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From April 9, 2007, News-Sentinel
ORNL's climate modeling may reveal future
By BRAD WILLIAMS, email@example.com
Most major scientific organizations and the Intergovernmental Panel on Climate Change agree global warming is here.
They now face the next problem: predicting what will happen.
Current predictions are based on climate modeling, a highly complicated process done at Oak Ridge National Laboratory. About 200 peer-reviewed studies that were analyzed by the IPCC stood on ORNL's work.
John Drake, group leader for the Computational Earth Sciences at ORNL, said the lab worked with three other computer centers -- the National Center for Atmospheric Research in Boulder, Colo., the Department of Energy's National Energy Research Supercomputer Center in Berkeley, Calif., and the Japanese Earth Simulator Center in Yokohama -- to ensure the work had a strong scientific basis.
"We essentially took over about half of the resources at ORNL for the better part of a year to do these simulations," Drake said. That work finished in 2005.
Models start with scientists isolating a few factors in experiments. Once a relationship is understood, it becomes part of the huge web of interactions integrated by the model.
To analyze the vast output of information, scientists at ORNL use 27 projectors to make a 30-by-8-foot wall into a screen called Exploratory Visualization Environment for Research in Science and Technology, or better known as EVEREST.
"When you try to visualize the results of these simulations, there's just such a large quantity of data that you need to be able to look at it," Drake said. "This screen is the equivalent of a 35 megapixel camera."
Roughly 10 scientists then comb through data together, decoding links among factors displayed on screen, Drake said.
Drake compared models to weather forecasting, only they're far more complex, viewing and predicting decades instead of days.
Some criticize model-based predictions, but they're a must, he said.
"You can't do experiments with the Earth," he said. So researchers run experiments in the model's virtual Earth.
He said scientists can view Earth's climate as "an engineering problem having to do with heat balances."
Drake said modelers use differences between predictions and observations to make improvements.
"We don't account for everything correctly," he said. "We don't account for the ice on Greenland appropriately yet."
Drake said land-use patterns -- the expansion of heat-absorbing concrete, the building of subdivisions -- are also difficult to account for, as are volcanic eruptions and effects.
Research tries to fill gaps.
One source of uncertainty in predicting impacts of global warming is feedbacks between things like temperature and soil respiration.
"This is the amount of CO2 that comes off the surface of the soil," said Mack Post, senior research scientist at ORNL.
Heat increases the rate microorganisms in the soil decompose organic matter by 20 or 30 percent for the first couple of years, and that in turn increases release of CO2 out of the ground, he said.
The rate returns to normal, presumably when microorganisms run out of accumulated organic matter they decompose.
The release of carbon stored in ecosystems could be a big factor in global warming.
In modeling, Post said, experiments use buried cables to add heat to soil to measure the effects.
"There's four times the amount of carbon in terrestrial ecosystems than in the atmosphere," Post said.
If creeping temperatures and warmer soil mean more CO2 -- a greenhouse gas -- gets released, it could lead to more warming, still more CO2 and more greenhouse warming.
CO2 and other greenhouse gases trap solar radiation in the atmosphere, which warms surface temperatures on Earth.
"Over the geologic record, when there's warming, it causes more CO2 to be released from terrestrial ecosystems on average and increases that warming," Post said.
On the positive side: More CO2 and its effect on temperatures help Earth get out of ice ages, he said.
But it could now be working against humans, whose hands are on the thermostat.
While the pieces are well understood, it's the puzzle that takes the work.
Environmental Sciences Division researcher Rich Norby said it's integrating balancing factors that come into play on a large scale that makes modeling tricky.
Great strides have already been taken.
"I certainly feel like the improvements in model accuracy and scope have been rather dramatic," Drake said. "The model is an integrator of what we know."
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Updated: Monday, 09-Apr-2007 14:07:44 EDT