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Low-Carbon Dairy: Cows present tremendous mitigation opportunity

Dairy cow with snowboard, part of climate solution
Recent climate science confirms that California’s dairy methane reduction efforts are an important climate mitigation strategy.

As Californians continue to endure the COVID-19 outbreak, we need to know we are working toward a better future. The pandemic has further highlighted the importance of food security and reliable access to nutritious foods that are environmentally and economically sustainable. Recent science confirms that methane reduction efforts are a significant opportunity to mitigate climate warming. California’s dairy families are leading the way toward low-carbon dairy production.

While methane (CH4) emissions—such as those from cow belches—have often been singled out for their climate impacts, their reduction represents a tremendous opportunity to help offset the long-lasting impacts of carbon dioxide (CO2). Even taking into consideration the increased potency of methane, it still accounts for a relatively small share, just nine percent (9%) of overall greenhouse gasses (GHGs) in California. CO2 is the primary human-caused GHG contributing to climate warming and represents a full eighty-three percent (83%) of all California GHGs.

Moreover, methane is a short-lived climate pollutant, with emissions breaking down after an average of 12 years. In contrast, CO2 emissions persist in the atmosphere for hundreds of years. As a result, CO2 accumulates in the environment, meaning new emissions are added on top of those that were previously emitted, leading to increases in the total atmospheric stock or concentration of CO2. Simply put, when additional CO2 is emitted, additional global warming occurs. Methane emissions, on the other hand, degrade in the atmosphere relatively quickly (12 years), so, if emissions of methane are stabilized at present levels or even reduced, they will will not further accumulate. No further accumulation of methane results in no additional climate warming.

Recent work by leading international climate scientists at Oxford University has shed light on these important differences between CO2 and CH4 and their ultimate impact on climate change. This improved understanding of how short-lived and long-lived emissions impact climate differently is critical for California policymakers and regulators, as we seek to limit further global warming. These scientists now recognize that moderately reducing methane emissions can quickly stabilize the climate pollutant’s powerful impact.

Flow of methane and carbon dioxide
This figure from the UC Davis white paper is based on research by Myles R. Allen, Keith P. Shine, Jan S. Fuglestvedt, Richard J. Millar, Michelle Cain, David J. Frame & Adrian H. Macey.

Two distinguished University of California, Davis scientists recently coauthored a white paper that applies this improved understanding to California’s dairy farms. California’s dairy sector is no longer expanding; the number of dairy cows and the amount of milk produced have been decreasing slightly since 2008. The amount of methane from dairy production in the state is less today, as more methane is being broken down and removed in the atmosphere each year. Additionally, our farms are currently achieving significant reductions of methane emissions through the Dairy Digester Research and Development Program (DDRDP) and the Alternative Manure Management Program (AMMP) — important climate-smart agriculture programs administered by the California Department of Food and Agriculture.

White paper about methane, cows, and climate change
The UC Davis white paper explains how methane reduction efforts will help California’s dairy farms reach climate neutrality in the near future.

A key takeaway from the white paper is that methane emissions, while more potent, need only to be stabilized to limit further global warming. California dairy farms have already stabilized their methane emissions and are now reducing them even further. In contrast, CO2 needs to be reduced to nearly zero, since it continues to accumulate and presents a much bigger challenge for policymakers and regulators, as we move forward to address climate change and its impacts. At the current rate, methane reductions will allow California’s dairy farms to offset their remaining GHG emissions and reach climate neutrality sometime in the near future. Additional reductions will provide climate-cooling impacts, as methane offsets the far more damaging impacts of CO2, which accumulate in the atmosphere for hundreds of years.

These findings provide a bit of fresh air here in California. However, it is important to note that our dairy farmers are already among the most efficient producers of milk in the world. Attaining California’s current level of production efficiency in all dairy regions would reduce total global greenhouse gas emissions by as much as 1.73 percent. Meanwhile, via public-private partnerships facilitated through the DDRDP and AMMP, California is already taking the next step—further reducing dairy methane emissions. These reductions will be accelerated as more projects are implemented. It will be critical to share these learnings globally, as California’s dairy farms continue on their planet-cooling path.

The latest climate science confirms California’s dairy methane reduction efforts are a super opportunity to mitigate warming.



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