I have just received a letter from Tim Groser, Minister Responsible for Climate Change Negotiations in response to a letter I wrote on the 12th July stating my concerns about the treatment of livestock emissions of methane in international agreements.
I quoted concerns about the use of the global warming potential (GWP) metric to calculate the carbon dioxide equivalents that livestock emissions are quantified in and the fact that the NZ ETS was based on values set by the GWP metric despite the widespread recognition that it is flawed.
The UN FCCC and the IPCC set up a working group to find a metric that was better. They can’t of course because the whole idea of having one unit (a carbon dioxide equivalent) to quantify all the different greenhouse gases is dumb. No metric will be able to fix the problem they have getting a fair value for these carbon dioxide equivalents.
The problem is this and I will use a bath to describe it.
You have a bath of water, it is a certain temperature. Now if you take a litre of water out of that bath and boil it and then put it back in, how much does it increase the temperature of the bath? The answer depends on over how long you measure it.
Same as methane the global warming effect depends on over what time frame you measure it. Under Kyoto it is 100 years and so the extra warming that occurs is averaged out over 100 years.
Back to the bath, if it was say 100 minutes the temperature increase would be the average increase over that time. So just as the methane is all gone after 8 years the effect of it is averaged over 100 years. The boiling water will be back to room temperature after 8 minutes but the increase is averaged over 100 minutes,
So the system of CO2equivalents and GWP’s is this. The effect of the emission of methane when averaged over 100 years is compared to the effect of an emission of CO2.
Back to the bath, 1 litre is taken out, boiled and poured back in. The temperature increase averaged out over 100 minutes is the same say of adding 21 litres of warm water.
So the 1litre of boiling water is given a value of 21 Warm Water Equivalents. As far as everybody is concerned the effect on the bath is the same whether you take a litre out and boil it and pour it back in or you take 21 litres of warm water from another source and add it to the bath.
Two problems, you and I both know that under the first scenario the bath level remains the same and under the second scenario the bath water level increases; so they are not the same.
And secondly the value of the warm water equivalents and the carbon dioxide equivalents depends totally on the time it is averaged over. If the bath temperature was averaged out over 200 minutes the Warm Water equivalent of the 1 litre of boiling water would only be 10 litres. Methane has a GWP of 21 over 100 years so an emission of a tonne of methane is equal to 21 tonnes of CO2. But methane has a GWP of 6 over 500 years so one tonne of methane is equivalent to 6 tonnes of CO2.
So whether one tonne of methane produces 21 tonnes of CO2equivalent or 6 tonnes of CO2equivalent depends entirely on the time horizon. NZ could get rid of 25 percent of our emissions by using a 500 year time horizon.
So that is the issue, the GWP of methane varies widely on what time horizon you use. A short one is biased against methane a long one is biased in favour, there is no sweet spot, no one time horizon that is just right for every gas, so that is why they want to replace GWP’s.
If I did not explain it too well all you have to remember is that the Govt says that when you take a litre of water out of the bath and boil it and add it back in that it is exactly the same as adding 21 litres of warm water to the bath from another source. And of course it is not.
Tim Groser is no fool he must know that under one scenario the bath is filling up and under the other the water level is constant, and that current Govt policy is based on the belief that the bath is filling up under both scenarios and is wrong.
He says this which is hopeful although lacking detail.
“NZ remains committed to meeting its international climate change obligations and advocates for an appropriate approach to agricultural emissions in the next agreement. The metrics applied to value the emissions from agriculture is one part of that approach”
Does this mean he is saying that the current approach is not appropriate?
Tim Groser is smart and has some integrity and now that he knows there is a problem with the way methane is treated he has realised that the current approach is not appropriate we can put the acid on him not to accept any new treaties that do not have an appropriate response to agricultural emissions . Just have to find out what he has in mind.