by Rick Pruetz, Vice President, Ecocity Builders
The generation of food emits almost as much greenhouse gas (GHG) worldwide as the generation of electricity. Yet the food-agriculture-land use sector, or FALU, gets far less attention in our pursuit of climate action. Project Drawdown aims to correct that oversight in its recent report: Farming Our Way Out of the Climate Crisis, freely downloadable at DrawdownPrimer_FoodAgLandUse_Dec2020_01c.pdf.
Project Drawdown, a non-profit organization formed in 2014, released its initial findings on climate solutions in the influential 2017 book Drawdown: The Most Comprehensive Plan Ever Proposed to Reverse Global Warming. We were fortunate to have Paul Hawken, Founder of Project Drawdown and editor of the Drawdown book, as our keynote speaker at Ecocity World Summit 2019.
Perhaps the impact of FALU is often overlooked because it is so ubiquitous. Croplands and pastures occupy about 35 percent of our planet’s ice-free land. No wonder FALU is responsible for 24 percent of GHG generation, almost as much as the 25 percent caused by electricity generation, the biggest single source of GHG emissions.
Within FALU’s 24 percent, nine percent comes from deforestation, six percent from methane caused by farm animals and rice cultivation, four percent from nitrous oxide generated by fertilizer and manure, and the remaining five percent generated by other agriculture-related activities such as fuel consumed in producing agricultural chemicals, operating machinery, and transporting farm supplies and products.
Because deforestation and land clearance for crops and pastures destroy habitat, FALU is the biggest cause of worldwide biodiversity loss. Agriculture is also responsible for 85 percent of water use on our planet. Overuse of fertilizers and manure pollutes streams, lakes, and oceans around the globe as well as exacerbating climate change by sending excess nitrogen into the atmosphere.
Many strategies for reducing emissions from FALU are well known but hard to implement. Preserving and restoring tropical forests, particularly in Brazil and Indonesia, would create the single biggest GHG reduction in this sector, followed by changing our livestock, rice-growing, and fertilization practices. We could also dramatically lower the impact of FALU by reducing or eliminating the behaviors that now waste 30 percent of the food we grow and by changing to plant-rich diets.
In addition to mitigating GHG emissions, the Project Drawdown report summarizes the current status of using FALU to increase carbon sequestration in biomass and soil. The strategies include forest restoration, regenerative annual cropping to rebuild soil, and increased adoption of perennial crops using agroforestry, intercropping trees with annual crops, and farming approaches that use multiple layers such as shade coffee. In addition to sequestering carbon, regenerative agriculture improves water retention, reduces erosion, and improves agricultural productivity, perhaps freeing more land for agroforestry and perennial cropping, the farming practices that generally produce higher sequestration rates.
Agroforestry solutions are already widely used in some parts of the world and there is greater scientific certainty in their ability to sequester carbon. Sequestration of methane can also be increased by reestablishing forests, integrating trees into pastures, increasing organic matter in soils, and retaining crop residue after harvesting. However, the report warns that grasslands are capable of capturing no more than 15 percent of the methane generated every year by grazing ruminants.
The report quantifies the role that agricultural practices can play in mitigating GHGs but cautions that there are still many questions about how much carbon can be sequestered by agricultural biomass and soils. Using one method, Project Drawdown calculates a best-case scenario of recapturing about two-thirds of the carbon originally held in soils. In an alternative method, the report estimates that soils could capture up to five years of the world’s GHG output at today’s emission rates.
Once sequestered, carbon can again be lost if carbon-friendly practices are abandoned or if carbon is released by drought, fire, and floods – events that will become increasingly common with climate change. Consequently, permanent management is critical, particularly if carbon credits are being sold based on sequestration claims. “While the potential for regenerative agriculture to sequester carbon has been, at times, overpromised and overestimated, it does indeed have the impressive capacity and an essential role as part of a broader program to cut emissions and promote carbon sinks (Project Drawdown 2020, 40).
In addition to substantially reducing almost one-quarter of total GHG emissions and removing a big chunk of carbon from the atmosphere, regenerative agriculture also safeguards aquatic ecosystems, protects water resources, improves health, and benefits local economies. The report ends with the following reminder that improvements in the FALU sector are important but only part of the solution: “There is no single answer to addressing climate change. No silver bullets exist. But a silver buckshot does” (Project Drawdown 2020, 41).
Project Drawdown. 2020. Farming Our Way Out of the Climate Crisis. Accessed 3-15-21 at DrawdownPrimer_FoodAgLandUse_Dec2020_01c.pdf.