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LCA and the Dynamics of Agriculture’s Environmental Impacts

Sangwon Suh

Researchers who work in life-cycle assessment (LCA) rely heavily on databases to
quantify the environmental impacts of products and services. In industries that change rapidly, such as the electronics and high-tech sectors, LCA data sets are updated frequently to ensure the most accurate analyses. However, data sets for agriculture, which is perceived as changing slowly, tend to be updated infrequently.

“People tend to think of agricultural as an industry of the past that doesn’t change much, and that its environmental impacts are more or less constant over time,” says Bren professor Sangwon Suh. “They may think that using twenty–year-old LCA data is OK for agricultural products.”

But in “Change in environmental impacts of major crops in the US,” published Sept. 11 in the journal Environmental Research Letters, Suh and his co-author, Bren School alumnus Yi Yang (PhD 2015), show that agriculture in the 21st century is highly dynamic as the result of several factors, including climate change and technological advances.

The researchers gathered a large amount of new data for four major crops, examining ten years of environmental impacts resulting from the cultivation of corn, cotton, soybeans, and wheat. They measured acidification (air), eutrophication (water), smog formation, freshwater ecotoxicity, and several human health criteria.

While several impacts remained relatively stable over time, others varied significantly.

Yi Yang

For instance, the impact per acre of both cotton and corn cultivation on the ecological health of freshwater systems decreased by about 60% and 50%, respectively, in the past decade. The decreases are believed to have resulted from expanded use of genetically modified crops, which require fewer pesticides and herbicides.

But the researchers also found that the freshwater eco-toxicity impact of soybean production quintupled, largely owing to the spread of an invasive species, the soybean aphid, which led to increased use of insecticides.

The authors write that understanding the factors that drive change in the environmental impacts of agricultural systems is essential for making informed decisions, prioritizing which LCA data to update more frequently, and interpreting LCA results that use older data.

“Our study implies that it is worthwhile focusing on the rapidly changing categories when updating agricultural LCA databases under time and resource constraints.”