Nitrous Oxide: The new pollutant in town

Health: When decoupling the roots of our global climate crisis, carbon dioxide (CO2) and methane emissions garner the majority of mainstream media attention. But those are not the only pollutants that pose intractable problems for our planet. For years, scientists have warned about the risks associated with one greenhouse gas (GHG) in particular - nitrous oxide (N₂O). In 2018, N₂O accounted for 6.5 percent of US emissions. Yet when it comes to depleting the ozone layer, which protects the Earth from the sun’s ultraviolet radiation, it is markedly more damaging than CO2 or methane. N₂O touts 300 times the warming power of CO2 and traps heat in the atmosphere, where it remains for an average of 114 years. Methane, on the other hand, only exists in the atmosphere for 12 years.

In 2013, the United Nations found that since the pre-industrial era, N₂O from human activities has increased 20 percent. And by the 1990s, human-made sources accounted for up to 50 percent of the N₂O released into the atmosphere. Yet little global action has been taken to curb the pollutant despite its adverse effects on the ozone layer. In the US, over 80 percent of nitrous oxide emissions are a byproduct of industrial agriculture. The biggest culprits: the increase in synthetic fertilizer use and the mismanagement of animal manure.

Since the 1960s, in the US alone, the use of nitrogen applied to farmland in the form of synthetic fertilizers has risen more than 300 percent, even though the amount of cropland has stayed relatively constant. The excessive amount of nitrogen is meant to boost yields. But only about half of the nutrient gets taken up by the plant when farmers add synthetic fertilizer to their land. The remainder of the nitrogen seeps into groundwater, stimulating a massive algae bloom that chokes out aquatic life. And the overuse of nitrogen creates N₂O through microbial processes in soils. Regenerative agriculture can help growers combat this super pollutant by:

• Transitioning to a nature-based protocol: Conventional growers can make an outsized impact on emissions by adopting natural practices like crop rotations and no-tillage, which help build organic soil matter. A 20-year study at the University of Illinois revealed that in the aggregate, these techniques accounted for a 20 percent increase in yields and a reduction of N₂O by 35 percent. Crop rotations also allow farmers to integrate grazing livestock - reducing their dependency on synthetic manure. And a 2020 report by McKinsey found that no-tillage not only reduces denitrification but also decreases on-farm fuel usage by up to 75 percent.
• Decreasing our reliance on nitrogen-fertilizer: The US consumes 12 percent of global nitrogen-fertilizer production to apply to annual crops - e.g., corn, wheat, and most other grains. Producing nitric acid, a primary ingredient in synthetic fertilizer represents the largest source of N₂O in the chemical industry. The most efficient way to reduce the use of synthetic inputs is to switch to organic fertilizers. Natural biofertilizer slowly releases nitrogen and ensures that the nutrient is available to plants only when they need it, resulting in less runoff.
• Moving away from industrial animal agriculture: Centralized animal feed operations (CAFOs) can produce more than one and a half times the waste than some US cities. Yet, many CAFOs do not grow their own feed and therefore cannot utilize the manure they produce as fertilizer. Instead, ground application of untreated feces is a common disposal method due to its low cost. Before the animal waste is even applied to land, it is stored in lagoons, where it converts into N₂O. And when factory farms apply manure too frequently or in too large a quantity to an area, nitrogen runoff seeps into the soil, groundwater, and surface water.

Many conventional US farmers abstain from using natural practices and inputs because they assume it will decrease yields. Luckily, experts now have ample data supporting the claim that in the long run, farmers can increase profits and decrease emissions by managing agroecosystems to reduce N2O - through the use of no-till farming, holistically managed grazing, cover cropping, and other regenerative practices. While it doesn’t look like the US will kick its deadly nitrogen addiction anytime soon, farmers, policymakers, and innovators must increase mitigation efforts to avoid the doubling of N₂O emissions by 2050

Watch: “Part love letter, part political exposé,” The Patagonia film Public Trustraises awareness about the fight for America’s 640 million acres of public lands through three conflicts - the Bears Ears National Monument in Utah, the Boundary Waters in Minnesota, and the de facto sale of the Arctic National Wildlife Refuge. As climate change threatens the health of our planet, America’s federally protected ecosystems support biodiversity and carbon sequestration while protecting vulnerable wildlife. Despite bipartisan support from voters, our public lands face ongoing threats from greedy oil drillers, miners, and others who seek to extract natural resources from wild refuges. Conservation isn’t a left-versus-right fight. As Americans, it is our responsibility to advocate for the continued preservation of the national environment that preceded our existence.

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