Nearly half of New Zealand’s emissions are from livestock. A shocking 46.1% for the year 2012 as calculated by the Ministry for the Environment. (MfE). A large proportion of this comes from beef and to a less extent sheep. The MfE paper tells us tells us that in 2012 we had 6.4 m dairy cattle, 3.8m beef cattle, 3.1 m sheep and 1 m deer. So a total of 14.3m ruminant livestock.
So I read their paper calculating our emissions, or more accurately skimmed through it, reading the less technical parts of it as it is hundreds of pages long. I was looking for indications of what Global Warming Potential they were using for methane. It was only when I was reading a book by Richard Oppenlander that I saw the statement that methane is 72 times as powerful as carbon dioxide over a 20 year period and checked this out with Prof James Renwick of Victoria University. Yes he said that is the figure that scientists are taking now.
I finally discovered on a Stats NZ site that we do calculate our methane contribution with a GWP of 25 and once again questioned the climate science professor. He answered,
“Yes a GWP of 25 sounds right as they’ll be using GWP100. That’s still the standard under the UNFCCC so is how we are required to report emissions (as I understand things), even though the science has clearly moved on to the two baskets approach. ”
But then I asked him if I was right to say the percentage contributed by agriculture would rise if methane GWP was 72, and he said no it would fall. So I was wrong, the headline above is misleading now and I will change it.