Keith Woodford exposes another difficult issue that has to be understood and resolved in relation to New Zealand’s proposed Zero Carbon Bill

Keith Woodford exposes another difficult issue that has to be understood and resolved in relation to New Zealand’s proposed Zero Carbon Bill

This is the second of a series of articles from Keith Woodford discussing some of the difficult issues that have to be understood and resolved in relation to New Zealand’s proposed Zero Carbon Bill. The first article is here.

For many years, we have been told that agriculture contributes approximately half of New Zealand’s greenhouse gases. This supposed fact has been seared into the minds of every New Zealander who reads newspapers, listens to radio or watches television.

What very few people understand is that this supposedly simple fact is based on a dodgy assumption that the effects of methane can somehow be turned into equivalent units of carbon dioxide.

I liken it to the silly statement that if you have one carrot and one banana then you have three banana equivalents. The problem with such a nonsensical statement is that carrots have a totally different nutritional profile to bananas in terms of fat, starch, sugars, fibre and various micro nutrients.

Everyone can therefore quickly see that making a global assessment about how many carrots equals one banana is nonsense. It all depends on what nutritional component you are talking about.

Similarly, the number of units of carbon dioxide that is equivalent to one unit of methane depends totally on the time horizon on which the comparison is made. One is a short-lived gas and the other is a long-lived gas.  This means that a short time horizon captures all of the effects of the short-lived methane but only a small proportion of the long-lived carbon dioxide.

When methane and carbon dioxide are bundled up into units of carbon oxide equivalents, it is conventional to use a 100-year time horizon. The relative number for each gas is given as a GWP100 index figure, with GWP being shorthand for ‘global warming potential’.

By definition, the GWP100 for carbon dioxide is 1.  The relative value for methane, according to the latest estimate of the IPCC is 28, although all accept that there is uncertainty around the precise number. Back in 1995 it was supposedly 21, by 2007 it was believed to be 25, and there are some who believe a more appropriate figure might be 34.  It seems that the New Zealand official national inventory is currently calculated using a figure of 25.

This illustrates that although there is general agreement among scientists that methane has strong global warming potential, the specific value is far from settled science.

The key point for the current discussion, however, relates to the choice of 100 years as the relevant time horizon. This is not a matter of science but a value judgement. 

For those who do not care about what happens to the world beyond 100 years, then a GWP100 would be reasonable. For those who believe it is important that the world survives beyond 100 years then a longer time horizon is appropriate.

In its early reports, the IPCC provided GWP500 estimates for the three key gases of carbon dioxide, nitrous oxide and methane. By definition, the values for carbon dioxide must still be ‘1’ given that carbon dioxide is the reference gas. However, the number of heating units captured within this reference value now increases by a factor of more than three compared to the GWP100 figure.

Accordingly, the GWP500 for short-lived methane will drop by a factor of more than three compared to the GWP100, because all of methane’s warming is already captured in that GWP100.  

In 1995, the GWP500 estimate for methane was 6.5 units of CO2 equivalent, in 2001 the estimate rose to 7.0, and in 2007 to 7.6. Thereafter no new values have been provided, a point I will return to later.

The key take-away message from what may seem a complex and thereby confusing story, is that with a GWP of 500 years, the relative importance of methane as a global warming gas compared to carbon dioxide declines by a factor of more than three.  And so agricultural greenhouse gases, and methane in particular, would be considered of much less critical importance if we were using GWP500.

So, next time someone says that agriculture contributes close to half New Zealand’s greenhouse gases, ask them what time horizon they are using. If the response is 100 years, then ask the reason why they have chosen 100 years. The correct answer is actually a non-answer that ‘it is the convention’.

However, the more likely response to the first question will be a blank stare. This is because very few people appreciate the hidden assumption about time horizons in the current mantra.

I first wrote about this issue way back in 2006 in the journal Primary Industry Management. However, that article did not reach the mainstream media. Also, I was more than a little pre-occupied by many other things at that time. And so, I let the matter rest.

Coming back to the issue of why there have been no updated figures for the methane GWP 500, the answer is that it is because of increasing uncertainties around the atmospheric life of carbon dioxide. Quite simply, we know that both carbon dioxide and methane are greenhouse gases, but we don’t have the science yet to make good comparisons over long time horizons.

Accordingly, for those of us who do believe that saving the planet is indeed important beyond time horizons of 100 years, the whole concept of carbon dioxide equivalents should be considered as simplistic nonsense.

Putting the issue of time horizons aside, there is another key reason why methane needs to be considered separately. It relates to the difference between gross and net emissions.

In the case of New Zealand’s ruminant-sourced methane, the gross emissions have been close to static for the last 30 years.  This is documented in the national inventory of greenhouse gas emissions and is not controversial.

Given that the average resident time of methane is believed to be around 12.4 years, we have now reached a point where the atmospheric cloud of ruminant-sourced methane is no longer growing. 

What this means is that net emissions of ruminant-sourced methane into the atmosphere are effectively zero.  The carbon cycle is working nicely with a new balance having been reached. To the extent that global levels of methane are still increasing, they are from sources other than New Zealand’s ruminants.

This stability of the ruminant-sourced atmospheric methane cloud contrasts greatly to the carbon-dioxide cloud. Both in New Zealand and globally, the levels of carbon dioxide continue to increase. Even if those emissions were to decline, then the atmospheric cloud would continue to increase because carbon dioxide lives there for hundreds of years.

New Zealand’s aim is to get to zero net emissions of carbon dioxide by 2050. Methane from ruminants is already at that point!

As a concluding comment, I emphasise that none of the arguments in this article say that methane is unimportant as a greenhouse gas. Nor is any claim made as to the importance or otherwise of global warming. What is said, however, is that working out how to treat methane emissions fairly in any regulatory framework requires an understanding of its unique characteristics.  There is lots of work to be done.

*Keith Woodford was Professor of Farm Management and Agribusiness at Lincoln University for 15 years through to 2015. He is now Principal Consultant at AgriFood Systems Ltd. His articles are archived at You can contact him directly here.

We welcome your help to improve our coverage of this issue. Any examples or experiences to relate? Any links to other news, data or research to shed more light on this? Any insight or views on what might happen next or what should happen next? Any errors to correct?

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Atmospheric methane has nearly stabilised - for a whole decade 1998-2008 it didn't increase, during which time global ruminant numbers increased by an estimated 10%. Rather contradicts the significance of ruminant emissions. Methane has gone up again since 2008 but what is the cause? Fracking? Greater plant growth? Increased rice production (notably rice production dipped during that paused decade, but has risen again since)

You are correct that atmospheric methane from all sources stabilised for a period of ten years around the turn of the century and in the first few years thereafter, but is now increasing again. The reasons why it stabilised for that period are not understood. That in itself demonstrates how we are not dealing with settled science. One of the few things we can say with confidence is that the latest increase in atmospheric methane is not due to New Zealand's ruminant emissions. We know with great confidence that these have not been increasing.

Not understood, not settled, but let's tax it anyway. "Atmospheric methane (CH4) mixing ratios exhibited a plateau between 1995 and 2006 and have subsequently been increasing. While there are a number of competing explanations for the temporal evolution of this greenhouse gas... ...The seasonal-cycle amplitude and secular trends in observed forcing are influenced by a corresponding seasonal cycle and trend in atmospheric CH4. However, we find that we must account for the overlapping absorption effects of atmospheric water vapour (H2O) and CH4 to explain the observations fully. Thus, the determination of CH4 radiative forcing requires accurate observations of both the spatiotemporal distribution of CH4 and the vertically resolved trends in H2O."

This is a fun site that points out that methane has twice the preindustrial levels.
They attribute that to eating so I guess we should all eat less.
Those so inclined could eat less meat.

The skeptical science site you refer to (actually John Cook's site that defines itself as 'skeptical about climate skepticism' - and very much a believer in climate warming) does need some updating in relation to methane. However, a key message from that site which remains valid is that although methane is clearly relevant to global warming concerns, it can also become a distraction from the big elephant in the room (for those who believe climate warming to be an existential threat) which is carbon dioxide. Note that in this conversation here (and more broadly in my article) I remain agnostic as to whether or not it is an existential threat. That is a debate for another day. My key point is that regardless of one's perspective on global warming, the focus on ruminant-sourced methane as a villain of some importance is largely a distraction from the big picture. However, we in New Zealand, because of our unique emission profile, cannot afford to sit back and ignore the distraction. If we do, we will be the little mouse, or perhaps huhu grub, that gets squashed under-foot.

I like that bit...

"New Zealand’s aim is to get to zero net emissions of carbon dioxide by 2050. Methane from ruminants is already at that point!"

That is not AT ALL what "zero net emissions" means in this context. Frankly I'm kind of embarrassed that you even wrote this, given the otherwise high quality of this article.

Zero net emissions means that for every 1 ton of CO2 emitted to the atmosphere by humans, another 1 ton is sequestered by humans. It is irrelevant what other sinks and sequestration of CO2 is happening naturally - the point is that humans must directly offset the emissions that they themselves made, not leave it up to nature to do. The whole point of the carbon cycle is that there is an atmospheric concentration of carbon that nature can comfortably recycle and sequester, but that humans have upset that cycle by emitting excess CO2 (and other gasses such as methane) into the atmosphere that the natural cycles cannot cope with, hence leading to a rising in global temperature that otherwise would not be happening.

If we are currently emitting 50 tons of methane each year from cows, and have been emitting 50 tons of methane from cows for the last 30 years, then the net emission each year is 50 tons. Not 0. For our net emission from cows to be 0, we would have to be emitting 50 tons and also directly sequestering 50 tons.

This, then, would result in a decrease in methane concentration in the atmosphere over time because instead of emitting net 50 tons each year, so that the total in the atmosphere was constant, we would instead be emitting net 0 tons each year, so that the total in the atmosphere will naturally reduce over time.

I am sorry that you are embarrassed.
A key point - which I think you in effect acknowledge - is that New Zealand's ruminant-sourced methane emissions are not leading to an increase in the atmospheric methane cloud. That part of the cloud has stabilised.
Yes, if New Zealand reduced its ruminant emissions substantially, thereby reducing the size of the ruminant-sourced component of the methane cloud, then that would help balance other emissions from other sources. In other words, one way of meeting overall targets is indeed to ask agriculture to 'carry the can' for other sectors. And where would that leave us, in 100 or 200 years, in relation to the real elephant in the room which is carbon dioxide?
Perhaps you have yet to work through the confounding that occurs when long-lived and short-lived gases are placed in the same basket?

"Perhaps you have yet to work through the confounding that occurs when long-lived and short-lived gases are placed in the same basket?"

I was simply refuting your completely erroneous claim that New Zealand has net-0 methane emissions today. We do not.

A key issue is that in regard to ruminant methane, nature does help us out, in that what domestic ruminants are adding and have added, is also being taken away by nature (back to carbon dioxide from where the methane came on average 12.4 years previously). So in net terms, the gains and losses do indeed net out to zero.
If you wish to ignore what nature is taking back out of the system then you will indeed have a net figure which equals the gross emissions figure. But that partial analysis of the system does not help us understand what is actually going on.
The problem with the so-called net emissions of carbon dioxide is that the offsetting system allows the anthropogenic emissions of the majority of people to be offset against trees that other people have planted. This offsetting system linked to a carbon price is considered to be economically efficient (and I don't argue with that). But the offset benefits are all credited to the first 30 years (for Pinus radiata) and the liabilities for subsequently using this land are transferred to future generations. This is illustrated by the fact that land that has high carbon liabilities attached to it has very little capital value.

"So in net terms, the gains and losses do indeed net out to zero."

Globally, yes, IF you are counting natural processes, I don't disagree.

For New Zealand's human-induced emissions, no. That's simply not what "net emissions" means, sorry.

If NZ's human-induced methane emissions were indeed net-0 as you claim(ed) them to be, then the global net emissions counting natural processes, would be negative. As you yourself have said, the global net emissions of methane gas are 0 / stable, not negative.

Talking about GWP100, GWP500 does beg some questions.
1) If our political time horizon is 3 years, should we just go for GWP3?
2) There is a "present value" of methane's warming effect and that is apparently 28% of total.
3) NZ contribution to that 28% is relatively generous.
4) The rapid effect on methane levels of reducing methane production makes this a target of preference.
So maybe NZ needs to focus more on methane, not less.

As a temperate climate Global warming appears to be mostly positive for NZ - equivalent of moving about 100km north for every 1°C of warming. That improves our climate, lifts our agricultural production, increased range of crops that can be grown, lowers production costsy. Most people in NZ would actually prefer to live in warmer climes - just see the vast shift in population to North over last few generations in NZ. All positives.
And before we hear complaints about sea level - be aware that it is only rising at 1-2mm/year around NZ, and has been for the last 100+ years, with higher rates in middle of 20th century (eg see dunedin data:, slow adaption is best and only answer to that.

Foyle - I agree a few degrees warmer sounds good to me. At the risk of being a denier ( similar to religion ) what gets me is the assumption that the current climate we have is the correct one ??
We must all agree that Mother Nature has had a varied history of temperature changes over millions of years so being convinced that we humans are really making a big difference is well - flaky, however changing our ways for the good of the planet earth seems a good idea. Knee jerk reactions to apparent climate crisis is at best foolish particularly if it penalising us unneccessarily.
Any sudden crisis that is pumped out into the media and rammed down the throats of kids in school is dangerous and cult like.
I know of teenagers that are fearful of their future that they will die before their time as the world is about to end, this is just control by fear modern day religious clap trap !
I am a forestry owner in a partnership, planted 1995 and we have sold 50% of our carbon credits 20,000 units at an average of $23.50/unit. Can anyone tell me how that has helped in any way other the swelling our pockets with cash we had no idea we would get when the forest was planted ??

Here is a very sensible video of common sense in a gigantic way -

A key question is 'whose target of preference'?
That may well be the case for urban New Zealand, particularly those who do not understand how pastoral agriculture underpins the export economy and hence their own lifestyles.
I have no problem with methane being part of the climate change debate - it is indeed a greenhouse gas.
But I do have problems when the debate is based on carrots being called banana equivalents.
As soon as short-lived and long-lived gases are bundled together then the debate gets horribly confounded.
And that is where the debate has been for the last few years.
Keith W

Our obsession with agriculture is recent history, just an easy way of earning a living by burning and pillaging.
Our soils aren’t suitable for grazing, as evidenced by the destruction of Nauru and now Morocco, lets take the pressure down and restore the Forest

The issue of phosphate (and hence the historic issue of Nauru and the current controversy with Morocco) is indeed relevant to issues of agricultural sustainability. Some day I may join that debate. The alternative of rock phosphate will be part of that debate.
In the meantime, I would love to know what the new foundations of the export economy might be?
Are you proposing that the grazing lands of the world should all be transformed to forest?
And if 'agriculture' has been an 'obsession', then perhaps there is a reason for that, linked to the basics of survival.

I’m supporting NZ pastures that require high levels of fertiliser being returned to less demanding uses, including forestry.
Of course it is already happening, 400,000 hectares from memory.
In the last 30 years the contribution of agriculture to nz fortunes, as a function of GDP, has halved and it will continue to decline to without any great difficulties.

It is important to recognise that the GDP of agriculture only includes the on-farm value-add. The value of all purchased inputs is deducted from the farm gate values, and there is no allowance of value-add post farm gate, including processing. It is a concept of agriculture that precedes the concept (way back in 1957) of agribusiness, or, as alternatively stated, a food system.
As such, it is greatly flawed but widespread notion that the 'contribution of agriculture to NZ fortunes' can be measured through so-called agriculture's contribution to GDP.
It is also relevant that cropping activities require a lot more fertiliser than does pastoralism as a consequence of many more nutrients being removed in the products thereof.
As for forestry, it is important to separate out conservation forestry on steep country from production forestry, including carbon farming, on more productive country.

It’s all true, but how are we going to explain that to the kids....

I'm not saying that GWP500 is not valid in the longer term, it is. But we are living in the short-term as some defunct economist once pointed out. So the preference is a temporal one based on what is possible soonish. The longer-term need to reduce CO2 (eg. for ocean acidification) does not go away but that is even harder. Physics doesn't care about our human concerns re fairness or lifestyle.

Mogador and Kate
It is important that we do not conflate short term action with short term thinking.
Rather, for those that are environmentally focused, the key question is what should be done now to reduce the long term risks.
If that is indeed the right question, then it is the long term GWP values that are important.
And that leads inevitably to placing the key focus on carbon dioxide (and nitrous oxide, although to a much lesser extent).
It also means still including methane within the debate, and also including the sub component thereof that comes from ruminants. But this needs to be done within the correct perspective as to their contribution to the long term implications for global warming.

I disagree with this:

Rather, for those that are environmentally focused, the key question is what should be done now to reduce the long term risks.

I do think of myself as environmentally focused and to me the issue is what should be done now to reduce the present day and near term risks. It is not as if we don't have urgent issues to address. But the longer out we legislate for the easier it is to avoid real/present day action. It is the problem with viewing things through what is called a 'weak sustainability' lens. That 'weak' lens being, we haven't got the technology to solve our known problems today (in order to carry on with the status quo), but we hope that someday in the future we will have that technology - so in the meantime let's carry on as per the present and plan for 100 - 500 years hence.

Kids aren't buying it and adults ought to stop peddling it.

To introduce the idea that having a long term focus is to argue for the status quo is to introduce a straw man.
At no point have I argued for a status quo.
As for today's children, I think their focus is indeed on the longer term, when we will be gone, but when their children, and their children's children, may still be around.
In the same way that, in relation to broader environmental issues, many would argue that one needs to 'think global but act local', in relation to global warming, if one believes that it is an existential threat, then one has to focus on when and how the risks might play out, and then act now.
If we use the wrong metrics (which focus on the short term) then we are aiming at the wrong target.
The irony of focusing on the wrong target is that it allows people (in ignorance) to put undue emphasis on what other people should do rather than on what they themselves can do.

Keith, you say To introduce the idea that having a long term focus is to argue for the status quo is to introduce a straw man.

I again, would disagree. But that aside, how do you argue against the status quo? In other words, what should we do today to make a difference next year, or even five years hence? My grandchildren are too young to understand any horizon beyond five years - and they want to know that in five years from now - things will be better.

So, what would you suggest we do this year to ensure that in five years time we can measure an improvement?

If people want to do something this year that will lead to an improvement (less CO2 in the air) within five years (and beyond) then they should stop flying, sell their car, use public transport and cycle. However, most people are insufficiently committed to 'the cause' to do that. They would prefer to make other people (such as farmers) make the drastic changes. My aim in this paper is to help people to understand the importance of the choice of metrics when society makes its choices.

I'm all for a shorter horizon given the longer out the timeframe, the less reliable the projection. And we do need to appreciate that the IPCC produces projections, not predictions.

For example, the NZCPS requires projections of SLR out to 100 years. I'd be far more in favor of a regulatory regime that projected out every 10 years up to 50 years, and revised regulatory rules every 10 years in accordance with actual/observed data/measurement.

Kate, this is what I've argued for as well. Effective SLR = Measured SLR at a lat/long point. So 5, 20, or 200km up or down the coast, Effective SLR is quite different. Poster child: Oaro village, where effective SLR = Measured SLR for the most part. But just 2km north, at Boat Harbour, Effective SLR = Measured SLR - 1500mm. Because the Kaikoura quake sequence lifted the entire block by 1500 - 2000mm in 2015. And at Marfell's Beach, 120km north again, it's Measured SLR - 4500mm. And so on.

It would be extremely simple, technically if not financially, to pop a measurement trig station every 10km up and down our coasts and log the effective SLR over time. Thus acquiring a solid measurement baseline against which to judge the actions needed to mitigate Effective SLR. Until then, the hue and cry over '1 metre SLR in 100 years' is just pop-sci.....which is headed for massive capital mis-allocation if taken seriously.

Could not agree with you more, waymad. I am very concerned about the current "call" for setting up a fund (like EQC) to deal with buying out/compensating private property for SLR risk/damage as projected out by 50-100 years, i.e., to compensate them for a policy of managed retreat. That is a matter between the private owners of property and their insurers - surely!!!!!!! Leave me - the average taxpayer, out of it!

There does appear to be some urgency in sorting out a fairer way of dealing with methane. The EU elections favoured the Greens and the nationalists, but as the nationalists are not part of the establishment, and undermined the non-Green segment that actually is part, you can bet the Greens are going to get a bigger say. Against this backdrop, it appears "flygskam" (flight shame) is actually a thing and is the prime suspect in reducing Swedish air travel by 5%. Although an embryonic movement, this does not bode well for NZ's tourism industry.
We are likely to face an economic reckoning that we can't control, over our contribution to verifiable carbon emissions (ie air travel), so it would be prudent to limit the damage to our economy by coming down too hard on the much hazier area of agricultural emissions.

Maybe it's a good thing that methane is the center of debate first up. It allows a chance to put forward agriculture's point of veiw early, when the discussion heads towards airline emissions and eventually transport as a whole the s$&t will really hit the fan with people suddenly realising just how in unsustainable their lifestyle is. With a bit of science and common sense agriculture can survive in some form. When the realization of what a crock the offsetting by sequestering is finally sinks in and the true price is paid for fossil fuels minorities like farmers won't get a word in edgeways.

I hear what you're saying redcows, but we need to stop concerning ourselves with agriculture's point of view, or tourism's point of view, or anything/anyone human's point of view.

We need to consider the rights of nature, because without nature humans won't exist, let alone thrive. So the question needs to be re-framed in terms of what's best for nature? We're beginning to go down this legal path in NZ with the Whanganui River a Te Urewera Forest - both of which will be represented in court in future in the same way that loco parentis works for children who cannot speak for themselves.

But there is only one answer to that , no stuffing around with offsets and or worrying about bioemissions . We stop digging up fossil fuels, end of story.
We live within the cycles that nature has in place and we only get to use renewable energy. That will automatically bring the likes of methane into line by destroying transport infrastructure. We would simply have to return to localised production.
By having methane in the discussion just allows transport and hence the cities a free ride when they really need to front up.

Or we behave in a more rational and economically sensible fashion and wait the 20 or 30 years it takes for technology and economics to achieve the same transition away from fossil fuels because it has become cheaper than fossil fuels (which it basically has).

No Kate - Foyle is avoiding.

Energy underwrites money, 100%. This, the economists have 100% wrong.

So there is no way a lower EROEI can actually 'become cheaper' than a high EROEI source.

And technology is a fudge we should be beyond discussing, here. The Second Law of Thermodynamics (and the Carnot split ) is the limit to efficiencies, and we're fast closing in on that - hence 'productivity gains' levelling off.

Sigh - it's frustrating waiting.

Very cool. Foyle is exactly in the 'weak sustainability' head-space. You are asking questions with respect to ... if we took a 'strong sustainability' point of view. And being an advocate of strong sustainability, I'd say, exactly! Leave the fossil fuels in the ground - as we are going to have to learn to live without them anyway. And yes, let's return to localised production and distribution.

They way I look at it - NZ is in the 'sweet' zone. If these apocalyptic climate projections come true - we're one of very few land masses that will be inhabiltable (able to sustain life) going forward. Hence, we need to prepare ourselves for self-sufficiency. i.e., sufficient biodiversity, sustainable agriculture and civil society. To my mind, we can't start soon enough - but before we start we have to admit what that looks like.

I often think to myself ... I doubt we have any children of farmers experiencing mal/under-nourishment. But we do have many parents of farming children experiencing mental illness/unrealistic stresses. The key surely is to reducing those stresses on our farming community and ensuring that all children (urban and rural) are well nourished. How hard is that?

The real issue is that if we are to change our ways for the good of the planet earth than theres nothing surer than the reduction of the human population to sustainable levels (whatever this may be). Who's going to play god and determine who gets to live, breed & die?

Chill out Grumpy - peak baby was so 1990's. "by 2030 around two thirds of the world’s population will live in countries where fertility lies below the replacement level. A few years earlier, between 2020 and 2025, it is projected that the world will reach another historic milestone. Those years will mark the first time when at least half of the global population will reside in a country where women will have, on average, fewer than 2.1 births over a lifetime."

When we talk about planet earth, it seems people forget that most humans live in places other than NZ. The "developing world" wants to get where the "developed world" is today. And they will destroy their nature and ecosystems to get there (exactly the same thing that the developed world has done). How will you stop China, India, Brazil, Indonesia, Malaysia, Russia etc, from utterly destroying planet earth? The wealthy citizens of the world (who got rich by recklessly consuming nature) want rest of the world to do not replicate them. Unfortunately, the poorer citizens are extremely unlikely to listen. I think it is a much more important for NZ to focus on local pollution: water, air and soil. Get smart with waste management etc and dont waste time with Global Warming. NZ priority must be protecting NZ nature and ensure human impact is reduced and is sustainable.

Bzzt - wrong. There are only four core collective activities: food, shelter, transport, security. Singling out Food for sanctions is just sawing off the branch we sit on.

And as for the human Vs nature - we're as much a part of it as any other organism. No distinction.

As to our 'influence' on the weather in 2100, a meteor, another Taupo event, another 1703 storm, another Carrington event - none of which have the slightest anthropocentric component - would see a majority of us shuffle off the mortal coil quick smart. No need to wait for that Gold Coast climate in 2100.

Gaia is a cruel mistress......

Gaia isn't a cruel mistress - she is what she is - nature. And if we ignore and/or try to overcome or deny her, we will pay the consequences. And if we work with her, there will be less suffering. There will never be no suffering - as there never has been. But, there needn't be as much suffering as we presently see, because we waste so much and fail to understand how to share. Silly thing is, we can give the gift of life to a childless couple by way of IVF, but we can't prevent the cruel taking of life of an already born child in Africa or the Middle East.

That's got nothing whatsoever to do with Gaia making a "cruel" choice, waymad. You and me made that cruel choice. You and me.

Not gaia, not god, not allah, not atua. You and me.


Keep up the good work, and the education of urban commenters, Keith. Someone has to.....otherwise their skewed views and 'science' misapprehensions are likely to unembiggen our economy in fairly short order.....

Urban vs rural - all humans, waymad. Neither more virtuous than the other.

The concept of GWP100 for carbon dioxide is new to me and it is a useful concept. Like many of the commentators I think we should be using a low figure say GWP31 not GWP500. In 2050 they plan (or at least hope) to achieve zero carbon. To do so they intend planting many trees. By 2050 there will be few places to plant more trees so clearly our current plan is only intended to help us for 31 years and then new solutions will be needed.

I sense your comment might be tongue in cheek re the GWP31. If we used that as the metric then we would probably indeed go for drastic action to stop farming ruminants and do very little else. We would thereby go a long way towards satisfying our 2050 commitments but leave ourselves totally unprepared for the world thereafter.

Not tongue in cheek but GWP100 and GWP31 would not be drastically different. Other info rates methane as 30 times CO2 so that is rather similar to the GWP100 figures you quote. As per comment below I wonder how they calculated - if CH4 diffuses to the upper atmosphere quickly then its effect would be different and I suspect far less.

""While carbon dioxide is typically painted as the bad boy of greenhouse gases, methane is roughly 30 times more potent as a heat-trapping gas. New research in the journal Nature indicates that for each degree that Earth's temperature rises, the amount of methane entering the atmosphere from microorganisms dwelling in lake sediment and freshwater wetlands -- the primary sources of the gas -- will increase several times. As temperatures rise, the relative increase of methane emissions will outpace that of carbon dioxide from these sources, the researchers report.""
Sounds as if we should drain our wetlands making new pasture!

I've mentioned before how lucky we are in NZ that we have already destroyed 90% of our wetlands.

The specific gravity of Air is 1, for carbon dioxide it is 1.5 and for methane 0.55. So logically methane will rapidly rise into the upper atmosphere where it is more likely to rapidly mutate into water and carbon dioxide which greatly reduces its effect. Have the estimates for its warming effect been measured in an enclosed greenhouse at sea level or has it been calculated in the real atmosphere?

The IR absorption bands for methane will have been measured in a tube.
There is an important question relating to the distribution of methane in the atmosphere. I have not researched the information on that.
The rate of breakdown will depend on the level of hydroxyl ions and their distribution at different altitudes (and no doubt also some other paramters and variables.
I presume the atmospheric physicists have taken all of these things into account in making their estimates. There will be something on all of this within the latest IPCC report but these things take quite some digging out. Like everything to do with climate, there are always uncertainties around the quantification, and hence the science is not settled.

You’ve got to love the new 100yr target, which is so convenient. Al Gore’s epic fail in predicting the end of the arctic ice shelf by 2013 was a lesson to the faithful to push the prediction out beyond anybody’s lifetime, much like the religious nuts that used to predict the end of the world on a specific date. In the same vein, the cyclical output of the sun (heading down) and the power of the universe will trump all us mere mortals and our deluded attempts to alter the climate. However, you’ll be pleased to know that all your climate taxes will be making some people very rich and they won’t be accountable to anyone for failing to change the climate one iota.

Watch video please.

Your statement that the methane cloud is stable is irrelevant and assuming you have a basic understanding of chemistry extremely disingenuous. You are conflating the delta with the integral of its impact.

It's the equivalent of driving in your car and saying "hey our acceleration isn't increasing (it's stable) we must be at a constant speed" where as in reality any acceleration whether increasing stable or decreasing still equates to an increase in velocity...

Yes, this is effectively what I said up above in the comments. Keith doesn't quite seem to get it, though.

Or doesn't want to get it?

Or perhaps, given the tone and oratory techniques used in the article, does get it yet argues otherwise...

If all else fails, obfuscate, sow doubt and make false comparisons based on partial analysis/selective data...

Yeah, really it could be any of those 3.

Lanthanide and Sammy D,
One of the nice things about is that commenters generally do not impugn motives but instead focus on a constructive debate.
In relation to this current debate, the ruminant-sourced NZ methane emissions have been close to constant for some 30 years, with minor fluctuations during this period. This is not controversial. As a consequence, and as a function of the short residential life of methane in the atmosphere (currently estimated at 12.4 year), the methane cloud has essentially stabilised. There is no acceleration of any parameter within this system.This is easily modelled within a systems dynamics framework using either specific SD software or indeed simply applying the same principles within a spreadsheet. It can also be demonstrated using calculus and determining the turning points although those calculations do get very complex because of the residual effects of history. Much better to model using a systems dynamics framework, that captures those effects.
I don't think the car analogy is very helpful, but if you do use it then the analogy is that the car is indeed travelling at constant speed, and if anything is slowing down a little. You can check this from New Zealand's official GHG emissions inventory.

You're obviously an intelligent person, but persist in making this really rudimentary mistake, hence the questioning of motives.

Can you elaborate in your point please lanthanide. I can't see the acceleration either.

To fully explain this in a satisfying way would take a long time and a lot of effort (and I'm not 100% sure where to start). Instead I'm going to take a shortcut to explain the crux of the matter and say "trust me". You'll be able to find fuller explanations online about the topic of net emissions, I'm sure.

All figures below are entirely made up by me for illustrative purposes and I have no idea how much they reflect reality. I'm going to talk about CO2 emissions mainly, because they're easier to wrap your head around (trees are a natural sequesterer of CO2, AFAIK there is no specific nature sequesterer for methane).

When talking about "net emissions", we are talking about the emissions contributed by a particular system. A system in this context is just an arbitrary grouping of things that is helpful for humans to talk about.

For example a system could be a single car, and we could say that this single car when driven for 1 year will produce net CO2 emissions of 10 tons. This is because burning petrol in the car creates CO2, and there is nothing within the car that sequesters CO2 directly, so its a net emitter.

The system can be larger than a car though: lets imagine the system is all of the assets owned by person A. Person A owns the car mentioned above, but they also own a large block of forest which is capable of sequestering 10 tons of CO2 per year. In this system, the car emits 10 tons and the forest sequesters 10 tons, so the emissions of this system - the assets owned by Person A - are net 0. Every 10 tons of CO2 produced by their car are directly offset by the forest.

If person A doubles the size of their forest, they would start sequestering 20 tons of CO2 per year, vs the 10 emitted by their car, given person A's system a net negative emission profile of 10 tons of CO2 per year.

When talking about systems in *this context*, what happens outside the system is *completely* irrelevant to the net emission profile produced by the system. If person A happens to live next to a huge ginormous forestry plantation that sequesters 10,000 tons of CO2 per year, this does not change the net emissions of person A's assets: they don't somehow now have negative net emissions of 10,000 tons of CO2 per year, because the system we have defined is only person A's assets, and person A doesn't own that forest. Whoever owns that forest will get the benefit of the CO2 offset, not person A.

Now, this asset-based form of emissions profiles does actually exist - there are various companies that will give you CarboNZero certification and the like, where they tally up the various emissions produced by your company's day to day operations, and then calculate how many trees you need to plant in order to offset those emissions, and then hook you up with forestry places that can plant those trees and turn over the carbon credits. Ignoring the nitty-gritty as to whether this is an accurate approach or whether it's just a green wash, it is clear that you can have individual companies (which could be farms) that are net zero emitters of CO2 (or CO2 equivalents), even if the larger system they are in - New Zealand in this case - is a net positive emitter.

So, zooming back out, the mistake that Keith persists in making, is that he has referred to New Zealand as being a net-0 emitter of methane gas today - which in our example above would mean for every 10 tons of methane emitted, some part of the New Zealand system is also sequestering 10 tons of methane. His faulty reasoning for why New Zealand is a net-0 emitter, is because he is considering what is happening *outside* of the 'New Zealand system' as being part of the New Zealand system - in this case he is saying that because methane has a short residency in the global atmosphere and the level of gas in the atmosphere has been constant over the last couple of decades, that New Zealand must have net-0 emissions. In my example, this would be like person A owning all of New Zealand and declaring that even though all of New Zealand is a net positive emitter of 100,000 tons of CO2 every year, because New Zealand sits next to the Amazon rainforest which is sequestering 100,000 tons of CO2 every year, New Zealand must be a net-0 emitter of CO2 because +100,000 tons and -100,000 balance out to 0. But it simply isn't - the Amazon rainforest isn't part of New Zealand in exactly the same way that atmospheric processes and the natural residency time of methane in the atmosphere are not part of the 'New Zealand system'.

A country (or any other system) being a net positive, net 0 or net negative emitter of a particular gas has a very specific meaning. Keith is (un?)intentionally blurring the boundaries and making the claim that today New Zealand is a net-0 emitter of methane.

Keith will find that officials and experts in New Zealand will persist in saying that we are a net emitter of methane for the next several decades. He may continue to think that the officials and experts are wrong because the global atmospheric concentration of methane is constant and so doesn't understand why they keep claiming we're a net emitter - and the reason they keep claiming that NZ is a net emitter of methane is because New Zealand *is* a net emitter of methane, and Keith's interpretation of what being a net-0 emitter of methane means is wrong.

The other key point, which I'm not going to elaborate on but is basically what Sammy was getting at with his car acceleration analogy, is that even if the 'cloud' of methane in the atmosphere is not increasing in size, it is still having a warming effect on the planet. If you take Earth with the current global cloud of methane, and then take another Earth that is identical in all other respects except that it doesn't have that cloud of methane, the first Earth will be hotter than the second. Pretending that because the size of the cloud is stable and unchanging that therefore it doesn't matter is wrong - it does matter because it is contributing to heating of the planet, even if the amount of heating it is contributing is static and not increasing (in the way that the amount of heating contributed by CO2 is increasing each year because the concentration of CO2 is increasing each year).

Nah sorry, I'll stick with Keith. Your car and tree comparison is a net emmissons comparison( though on another level I think that is B's as the sequestering is simply not) but your then comparing that to a system in which you close by putting a line through the animal as a start and atmospheric methane as a finish and that is simply not how it works. Infact that's why I object to the offsets applied to CO2 from Fossil fuels . Unlike with methane and animals which have a complete cycle, CO2 from Fossil fuel starts of sequestered underground and is then placed into the cycle with those trees you mentioned only having a very tiny, in geo terms, lifespan. They then die and breakdown one way or another, not surprisingly producing some methane along the way.

"but your then comparing that to a system in which you close by putting a line through the animal as a start and atmospheric methane as a finish and that is simply not how it works."

That is exactly how it works. The cow only exists because humans allowed it to be born. The cow exists in New Zealand because that's where the cow lives. The emissions from the cow are therefore attributable to NZ as a country overall.

That's what emissions from nation states are trying to track - all the economic activity created by humans going on within the country that result in emissions. Natural sources of emissions such as volcanoes are generally excluded, but so are forest fires, which is problematic because forest fires are often a result of human activity as well - the forest wouldn't exist if it weren't for humans planting them.

"Unlike with methane and animals which have a complete cycle, CO2 from Fossil fuel starts of sequestered underground and is then placed into the cycle with those trees you mentioned only having a very tiny, in geo terms, lifespan. They then die and breakdown one way or another, not surprisingly producing some methane along the way."

So again you are using effects from outside the system to change your definition of the emissions of the system.

How does what you wrote change if every molecule of methane (or CO2, or any other gas) immediately left the earth's atmosphere and drifted off into space? Would New Zealand be a net positive, net negative or net-0 emitter of the gas? What if the gas NEVER left the atmosphere ever, and just built up eternally to greater and greater concentrations? Obviously for both CO2 and methane the gasses are at neither of those extremes, and their activity in the atmosphere with respect to longevity are different. But what happens to the gas in atmosphere after its emitted is entirely irrelevant to the system of New Zealand emitting the gas to begin with, due to human activity.

"Natural sources of methane, such as volcanoes, are generally excluded..." Quite a large source to leave out. "The seepage of ancient hydrocarbon gases to the Earth’s surface is recognized as a significant natural source of methane to the atmosphere, second only to emissions from wetlands. ...All results obtained so far emphasize the potential significance of solid Earth geophysical processes to the atmospheric greenhouse gas budget. This effect should not be forgotten in appraisals of pre-industrial, contemporary and future methane budgets."

Sure, but I'm not arguing about the merits of any of this, or whether trees truly sequester carbon, whether CarboNZero certification is worthwhile etc.

I'm simply saying that Keith's statement that New Zealand is today a net-0 emitter of methane is wrong.

Either way it is in rounding error territory on a global scale, and taxing it is going to make net zero difference to the global climate. The money spent of this posturing could be better spent elsewhere.

Hi Keith, been traveling so sorry to take so long to come back to you - this will all be well down the reading list now but hopefully you do get a chance to read this. We're just seeking to uphold the veracity of what's published here, apologies for lashing out but as Lanthanide outlined several times above there's a fundamental error in some of your claim which you don't acknowledge hence our suspicions about your intentions.

Neither of us are arguing that atmospheric methane levels haven't broadly leveled out over recent periods, however the level at which they have stabilized at nominally 2.5x the pre-industrial levels and hence their contribution to net global energy gain is 2.5x what it used to be - this is the point of concern. Global energy gain via the green house effect is the key parameter of concern and this is indeed increasing, it won't level out until GHG levels return to nominally their pre-industrial levels.

When we talk about being emissions neutral it's on a man-made systems basis, to suggest that because atmospheric methane levels aren't rising and therefore we (farmers) are emissions neutral is wholly misleading in this context.

With regards to my example the analogy is correct - again you're conflating the delta with the integral, equally you could switch these out for velocity and distance traveled (distance is the integral of velocity). On this basis what you're arguing that we may be traveling at 100 km per hour but as our velocity isn't increasing we must be standing still - clearly this is an absurd statement - as is the claim that because methane concentrations aren't increasing (they're stable at 2.5x pre-industrial levels) the planet isn't warming because of it.

I don't expect you to take the word of a poster on an internet site (I do have a masters degree in engineering and five years experience in applied gas phase chemistry however) but I would strongly recommend you consult with a trusted physicist/chemist/climatologist before repeating these claims any further. As a thought leader it's essential that you ensure the information that you are sharing is correct - in this case (the claim that atmospheric methane is stable & therefore farmers are emissions neutral & therefore farmers are being asked to carry the can for the rest of society) it is not.



It’s been a enjoyable chat for a wet Saturday Keith, keep up the good work

Thanks positivelywallstreet.
Down here in Canterbury it is Sunday and still raining, but with lots of snow to low levels.
Despite the so-called global warming, it is setting up beautifully for an amazing ski season, and there is another squadron of souwesters lining up for this coming week. I don't recall such an amazing start to the season in 50 years. But of course, what comes can also go.

I’m watching winter tomatoes ripening slowly, we shall see what happens, the garden is one big experiment.

The same politicians who can't build 1000 houses are going to change the climate... "Encouraging motorists to trade in their petrol cars for diesel vehicles was one of the last Labour government’s biggest environmental mistakes. "Barry Gardiner, the shadow Environment minister, said the party was trying to cut CO2 emissions when it introduced new vehicle tax rates in 2001. It meant that motorists switched to diesel vehicles and parts of the country saw a big increase in nitrogen dioxide and other harmful chemicals in the atmosphere."

That article is a little old....2015 I think
Euro 6 diesels are allowed in low emissions zones without penalty I believe.
All vehicles pollute even if it is just rubber particles from the tyres.

Pity those engines weren't around in 2001 when the disastrous policy was put in place. Noble cause corruption is at the heart of every green policy balls up.

Europe lagged behind the US in emissions control and it proved to be expensive in the long run.

Profile is a paid obfuscator. Tends to 'spoil' if possible.

The problem is that there are already too many of one species on the planet, and that species was stupid enough to lever itself on below-ground, once-off stocks (read: acreage). In doing so, it introduced the entropic wastes of said extraction, into the above-ground environment. There are only a few valid pathways from there - reduce population, reduce consumption, restore degradation, and construct a full nutrient/mineral recycling.

Whether ruminant-keeping fits into that, and now much, is a follow-on question (bearing in mind that the ruminant/domestic biomass has massively displaced wild biomass already).

I’m inclined to believe we will continue to reduce forms of pollution because of their disruptive effects on society.
However climate change will be imperceptible over one lifetime and generally ignored.
Life goes on.

There is a lot of gloominess in the climate cooling/warming/changing community. Can you let me know when the world is going to end so I can get my affairs in order, thanks. At the moment I'm waiting until I see Mangoes growing in the Waikato, but that's a bit rough and ready.

No concern there,
Wait until NZ starts subdividing Antartica.
My understanding is about 1000 years from now.

Nah, RMA Effects (such as hazards from the 138 volcanoes below the ice) would rule out Subdivision as such. Or at least attract a swingeing Development Contribution. Mitigation fund....