Normally, the sounds of birds and frogs are about all anyone will hear in the peat bogs of Itasca County. But lately the Marcell Experimental Forest has buzzed with the hum of bobcats as workers build a large network of boardwalks into the bog.
Scientists in north central Minnesota are preparing for a massive federal research project to study the effects of climate change on peatland ecosystems. Funded by the U.S. Department of Energy, the $50 million project in a remote bog north of Grand Rapids could help researchers over the next decade answer critical questions about global warming.
Work crews are laying the groundwork for this fall, when crews will begin constructing more than a dozen huge transparent chambers — 36 feet wide and 32 feet tall. Scientists will use the chambers to artificially raise the temperature in the bogs.
"This is going to be a unique experiment on the planet," said Randy Kolka, a research soil scientist for the U.S. Forest Service in Grand Rapids. "No infrastructure like this has ever been put in place into a similar ecosystem."
During the growing season, researchers will heat the air and soil inside the open-topped chambers. They'll also raise carbon dioxide levels, exposing plants and trees to the changes.
Following methods tested in a prototype of the octagon-shaped warming chamber at the Oak Ridge National Laboratory in Tennessee, researchers will use electric heaters inserted into the soil to warm below ground. They'll raise air temperatures using four propane heaters per chamber.
Kolka said the experiment will measure how the ecosystem behaves under conditions up to 15 degrees warmer than normal.
"It's sort of the 'if you build it, they will come' sort of mentality, and if we build something really neat that's going to be a novel experiment, we anticipate a lot of interest from the scientific community," he said. "Down the road probably more than 100 scientists, I would guess, would be involved in this experiment, scientists from all over the globe."
There's good reason why the research is being done in a bog. Peatlands cover only 3 percent of the earth's land surface. But they contain about 30 percent of the total carbon stored in soil. Peatlands hold organic material that has accumulated for thousands of years.
If global temperatures warm as scientists project, peatlands could release large amounts of greenhouse gases that could accelerate global warming.
Stephen Sebestyen, a research hydrologist for the U.S. Forest Service, said the peatland experiment will help scientists more accurately predict future climate trends.
"It's a very small area, but it has a very disproportionate effect on a much larger area, the entire globe," he said. "If you take all these pockets of peat around the globe ... they could have a very profound effect on the entire globe, because of the way that the huge accumulations of carbon may be released."
Sebestyen said scientists ultimately want to manipulate temperatures in the controlled environments until they reach a tipping point. A key question they hope to answer is at what point the areas reach a critical change in temperatures and carbon dioxide levels in the future that would push the systems into a new state.
"Instead of the current plant communities, would they shift to a different type of plant community more typical of areas that may be further south?" he asked.
Federal researchers chose the Marcell Experimental Forest site for their experiment for another good reason. Scientists there have been measuring temperature and collecting data on the peatland for more than 50 years. They know, for example, that the average temperature in the bog has risen nearly 4 degrees since the early 1960s.
Kolka said he believes the project is the largest ecosystem manipulation experiment ever attempted. He's hopeful the effort will produce valuable data for global climate modelers.
"If there's a place on the planet where we might be able to push these ecosystems to their limit," he said, "it's here in northern Minnesota."