Researchers focus on dairy's carbon footprint

Published on: May 31, 2013

Researchers at the University of Arkansas are attempting to help the U.S. dairy industry decrease its carbon footprint.

In 2007, Americans consumed approximately 17.4 million metric tons of fluid milk — not including milk used in dairy products such as cheese, yogurt and ice cream. The dairy industry has set a goal of 25% reduction in greenhouse gas emissions by 2020.

The University of Arkansas researchers' "cradle-to-grave" life-cycle analysis of milk will provide guidance for producers, processors and others in the dairy supply chain and will help these stakeholders reduce their environmental impact while maintaining long-term viability.

"Based in part on growing consumer awareness of sustainability issues in our food supply chain, the U.S. dairy industry is working to further improve the environmental performance of its production processes and supply chain in a way that is also economically sustainable," Greg Thoma, professor of chemical engineering at the university, said. "Our analysis provides a documented baseline for their improvement efforts. It is a source for understanding the factors that influence environmental impact."

Thoma and an interdisciplinary team of Arkansas researchers looked at all facets and stages of milk production, from the fertilizer used to grow the animal's feed to waste disposal of packaging after consumer use. Specifically, their life-cycle analysis focused on seven areas:

1. Farm production and processes;

2. Farm-to-processor transportation;

3. Processor operations, packaging and distribution;

4. Retail operations;

5. Consumer transportation and storage;

6. Post-consumer waste management, and

7. Overall supply-chain loss and waste.

The researchers found that for every kilogram of milk consumed in the U.S. per year, 2.05 kg of greenhouse gases, on average, are emitted over the entire supply chain to produce, process and distribute that milk. This is equivalent to approximately 17.4 lb./gal., they said. The greenhouse gases were measured as carbon dioxide equivalents and included methane, refrigerants and other gases that trap radiation. The largest contributors were feed production, enteric methane — gas emitted by the animal itself — and manure management.

The researchers identified many areas where the industry can reduce impact within feed and milk production, processing and distribution, retail and the supply chain. They focused on farms, where processes for feed production, handling of enteric methane and manure management varied greatly and, therefore, represent the greatest opportunities for achieving significant reductions.

The University of Arkansas researchers — Rick Ulrich, professor of chemical engineering; Darin Nutter, professor of mechanical engineering; Jennie Popp, professor of agricultural economics and agribusiness; and Marty Matlock, professor of biological and agricultural engineering, in addition to Thoma — partnered with researchers at Michigan Technological University. Their study was published as a special issue, "Carbon & Water Footprint of U.S. Milk, From Farm to Table," of the International Dairy Journal in April.

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