From the Dairy NZ website
Carbon goes through a series of cycles through pastoral systems, and ruminant animals do not add any new carbon to the atmosphere. But that is really unimportant because ruminants convert carbon dioxide to methane, the greenhouse gas that is more than twenty times as powerful as carbon dioxide. Thus farming ruminants tend to increase the proportion of carbon in the methane form rather than in the carbon dioxide form.
Let’s examine this statement
Carbon goes through a series of cycles through pastoral systems, and ruminant animals do not add any new carbon to the atmosphere.
Correct they do not add any new carbon to the atmosphere. Dairy NZ should regard that as the end of the matter, but they don’t.
But that is really unimportant because ruminants convert carbon dioxide to methane,
So What! You can convert CO2 to CH4 as much as you want if it does not increase the concentration of methane in the atmosphere (because it is only replacing existing methane that is being oxidised to CO2) it can not be responsible for global warming. END OF STORY. Dairy NZ is ignoring the United Nations definition of climate change and imposing one they must have made up of their own.
But that is really unimportant because ruminants convert carbon dioxide to methane, the greenhouse gas that is more than twenty times as powerful as carbon dioxide.
A misrepresentation here, CH4 as a gas is not 20 times more powerful, it is about 7 times. Probably not deliberate from Dairy NZ just sloppy.
Dairy NZ would have made this statement because one tonne of methane is more than 20 times more powerful than one tonne of CO2 but what Dairy NZ forgets is that there are a lot more molecules of CH4 in one tonne compared to CO2. This is because of molecular weights. CO2 has a molecular weight of 44 and CH4 is only 16. So it takes a lot more molecules of methane with a molecular weight of only 16 to make a tonne than CO2 molecules with a molecular weight of 44 (in fact it takes 2.75 methane molecules to weigh the same as a CO2 molecule). So saying, methane is more than twenty times as powerful as carbon dioxide is misleading. The true comparison is on a molecular basis because it is the molecules which trap the heat. If the one tonne of CO2 is converted to CH4 by the ruminant it will only produce 362 kgs methane. 362 kg methane if multiplied by 21 being its global warming potential comes to 7.6 tonnes CO2equivalent. So methane as a greenhouse gas is 7.6 times more powerful than CO2, not 20 times.
Thus farming ruminants tend to increase the proportion of carbon in the methane form rather than in the carbon dioxide form.
Again SO WHAT! If it does not cause an increase in actual methane who cares what proportion is in what. The planet certainly doesn’t.
I am not sure what Dairy NZ’s agenda is here, it does not appear to be helping farmers anyway. What ever it is I am glad I am not paying any levies to them to do it.