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What are the major sources of greenhouse gas emissions?

What are the major sources of greenhouse gas emissions?
According to the Environmental Protection Agency, transportation accounted for the largest portion (28%) of total U.S. greenhouse gas emissions in 2018.

Being married to a farmer and working on behalf of Iowa’s farmers, I notice there is an interesting ‘tug of war’ on how agriculture is viewed and represented. On one hand, people trust and are prideful in our state’s hardworking men and women in agriculture. On the other, agriculture also seems to receive exaggerated blame for environmental issues, particularly in media headlines and by brands attempting to attract customers with ‘virtue-signaling.’

But if there’s one thing I’ve learned in life, it’s that old adage—when you point a finger at someone else, there are three pointing back at you.

Take for example, the hot topic of climate change and greenhouse gases. I’m sure most of you have heard about, well, cow farts allegedly ruining our environment. It’s an interesting claim, as cattle farming in the United States accounts for 4 percent of our nation’s greenhouse gases while the largest culprits of emissions are transportation and electricity, each at nearly 30 percent.

In fact, new research by the University of Michigan studying 93 million American homes suggests residential energy use accounts for roughly 20 percent of greenhouse gas emissions in the U.S. Additionally, Americans with more means are estimated to have a per capita carbon footprint 25 percent higher than those with lower incomes due to the difference in home sizes. The study states phasing out the use of fossil fuels in electric grids would create a significant reduction in these residential emissions.

Interested to see an estimate of your carbon footprint? The Environmental Protection Agency (EPA) has created a carbon footprint online calculator, and (spoiler alert) it doesn’t ask you how many burgers you eat a week.  Eating less meat may seem like an easy option to reduce our environmental footprint. However, if Americans eliminated all animal-based proteins from their diets, it would only result in a 2.6 percent reduction in U.S. greenhouse gases and 0.36 percent reduction in global greenhouse gases.

When it comes to greenhouse gases, the methane emitted from cattle are short-lived gases. This is because they are absorbed from the atmosphere back into the plant matter that is fed to livestock. This creates a natural cycle where methane is destroyed at almost the same rate it is created. However, the carbon dioxide emitted from travel emissions and extraction of fossil fuels continually accumulates into the earth’s atmosphere where it stays for 1,000 years.  


What is agriculture doing to lower greenhouse gases?

Farmers continue to harness renewable energy and use 132 percent more geothermal, solar and wind energy sources than in 2012.

The use of genetically modified crops has also been a game-changer. GMO crops have traits built into them that resist insect and disease pressure. This means farmers use less fuel and machinery for spraying, reducing emissions. Additionally, GMOs have helped reduce tillage. Farmland is left undisturbed after a crop has been harvested, which not only curbs machinery use but helps trap carbon beneath the soil. Research has shown because of these benefits, GMOs have helped reduce carbon dioxide emissions equivalent to nearly 16 million vehicles for one year.

Another way farmers promote capturing carbon in the soil—often called “sequestration”—is by rotationally grazing their cattle. By sectioning off pastures and moving cattle around, grasses are not overgrazed, keeping soil intact. Some studies have seen farms that participate in this practice have produced anywhere from 20 to 35 percent fewer emissions.

Better animal genetics, breeding, more digestible livestock diets and manure management have also contributed to lowering greenhouse gas emissions. Since 1990, methane emissions in beef have declined by 8 percent, pork by 18 percent and milk by nearly 25 percent. In the case for milk production, today’s U.S. dairy cattle produce more than 200 million tons of milk with 9 million cows. This is one-third of the amount of cattle it would have taken in 1950 to produce roughly the same amount. This amounts to an 80 percent increase in milk with 60 percent less cows and a one-third decrease in carbon footprint—a cool example of how the continuous improvement in animal agriculture continues to find solutions to protecting the planet.

Reports have shown with today’s technology, agriculture is on a path to reducing greenhouse gas emissions by 50 percent with researchers and farmers leading the way. With further investment into technology, agriculture has the potential to even become net-negative!

While agriculture continues to do its part, that doesn’t mean the rest of us are off the hook. There is work to be done.

So, what can we all do to lower our carbon footprints?

The EPA has a comprehensive list of 25 actions we can all take to reduce our carbon footprints. From using more ENERGY STAR qualified light bulbs, which use 75 percent less energy than standard lighting, to making sure your home’s heating and cooling equipment is properly maintained.

When it comes to travel, it’s also important to get regular tune-ups for your car and check your tire pressure regularly as underinflated tires reduce the fuel economy of your vehicle. And speaking of fuel… many cars (2001 models and newer) and larger vehicles are compatible with renewable fuels like E15 and E85. In 2018, the use of ethanol and biodiesel—fuels made from corn and soybeans—reduced greenhouse gas emissions equivalent to 17 million cars off the road. Another great opportunity to do your part at the fuel pump!

If you’re looking at food as a source of lowering your environmental footprint, a better solution than limiting your diet is making the most of it. Recently, the United Nation Food and Agriculture Organization said if food waste was a country, it would be the third largest global greenhouse gas emitter, behind China and the United States. In the U.S., 30 percent of all available food is wasted and much of it at the retail and consumer level, ending up in landfills. A few at-home tips to reduce waste are to plan meals in advance, avoid overbuying, properly store foods and have “leftover” nights at home.

Everyone has a part to play in promoting a sustainable planet. For the family farms I work with, sustainability is a top goal. Farmers have a deep passion to pass down the farm from one generation to the next. To do so means being adaptable, taking personal responsibility for what we can control and continuously seeking ways to improve upon what we’re doing—lessons we can all learn from!



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