As protests at the Copenhagen "climate summit" heat up and talks reach a critical stage, the media are looking at a variety of ways humans can slow carbon emissions into the atmosphere, such as changing the way we farm.

In an Ask Pablo column on a Web site called Treehugger, writer Pablo Paster considers whether people should go back to using horses instead of tractors to farm. At first glance, I thought the piece was meant to be humorous, but in fact, Paster researched whether such a change would reduce greenhouse gas emissions.

Among the data Paster used to support the idea was a 2008 UC Davis Cooperative Extension cost study on wheat production. The columnist noted that UC scientists determined it takes 5.43 gallons of fossil fuels per acre to produce 3.25 tons of wheat.

"When combusted this fuel turns into 122 pounds of carbon dioxide (CO₂). Although this number is not going to be the same for every crop we can assume that it is within the right range for all grain crops," Paster wrote.

Combining this information with other data he collected, Paster concluded that tractors emit 122 pounds of CO₂ per acre compared to the 21.5 pounds of indirect emissions from the horse. "If the horse feed were also cultivated by horses this number would be even smaller," Paster wrote.

He acknowledged the difficulty of producing all the world's food using horses, but said small-scale, organic farms could find many advantages to using draft horses.

"Horses have a lower upfront cost and their fuel (feed) also costs less, they tread lightly on the ground, and they even bring their own fertilizer to the fields," he wrote.

Meanwhile, National Public Radio reporter Christopher Joyce joined UC Berkeley environmental science professor Whendee Silver on a visit to a Marin County research site where she is looking at the use of compost on rangeland to increase its carbon-holding capacity.

The compost, a mix of plant clippings and animal manure, "increases plant growth, it actually also lowers the temperature a little bit, so the soil doesn't get quite as hot, it doesn't stimulate as much microbial activity."

The taller grass and minimized soil activity mean the acreage stores more carbon.

"Hopefully, (farmers will) be able to participate in a carbon market, where we can quantify how much carbon is being stored on the land, and they can sell that as a carbon offset," Silver told the reporter.