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Tucson residents may have the Southern Ocean to thank for keeping temperatures down in the face of global warming, research conducted by a University of Arizona professor shows.

A climate model that Joellen Russell worked on shows that the Southern Ocean could help slow global warming because the ocean will take up about 20 percent more heat from the atmosphere than another, identical model predicted.

Eighteen different models from around the world all show that the westerly winds have moved south toward Antarctica in the last 30 years, but different models place the winds in different locations, which accounts for the conflicting results.

Russell, an assistant professor of geosciences, said she and her team were surprised by their findings.

The model was run at the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory in Princeton, N.J., and could mean good news for Tucsonans. Russell said that the ocean may help slow the increase of peak summer temperatures in the next 20 to 50 years.

The westerly winds run in a current around Antarctica. Because there is no land to disrupt its flow, the current is, on average, 30 times stronger than the jet stream that runs across the United States, Russell said.

Those strong winds bring water to the surface from as deep as 3 miles, Russell said.

The cycling of the surface water away from Antarctica brings more water from the deep ocean to the surface. The water can absorb more heat and carbon dioxide, which is why the ocean can help slow global warming, Russell explained. She also compared the Southern Ocean to a kitchen and the atmosphere to an oven.

"When you turn the oven on with its door closed, the oven heats up and so, more slowly does the entire kitchen," she wrote in a paper co-written with other NOAA researchers in the December issue of the Journal of Climate.

"The winds over the Southern Ocean act like an oven door. If you open the oven door, the kitchen heats up more quickly, but the oven heats up more slowly," Russell said.

Erik Pytlak, a meteorologist with the National Weather Service in Tucson, said his agency is unsure about the effects of global warming on Tucson.

"The literature we've seen is actually conflicting for what global warming will do here in Tucson," he said. "We're just starting to get our arms around what the impacts will be in specific locations."

The average low temperature from 1901 to 1930 was 50.8 degrees Fahrenheit; from 1976 to 2005, it was 55.5 F. Pytlak said that the weather service thinks the five-degree increase had more to do with Tucson's rapid growth and the addition of concrete and buildings through the years, known as the urban heat island effect, than with global warming. The average high temperature increased by less than 1 degree in those two timeframes.

In the next 20 to 50 years, temperatures are predicted to increase 5 to 7 degrees, without factoring in the urban heat island effect, said Gregg Garfin, program manager for the Climate Assessment for the Southwest. The group is a NOAA-funded organization at the UA that makes climate research and information more accessible to university researchers, scientists, educators and decision-makers.

The research models also have shown that we may be in for less precipitation and that less of it is likely to come as snow, Garfin said.

"If the snow starts melting earlier and less precipitation comes as snow, that will have an impact on anyone on the Colorado River," he said, adding that this could lead to a greater demand for groundwater, already in short supply.

There are two downsides to Russell's team's findings.

First, storing more heat in the ocean raises the sea level, and "one meter puts Miami under water," Russell said while lowering her hand to the ground to show that 1 meter is equal to a little more than 3 feet.

The second downside is that when carbon dioxide is absorbed in the ocean, it alters the chemistry of the water. This could pose a threat to photosynthetic organisms that live at the bottom of the ocean.

Russell will run another model this spring at UA that will factor in more biology and chemistry.