How Minnesota's land use contributes to climate change

If a society's land use reflects its priorities, then Minnesota prioritizes feeding livestock. That's quite common worldwide, especially in the Midwestern United States.

But it also has some major implications on the climate.

Let's take a look at where the state's land use stands today:

Data from the 2013-14 statewide land cover update, funded by the Minnesota Environment and Natural Resources Trust Fund. Compiled the University of Minnesota's Joe Knight. (Note: The section labeled "Other" on the legend is for extraction [mining, gravel pits, etc.]. It comprises 0.1 percent of Minnesota's land, or about 54,000 acres.)

It wasn't always like this. In 1860, Minnesota's landscape was about one-third prairie.

Today, a blink forward in human history, it's about a third row crops — mostly corn and soybeans to feed all kinds of animals that aren't humans. About 11 percent is grass, and not all of that is prairie grassland.

There's one reason for this mass shift in land use: agriculture. Specifically, animal agriculture.

"It's dramatic. I think dramatic, a little bit depressing too," University of Minnesota researcher Joe Knight said while looking over the land use data he compiled at MPR News' request.

Humans don't eat most of what's grown on the 17.2 million acres in Minnesota dedicated to row crops.

"When you look at how much it takes of feed to raise a chicken or a pig or a cow, what you end up finding is that only about a third or less of those calories end up on the plate," said ecologist Paul West, the co-director and lead scientist of global landscapes at the University of Minnesota's Institute on the Environment.

How this affects the climate

• Trade-offs made converting land to agriculture. Of course, Minnesota wasn't always farmland. There used to be a lot more prairie. And wetlands and forest. Each of those landscapes is great at cleaning the air and storing carbon, which, once airborne, becomes the primary climate-warming greenhouse gas carbon dioxide. But as society develops, it emits more greenhouse gases while continuing elimination of prairie, wetlands and forest.

• Most crop growth causes carbon to escape into the atmosphere. All major crops grown in Minnesota require intensive plowing. Soil can store carbon, but not when plowing and tilling for the state's 17.2 million acres of row crops stirs it up.

• Methane emissions. Climate-change deniers like to joke about it, West said, but the truth is "cow burps and farts actually are a huge source of greenhouse gas emissions around the world." About half of global methane emissions come from agriculture. And methane is a wicked greenhouse gas — almost 30 times stronger than carbon.

Two ways you can make a positive impact

West suggested two primary ways people can mitigate climate-destructive land usage.

• Eat less beef. Beef is among the most resource-consuming parts of the human diet. It takes about 33 calories of feed to make a calorie of beef, West said. So, it takes a ton of space to feed them — plus, the toxic bodily functions mentioned above.

• Don't waste so much food. Food waste is associated with 3.3 billion tons of carbon dioxide emissions, according to U of M research. Plus, wasted food is wasted money, water, cropland and fertilizer.