Abstract
Climate stabilization wedges are defined as strategies that contribute to greenhouse-gas (GHG) mitigation that – in aggregate – achieve a particular goal. Wedges have been proposed as a GHG mitigation framework because no single technology or economic sector can sufficiently reduce emissions to acceptable levels. To avoid the most dangerous risks of climate change, we argue that mitigation of ~9000 teragrams of carbon equivalents (Tg Ceq) will be required by the year 2030. We estimate that agriculture could provide wedges of 1350 to 3900 Tg Ceq under attainment of technological and human behavior mitigation potentials. Improved agricultural management can decrease nitrous oxide and methane emissions and increase carbon sequestration. Consumption of fewer livestock products along with agricultural intensification through available technologies can result in reduced emissions in both developed and developing countries. Decreasing excess protein and calorie consumption in developed countries improves personal health, while reforestation and avoided deforestation in developing countries help to maintain biodiversity. The mitigation wedges have varying economic costs but also have multiple benefits.
Generated Summary
This research investigates the potential for agricultural practices and changes in human behavior to contribute to climate stabilization by reducing greenhouse gas (GHG) emissions. It uses the climate stabilization wedge framework, initially proposed by Pacala and Socolow (2004), to assess how various strategies in agriculture, including technological advancements and dietary shifts, can mitigate GHG emissions. The study focuses on global and U.S. national scales, examining the mitigation potential of different agricultural sectors and human behavior modifications, to determine if agricultural production and GHG reduction goals can be achieved. The methodology involves analyzing agricultural emissions, estimating mitigation potentials for various strategies, and comparing these with the overall mitigation targets needed to stabilize atmospheric CO2 levels. The analysis considers both technological mitigation options, such as changes in land/livestock management practices, and behavioral changes, including dietary modifications and population growth rate adjustments. It aims to quantify the ability of these changes to reduce emissions of CO2, CH4, and N2O.
Key Findings & Statistics
- Agriculture is directly responsible for about 10-12% of global GHG emissions, mostly nitrous oxide (N2O) and methane (CH4) from crop and livestock production (Flynn and Smith 2010).
- Carbon dioxide emissions from production and transport of farm inputs plus operation of farm equipment contribute an additional 1-3% of global emissions.
- If CO2 emissions from land-use change for agriculture (mainly deforestation in the tropics) are included, based on the Global Carbon Project (Friedlingstein et al. 2010), agriculture’s contribution to total GHG emissions increases to ~22%.
- In the US, agriculture is responsible for only about 7% of US GHG emissions, and land-use change in the US is actually a large CO₂ sink.
- Global emissions from agriculture (including land-use change) are currently ~3000 teragrams of carbon equivalents (Tg Ceq).
- In the US agricultural sector, emissions excluding land-use change currently constitute about 133 Tg Ceq.
- When land-use change is included, agriculture represents a sink of ~144 Tg Ceq.
- Major sources of agricultural GHGs both in the US and worldwide are N₂O from soils, enteric CH, from domestic livestock, CO2 from manufacture/transport of farm inputs and operation of farm equipment, and CH4 and N₂O from manure management systems.
- Agriculture is estimated to increase to ~3700 Tg Ceq by 2030 under a business-as-usual scenario.
- Worldwide, agriculture could supply wedges of approximately 1350 (15%), 2450 (27%), and 3900 (43%) Tg Ceq of the total required mitigation of 9000 Tg Ceq by 2030 for the low, medium, and high scenarios.
- The US was responsible for ~18% of global GHG emissions during the first decade of the current century, we assumed that the total wedge required by the US in 2030 would be about 1600 Tg Ceq.
- For the US, the low scenario falls about 30% short.
Other Important Findings
- Climate stabilization wedges, as defined by Pacala and Socolow (2004), are strategies that can collectively mitigate GHG emissions to achieve specific goals.
- The study emphasizes the need for a substantial reduction in GHG emissions, estimating that approximately 9000 teragrams of carbon equivalents (Tg Ceq) of mitigation will be required by 2030 to mitigate climate change effectively.
- Improved agricultural management practices, such as reduced nitrous oxide and methane emissions and enhanced carbon sequestration, are key strategies.
- Decreasing consumption of livestock products and agricultural intensification are proposed as effective mitigation strategies in both developed and developing countries.
- Reducing excess protein and calorie consumption in developed countries and promoting reforestation and avoided deforestation in developing countries can contribute significantly to reducing emissions.
- The biggest mitigation wedges at the global scale are from land-use conversion, soil C sequestration, and soil N₂O emissions.
- The study highlights that human diet has the largest impact on land-use conversion because, as consumption of animal products declines, less tropical forest is converted to agriculture and reforestation can occur.
- The study suggests that both the implementation of technologies and changes in human behavior are likely required to meet climate security goals.
Limitations Noted in the Document
- The uncertainty associated with the effectiveness of technological GHG mitigation practices is high, as their performance varies widely across different studies and experimental conditions.
- The study acknowledges the challenges in quantifying the actual mitigation achieved in working agricultural production systems.
- The reliability of models and decision-support tools to accurately represent mitigation options is uncertain.
- The study notes uncertainty in the extent of diet and human fertility rate changes.
- The study does not consider how implementation of agricultural wedges interacts with other economic sectors.
Conclusion
The study concludes that the agricultural sector has a significant role to play in mitigating climate change, with a combination of technological advancements and behavioral changes being necessary to achieve substantial reductions in GHG emissions. The authors emphasize that agricultural production and GHG mitigation goals are not mutually exclusive and that healthier diets could allow sufficient decreases in agricultural production to meet GHG mitigation goals. Key recommendations include incentivizing agricultural producers to adopt emission-reducing technologies, promoting the adoption of the recommended healthy diet, and clarifying the costs and benefits of various agricultural systems to consumers. The study underscores the importance of integrating technological and behavioral changes to effectively address climate change within the agricultural sector. The authors highlight that the most effective mitigation strategies involve changes in land-use conversion, soil C sequestration, and reductions in N₂O emissions. They also suggest that the reduction in consumption of animal products is linked to larger benefits than changes in the human population. The study emphasizes that while technological advances are important, they are most effective when combined with dietary changes and other modifications in human behavior. The authors also suggest that implementing GHG-reducing technologies could have multiple benefits, such as the use of stabilized N fertilizers can also reduce the amount of reactive N lost from agricultural systems, and sequestration of C in soils can improve soil water and nutrient holding capacity.