Pesticide use is a significant factor in harmful climate change, contributing to greenhouse gas emissions in multiple ways, according to a report issued this week.
The report released by the Pesticide Action Network North America (PANNA) found that greenhouse gases are emitted during production of these pesticides as well as when they are applied to crops, and later on, as they linger in the soil. In turn, climate change creates conditions that lead to greater pesticide use, creating a vicious cycle.
“Some pesticides themselves are powerful greenhouse gases,” Margaret Reeves, a senior scientist at PANNA in California and an author of the report, said during the webinar announcing the report.
Reeves cited a pesticide called sulfuryl fluoride as an example. The fumigant has nearly 5,000 times the potency of carbon dioxide, and in 2018 alone, three million pounds of sulfuryl fluoride were applied in California for agricultural purposes, Reeves said.
A 2021 study found that sulfuryl fluoride remains in the atmosphere for about 36 years.
Last year environmental groups filed a petition urging the California Air Resources Board to phase out sulfuryl fluoride due to its impact on climate change, arguing that phasing out sulfuryl fluoride would provide the same climate benefits as taking 1 million cars off US roads each year.
Reeves said many pesticides also release volatile organic compounds (VOCs), which react with nitrous oxide to produce ground-level ozone, a greenhouse gas that harms human lungs and burns plant tissue. The US Department of Agriculture has found that ozone may damage plants more than all other air pollutants combined.
Synthetic pesticides are, in essence, petrochemicals, and the fossil fuel industry and pesticides are inextricably linked, according to Asha Sharma, organizing co-director for PANNA in California and an author of the report.
“We can’t address climate without addressing the dependency that conventional agriculture has on fossil fuels and pesticides,” she said.
Problematic from the start
Sharma and colleagues found that synthetic pesticides are problematic from the start, determining that one kilogram of pesticide requires, on average, about 10 times more energy to manufacture than one kilogram of nitrogen fertilizer, which has been found to contribute over 20% of annual agricultural emissions.
“We would like to see pesticides raised to the same level of visibility as nitrogen fertilizers when we’re talking about contributions to greenhouse gas emissions from the agriculture sector,” said Sharma.
Pesticides result in further emissions when they are applied to fields. PANNA found that fumigants such as chloropicrin, which is sprayed on strawberries and other fruits and vegetables, increase soils’ production of nitrous oxide, a greenhouse gas 300 times more potent than carbon dioxide, seven- to eight-fold.
As climate change intensifies under agriculture’s pesticide dependence, the report suggests dependence on pesticides today will amplify pesticide use in the future. With rising temperatures, crops become less resilient and more vulnerable to pests, which will grow increasingly prevalent in some agricultural regions, including the US Midwest. The report also finds that certain effects from climate change may cause pesticides to break down faster in the environment, making them less effective over time and leading to more frequent pesticide applications.
While writing the report, Sharma noted that the authors encountered a lack of available research on how pesticides contribute to greenhouse gas emissions.
“Pesticides are notoriously really difficult to study because so little information on what’s in the formulation is available,” said Sharma. “It’s very difficult to do full lifecycle studies on cumulative greenhouse gas emissions related to pesticide use. The folks that are predominately studying pesticides are pesticide manufacturers.”
“If the concerns about pesticides are public concerns, one would think that the public universities would be at the forefront of doing the research to protect public health and the environment,” added Reeves. “Most unfortunately, over the last 50, 60 years, the control of the research agendas at the public universities has been increasingly led by the industry interests.”
The researchers concluded that both oil and gas companies and pesticide manufacturers also promote what they consider flawed solutions to the climate crisis.
“For oil and gas companies, this includes promoting carbon capture and storage through new technologies,” said Sharma. “For pesticide manufacturers, this includes promoting things like new digital agricultural tools such as precision agriculture [which uses computer-aided technologies to guide more accurate pesticide application].”
“Both of these examples ultimately offer limited climate benefits while allowing these corporations to continue business as usual and continue profiting off of fossil fuels,” said Sharma.
Another industry-supported solution, carbon markets, allows agribusinesses to sell carbon credits corporations to offset greenhouse gas emissions. The report says carbon markets have “a poor track record in terms of long-term climate mitigation” and only perpetuate the world’s reliance on fossil fuels.
Instead of turning to high-tech solutions, the PANNA report suggests tackling pesticides’ detrimental effects on human health and the environment through sustainable farming, or agroecology.
“‘Agroecology’ means working with nature rather than against it,” said Sharma. “[It involves] using ecological principles, minimizing the use of synthetic chemicals – that includes both synthetic pesticides and fertilizers – all while centering the decision-making power and knowledge of farmers, farmworkers, indigenous people, and local communities.”
Unlike conventional agricultural practices, the report states that agroecology can support “vigorous, pest-resistant crops.” Such practices sequester carbon in the soil and support healthy ecosystems above the ground, controlling pests and supplying crops with nutrients without synthetic chemicals.
Sharma said two California farms provide good examples of this alternative to conventional agriculture. CRECE Urban Farms, a small cooperative in Santa Ana that supports the Latino migrant community, relies on high crop diversity, healthy soil, and crop rotation instead of pesticides. Kandarian Organic Farms, which stretches across more than 130 acres in Los Osos Valley, produces more than 1,000 plant varieties and cuts weeds to a manageable level instead of killing them.
“This is a key moment to raise the profile of the benefits of agroecology and pesticide use reduction from the perspective of mitigating and adapting to climate change, especially with billions of dollars currently being invested in climate-smart agriculture programs,” said Sharma.
The agrichemical company Syngenta says on its website that it is encouraging growers to adopt sustainable practices such as planting cover crops, minimum tillage, crop rotation, and effective nutrient management. It also states it is aiming to reduce the carbon intensity of its operations by at least 50% by 2030.
Pesticides can be beneficial, Syngenta maintains. The company states that its paraquat herbicide paraquat, which research has linked to Parkinson’s disease, “helps reduce soil erosion, protects soil health and the effects of climate change.”
And the agrochemical industry trade group CropLife International states on its website that pesticides, also known as “crop protection products,” are among the tools that “help farmers and our food systems adapt to and mitigate climate change while improving agricultural productivity and delivering food security.”