March 4, 2005
St. Paul, Minn. — Very few other people in the world -- and no one else in Minnesota -- was measuring soil temperatures dozens of feet below the ground when Don Baker began recording them in 1960.
"In the particular line of research he has undertaken, he's a real pioneer," says University of Michigan geophysics professor Henry Pollack, a world-renowned climate change scientist. He has cited Baker's soil temperature readings as evidence for global warming.
These days soil temperatures are being monitored at hundreds of sites around the the world.
Baker's work, Pollack says, illustrates the discipline needed for meaningful research.
"Keep reading the thermometers for four decades, and he has this archive, this long record of soil temperature changes, and they have been warming," Pollack says.
As scenery goes, the site of Don Baker's research is unremarkable. It's a patch of snow-covered ground a bit smaller than a tennis court on the U's St. Paul campus. A high metal fence surrounds a collection of wind and temperature gauges.
The science is happening below, where probes measure the soil temperature down to 43 feet -- which is a level beyond that affected by summer warming.
Don Baker says for a long time he was a global warming skeptic. But his research has convinced him. Baker says he and his colleagues have measured a three-degree soil temperature rise over the past four decades at depths where, in a more stable climate, the temperatures would be expected to be unchanged.
"That's one thing that has made me change mind as to what's going on at the surface," Baker says.
What's going on at the surface, Baker now believes, is global warming influenced in part by human activity.
Don Baker, 81, is a tall, lean man with a neatly trimmed moustache. His head is topped with a crop of white hair.
Baker was born and raised in St. Paul. He's a railroad enthusiast, due in part to the fact that his parents didn't own a car. They travelled everywhere in the Twin Cities by trolley, and on long distance trips by train.
As a college student, Baker thought he might be interested in becoming a mining engineer, and took a summer job underground at a Montana copper mine. He worked in tunnels 2,800 feet below the surface, and says he didn't like the 87 degree heat and high humidity there. The only beneficial effect, he recalls, was for miners who came to work drunk.
"After about two hours down in the mine they were stone cold sober. It was like going into a sauna," he says.
Baker discovered his true calling in life was doing something else. He signed up for meteorology training with the military.
During World War II he was a military weather forecaster. He sent balloons aloft to measure wind speed and temperature change. The results helped the forecasters predict weather for pilots.
After another stint of military weather forecasting during the Korean War, Baker went back to college. He got his Ph.D. from the University of Minnesota and won a faculty job there.
He began taking measurements, which over the years show another striking change. Average annual rainfall amounts in parts of Minnesota are rising.
"Precipitation at Waseca has increased something like six inches," he says.
In the Twin Cities area, Baker says, yearly rainfall amounts have risen more than three inches.
Baker says rising soil temperatures, and the added precipitation, won't necessarily benefit Minnesota's agricultural economy by extending growing seasons and increasing yields. The problem is timing.
If the increased precipitation doesn't come at the right time, the rising temperatures dry out the soil.
"The distribution, the time of year when we get this extra precipitation may affect things, so it may not be as efficiently received as under previous circumstances," Baker says.
For his work, University of Minnesota climatology professor Don Baker will be awarded the University's lifetime achievement award.