Nitrous Oxide Responsible for Most Ozone Depletion

Greenhouse gas nitrous oxide – better known as “laughing gas” – is now the dominant ozone pollutant, according to new scientific thought expressed on August 28th 2009.  What’s more, emissions of nitrous oxide as a result of human activities will probably remain the ozone layer’s most powerful degrader until 2099, scientists working at the US National Oceanic and Atmospheric Administration said. 

N20 Emissions

In its new study on the impact of nitrous oxide on the environment, the administration urged for N20 emissions to be better regulated, adding the result would be a “win-win for both ozone and climate.”

“Nitrous oxide emission currently is the single most important ozone-depleting substance emission and is expected to remain the largest throughout the 21st century”, the scientists stressed, adding: “Limiting future nitrous oxide emissions would enhance the recovery of the ozone layer from its depleted state.”

The previous top ozone depleters were CFCs (chlorofluorocarbons), which were linked for a long time with refrigeration.  As a result of the 1987 Montreal Protocol, CFCs are now being used less and less.

Nitrous Oxide Emissions

Human activities such as industrial fossil fuel incineration and farming generate an annual nitrous oxide emissions total of approximately 10,000,000 tonnes, which represents over 30 per cent of all emissions.  Natural processes, meanwhile, generate over 65 per cent of total N20 emissions, resulting in an ongoing thinning of the ozone layer which acts to filter UV (ultraviolet) rays.

“The main reason for the large role of nitrous oxide is the success of the Montreal Protocol in that it has reduced the emissions of CFCs and other ozone-depleting chemicals”, A.R Ravishankara – the report’s main writer – advised the media.

Ozone Depletion

According to the United Nations, the Montreal Protocol’s impact will reverse ozone depletion and lead to the ozone layer eventually being preserved.  N20 itself does not feature within this protocol, but it is regulated by another one – the 1997 Kyoto Protocol.  This gives until 2012 for developed countries to reduce overall emissions to five per cent below where they stood in 1990, and is due to be updated at the end of 2009.

The new NOAA report appears in the latest edition of industry publication Science.