New Culprit Seen in Ozone Depletion

Government scientists who study the depletion of Earth’s protective ozone layer are pointing to a previously unheralded culprit: nitrous oxide. Most of the nitrous oxide in the atmosphere emerges naturally, through the action of bacteria in the soil, the researchers say. But the gas is also produced by human activity, through the use of nitrogen-based fertilizers, the application of livestock manure to fields, the burning of biofuels and in other ways. Though nitrous oxide is not regulated under the Montreal Protocol, the 1987 agreement to limit emissions of ozone-depleting chemicals, the researchers say it is emerging as the leading artificial cause of ozone loss. The researchers, from the National Oceanic and Atmospheric Administration, report their findings in Friday’s issue of the journal Science. The Environmental Protection Agency is already contemplating action on nitrous oxide because it is a heat-trapping gas linked to global warming. In April, the agency declared it and five other gases, including carbon dioxide, to be pollutants that endanger public health, making them subject to regulation under the Clean Air Act. In a statement, the agency said Thursday that work on a reporting system for emissions of nitrous oxide and the five gases was under way...NYTimes