Climate-neutral dairy in California? A study based on life cycle assessment and radiative forcing

Ruminants play a key role in achieving the global climate goal of limiting surface temperature increase to 1.5°C to 2°C by 2100. In California, the dairy sector is subject to ambitious methane (CH₄) reduction targets, specifically, a 40% decrease by 2030 from 1990 levels, through strategies such as alternative manure management, anaerobic digestion, and antimethanogenic feed additives. These mitigation measures are intended to put California dairy on a path toward climate neutrality. However, questions remain: Are current technological improvements enough to achieve climate neutrality in dairy? What is the role of non-CH₄ GHG, such as carbon dioxide (CO₂) and nitrous oxide (N₂O), in shaping long-term climate impacts? This study analyzes the historical climate impact of California dairy from 1950 until 2020 and forecasts different scenarios to 2030, 2050, and 2100 based on current public policies and technological development. The analysis integrates life cycle assessment with the recently developed radiative forcing climate footprint (RFCF), a metric that quantifies climate impact over time in terms of radiative forcing (W/m²), later translated into temperature change (°C). The RFCF results were further processed to assess climate neutrality and stability, as well as the sector's relative contribution to achieving global climate goals. Results indicate that projected reductions in CH₄ emissions drive a rapid decline in short- and middle-term climate impacts, decreasing from 1.67 mW/m² in 2020 to 1.32 mW/m² in 2050 and 0.98 mW/m² in 2100 under the lowest-emissions scenario. However, achieving long-term climate goals is likely to require additional reductions on CO₂ and N₂O emissions. The study also identified the need for systemic changes in livestock and food production systems to achieve climate neutrality in the 21st century.