees Fahrenheit lower than computer models showed.
Various models are used to predict global climate, and some assumptions have had to be made, including air temperatures over Antarctica.
Writing in the American Geophysical Union Letters, Chester Gardner, a professor of electrical and computer engineering at the University of Illinois; Weilin Pan, a doctoral student at the university; and Ray Roble of the U.S. National Center for Atmospheric Research say the models are wrong.
"Because of the obvious challenges, until now, the only temperature data we have had from either the North or South Poles has been from surface measurements and weather balloons that don't go any higher than about" 12 to 18 miles, Mr. Gardner said.
The researchers used a laser radar system from the South Pole to make the first measurements of the temperature higher up and found that it was much colder than assumed.
Global warming could be caused by greater concentrations of carbon dioxide, which is a strong absorber of infrared radiation.
In the lower atmosphere ? known as troposphere ? carbon dioxide absorbs the heat. Although carbon dioxide also emits heat, other carbon dioxide absorbs it. In the thinner stratosphere (the second level of the atmosphere from the Earth) and mesosphere (the third level), much of the heat emitted by carbon dioxide is radiated into space. So in the upper atmosphere, the primary effect of carbon dioxide is cooling.
"Thus as CO2 levels continue to rise in the atmosphere, we expect the lower atmosphere to continue warming while the upper atmosphere will cool," the report says.
In the winter, Antarctica receives little sunlight and its atmosphere is sealed off by a vortex of winds preventing warmer air from lower latitudes from traveling to the pole.
"As a consequence, the region cools to very low temperatures in winter, primarily by radiation of heat into space."
In May, June and July, the stratopause ? the boundary between stratosphere and mesosphere ? was considerably colder than model predictions. The greatest difference occurred in July, when the measured stratopause temperature was about 0 degrees Fahrenheit, while the models predicted it to be about 40 degrees Fahrenheit.
The team's measurement is expected to become a baseline for temperature studies. Mr. Gardner said the team's South Pole measurements will help modelers and theoreticians better understand the atmosphere and incorporate that understanding into their models, making their predictions more accurate.
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