Washington, Apr 3 (IANS): Increasing reliance on fertilisers has caused a dramatic spike in atmospheric nitrous oxide (N2O), a major greenhouse gas contributing to global climate change, says a new study.

Climate scientists have assumed that the cause of the increased N2O was a nitrogen-based fertilizer, which stimulates soil microbes to convert nitrogen to nitrous oxide at a faster rate than normal.

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

(Isotope is each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei).

"Our study is the first to show empirically...that the nitrogen isotope ratio in the atmosphere and how it has changed over time is a fingerprint of fertiliser use," said Kristie Boering, University of California-Berkeley professor of chemistry and of earth and planetary science, who led the study.

"We are not vilifying fertilizer. We can't just stop using fertilizer. But we hope this study will contribute to changes in fertilizer use and agricultural practices that will help to mitigate the release of nitrous oxide into the atmosphere," Boering added, according to a California statement.

A steep ramp-up in atmospheric N2O coincided with the green revolution that increased dramatically in the 1960s, when low cost synthetic fertilizer and other developments boosted food production worldwide, feeding a burgeoning global population.