Carbon reduction method ineffective

A study by researchers at the University of Minnesota shows that a method to decrease carbon concentrations by converting farmland to woodlands would be ineffective.

In late 2007, the University began an evaluation of a technique to reduce this gas by creating more forests and grasslands out of land currently used for agriculture.

The technique is called carbon sequestration, and the goal is to offset carbon dioxide emissions by taking the agricultural lands and converting them for uses that take high amounts of the gas out of the atmosphere.

“Basically, this was going to be afforestation [planting seeds or trees to make a forest on land that has not been a forest recently],” Cinzia Fissore, postdoctoral associate in the department of soil, water and climate, said. “We looked at planting forests and restoring grasslands because these practices sequester the most carbon.”

Carbon dioxide is a gas that makes up a large portion of greenhouse gases, which are believed to contribute to global warming.

The first scenario used in the study looked at the amount of agricultural land needed to reduce 29 percent of the area’s 2004 carbon emissions.

In order to achieve the desired 29 percent reduction, almost two-thirds of existing agricultural land in the area would have to be converted, Ed Nater, professor and department head of soil, water and climate, said.

“We knew that this was far from ecologically feasible,” he said.

A second scenario looked at the amount of carbon that can be reduced by converting 10 percent of agricultural land — a number Nater said was still very high.

“It converts to almost 6 percent of the total row crop yield in the United States,” he said. “That is many billions of dollars.”

The results said this strategy would, at best, offset only 4.7 percent of current carbon dioxide emissions.

The Minnesota Climate Change Advisory proposed that carbon sequestration would account for 38 percent of its 2025 carbon emission reduction strategy.

“We kind of knew these numbers were impossible to achieve,” Fissore said. “But I didn’t think they would ever be as low as they turned out.”

Nater said the emission reduction process has to come from other sources that may not be as easy.

“People really want to solve this problem, but they want to do it in the most politically effective way,” he said. “And that doesn’t involve you cutting back on what you’re doing.”

Nater said other options, like a higher tax on gasoline to discourage people from driving as often, may be the only sure way to reduce carbon emissions.

“Our take-home message is that this is not going to solve the problem,” he said.

Professor in the department of forest resources Peter Reich, who co-authored the study, said there are methods available to reduce these emissions.

“We already have a lot of them; we just don’t do them,” Reich said. “Things like using thermostats that are programmable would save us money, but we aren’t doing them.”

With the ineffective practice of carbon sequestration being revealed, Reich said he hopes we can now focus on more productive methods.

“It distracted us from the things that we needed to do that could actually improve our carbon and energy situation in the state,” he said.

The study began when the Minnesota Legislature contacted the University about providing an evaluation of the state’s potential to use carbon sequestration as a tool to offset carbon dioxide emissions.

The results of the study prompted the group to take the same circumstances and provide them to a larger region.

“We filed our report, and we found that our results were very interesting,” Fissore said. “We decided to apply the same approach to 11 states in the upper Midwest.”

The upper Midwest is a region that provides a best-case scenario for the study, according to Nater.

Nearly three-fourths of the land is being farmed, which typically depletes the land of its carbon stock. Carbon sequestration then converts the land into a high-carbon stock area, Nater said.

Fissore said they then looked at the carbon data provided by prior studies on a number of different land uses, which range from row crops to woodlands.

“We selected studies that were taken in the upper Midwest and had to do with the conversion of land into a number of uses,” she said.

With this carbon data, the group applied the carbon rates to hypothetical carbon dioxide emission reduction scenarios.

“There isn’t a better area to come up with this kind of solution in the United States,” he said. “If it can’t be done here, it can’t be done.”