Nitrous Oxide is laughing gas and it is laughable how it is being treated by journalists.
Now called the most significant ozone depleting gas nitrous oxide’s association with agriculture sees farmers now taking the rap for depleting the ozone layer as well as frying the planet.
Refer NZ Herald article by Eloise Gibson Livestock gas now biggest risk to ozone layer
Some perspective is needed here and some facts as well.
Nitrous Oxide is produced during the biological process of decomposition of matter in soil and oceans.
Not much is known about it really but the estimate is that between 70-80 percent of it is produced naturally with the other 20-30 percent anthropogenic.
It survives in the atmosphere around 120 years
It is a neat little gas in that it is part of the amazing process of life. Nitrogen is the most abundant gas in the atmosphere and the nitrogen cycle is one of the most important chemical reactions on Earth. Nitrogen can not be used by higher order life like plants and tiny bacteria turn it into ammonia and nitrates. N2O is produced during this process.
It is produced in the process of nitrification and denitrification. Nitrification is the oxidisation of NH4 or NH3 to NO2 or NO3. Denitrification is the respiratory bacterial reduction of NO3 or NO2. When plants die the bacteria feed on it releasing the nitrogen for other plants to use and N2O is released in that process as well.
So the production of N20 is part of a pretty vital process.
Anthropogenic sources are forestry, agricultural soils, combustion, motor racing fuel, laughing gas for medicine and recreational purposes.
The use of catalytic converters in vehicles has dramatically increased the production of N2O. They were designed to prevent smog but the downside of them is that they produce N2O. Bio fuel powered vehicles can also have a higher percentage of N2O in their exhaust than conventional fuel.
Current levels in the atmosphere are 315 parts per billion. This is an increase from 275 ppb in 1750. Levels are increasing by 0.25 percent per year. At this rate of increase In 100 years it will be responsible for depleting ozone at 30-40 percent the rate CFC did at its peak.
Causes of the increase are not clear, most point to increased artificial nitrogenous fertiliser use but they are silly people because they ignore the dramatic increases in catalytic converters as just one example.
New Zealand does not know how much N2O it produces from transport and energy sectors. Nor does it know how much the forestry sector produces. Forestry emissions will be significant. Funnily enough they do know exactly how much the agricultural sector produces.
Because they do not know how much other sectors contribute they can not say what percentage of N2O emissions come from agriculture. The figure of 95% they use only applies to the NZ Inventory of greenhouse gases which ignores the emissions from forestry and most other sectors.
Of the agricultural emissions 60% come from soil bacteria breaking down animal waste, 27% from soil bacteria breaking down organic matter and 13% from the use of artificial and natural nitrogenous fertilisers.
The 27% from organic material break down occurs on all New Zealand land whether under pasture, trees, lawns, parks, etc. Less than one third of New Zealand is in pasture. So this means two thirds of the N2O that is produced in this way is ignored.
N2O does not actually deplete the ozone but it degrades in the stratosphere to nitric oxide which does the damage. Nitric Oxide is only 1/50th as potent as CFC-11 at reducing ozone.
CFC did not deplete the ozone either but it was the chlorine oxides it broke down to that did it. There is a relationship between N2O and CFC in that they suppress each other’s ability to cause depletion of the ozone. Reducing the output of CFC’s has removed the suppression of N2O by CFC and this allows it to deplete the ozone more.
The process is different to that which led to the hole in the ozone layer over the Antarctic. This is because ozone is always being produced and destroyed. This is by the ultra violet radiation from the Sun that breaks up oxygen from O2 to O&O which then combine with an O2 to form ozone O3. Likewise the same radiation breaks up the O3 into O2 and O. And so it goes on continually producing and destroying ozone. This happens more at the equator for obvious reasons and the ozone circulates to the Poles. There is no Sun at the Pole so no ozone forms there in the winter, and this combined with the action of chlorine oxide some of which came from CFC, causes the hole.
N2O will not do this; it just attacks the O3 and breaks it down in a similar fashion to the Sun, so it lessens the concentration of O3 molecules. Ozone layer is not like a blanket it is just that the ozone floats around in the stratosphere which is itself a layer. There are about 10 ozone molecules per million molecules in the atmosphere and 90 percent of those are in the stratosphere, hence the use of the word layer.
South American rain forests are significant producers of N2O. It is to do with the type of soil, the moisture and the temperature. Clearing these forests for palm oil production should benefit the ozone layer.
N2O is a greenhouse gas, as is ozone (when it is in the lower atmosphere) and others. Ozone is also a pollutant when in lower atmosphere. It causes respiratory problems in people and animals.
N2O exists in very small amounts; CO2 is 1180 times more prevalent in the atmosphere. But it is more significant than methane as a greenhouse gas because over a 100 year time horizon it is 310 times more potent as a greenhouse gas than CO2. Over a 500 year time horizon it is 170 times as potent. It contributes 0.95 % of the greenhouse gas affect of all greenhouse gases including water vapour compared to methane’s 0.36%. CO2 produces 3.618% of the effect.
Of all greenhouse gases, excluding water vapour, it contributes 19% of the greenhouse gas affect compared to methane at 7.199% and CO2 at 72.369%
DCD is being trumpeted as a saviour for global warming and now ozone protection.
Using DCD to reduce greenhouse gas emissions is a pretty nutty idea, because to burn a fossil fuel to spray the ground so that a naturally occurring chemical can be suppressed is going to cause more global warming than it stops.
Any one who suggests DCD’s should be used to save the ozone layer is seriously lacking in IQ to say the least. The ozone depletion from N2O is so minor compared to the environmental impact of producing and spraying this stuff on the ground that it should not be considered for this reason.
As I have said before DCD should be used for productivity reasons not environmental ones because most of the environmental impacts are questionable.
So big ups for nitrous oxide, it is not a livestock gas because most production is natural and essential to life. If you are really worried about the ozone layer rip the catalytic converter out of your car, don’t use bio fuel, discourage practices like composting and mulching and if after having worked hard all day and put up with the farmer bashing on the radio and in newspaper articles by yet another dumb journalist and you feel you need to take your mind off things, don’t get on the laughing gas have a drink instead.