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The methane debate is more about politics, policy and value judgements than it is about science

Rural News / opinion
The methane debate is more about politics, policy and value judgements than it is about science
methane CH4 insults

In my previous article, I explained how there is much controversy about how methane should be compared to carbon dioxide in terms of global warming. The problem arises because methane is a powerful greenhouse gas but it lasts only a short time in the atmosphere. In contrast, carbon dioxide is a weak greenhouse gas but it lasts much longer. Also, there is a lot more carbon dioxide than methane released into the atmosphere.

Big problems arise when methane is shoe-horned into carbon dioxide equivalence. Here I will explain some of the problems.

First, many people will be surprised that this issue of carbon-dioxide equivalence and the associated controversy is not really about the science. Scientists understand the nonsense of trying to estimate how many apples it takes to equate to one orange, with the answer depending totally on the chosen measures. Similarly, scientists understand that methane has a totally different emission profile than carbon dioxide and there is no simple equivalence measure.

However, the general public together with policy makers and politicians like to keep things simple. They want to be able to add the two together regardless of the problems and flawed thinking this creates.

The internationally accepted way for reporting emissions back to the UNFCCC, which is where climate-change policy issues are decided, is to think of carbon dioxide as the big brother and methane as the little brother. Little brother has to fit in with big brother. Accordingly, methane is typically converted to units of carbon dioxide equivalence (CO2e) on a 100-year timeframe of global warming, with this denoted as the GWP100 effect.

In doing the calculations, the methodology looks forwards rather than backwards. It doesn’t matter what emissions might have occurred in the past. The only question being answered is how much warming over the next 100 years will be caused by the new emissions.

Given that specific question, and within the current limits of scientific knowledge, the GP100 metric gives correct answers. If you want another answer, then you also have to change the question.

When Government officials report that agriculture makes up almost half of New Zealand’s emissions, this is based on this 100-year assumption, although that caveat is almost always lost in media reporting. Similarly, if agriculture were to enter the Emission Trading Scheme as currently structured, then it would be using the GWP100 equivalence assumption that underpins that system.

I will use two examples to illustrate the importance of this assumption.

Some people are concerned about what will happen to the Greenland and Antarctic glaciers. If these glaciers melt, it will be over a period of many hundreds and possibly thousands of years. If they do melt, sea levels will rise many metres and mega-cities across the world will be drowned.  

If this occurs as a consequence of greenhouse gases, then it will be almost totally due to carbon dioxide that is piling up in the atmosphere. This is because much of the carbon dioxide released today will still be in the atmosphere in another 500 years. In contrast, the methane that is released in the next 50 years will all be gone, and hence is essentially irrelevant to that long-term situation.

The second example relates to a current focus on short-term temperatures with 2050 being a particular focus. We read continually in the media about the so-called challenge of keeping the accumulated global increase in temperature to less than 1.5 degrees C compared to pre-industrial 1850.

In a scientific framework, there is nothing special about 2050. But society likes targets that can be enunciated in simple terms. This 2050 target, linked to a pre-industrial 1850 baseline, is what climate-science politicians and lobbyists are focusing on. This is despite the pre-1950 component of the change almost certainly being largely natural and unrelated to human activities.

Given this target, combined with the scientific fact that it is impossible to reduce the ongoing temperature effects of past emissions of carbon dioxide, it makes sense to place significant emphasis on reducing global methane emissions. It could indeed be an important way to influence temperatures in 2050, albeit by in all likelihood less than 0.1 degree Centigrade at that time, even if undertaken globally.

The key take-home from these examples is that just like apples do not have an orange equivalence, so too it is important to not conflate issues of short-term versus long-term greenhouse gases.  There is no simple overarching metric for comparison.

Many and probably most climate scientists would agree with the above paragraph about not conflating short and long-life greenhouse gases. But alas, many politicians and lobbyists have no understanding.  

Accordingly, some climate scientists have stepped forward from analysing the climate itself to try and find alternative metrics that can be used in the policy framework where politicians and lobbyists work.

In understanding these alternative methane metrics, I often refer to the invisible methane cloud sourced from New Zealand’s pastoral animals. It is the current size of this invisible cloud that determines the current temperature effects of New Zealand’s historical pastoral emissions.

Think of this atmospheric cloud as being the atmospheric equivalent of a bath-tub effect with a tap running and the plug partly removed. Water flows in and water flows out. The stock of water in the bath will depend on how fast the taps is running and how fast the water is leaving down the plug hole.

With methane, scientists know that the flow of methane into the atmosphere from New Zealand ruminant animals is close to what it was 30 years ago.  As a consequence, and linked to the scientific knowledge that about eight percent of methane molecules decompose each year, an approximate balance in the atmospheric ‘bath tub’ has been reached and the atmospheric cloud of NZ pastoral-sourced methane is close to stable. Hence, this argument goes, New Zealand’s agriculturally-sourced methane is contributing to further global warming in a minimal way.

In contrast, with carbon dioxide only a small amount of carbon dioxide leaks out through the plug hole and the stock of carbon dioxide in the atmosphere keeps increasing each year. 

This insight, variously stated, underpins the GWP-star metric, written GWP*, which some people are now promoting vociferously. Whereas GWP100 looks forward at the effect of this year’s emissions, the GWP* metric focuses on the changes in emissions that have occurred compared to a historical period and hence, in relation to methane, on the change in size of the atmospheric-warming cloud.

The argument then goes that because the NZ-sourced atmospheric methane cloud is essentially stable, New Zealand farmers should not be charged for doing what they, or more particularly their animals, have been doing for a very long time.

Recall that earlier in this article I said that GWP100 metric provides an accurate measure of the 100-year warming effect of current emissions, with this effect being measured relative to if those emissions did not occur. In contrast, the GWP* metric answers a different question, which is whether or not the atmospheric methane cloud is increasing. Each is correct for the question that is answered.

Many people in NZ agriculture are very keen on GWP*. This is for the obvious reason that it leads towards a conclusion that any methane charges incurred by NZ agriculture should be minor.  

However, the GWP* metric gives a very different answer in situations where the atmospheric cloud is increasing from new emitting activities.  Accordingly, using this as a basis for emission charging leads to new emitters being charged heavily.

The principle of using past emissions to justify ongoing emissions is called ‘grandfathering’. It is the reverse of a key principle within the Paris Agreement that developed countries with current high emissions must carry the main burden of emission reduction.

Here, I will give just one of many examples of grandfathering effects.

Some eight years ago, I led an MFAT-funded dairy-development design team to Colombia. Although close to the equator, Colombia includes temperate lands between 2000 and more than 3000 metres altitude that is highly suitable for dairying. Also, the Colombian Government sees dairying as a wonderful alternative to growing cocaine. However, if the GWP* metric were to be used to assess greenhouse gas effects, then Colombian dairy developments would show up badly because they generate new emissions.

So, given these ethical issues, how do we move forward here in NZ, where pastoral-sourced food underpins so much of our export-led economy?

Once again, in this article I have only scratched the surface of multiple complex issues. Although I think there is a path forward for both NZ agriculture and NZ society, that must be another article.

So, my final take-home message from this article is that climate-change issues are indeed complex. Also, much of the debate is ill-informed. It is like two warrior groups standing on either side of a wide gully shouting insults at each other, with each group accusing the other of being ignorant. Each warrior group can only hear itself.


*Keith Woodford was Professor of Farm Management and Agribusiness at Lincoln University for 15 years through to 2015. He is now Managing Director at AgriFood Systems Ltd. He can be contacted at kbwoodford@gmail.com  Previous articles can be found at https://keithwoodford.wordpress.com.

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33 Comments

This is despite the pre-1950 component of the change almost certainly being largely natural and unrelated to human activities.

Keith, isn't that just the climate part of it though? Weren't the oceans were soaking up the extra heat/CO2 to start with...?

(and great article, thanks)

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actually this graph explains why things really took off about 1950

https://ourworldindata.org/grapher/global-energy-substitution?country=~OWID_WRL

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The graph linked does not explain why warming started after 1850 - at rates similar to today but with only a fraction of anthro CO2.

"Our reconstruction, which agrees with other estimates for the well-observed period, demonstrates that the ocean absorbed as much heat during 1921–1946 as during 1990–2015."

https://www.pnas.org/doi/10.1073/pnas.1808838115

"Temperature data for the period 1860-1880 are more uncertain, because of sparser coverage, than for later periods in the 20th Century. The 1860-1880 period is also only 21 years in length. As for the two periods 1910-40 and 1975-1998 the warming rates are not statistically significantly different.

1860-1880  0.16 degrees/decade

1910-1940  0.15

1975-1998  0.16

1975-2009  0.16

UAH Satellite era 1979 - present  0.13

http://news.bbc.co.uk/1/hi/8511670.stm

 

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I think False economies is pointing to the lift in oil consumption since the 1950's. Coinciding with the Eisenhower highway construction program , ex servicemen been given ex army trucks to start freight service , and the boom in private motorcars. 

not particularily picking on the USA ,although it did lead to them using 80% of the worlds oil production by 1970. Other new world developed countries followed suit.  

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Why not just measure the total area under the curve for both CO2 and CH4 over each's E[life expectancy in the atmosphere]? That would surely be better than a measure which massively distorts the value ascribable to methane and be a lot closer to equivelance. 

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buyandhodl,
Area under the curve is precisely how the GWP100 equivalence is calculated - but using a 100 year time period for each gas.
Life expectancy is a complex measure in itself. The quoted 'average residence time' is the period when half the warming has occurred. 
This is a different concept than 'half life'.  
For a first order decay function (i.e., where decay in period 't' is a fixed proportion of the gas in the atmosphere at the start of  period 't') then the half life is the average residence time divided by the square root of 2 (i.e. divided by 1.414).

We know the decay function for methane with reasonable accuracy (about 8% per annum) but the decay function for carbon dioxide is complex and with big uncertainties as to whether the residence time is hundreds or thousands of years.

But putting those uncertainties aside, we know that the decay functions are indeed very different, and hence there is an important underlying assumption when comparing short and long-life residence times that is important:
1) the Year 1 warming should be given the same weighting as the year 100 warming - in economists' language there is zero discount rate for the first 100 years.
2) Years 101 and every year thereafter do not matter at all - in economists' language we shift from zero to 100% discounting at that point.

This assumption becomes important when we are comparing short and long-life gases.

Because NZ produces large amounts of pastoral products from ruminant animals, the profile of short and long-life gases is very different to almost all other countries, excluding Uruguay and to a lesser extent the Republic of Ireland.

If we were to use a residence time of 11.8 years for methane (the estimate in the IPCC6 report) and if we used a residence time of 100 years for CO2  then the CO2 equivalence figure for methane would drop from approximately 30 under GWP100 to approximately 15.

KeithW

 

 

 

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The other complexity is that when looking at the complete system, biological methane has a different impact to fossil methane.

Fossil methane is underground carbon being brought to the surface, biological methane is existing airborne carbon temporarily changing form.

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This is taken into account. The biogenic methane has  an equivalence figure one unit less than for fossil methane.
KeithW

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Good article Keith - and completely agree on the 'warriors shouting at each other' point.

I am equally frustrated with both the villification of agriculture (and farmers in particular) and the view that shaving a few per cent of our methane emissions will see us through the next decade. We need to get into a more meaningful conversation about how we support our economy and the actors within it to a more sustainable economic model.

On comparing CH4 and CO2 metrics - I found this article really useful as it compares a very wide range of different models and approaches.

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Jfoe
I agree that article you linked to is useful.
It reinforces the perspective that there are multiple metrics that can be used and none of them provide a comprehensive answer.
Those problems arise from the fundamental flaw in the concept of carbon dioxide equivalence.
KeithW

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Great article Keith! I find it hard to seperate the science from the politics when it comes to CC issues.
Great to read something from a balanced scientific point of view. As a farmer I hear alot about our methane “production”, how much we’re to pay, and what the policy etc will look like but not much about the why. Much appreciated.

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Thanks Normac.
KeithW

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So, given these ethical issues, how do we move forward here in NZ, where pastoral-sourced food underpins so much of our export-led economy?

This was my suggestion back in 2019 when the Zero Carbon Bill was going through the legislative process:

An alternate, and perhaps less punitive approach, to lowering our GHG emissions is called climate pragmatism.  It has three regulatory objectives:

  • accelerate energy innovation,
  • build resilience to extreme weather, and
  • pursue no regrets pollution reduction measures.

Pursuing water quality improvement in New Zealand is one such no regrets pollution reduction measure, that will co-benefit our GHG emissions trajectory.  No one will regret having fewer algal blooms and a restoration of our clean green international reputation.

 

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Kate
I agree that more could be done to reduce nitrate leaching. And that is where the composting mootels and composting shelters can be transformational. I find it ironic that most of the progress to date is by farmers rather than through formal R&D, although I am hoping to change that.  Those technologies are also likely to be have co-benefits in relation to nitrous oxide emissions but we need some R&D to actually prove that. However, methane issues largely sit separate from nitrate leaching and nitrous oxide emissions, and need different approaches.
KeithW

 

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Yes, like you, I think the mootels and shelters could be transformational.  Just think if all the R&D monies that have been put into trying to lower our methane emissions had instead been spent on those initiatives instead?

And sure, methane needs different approaches (to what is essentially water/groundwater pollution control) but even if such different approaches in NZ are wildly successful - as you point out in the stats above, CO2 accumulation is the exponentially bigger planetary problem. 

We (NZ) needed a NZ-unique approach to CC, but instead we modelled our legislation on popular opinion and the UK approach. Even the Commissioner can't manage to write an honest budget to deal with the silly time-bound targets. When was the last time any Government here met a time-bound target.  I can't think of one in my lifetime! 

 

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I share JFoe's frustration upthread.

Imagine if the construction industry in NZ is to decline sharply. There would be a ready source of internal labour the government could tap into to getting up and running with building mootels starting on the most vulnerable soils and catchments (if that is the only impediment to dairying for example being economically viable going forwards). I'd be quite open to seeing some tax dollars going towards this where the environment gets a win and as a country we support industry that pulls some money in.

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I agree - I'd be more than happy for the government to subsidise the building of these in those vulnerable catchments.  In the article I linked to above - I discussed the concept of Payment for Ecosystem Services (PES).  That's what our CC legislation where agriculture should have focused on - environmental improvements that benefit industry as well.  Win-win all around.

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We had another 30mm of rain last night to go with the other 500mm for the month. My cows were still on the paddocks and it's so bloody frustrating, we should be past this. I've always worked hard to not make a mess and destroy soil structure for 30 odd years as it's a basic. But after that long we should be past that and as Kate stated we could win many ways moving forward 

Worst part is the next door property was milking goats with two huge covered areas ideal for barns. The goats are gone after only three years so the sheds are sitting there empty. If only I could get things moving in the right direct.

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See what's happening in the Netherlands farmers getting red hot about politics and misleading people on basically every front. I reckon Governments need to push inflation as hard as they can to cover all their uncontrolled spending. We go that way too. That's what you get with putting people in power that go to school to bend everything what's straight.

 

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I posted some  for KW in the Rod Carr article stuff. This is probably the more approriate place which I have just read.

In one of my replies a week or three ago on biological methane quantities I made reference to the biological  methane quantities proposed by the CCC that this figure needs scrutiny. In the last week I came across an article referencing a professor  Dr. Wilhelm Windisch of the Technical University of Munich published in 1991. He maintains the effect of methane is overstated by 3 to 4 times. I leave it to someone like KW to analyse. Full of heavy duty agricultural cattle stuff. Beyond me.

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Declining oil reserves are a far greater problem than "climate change".  The irony is that methane will probably play a large role in both transitioning us from drilled oil, and storing intermittent energy from renewables.

The technology of direct conversion of methane to electricity is already commercialised with numerous megawatt plants in operation all around the world (see bloom energy).  It's also possible to convert electrochemically generated hydrogen and carbon dioxide to methane for energy storage.

It would be unfortunate if the "climate change" agenda hampered or interfered with the worlds future energy economy.     

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"In a scientific framework, there is nothing special about 2050. But society likes targets that can be enunciated in simple terms. This 2050 target, linked to a pre-industrial 1850 baseline, is what climate-science politicians and lobbyists are focusing on."

Nothing special about 2050 but in a scientific framework there is something special about 1850 - it was the end of the Little Ice Age. A great time to start a chicken little runaway global warming narrative.

"The Little Ice Age was a period of wide-spread cooling from around 1300 to around 1850 CE when average global temperatures dropped by as much as 2°C (3.6°F), particularly in Europe and North America." So with ~1.1 C warming since we are getting back to normal again! Our kumara growing range is only getting back to where it was in the Polynesian Warm period.

The Making of the Māori Middle Ages

"Taking these data as representative, it can be suggested that kumara cultivation in the
early period had reached as far south as the Kaikoura coast, and possibly to about Banks
Peninsula (about 430S). By the late sixteenth century it no longer existed south of about latitude
410S (Tasman Bay—Kapiti Coast—Castlepoint). This represents a retreat northward of around
150 km from Kaikoura during the middle phase. Furthermore, just as gardening was relatively
scarce between its absolute southern limit and Tasman Bay, so it is probable that by the
sixteenth century gardening north of the new southern limit was marginal up to southern
Hawkes Bay and South Taranaki (Figure 3).

Climate change seems a plausible explanation for the retreat of gardening, if not
necessarily the only one. Kumara will not produce in soil temperatures of less than 15 C for
five consecutive months, conditions barely met in central New Zealand even today. A
northward retreat of 150 km on temperature grounds implies a decline in mean annual
temperature at sea level of about 1 C. Looking at evidence of changing temperatures over the
last millennium, it is apparent that an early period, estimated as 0.3-0.5 C warmer on average
than the twentieth century, was followed by a cold period of similar deviation below the
twentieth century average. This is recorded in various sources."

229705163.pdf (core.ac.uk)

 

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Profile,
Your quote and reference to Emeritus Professor Atholl Anderson's paper is insightful.   Professor Anderson is a renowned NZ archeologist.

I encourage others to read it and here is the link again.

https://core.ac.uk/download/pdf/229705163.pdf

What the paper demonstrates is how the Little Ice Age had a very large impact on the life of Maori in New Zealand in those pre European times.

For those who wish to understand something of the power of the Little ice Age in NZ, then a walk up the Hooker Valley in Mt Cook National Park along a very nice walking trail will also demonstrate that power, albeit only to those who know what they are looking at.   

At the start  of the trail, lie the large moraine walls that hold the Mueller lake in place, and which were all deposited in the Little Ice Age, just a few hundred years ago. Similarly, further up the trail the moraine walls that hold Hooker Lake in Place were deposited in the Little Ice Age at the same time. And it is the same story in the Tasman Valley - the next valley over to the north.

Fifty years ago when I was working as an alpine guide at Mt Cook and climbing among the high peaks those lakes did not exist. The moraine barriers placed in the Little Ice Age were there, but the ice behind was still to melt allowing the lakes themselves to form.

The advancing ice of the Little Ice Age, all in the last 800 years, was the biggest advance of the last 20,000 years since the glaciers extended down to the bottom of Lakes Pukaki, Tekapo and Ohau. Life was not easy during the Little ice Age.

KeithW

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profile,

"A great time to start a chicken little runaway global warming narrative".  I suggest that you consult the World Glacier Monitoring Service for up to date information on glacier shrinkage globally. You might also consult the Chapter on Glaciers and Climate by Salinger and Chinn in Living In A Warmer World.

You are quite correct to point to the end of the Little Ice Age as a time when we saw glacier retreat. For example, the naturalist John Muir visited Alaska in the 1850s and again some 30 years later and found significant retreat in a number of them.

However, when you use this to then make the statement above, i am afraid that all you actually achieve is to make your confirmation bias all the more obvious. I can recommend another book to you; The Intelligence Trap by David Robson. You seem to fit the mould perfectly.

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"To find the carbon dioxide emissions that would actually have a similar impact on global temperature as methane emissions, you need to multiply those methane emissions by seven (not 28), and add the rate of change of methane emissions (measured in tonnes of methane per year per year), multiplied by 2100.  

Academics can quibble (it’s what we do best) about the exact factors, but the fact that this formula is vastly more accurate than the traditional accounting rule is indisputable. 

...Even more strikingly, if an individual herd’s methane emissions are falling by one third of one percent per year (that’s 7/2100, so the two terms cancel out) – which the farmers I met seemed confident could be achieved with a combination of good husbandry, feed additives and perhaps vaccines in the longer term – then that herd is no longer adding to global warming. Yet if methane were included in a European-style Emission Trading System (ETS), the owner of the herd would have to pay just as if it was. "

https://www.nature.com/articles/s41612-018-0026-8

https://www.newsroom.co.nz/@ideasroom/2019/03/29/510792/a-climate-neutr…

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Keith,

In a report from Manaaki Whenua-Landcare Research policy brief no. 27 Nov '20; Rethinking New Zealand's food security in times of disruption, it lists at-risk commodities such as wheat, maize, sugar, rice and coffee.

By how much do you think we could realistically increase our wheat production? Should we?

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Sugar, rice and coffee are definitely not options for local production.

Maize can be grown for grain in much of the country but demand is limited and there is no chance of being competitive on the international market.

Wheat could be grown meet all of NZ's demand for wheat. But the millers tend to prefer Australian wheat. Getting wheat from Canterbury to Auckland has a similar transport cost to getting Australian wheat to Auckland.

There is some debate as to the relative baking quality of NZ versus Australian wheat but this is not an issue for feed wheat. New Zealand farmers would soon grow more wheat if it were economic to do so.  NZ wheat would be hopelessly uneconomic on world markets - the NZ biophysical environment is not conducive to low cost grain production.

KeithW

 

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keith,

Thank you. What you say doesn't really surprise me, so here it seems like Riccardo's theory of comparative advantage still holds good. However, might it still be in our best long-term interests-greater resilience- to grow more wheat even if that required some level of subsidy?

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The Free Trade Agreement with Australia would almost certainly prevent it.
We depend heavily on that trade agreement.
KeithW

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Keith is there any research being done to determine how much carbon is being absorbed by soils and pasture in a nz farming system? I get animals realese methane but it didn't just magically get there. For them to be able to make methane then surely carbon has had to been absorbed by pasture/crops in the first place. 

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Yes, that research has been going on for  a long time.

Carbon accumulates in pasture over the first few years but then it stabilises. Most NZ soils are stable so it is not possible to claim sequestration.

Cultivation for crops - both grain and fodder crops -  is highly depletive of carbon.

Farming of peat soils - including pastures - is highly depletive.

American farmers have been mining their carbon through cropping for more than 100 years so this can be built up again with so-called regenerative farming practices. Bu that scope does not exist in NZ.

The greenhouse rate allocated to biogenic methane includes a credit for the fact that the carbon within methane has come from CO2 via photosynthesis and plant material. Fossil methane does not get that credit.

KeithW 

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Whatever happened to acid rain? That used to be cool. Nobody did much about it, but it has disappeared completely from the usual suspects' news sites.

I also thought our problem was CO2. How come Methane has leapt into prominence over the last couple of years? It was never a problem until just recently. 

Lastly, why has the famous photo of the Statue of Liberty a hundred years ago got the sea level at the exact height it was in this years photo?

All this stuff makes a lot of us very cynical about quasireligious faithbased opinions rammed down our throats as facts, as we all know something else will come along in a little while to keep everyone's attention spans going for another little while.

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https://www.youtube.com/watch?v=WIdWjqZsGgg. Science fixed it , at least in the west . 

Pretty sure New York has tides , just like us , so you could probably compare photos to "prove" whatever you want .

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