Livestock emissions continue to track downwards

Pastural farming Climate Research- by Robin Grieve 

27 April 2011 

Livestock emissions continue to track downwards, according to the just released New Zealand’s greenhouse gas inventory update for 2009.  I loathe giving these CO2equivalents any credibility as a unit by using them but that is how methane and nitrous oxide are reported in the NZ Inventory.

Methane produced from livestock when quantified in CO2equivalents was 32810.5Gg (Gg =1000 tonnes) down from 32866.9Gg in 2008.This has been attributed to less nitrogen fertiliser being used and a drop in agricultural output.

The reduction in emissions due to less nitrous oxide produced because less N fert was applied is very small. This is because N fert does not produce much N2O directly. The only direct N2O emissions from nitrogenous fertiliser occur when NH4 is lost to the atmosphere just after spreading by volatilisation of which some is then returned to the soil if it rains soon after. Most of this is used to grow grass but the small amount that is not is then lost into a waterway and escapes to the sea and is then converted to N2O and returned to the atmosphere. It is a tiny percentage of a tiny percentage.

The trend of reducing greenhouse gas emissions from livestock which has been happening since 2005-6 is bad news not good news because most of it is caused by declining productivity which will ultimately mean declining prosperity. I am sure the greenies and the global warmers will be delighted at the decline in emissions because prosperity is not terribly important to them.

Enteric methane produced in 2009 when expressed in these CO2e’s was 22506Gg down from 22657.5Gg in 2008.

Emissions of enteric methane are lower than they were 10 years ago having tracked upwards until declining over the last 4 years. Enteric methane produced in 2009 is up only 2.9% on 1990 level. More importantly it is lower than it has been since 1999 which means all the enteric methane produced in 2009 is not even replacing the oxidising methane produced a decade before. Methane needs a steady state of production to replenish continuously depleting stocks; the 2009 production was too low to do that, methane levels in the atmosphere will have dropped as a result. Livestock emissions are responsible therefore for global cooling not warming.

These figures show there is no justification for spending millions of dollars on mitigation research. The taxpayers and farmers are being ripped off.  There is no justification in any case for charging for emissions of methane because they have no impact on the atmospheric concentration of any greenhouse gas.

To put things in perspective enteric methane has increased 2.9% from 1990 to 2009. Compare this to NZ’s emissions from road transport which have increased 66.2% and electricity generation emissions up 72.1%

Also NZ’s total emissions have increased 19.4% since 1990 compared to the USA which has had an increase of only 7.3% (isn’t it us who is supposed to be clean and green?)

The other change noted in the NZ Inventory review is a reduction in N2O estimated to be produced from animal waste. Previously dung and urine were lumped into one calculation to guess the N2O produced, but after much research and no doubt much money scientists have discovered that urine produces more nitrous oxide than dung. (Who’d have thought that!)  This means previously agricultural emissions were overstated by about 1500Gg or 5%.

So now they have an emission factor for dung and an emission factor for urine. The result is an overall lowering of the nitrous oxide produced from animal waste. Total emissions for 1990 have been recalculated downward as have those for 2009 emissions using these new emission factors.

In other words the 1990 figure when released was bullshit!

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