Note: All emission estimates are sourced from the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990–2022.

UC Berkeley chemists have analyzed the isotopic composition of nitrous oxide – a greenhouse gas - in air samples from as far back as 1940 and found the fingerprint of nitrogen-based fertilizer, proving definitively that the 20 percent increase in atmospheric nitrogen since the Industrial Revolution is largely due to the Green Revolution.

By Robert Sanders

April 2, 2012

University of California, Berkeley, chemists have found a smoking gun proving that increased fertilizer use over the past 50 years is responsible for a dramatic rise in atmospheric nitrous oxide, which is a major greenhouse gas contributing to global climate change.

Climate scientists have assumed that the cause of the increased nitrous oxide was nitrogen-based fertilizer, which stimulates microbes in the soil to convert nitrogen to nitrous oxide at a faster rate than normal.

The new study, reported in the April issue of the journal Nature Geoscience, uses nitrogen isotope data to identify the unmistakable fingerprint of fertilizer use in archived air samples from Antarctica and Tasmania.

“Our study is the first to show empirically from the data at hand alone that the nitrogen isotope ratio in the atmosphere and how it has changed over time is a fingerprint of fertilizer use,” said study leader Kristie Boering, a UC Berkeley professor of chemistry and of earth and planetary science.

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