This is a repost of a blog originally published by our partners at PAN UK, written by International Project Manager for agricultural supply chains Rajan Bhopal.
The Intergovernmental Panel on Climate Change (IPCC) warns that we are on course for global warming of more than 2°C without “deep reductions in carbon dioxide and other greenhouse gas emissions” and that a “rapid and far-reaching transition is required”.
Not only do pesticides affect our health and the environment, but they also play a part, both directly and indirectly, in climate change: For example, fossil fuels are used in the production and transportation of pesticides; their use supports highly unsustainable food and farming systems; and they affect the soil’s ability to sequester carbon.
Tackling climate change will require a widespread shift away from pesticide-dominated agriculture to agroecology. This will lead to resilient, regenerative farming systems that emit less greenhouse gases, improve biodiversity and produce good yields and fair rewards for farmers. What is more agroecological farming systems are inherently more resilient and better able to withstand climate shocks such as extreme flooding and drought.
“Synthetic pesticides harm workers, pollute our environment and are driving emissions of greenhouse gases. Not only do they contribute to climate change through the direct emissions associated with their production, but perhaps even more importantly, they underpin and enable the damaging practices of industrial agriculture.” Dr Keith Tyrell, Director, PAN UK
An IPCC report in 2019 on climate change and land estimates that 21-27% of total greenhouse gas emissions (GHG) are attributable to the food system, with 9-14% of these emissions from crop and livestock activities within the farm gate. Across many parts of the world, our diverse agroecosystems have been lost to industrialised, intensive, highly mechanised, single-crop farms. Monoculture farming increases the risk of pest infestations and farmers rely primarily on fossil fuel-based inputs for pest management and soil fertility (many pesticides and fertilisers are petrochemically-derived).
Synthetic pesticides also disrupt the complex web of life in our soils and impact on soil fertility. Soil organisms are critical to building soil organic matter and recycling nutrients and this loss of soil biological activity reduces the soil’s ability to sequester carbon. Soil is one of our largest carbon sinks. However, over 30% of soils worldwide are degraded by unsustainable land management. In a vicious cycle, ever more fertilisers are required to provide the soil’s missing nutrients and highly-fertilised plants become more attractive to pests, leading farmers to apply even more pesticides. In a well-managed agroecological system, plants are hardier and pests are largely managed by natural predators.
While the effects of pesticides on soils are complex, global comparisons between organic and conventional farming systems show that organic farms hold more carbon in total and sequester at approximately a 14 times higher rate.
The manufacture, transport and application of pesticides creates greenhouse gas emissions through energy use in production and the release into the atmosphere of active ingredients and ‘inert’ adjuvants. Pesticides also cause further emissions through their effects on soils – though these effects are not well understood. Researchers in the USA have shown that widely used soil fumigants such as chloropicrin can increase soil N2O emissions seven-fold and their effects last far longer than fertiliser-induced emissions. Effects such as these are not currently included in our estimates of agricultural greenhouse gas emissions but could be significant.
The impact pesticides have on emissions is likely to be underestimated due to the potential for severe effects on soil carbon sequestration and their role in making highly industrial forms of agriculture possible.
Pesticide manufacturers are marketing their products as solutions to climate change. The use of herbicides to clear land of weeds and old crops is promoted as an alternative to tilling which breaks up the soil and affects its ability to sequester carbon. However, we know that soil biodiversity is heavily affected by herbicides and is critical to carbon sequestration.
A 2017 report by the UN’s Special Rapporteur on the Right to Food found that, “it is commonly argued that intensive industrial agriculture, which is heavily reliant on pesticide inputs, is necessary to increase yields to feed a growing world population, particularly in the light of negative climate change impacts and global scarcity of farmlands”. But noting that 200,000 people die of acute pesticides poisoning each year, it added that “reliance on hazardous pesticides is a short-term solution that undermines the rights to adequate food and health for present and future generations.”
The good news is that agriculture can play a key role in climate change mitigation – and adaptation – as well as better protecting the health of farmers, farm workers, the general public and the environment, by adopting agroecological farming methods. We can increase soil fertility and soil carbon, while producing healthy and nutritious food to feed the world. Agroecological farming promotes diverse farming systems and healthy crops that are better able to resist pests and diseases. This approach also improves resilience to climatic and other shocks. Healthy soils that are rich in organic matter, for example, retain more water and provide better protection from both flooding and drought.
In the ongoing global climate negotiations, farming and land management must be put on an equal footing to energy and transport while nations must put agroecology at the heart of farming policies fit for the 21st century.