NOAA Research: Nitrous Oxide Depletes Ozone

Recent environmental research shows that nitrous oxide, most recognized as “laughing gas” is in fact, no laughing matter.

A recent New York Times article describes how researchers from the National Oceanic and Atmospheric Administration, or “NOAA” present their findings:

They note that the health of the ozone layer has been improving since the adoption of the protocol and that nitrous oxide looms large today as an artificial destroyer of the ozone layer, in part because the emissions of other harmful chemicals have been so sharply reduced. But major chemical targets of the Montreal agreement, chlorofluorocarbons, inhibit the ozone-destroying actions of nitrous oxide, the researchers said. So as their levels fall, the harmful influence of nitrous oxide increases.

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. John S. Daniel, one of the authors of the new report, said scientists had for some time known of the ozone-depleting potential of nitrous oxide. But, Mr. Daniel said in a telephone news conference, “there is a sort of gap between the scientific understanding and the policy.”

The researchers did not make any policy recommendations in light of their finding.

“It is not for us to gauge how much risk there is,” said A. R. Ravishankara, who led the work. In any event, he said, at the moment researchers could not say with confidence “how much nitrous oxide comes from where.”

“The uncertainties are significant,” Dr. Ravishankara said.

Dr. Ravishankara estimated that worldwide the ozone layer had been reduced by about 6 percent from what it was before industrialization.

At ground level, ozone is a pollutant, but in the upper atmosphere it blocks ultraviolet radiation that would harm plants and animals on Earth’s surface. When researchers discovered that chemicals like chlorofluorocarbons were depleting this high-level ozone layer, and especially after the discovery of a highly depleted ozone hole over Antarctica, international negotiators produced the Montreal agreement.

Because of the unusual atmospheric chemistry above Antarctica, nitrous oxide does not affect the ozone hole there, Dr. Ravishankara said.

Now, it’s worth pointing out that nitrous oxide is naturally emitted out into our atmosphere from soil based bacteria. While that’s one contributing source, nitrous oxide is also released when nitrogen based fertilizers are used, when livestock manure is used in farming, and in the burning of some biofuels.

Categorized | Pollution & Toxins
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