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What bison in South Dakota can teach us about fighting climate change

One rancher is deploying a controversial holistic grazing strategy to restore the land and capture carbon dioxide.

A carbon engineer?
Umair Irfan is a correspondent at Vox writing about climate change, Covid-19, and energy policy. Irfan is also a regular contributor to the radio program Science Friday. Prior to Vox, he was a reporter for ClimateWire at E&E News.

The Weather Channel earlier this year launched a fantastic package on the impacts of climate change across the United States, with 50 stories about how rising temperatures will affect all 50 states.

One that really stood out was about South Dakota — a part of the country often overlooked for its climate vulnerability — tying together bison herds and a clever tactic for pulling carbon dioxide out of the air.

The piece, by Pam Wright, emphasizes two key points about climate change in the United States that I think often get lost in discussions: 1) While we often tend to focus on dramatic impacts of climate change — higher seas and more intense hurricanes on the coasts — regions like the Great Plains are facing dire economic threats too. And 2) Not all of the solutions for climate change have to do with technology.

Rising temperatures may shrink cattle herds in South Dakota, threatening the state’s economy

Average temperatures in South Dakota have already shot up by 2 degrees Fahrenheit since 1900, and the number of triple-digit temperature days is poised to double by 2050, Wright reports. The concern is that these rising temperatures will lead to more severe droughts, which in turn will harm the livestock this state relies on heavily for its economy.

South Dakota has about five beef cattle for every one of its 865,000 residents, and they’re worth almost $2.8 billion to the state’s economy.

The value of livestock in South Dakota.
South Dakota Department of Agriculture

Using bison as a proxy for cattle, one study found that every degree Celsius of average temperature rise would cost the livestock industry an additional $1 billion as the market weight of cattle declines.

Projections show that under a business as usual trajectory for greenhouse gas emissions, the region will see average temperature rise by 4.65 degrees Fahrenheit by 2065, which will take a big bite out of the state’s cattle industry.

Bison are being harnessed as carbon engineers

While greenhouse gases from transportation and power plants (rightfully) dominate the discussions about the causes of climate change, agriculture, and, more fundamentally, the way we use land, also produces a lot of emissions.

Take a look at this chart from the Environmental Protection Agency on the sources of greenhouse gases in the United States:

Environmental Protection Agency

Agriculture has a 9 percent share of emissions, but conspicuously absent from this chart is land use, land use change, and forestry (LULUCF, in environmental policy jargon). Cutting down forests and paving over grasslands destroys organisms that naturally breathe in and hold onto greenhouse gases from the atmosphere.

But the United States has managed land in a way that has made it a net carbon sink, soaking up more carbon dioxide than it releases. Trees, shrubs, and grasses drink in carbon dioxide and exhale oxygen as they stretch their branches and spread their leaves. And as a result, LULUCF offset 11.8 percent of US greenhouse gas emissions in 2015.

An overview of the carbon cycle in forests.
S. Luyssaert Et Al./Global Change Biology - 16, 1429–1450 (2010)

That means putting more thought into how we cultivate pastures, grasslands, and forests could help bring down the country’s total greenhouse gas emissions. (The United Nations also counts LULUCF as an important tactic for fighting climate change.)

Wright profiles 777 Bison Ranch, which is deploying a holistic grazing method that proprietor Mimi Hillenbrand says will help restore topsoil, cultivate grasses, and draw carbon dioxide out of the air. The approach was pioneered by biologist Allan Savory, who argued that rather than reducing the amount of livestock to curb problems like climate change and desertification, animal herds should be cultivated in a way that mimics their ancestral habits.

Conventional pasture grazing, with animals pent up in one area, can denude the soil of vital grasses, reducing its carbon dioxide uptake and leading to soil erosion. However, the 777 Bison Ranch is home to just under 2,000 bison that graze, trample, and defecate as they travel through 35 pastures in search of fodder, enriching and aerating the soil while allowing native grasses to regenerate.

Some scientists have criticized Savory’s ideas, finding flaws in his foundational research in Africa, like the fact that that livestock in his initial experiment received supplemental feed due to weight loss, and that grass cover didn’t improve much despite unusually high rainfall in the region. Other researchers have also found that Savory’s short-duration grazing tactics yielded disappointing results when tried in the United States, which is why it hasn’t caught on more.

Regardless of whether or not bison can go hoof-to-hoof with carbon dioxide scrubbers on power plants as a climate change mitigation strategy, it’s worth remembering that fighting climate change is more than a matter of hardware.

And while holistic grazing remains a fringe practice in US agriculture, farms are increasingly deploying technologies to limit emissions, like trapping methane from livestock waste and using anaerobic digesters to produce electricity, thereby reducing their total greenhouse gas emissions. We’re going to need all of these tactics and more to decarbonize as fast as we possibly can.

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