Arguments
How much does animal agriculture and eating meat contribute to global warming?
Posted on 30 November 2015 by dana1981
This is the new rebuttal to the myth 'animal agriculture and eating meat are the biggest causes of global warming.' It's available at the short URL sks.to/meat
The burning of fossil fuels for energy and animal agriculture are two of the biggest contributors to global warming, along with deforestation. Globally, fossil fuel-based energy is responsible for about 60% of human greenhouse gas emissions, with deforestation at about 18%, and animal agriculture between 14% and 18% (estimates from the World Resources Institute, UN Food and Agriculture Organization, and Pitesky et al. 2009).
Global human greenhouse gas emissions flowchart, from the World Resources Institute.
So, animal agriculture and meat consumption are significant contributors to global warming, but far less so than fossil fuel combustion. Moreover, fossil fuels are an even bigger contributor to the problem in developed countries, which use more energy and have increased livestock production efficiency (Pitesky et al. 2009). For example, in the United States, fossil fuel-based energy is responsible for about 80% of total greenhouse gasemissions as compared to about 6% from animal agriculture (estimates from the World Resources Institute and Pitesky et al. 2009).
US human greenhouse gas emissions flowchart, from the World Resources Institute.
How does animal agriculture cause global warming?
On of the main ways in which the livestock sector contributes to global warming is throughdeforestation caused by expansion of pasture land and arable land used to grow feedcrops. Overall, animal agriculture is responsible for about 9% of human-caused carbon dioxideemissions globally (UN FAO).
Animal agriculture is also a significant source of other greenhouse gases. For example, ruminant animals like cattle produce methane, which is a greenhouse gas about 20 times more potent than carbon dioxide. The livestock sector is responsible for about 37% of human-caused methane emissions, and about 65% of human nitrous oxide emissions (mainly from manure), globally (UN FAO).
Beef is a bigger problem than other sources of meat
Producing beef requires significantly more resources (e.g. land, fertilizer, and water) than other sources of meat. As ruminant animals, cattle also produce methane that othersources (e.g. pigs and chickens) don't.
Eschel et al. 2014 estimated that producing beef requires 28 times more land, 6 times more fertilizer and 11 times more water than producing pork or chicken. As a result, the study estimated that producing beef releases 4 times more greenhouse gases than a calorie-equivalent amount of pork, and 5 times as much as an equivalent amount of poultry.
Eating vegetables produces lower greenhouse gas emissions yet. For example, potatoes, rice, and broccoli produce approximately 3–5 times lower emissions than an equivalent mass of poultry and pork (Environmental Working Group 2011). The reason is simple – it's more efficient to grow a crop and eat it than to grow a crop, feed it to an animal as it builds up muscle mass, then eat the animal.
Greenhouse gas lifecycle assessment for common proteins and vegetables (EWG 2011).
How do the numbers get misrepresented?
There are often suggestions that going vegan is the most important step people can take to solve the global warming problem. While reducing meat consumption (particularly beef and lamb) reduces greenhouse gas emissions, this claim is an exaggeration.
An oft-used comparison is that globally, animal agriculture is responsible for a larger proportion of human-caused greenhouse gas emissions (14-18%) than transportation (13.5%). While this is true, transportation is just one of the many sources of human fossil fuel combustion. Electricity and heat generation account for about 25% of global humangreenhouse gas emissions alone.
Moreover, in developed countries where the 'veganism will solve the problem' argument is most frequently made, animal agriculture is responsible for an even smaller share of the global warming problem than fossil fuels. For example, in the USA, fossil fuels are responsible for over 10 times more human-caused greenhouse gas emissions than animal agriculture.
That's not to minimize the significant global warming impact of animal agriculture (as well as its other adverse environmental impacts), especially from beef and lamb, but it's also important not to exaggerate its contribution or minimize the much larger contribution of fossil fuels.
saileshrao @50:
From Vaclav Smil's book, "Should We Eat Meat? Evolution and Consequences of Modern Carnivory"
"On the other hand, Goodland and Anhang (2009) argued that CO2 from livestock respiration is an overlooked source of the gas and that overall greenhouse gas emissions attributable to livestock should be much higher, accounting for no less than half of the total. Unfortuanately, they accepted some faulty calculations by Calverd (2005) who concluded that farm animals generate about 21% of all CO2 attributable to human activities."
and
"In any case, CO2 emissions from livestock metabolism are not, much like those from human respiration, considered as anthropogenic sources of a greenhouse gas. They result from the metabolism of phytomass that aborbed the gas from the atmosphere and that will again sequester it once it will have been respired and are thus a part of relatively rapid sub-cycle of the global carbon cycle that does not result in any significant net addition to atmospheric CO2 burden."
@ scaddenp #49
Not at all, just the opposite conclusion should be drawn from those studies. In the soil you can simplify it and think of it this way. There are basically 2 pools of carbon in the soil, an active fraction and a stable fraction. The active fraction of the carbon pool in soils can safely be largely ignored as a cause of AGW as it will return to the atmosphere anyway and then back to the active fraction again via photosynthesis and so on as a relatively short term cycle. It is only temporarily stored and thus not part of the long term carbon cycle. The stabilized organic matter fraction is however part of the long term carbon cycle and is much more important to calculating AGW.
Intensive grazing effects this rapidly cycleing fraction both by increasing live biomass production and by increasing the rate of decay BOTH. This actually increases the quantity of carbon leaving the active fraction and turns into stable humus that can no longer decay and is stable for thousands of years unless disturbed.
Remember the only part of soil carbon that actually is important to AGW is the stable fraction. By increasing the rate of decay, that small % that get sequestered into the soil after all the processes of decay are finished also increases. It speeds up the whole system, and the system as a whole is a net sink of carbon into the soil. So that part of the system speeds up as well. The more biologically active a soil is, the more long term stable carbon is sequestered... Unless one disturbs that soil with a plow or other means of course.
RedBaron - are you actually claiming that the total amount of soil organic carbon has increased this century due to intensification of agriculture and expansion of farmland into natural vegetation? Or are you just claiming grazing is better for retaining SOC than say crop tillage?
Saileshrao, thank you for the link to Barnosky's PNAS paper on prehistoric megafauna, I will look at it tomorrow.
And thanks to OnceJolly for the quote from the Smil book that says pretty much the same thing I said: livestock respiration adds no new CO2 to the atmosphere.
Reason_4, if you mean that CH4 from ruminants is different from CH4 from say fugitive natural gas, then I agree with you. The methane counts as greenhouse forcing until is oxidized, after that it is no different from CO2 from respiration. Fugitive gas by comparison is adding net new carbon into the atmosphere, first as CH4 and then as CO2.
@scaddenp #53 In ref to my post #52
I was specifically refering to Managed Intensive Rotation Grazing, not other forms of agricultural intensification. MIRG
OnceJolly @51:
Vaclav Smil is making the assumption that livestock production is in equilibrium with the environment, similar to Ray Pierrehumbert making the assumption that the methane concentration is decaying exponentially in the atmosphere.
I invite Vaclav Smil to accompany me to Rajasthan, India, on my upcoming field trip later this month as we work with people to reverse the expansion of the Thar desert. I would be happy to show him how livestock production is decidedly not in equilibrium with the environment as livestock production has been rapidly desertifying pasturelands through overgrazing. Annually, the UNCCD reports that 30 million acres of land gets desertified mainly through livestock overgrazing, but this CO2 emissions is counted as part of the human contributed 11.6 GtC red arrow in the IPCC carbon cycle block diagram (insert diagram from IPCC AR5 WG1 CH6), accompanied by the caption, "Total Respiration and Fire".
This post by Dana Nuccitelli and the comments have illustrated many of the numerous forms of denial (FLICC) that were discussed in the excellent EdX course: Making Sense of Climate Denial, but directed towards our continued enslavement and exploitation of animals. Vaclav Smil is not a land carbon expert and therefore, using his statement to justify that livestock breathing is part of the "natural carbon cycle," could fall under the "False Experts" category of denial, discussed in the course.
OnceJolly @51,
Also with respect to Calverd's "faulty calculations," the IPCC AR5 WG3 CH11 land use block diagram (Fig 11.9, page 836) confirms that the breathing contribution of livestock is around 8.77 Gt CO2.
The annual net dry matter biomass input to the livestock sector is 7.27 Gt, while the net dry matter biomass output is 0.4 Gt and the waste stream is 2.18 Gt. The missing biomass must have been metabolized, which works out to 4.69 Gt. Assuming that half the biomass is carbon, this is 2.35 GtC or 8.62 Gt CO2, which is pretty close to the Calverd estimate.
@saileshrao #57
That brings up an important point. Just because there are unsustainable foods in our marketplace does not mean we have to stop producing those foods, all it means is we need to change the production methods. The overgrazing you mentioned and the environmental harm it creates, supports less animals, not more. Certainly overgrazing creates desertification, and that adds to AGW, and reduces yields from that land. ie less animal production, not more. The key is education. There are alternative intensive models of production to almost every form of intensive agriculture that actually yield more food per acre, not less. Most of them include animal husbandry too.
Rice was mentioned earlier as another source of AGW. Certainly intensification of rice production in the green revolution increased yields, but at a cost to the environment. More modern forms of rice intensification though like SRI, yield even more that the old antiquated green revolution intensification, but without the environmental harm.
In a post earlier #52 #56 I had to clarify the difference between the standard intensification of animal husbandry which uses CAFOs and has an associated negative impact on the environment and climate, and more modern forms of animal husbandry intensification like MIRG which can actually regenerate the environment and help mitigate AGW.
Even though most current intensive rice production does in fact add to AGW at least somewhat, no one would say everyone needs to stop eating rice. It is a silly fallacious argument. Claiming everyone needs to stop eating meat is equally silly. And so is the fallacious argument that all intensive agriculture must end because it is a source of AGW. And so is the argument that our current antiquated forms of green revolution intensification must be done to meet demand of a growing population. They are all lunatic fringe arguments that use poor logic skills and often unreasonable misleading statistics as well. One, animal husbandry, is being rightfully debunked right here in this thread.
Yes, intensive agriculture is required to meet worldwide demand. But there are alternative forms of intensification that yield more, reduce emissions, and increase profits for almost every major food crop.
Typically the major things preventing this change to new modern ecologically sound systems include education, subsidies for competing antiquated systems to keep them economically viable, misguided onerous regulations, and occasionally but not often infrastucture changes are needed.
saleshrao @57 & 58,
Calverd (2005) is a one-page editoral from someone with no expertise in carbon accounting who makes no claims about disequilbrium between respiration and photosynthesis. Furthermore, he doesn't provide a value of 8.77 GTon...this is from Goodland and Anhang, who apply his 21 percent figure to the WRI's estimate of total GHG emissions for the year 2000, rather than (as Calverd actually does) the 21 percent of CO2 from the combination of fossil fuel combusion and respiration of humans and livestock. Despite not using the FAO's own estimate of respiration, they further inflate this figure by 12 percent (for after period increases in livestock tonnage) and 10 percent (for alleged undercounting of animals by the FAO, though there is no indication that Calverd's actually uses these estimates to obtain his own figure).
My understanding is that no one is making the equilbrium assumption that you're asserting. The degradation of surface and soil carbon sequestion is included in the land use category of greenhouse accounting. Goodland and Anhang provide no evidence that there were 10.8 Gton of *net* CO2 emissions missing from the GHG inventories in 2000 that can be attributed to land use and land use change due to livestock. In a follow-up to their original World Watch article, when asked how previous GHG inventories missed 22 GTon of CO2e, Robert Goodland writes: "“If respired GHGs are counted as a proxy for foregone carbon absorption, then most of the 22 billion tons of emissions that we claim were previously not counted can be understood as a potential carbon sink rather than an actual carbon source.”"
saleshrao @58: " The missing biomass must have been metabolized, which works out to 4.69 Gt. Assuming that half the biomass is carbon, this is 2.35 GtC or 8.62 Gt CO2, which is pretty close to the Calverd estimate."
Not everything that is metabolished is respired; some of that carbon will be incorporated in the mass of the fauna. In any case, Smil makes reference to a peer-reviewed estimate of respiration by <a href="http://www.biogeosciences.net/4/215/2007/bg-4-215-2007.pdf">Prairie and Duarte (2007)</a>, which estimates livestock respiration at 1.5GtC (5.5 GtCO2). Smil argues that their underlying estimates of animal mass are inflated. These figures (and the FAO's own estimate of 3.2 GtCO2) were available when Goodland and Anhang were conducting their analysis.
Saleshrao wrote: "our continued enslavement and exploitation of animals."
Ah, now we get to the root of saleshrao's argument. It's not about climate at all.
The other thing of note is that we have to eat, we do not have to fly (aside from the very self important) for example and we can cycle, or use renewanle energy (in Austrialia everyone is offered the option and very few take it up) but we still have to eat.
Cut out lamb and beef, substitute those meals for vegan meals and that's a great start. Often overlooked are meat eating pets, vast CO2e emisions from owning a large dog for example, about the same as an SUV
abcnews.go.com/Technology/pet-dogs-damaging-environment-suvs/story?id=9402234
so own one, or the other but not both.
Trevor_S @63, I refer you to Clark Williams-Derry's response to the claims about dog food. In short, the claims made in New Scientist are based on underestimate SUV impacts 80% if you just consider onroad energy costs. It is far worse than that because Robert and Brenda Vale claim to include emobdied energy of manufacture as well (not included in the above calculation). Further it includes only energy costs in the estimate, not the ecological footprint from pollution, including carbon pollution, thereby significantly biasing the comparison in favour of SUVs.
Worse, the Vale's do not take into account that pets primarily eat waste products - ie the cuts of meat that humans will not eat. From that and the fact that pet food expenditure in the US is just 1% of that spent on humans, the additional ecological footprint of pets to that of humans alone is negligible. That is, if we eliminated pets and pet foods, there would be no reduction in the number of live stock in the combined human/pet food chain.
To conclude in the words of Clark William-Derry:
The questions about whether we should treat methane emissions from fast biogenic parts of the carbon cycle differently from emissions of fossil methane are interesting. I would have expected this to have been addressed in the literature, but I haven't found much. Admittedly, I haven't looked very hard.
Note: Much of the following was off the top of my head and is incorrect. I have struck through the wrong bits. See later posts for more correct inffromation
By my calculations, the GWPs of biogenic methane from agriculture should be reduced by 2.75 compared to fossil methane releases. Basically, the biogenic methane removes 2.75 kg of CO2 from the atmosphere while it is kicking around as 1 kg of methane. (GWPs are measured according to mass, not moles. If you combust 1kg of methane you get 2.75 kg of CO2.) Fossil methane adds new carbon to short-term cycles.
This would mean that the 20 year GWP for biogenic and fossil methane for 20 years should be 83.25 and 86 respectively. Here's the graph for methane from AR5:
The GWP curve asymptotes (if that's a verb) towards 2.75, as it would for methane introduced from fossil fuel, the 2.75 representing the residual CO2. If the methane were instead sourced biogenically, in effect replacing CO2 for a short while with CH4, then we should shift the incremental GWP line down by 2.75 so it asymptotes towards zero, since once essentially all of the biogenic methane in the pulse is back to CO2, we are back where we started from.
And here's the table
For 100 years the methane GWP should be 31.25 (bio) and 34 (fossil). For very long time periods it would be ~zero and ~2.75.
It's possible that I have miscalculated and misunderstood matters here. I can't find any mention of this in the IPCC reports, which raises a red flag that it's likely me who has the wrong end of the stick. The standard emissions accounting treats both kinds of methane equally.
Still, even if I'm right, biogenic methane is still ~90% ~93% as bad as fossil methane, using the conventional and somewhat arbitrary 100-year timeline. Considering that methane emissions of all kinds are really hard to measure precisely, this discrepancy may not matter. Also, the GWP used for reporting for methane is currently 25, lagging the latest research, so we are nowhere near using the "correct" number.
What this boils down to is that anthropogenic methane of all kinds is a significant contributor to the climate crisis over human timeframes and we should take reasonable steps to reduce it. Perhaps biogenic anthro methane is a little less bad than that sourced from fossil anthro methane, but it's still a problem and the GWPs the policy makers are currently using are still too low.
However, as Tom, Ray Pierrehumbert and many others have pointed out, the priority has to be reducing the long-lasting emissions of CO2.
Still, reducing beef and dairy consumption would help reduce our short-term impact on the atmosphere and our longer-term impact on the environment generally, while being good for our health, so why not do it?
Here is a blog post and a link to a paywalled paper (which I can't access) that asserts the opposite of what I assumed above. According to this, the IPCC GWP estimate would be appropriate for short term biogenic methane but not for fossil methane, which should be higher.
But it's from 2010, so it may be out of date now.
Added: Doh! The footnote to the table I posted said that the fossil methane should have a GWP of 1 or 2 higher. So, I was wrong. Apologies for posting first and doing the due diligence later. I will correct my original comment when I have a moment, later.
@Andy Skuce #65
You asked, "Still, reducing beef and dairy consumption would help reduce our short-term impact on the atmosphere and our longer-term impactt on the environment generally, while being good for our health, so why not do it?"
There is a very good reason why. As I stated in post # 21, what matters is the net flux from stable to active carbon cycles. Any agriculture of any type that increases the stable carbon pool in the soil is not creating AGW, but rather is helping mitigate AGW. That includes animal husbandry. If anyone wants to help mitigate AGW by giving up certain foods, give up foods produced from land decreasing in soil carbon, and replace it with food produced from land increasing in soil carbon. One emergent property of agricultural systems that increase SOC is that they also improve the nutritional qualities of that food too. Yes even animal products. [1]
This is an important distinction that is overlooked on many dogmatic advocate sites. No question we must change angriculture to production models that are more ecologically sound, but the good thing is that those same changes also make our food healthier too. There really is no down side to it, unless you operate a confinement dairy or feedlot. BUT if you refine your eating habits to increase demand for ecologically sound methods of production and reduce demand for those that cause AGW, you provide financial incentive for those confinement dairies and feedlots to change their operations. What does a confinement dairy or feedlot care about vegan boycotts? Vegetarians are not a customer no matter what the producer does. But a wise businessman will change their production methods if their customers demand it. If you want to change agriculture, you need to change the demand in the marketplace. A blanket boycott or reduction does not do that unless there is a corresponding increase in demand for products that help mitigate AGW.
RedBaron: I'm not for a minute dismissing the importance of good farming practices that increase the amount of stable carbon in the soil. My argument was just on the basis of other things being equal, which, as you point out, they may not be. Surely we agree that both carbon enrichment of the soil and reduction in greenhouse gases are important. If animal husbandary can be done that enriches the soil with carbon and that does not increase methane in the atmosphere, I'm all for it, since I have a hankering for cheeseburgers as much as anyone else does.
I have found the key reference for fossil versus biogenic methane GWPs, it's Boucher et al (2009). The process of methane removal from the atmosphere is more complicated than the simple oxidation that I imagined earlier. Some atmospheric methane falls out as formaldehyde to the surface where some of it is absorbed by soils or oceans and the rest oxidized, finding its way into the atmosphere as CO2.
Some atmospheric methane is taken up directly by soil biota that convert it to methanol and formaldehyde. Some proportion of those chemicals may be in turn taken up and stored as stable carbon compounds in the soil.
So, the overal difference between biogenic and fossil methane amounts to about 1 or 2 points to the GWP values, less than the 2.75 I (mis)calculated earlier. The biggest absolute and relative effects is on the longer-time interval GWPs as this table shows:
This is a fragment of a table from AR5 WG1 Chapter 8, page 731
Fossil methane has a roughly 7% bigger 100-year GWP than does biogenic methane. But there are uncertainties, of course.
@Andy Skuce #68
Absolutely you are correct! Of course there are uncertainties. Most notably because we are talking about complex biological systems that have highly nuanced interactions, interdependancies, and symbiotic relationships that cause unexpected emergent properties of the system.
One of those unexpected emergent properties with respect to ruminant animals is that a properly managed pasture is actually a net methane sink as well as being a net carbon sink. This is unexpected because while ruminants may produce more slightly methane (even if not grazed, grasses will decay and produce methane anyway), the other parts of the grazer/grassland system also increase. As you pointed out, the soil biota can increase, which not only reduce that methane, also in the process fertilise the system which allows even more plant growth, which allows even more grazing. That's why to get meaningful conclusions you must use systems science/holism. You must look at plants, animals, atmosphere and soil biota in all their functions and interconnections, rather than treating any area as a single-product system.
A properly managed grazer/grassland system is not only a net carbon sink, but also a net methane sink. I already posted one citation of this earlier, but look it up if you are skeptical. Also a properly managed grazer/grassland system has more animals on it not less. I know that is counterintuitive and many people can't grasp it, but maybe this riddle will help you understand.
You are driving down the road on the right side you see 10 fat cows, on the left side 5 skinny cows. All else is equal, no grain supplements fed, same breed and age of livestock, the cows are getting all their nutrition from the grass in their pasture only and the pastures are equal in size with the same soil type. No cheating. The only difference is one is being overgrazed and one is managed properly. Which pasture is being overgrazed?
This matters because for example in the US roughly 1/2 the pasture/rangeland is overgrazed, 95% of livestock reaches a feedlot eventually, and both overgrazing and feedlots are net emissions sources for both methane and CO2. Basically what is happening is the land is being overgrazed, so the animals won't get fat, so cropland is growing grains in an unsustainable manner to fatten them in feedlots, cropland being yet a third emissions source.
What needs to happen is the 10 fat cows on pasture instead of the 5 skinny cows that later get fattened in a feedlot. In other words we need more, not less, ruminants on pasture, but managed properly. I know it is very counterintuitive. Every vegan I ever met except one was completely incapable of making the connection. But this is what needs to happen to turn agiculture from the net emissions source it is now to a net sink. It is also what needs to happen to reduce the deforestation that is happening to support animal husbandry.
Again, any agriculture of any type that increases the stable carbon pool in the soil is not creating AGW, but rather is helping mitigate AGW. The type of production of livestock that increases the stable carbon pool in the soil produces more yields per acre, not less. We don't need people eating less meat. What we need is people boycotting any food production model, animal or vegetable, that doesn't increase the net carbon in the soil, and replacing it with food that does increase SOC. It's there. The models exist. They produce more food not less. They produce more real profit not less. There is no down side.
The primary reason it ever changed to the unsustainable models we have now is subsidies, misguided government regulation, and cheap fossil fuels. Yes green revolution agriculture was an improvement over traditional subsistence agriculture. So once upon a time those subsidies/regulations made sense. Now those same factors that advanced agriculture are preventing the next revolution in agriculture, carbon farming/ecoagriculture. So the same policies that were the future in the 1940s 50's and 60s are now Luddite.
Vegans are not helping.
Redbaron, maybe I being thick here but going through your references, I am not finding evidence that your desired farming practises (which I fully agree with are superior to other common systems) are net carbon sinks. I find evidence that SOC increases which is good but to show net carbon sinks (or rather CO2e sinks), then rate of SOC increase per hectare must be larger than CO2e emissions (CO2 equivalents which are the methane fraction) per hectare. (and that SOC increase is sustainable).
On unrelated point, the other issue I would have with vegan diets would be one of land use. I do agree that feeding grain to raise beef is bad news, but I would love to see much protein vegans could raise on farmlands where we currently raise sheep and beef cattle. Good luck on that. Grain-fed beef is practically unknown here.
Redbaron, maybe I being thick here but going through your references, I am not finding evidence that your desired farming practises (which I fully agree with are superior to other common systems) are net carbon sinks.
I have to say that I am struggling with this issue too. The whole 'holistic' system appears to me to be based on faith and annecdote. There are many conflicting opinions and very few controlled studies that support it as a method of mitigation of GHG emissions. As a grass fed beef farmer, I would dearly love to believe the hype but I'm not falling for it just yet...
Grain-fed beef is practically unknown here.
It's certainly more common in Auckland than I have ever seen before and strangely, it seems to command a price premium. Maybe there is a demand from tourists. Visitors from the US certainly seem to prefer it. I find it usually very tender but completely devoid of flavour. Different folks and all that...
And then again - just as I press send - this pops up in my feed.
intensive farming helps build soil
No mention of fossil fuel inputs or the environmental impacts of the water requirements but I guess it's early days.
And one more thing...
Can we be a little more carefull as to how we are labelling people here.
Despite being a farmer that eats meat, I am still a tad disturbed by the way vegans and vegetarians seem to be referred to as some unified body that is opposed to all those that don't follow their lifestyle choice. I know a few vegans who make no attempt to proselytize their beliefs. I have come across many that do. I try to treat them as individuals.
If we were to replace 'rabid Vegan' with 'rabid Jew', I think we would all be horrified. Would 'activist' not suffice?
foolonthehill - that is a very interesting news release. We share office with Landcare scientists and teatime conversation had more or less assumed SOC loss. I have heard this reported in conference as well. I wonder how robust this is since seems to be based on one drylands farm study? Earlier results were from more traditional dairying locations in Manuwatu and Taranaki.
I've never seen grain-fed beef at a supermarket here or in Wellington - is it imported? Huge fuss about suggestion of barning in Southland a few years ago...
Haven't seen grain fed in supermarkets. I noticed it on the menu of a couple of rather expensive restaurants and also in a couple of deli's. I assume it is imported but there's nothing to stop a local farmer from using a point of difference to make a better profit. It seems that anything that is slightly out of the ordinary is highly sought after by the real estate barons of Auckland...
The farming papers (NZ Farmer, Farmers Weekly, Rural News) are well worth a read to check how the agricultural pulse is beating. Palpitations are a common feature when it comes to climate change issues. They are free circulations but maybe you need a rural delivery address to receive them?
The long term evaluation of this study will be interesting to see. Maybe the vast increase in government science funding of $20million will be enough to ensure it's completion... Surely the price of a decent coffee, per capita, is sufficient for such a weighty matter? Or should a flag referendum take precedence?
Interesting. I will keep my eyes open more on this.
The location of the study with increasing SOC would be typical for Canterbury plain, but very different from most dairying areas. Forest lost around 800 years ago instead late 19th C; would have been under tillage for grains for much of 20th C in area known for windblown soil loss. So probably a very degraded soil before dairying and irrigation introduced. Irrigation alone has probably improved SOC.
By contrast, see this paper on long term (2-3 decades) SOC loss/gain under grazing with biggest losses under intensive dairying and gains on low intensity hill country grazing. 31 profiles from many parts of the country.
Perhaps reducing dairy consumption is more important the reducing meat.
@ scaddenp & foolonthehill Last several posts
Holism in science or systems science in agricultural management systems has absolutely nothing to do with magic or faith. It has to do with the very agressive and expanded comprehensive monitoring and how that data is applied to the adaptive management plan as a whole. I don't even know where you got the idea that it has anything to do with faith? Maybe because any science/technology sufficiently advanced seems like magic to those uneducated in that field? For example, quantum physics seems like magic to me, because it is beyond my field of expertise. Intellectually I understand it isn't magic, but I don't understand how it works. So it still seems mystical and I have to take it on faith those scientists know what they are doing. That's a different kind of faith though. That's faith with evidence as opposed to faith in the absense of evidence. Standard Newtonian physics I understand quite well. It was part of my general education. To someone well educated in conventional agricultural systems, carbon farming/ecoagriculture may seem mystical because it heavily relies on systems science and holism, but it is based on evidence.
Please read the definitions and short descriptions of these terms here, so we have a common foundation to communicate: systems science , holism We can discuss the exact nature of this monitoring and the context in which that data obtained applies to any adaptive agricultural management plan, but this is a bit outside the context of the thread. All that needs understood is that this is designed to obtain information about ecosystem function by monitoring key indicators. By tracking how changes in the adaptive management plan effect these key indicators over time, the plan is capable of being adjusted to optimize those beneficial aspects and minimize the negative. It is a given that no plan starts out optimised, nor is every change beneficial, but because of the monitoring, they improve over time. Over time as this is applied, the plan and thus the ecosystem function, profit, yields etc... improve. And yes that includes, but is not limited to, the carbon sequestration into the soil, which is a key component to any terrestrial agricultural system and actually any terrestrial natural ecosystem as well. This is what is important in the context of this thread.
Now to address the other questions about the carbon cycle. It is fundamentally a self adjusting complex biological system. Yes we humans can effect changes in how it functions, but it still remains a self adjusting complex biological system, and as such systems science is required to understand how it functions. This is nothing new to climate scientists. There are all sorts of complex forcing and feedbacks that must be taken into account in any climate model. Those models are dependant on systems science. Climate deniers are the ones who tend to cherry pick one part out of context to mislead people. But most conventional agricultural science is not based on systems science. With the exception of the newer carbon farming/ecoagriculture, most of that information is a bit antiquated or modern but not applicable, focused primarily on mechanization technology, genetics and simple chemistry, not ecosystem function.
No scientist can know every field though, so sometimes that antiquated information when plugged into the climate models can be deceiving. One of the most deceptive parts is the encouraged myth that the current somewhat antiquated agricultural production models are required to meet demand, so climate scientists are told to focus on fossil fuel emissions instead. Emissions are only 1/2 the cycle. It is fail from the start. It can help, but it can never succeed. And unfortunately, leads to further misleading things like what is being debunked in this thread. We do need to eat. So as long as that myth prevails, it keeps people away from looking to closely at the environmentally destructive agricultural practises. It is sidelined to "land use change" and it's impact minimized to only that part of the agricultural land that is newly added, or lost, not the bulk that has been in continuous production for many years. Unfortunately, minimizing its impact also minimizes the benefit of changing it and/or what changes need to be made. So this is what gets me aggravated and annoyed and it is not any vegan or vegetarians fault, they are being misled as much as anyone else. To any climate scientist reading this, I understand you cant be expert in all fields, and must take it on faith that the information you obtain from agricultural scientists is reliable. Just remember the difference between faith with/without evidence, and look at the condition of agricultural soils worldwide for your assesment about how reliable the information you are receiving. If they knew what they were talking about, the agricultural soils worldwide would not be in such poor condition. After all, the highly educated farmers in developed countries are following their instructions, and those soils are in general getting even worse at a faster rate than uneducated farmers from developing countries. OK sorry for the rant, but it had to be said to partly explain where the misleading information is coming from.
Carbon can be broken up into two parts, the active cycle and the stable cycle. Obviously fossil fuels is part of the stable carbon. So is about 30-50 % of the soil carbon, the stable fraction.
Atmosphere and biomass both living and decaying, above and below the soil line is all part of the active cycle or active pool that exchanges relatively quickly. (There are other pools with limited to no part in agriculture like methane clathrates, limestone, ocean floors and permafrost etc)
Living biomass gets its energy from photosynthesis and absorbs carbon from the atmosphere, both CO2 and Methane or from the processes of decay. So you have two sides, the living growing side, and the dead decaying side. But life on this planet is carbon based, so it is all part of the active carbon cycle. This active biological cycle being a complex self regulating adaptive system. If for example a large part dies, the biomass responcible for biological decay grows and emissions of C increase. Also that biomass has a life cycle too and parts of it dies, all resulting more C emissions, but also more nutrient release, fertilizing the other side of the carbon cycle, which pulls out C from the atmosphere. Or if you get more vegetative growth, that pulls out C from the atmosphere, but eventually dies, increasing emissions. So anything you do to one side of the active cycle, increase or decrease, eventually is roughly countered by the other side. Increase methane emissions causes increased methanotroph growth, increased CO2 increases plant growth which leads to more decay when that additional growth dies, bringing you right back where you started, all else equal. So the vast majority of the active cycle is approaching carbon neutral. Any push you make on one side for good or for bad is countered roughly equally by the other side. You can speed up the cycle or slow down the cycle, but harder to increase one side while slowing the other side down. To do that you must break a link in the cycle. Animals are an important part of that cycle, they are responsible for increasing the rate of decay, which in turn increases the rate of growth. If you remove them, you slow the whole cycle down. Yes the rate of emissions decrease, but so does the rate of sequestration. Functionally think of it like this, a grass plant grows sets seed and then above ground leaves die. But if an animal grazes it before it can produce seed, it regrows and attempts again to set seed. This can happen several times in a season before the grass finally gives up and waits to try again next season. All that extra grow is short term sequestered carbon canceling out the effect of increased emissions. Slightly different with methane. more methane increases methanotroph growth, but that fertilizes plant growth when the methanotrophs die and decay. I would call that getting nowhere, but faster.
So ask yourself this, what does matter? Well 2 things really. Each ecosystem has a total biomass. So regreening a human caused desert, or reforesting some land does increase the total biomass that is living growing and dieing decaying. In both cases, once the new larger biomass reaches equilibrium, it becomes saturated and approaches net neutral again. OR causing desertification/deforestation does the reverse, decreasing total biomass which then also approaches net carbon neutral again. Those do either add or subtract to atmospheric carbon, but are limited to the increase or decrease in total biomass before reaching net neutral again.
However there is another part of the carbon cycle involving the stable pools. Fossil fuels are 100% stable pool carbon. ~30-50% of the soil carbon is the stable fraction. Normally this carbon does not cycle with the active carbon, but exchanges very slowly. When we burn fossil fuels, we are turning stable carbon into active carbon. Reforestation increases the biomass pool, but the biomass pool has limited effect due to reaching a saturation point. A new grassland reaches that biomass saturation point even faster! Both are active cycle.
But there are processes that turn active carbon back into stable carbon. It is a much smaller amount, but is additive and never really reaches a saturation point. In fact, in the right conditions, it accelorates. In a grassland that is more than in a forest, because the majority of the biomass of the grassland is below ground, while in a forest the majority of the biomass is above ground. So when grassland biomass finishes decaying, more gets trapped in the soil and less reaches the atmosphere. (unless the soil gets disturbed)
What matters long term is the net flux between the stable carbon cycle and the active carbon cycle. So to improve that positively we try to limit disturbance, maximise total active biomass, reach that saturation point as quickly as possible, then cycle it as quickly as possible without disturbing the soil. This way that small % that leaves the active cycle and enters the stable pool in the soil also increases. The biomass is saturated yes, but the stable pool just keeps adding and adding. The observation is that SOC increases. Once SOC reaches a certain point and starts tapering off, then the A horizon of the soil begins to get deeper and deeper. B horizon (sub soil) is being converted to A horizon (top soil). This is why natural grassland soils are much deeper A horizons than forest soils. But in agriculture we can do it even faster and deeper than natural grasslands, because we are optimizing as many parts of that cycle as we can. That's why it is called intensive, even though requiring less outside inputs, little to no fertilizers or pesticides or fossil fuel use etc... like most other forms of intensive agriculture people are familiar with.
Thank you for your comment RedBaron. I am not a scientist but I am interested in climate change and my contribution toward it. I appreciate the participation of those on the same journey.
As far as I can tell from what I have been reading, on a very basic level, my farming practices affect climate change primarily through the cycling of carbon and its compounds (and to some extent nitrogen).
As I understand it, the methane that my cows (by virtue of being ruminants) emit, acts as a forcing for a short period until it is oxidised to CO2. This CO2 is not a forcing.
If I wish to reduce this forcing from their methane emissions, I can lower my stock numbers. Alternatively I can rely on some as yet non-existant technology to reduce the amount of methane my current number of cows produce.
The grazing of my stock may or may not increase the carbon content of the soil. It would be wonderful if that were the case, as it would contribute to the mitigation of their methane emissions. Even better would be that the quantity of carbon sequestered back in the soil was sufficient to completely offset the methane emitted.
Unfortunately, I still havent seen enough evidence that convinces me that any method of pasture management achieves this goal. Studies are ongoing and that situation may change. Until then, it appears to me that I am contributing to climate change. I hope that I, like everyone else, can make changes to reduce that as much as possible.
@Foolonthehill
So measure it. You don't need to be a scientist to measure your own operation. simply take soil samples in a carbon protocol, (carbon testing protocol is slightly deeper than standard soil tests) that gives you the sequestration side with a simple calculation. Then you obviously have your utility and fuel costs. Another simple calculation. Then compare the carbon you are sequestering in the soil against the carbon from fossil fuels you use. You won't be able to tell others what they are emitting/sequestering, but you will know what you are.
@RedBaron
I have only recently started farming on my present land and testing the soil carbon will definately be part of my plan. I would think that this testing would need to be done over a number of years to get an idea as to what is going on. We are expecting a drought this year and I would expect that would affect plant growth and hence carbon sequestration. My situation is complicated by the fact that my land has a wildly varying contour so to get the best calculation I will need to take many samples over a large area.
Then compare the carbon you are sequestering in the soil against the carbon from fossil fuels you use.
And to complete this calculation as regards climate forcing I will also need to calculate the amount of methane my cows emit and enter this into the equation too.
RedBaron - would your labels "stable" and "active" be equivalent to "immobile" and "mobile" from point of view of carbon flux? What is the form of the "stable" carbon?
The trouble with intensification of grazing from emissions point of view is more animals and thus more methane. Because methane is more radiatively active than CO2, you need sequester a lot of carbon to offset the extra methane. Again, I dont see evidence presented so far that says any form of intensive grazing achieves this. Where is the evidence for "All that extra grow is short term sequestered carbon canceling out the effect of increased emissions". To be convincing, a paper needs to show carbon stored per hectare per year is more than CO2e emitted per hectare per year.
For example, in the 20-30 year study on SOC change I linked to above, the best SOC gain was about 200g/m2/year (upland grazing). I make that 5480g/hectare per day for a CO2e of 20,000 gCO2e/ hectare/day. Compare that to emissions of 170g per day of CH4 per beef upland animal . With a stocking rate of 2/ha that would be 170x2x28 = 9520gCO2e/hectare/day. Now that is really offsetting CH4 and goes into the countries GHG inventories as an offset.
However, most soils showed much lower SOC gains and even losses, especially when grazing was intensified. Not only does stocking rate go up but emissions per animal increase as well. SOC gain of 100g/m2/yr, 4/ha and 190g CH4 per animal and suddenly it is 10,000gCO2/hectare versus 21,200gCO2e/ha emitted.
It is also worth noting that GHG inventories do take CO2 sequestration in grasslands into account. See here for the methodology used by IPCC.
That said, we need food, and farming practices that minimize total emissions in producing it are definitely part of the solution.
Scaddenp,
I have a small paddock that could support 2 cows or a small flock of sheep or goats. Would a small flock of either sheep or goats emit more/less/same greenhouse gasses than cows?
@michael sweet
Jumping in for no other reason than that I can...
I think you will need to narrow down quite a few variables before any quantitative decision could be made. The first would be 'small flock' - your piece of string may be of a different length to mine :-)
What forage is in the paddock? how old are the animals? are you rearing them for milk or meat? will your climate necessitate supplementary feeding in winter? do you intend to use fossil fuel derived fertilisers? Even the breed of animal is another complication to be factored in.
Any reliable calculation will be a very personal one.
It's likely that there will be a tertiary agricultural institute somewhere in your country that will be able to give you information that is better tailored to your situation.
You could take a different route with non-ruminants and get some pigs/chickens... Maybe bacon and eggs can salve a possible guilty conscience?
@scaddenp
OK Fair enough. Here is some evidence that leads me to believe it is not the ruminant at all, but rather the feedlot production system, including both the feedlot and the grainfields supporting the feedlot, and the petroleum derived chemical fertilizers supporting the grainfields, ie that whole "factory farming" system, that is to blame. Even when it comes to methane.
Starting with this comparing nitrogen fertilizers instead of organic fertilizers.
Environmental impacts on the diversity of methane-cycling microbes and their resultant function
"In a temperate agricultural soil, long-term fertilization with ammonium nitrate reduced methanotroph abundance by >70%, resulting a similar decline in methane oxidation rates (Maxfield et al., 2008; Seghers et al., 2003a) observed a similar pattern that was associated with reductions in the abundance of low-affinity type I methanotrophs. Different groups of methanotrophs may show different responses to fertilization, as observed in rice field and forest soils where type II methanotrophs were more strongly inhibited by mineral N fertilization than type I methanotrophs (Mohanty et al., 2006). In contrast, organic fertilizer addition can increase methanotroph abundance and associated rates of methane oxidation (Seghers et al., 2005)."
Here is the evidence that leads me to believe that this really is nuanced enough and the emergent properties of the system large enough to completely offset the CH4 produced when managed properly.
Methane fluxes from differentially managed grassland study plots: the important role of CH4 oxidation in grassland with a high potential for CH4 production.
"Under field conditions, heavy autumnal rain in 1998 led to a dramatic increase of soil CH4 concentrations upto 51 microliters l-1 at a depth of 5 cm. Nevertheless, no CH4 was released when soil surface CH4 fluxes were measured simultaneously. The results thus demonstrate the high CH4 oxidation potential of the thin aerobic topsoil horizon in a non-aquatic ecosystem."
And here is the evidence that the whole grassland ecosystem including the animals and the atmosphere can be included in my claim:
IMPACT OF METHANOTROPH ECOLOGY ON UPLAND METHANE
BIOGEOCHEMISTRY IN GRASSLAND SOILS
"At a global scale, soil uptake is the most important biological sink of atmospheric methane, offsetting emissions by about 30 Tg y-1 (Denman et al. 2007). Without this sink, Ojima et al. (1993) estimated that atmospheric methane through the 1990‘s would have increased at 1.5x its observed rate."
and
Cenozoic Expansion of Grasslands and Climatic Cooling
"Grasslands and their soils can be considered sinks for atmospheric CO2, CH4, and water vapor, and their Cenozoic evolution a contribution to long-term global climatic cooling."
So rather than blame the animals for the increase in atmospheric methane, rather blame Haber process nitrogen, something that is not needed in a properly managed pasture. From the systems science POV, when you remove the animal from the pasture and put them in a confinement system, you break part of the methane cycle, causing a nuanced chain of interactions with soil biota, quantifiably decreasing ecosystem function. Net result? You turn a net methane sink into a net methane emissions source. So it is very important to be very precise when discussing "intensive" agriculture. Managed Intensive Rotational Grazing is an intensive agriculture, but is very different than intensive agriculture reliant on expensive AGW causing inputs. Properly done, MIRG can actually help mitigate AGW, not cause it.
I believe it was foolonthehill that mentioned drought. Turns out that holistic planned grazing can also have a substantial positive influence on water content of the soil as well, making the system more resistent to drought. Here is that evidence:
Effect of grazing on soil-water content in semiarid rangelands of southeast Idaho
Of course at least in the USA, there is well managed, poorly managed, and non managed land. So even though 95%+ of all animal husbandry in the USA is the CAFO business model which I consider to be poor management, here is the evidence that leads me to believe all the land taken together is a net sink and thus refutes the myth that 'animal agriculture and eating meat are the biggest causes of global warming.'
"Agriculture (9% of 2013 greenhouse gas emissions) - Greenhouse gas emissions from agriculture come from livestock such as cows, agricultural soils, and rice production.
Land Use and Forestry (offset of 13% of 2013 greenhouse gas emissions) - Land areas can act as a sink (absorbing CO2 from the atmosphere) or a source of greenhouse gas emissions. In the United States, since 1990, managed forests and other lands have absorbed more CO2 from the atmosphere than they emit." [1]
Finally you asked me about what is considered the active fraction and stable fraction of carbon in the soil. I am using the Soil Food Web model taught by the USDA-NRCS. There are other models like the Century model. Either way the stable or long term cycle carbon is called humus which lasts from hundreds on into geological time measured in millenia, as long as the soil is not disturbed.
The Zero Carbon Australia Land Use Report published by Beyond Zero Emisisons and Melbourne Sustainable Society Instititue (University of Melbourne) pegged Land use emissions at 55% (using 20 year GWP) of Austrlia's national GHG emissions once complete examination of all flows of emissions and sequestration are accounted for. Their methodology went well beyond the methodology of UNFCCC specification that is typically used for these accounting exercises. Even using 100 yr GWP (which tends to obscure the effects of methane on a climate system that is already set for very dangerous weather) the emissions will approact 50% within years on present trend.
It's a while since I read it but because I was working with the principle authors I'm aware that they found sufficent evidence for them to reject the hypothesis often possed (the source of which is apparently a paper that contained an magnitude of ten error) that oxidation of methane by water vapour above grass neutralises the effects enteric fermentation (highest in pasture fed ruminets not lot animals as someone here seems to be claiming). Most cattle in Australia are lot fed for the last year or two of there lives to increase their weight for profit motive. They also rejected what is often refered to as the Alan Savory method by permiculutre types who like to think that zero emssions ruminent production is realsitic proposition. Of that 55% of national GHG emissions, emissions associated with livestock were calculated to be 90% i.e. 50% of national emissions associated with livestock production. Major emissions sources were land clearing, savanana burning and enteric fermentation.
The Land Use Report began a feasibility study of what kind of reforestation would be requierd in each IBRA Sub-region to offset the emissions assoicated with the predominant agriculutral use for the region.
it's interesting to me that this area of climate science is both one fo the least studied and one fo the most heatedly contested amoughst scientists and others who otherwise accept the general IPCC positions on human induced climate change (even if some of us think the IPCC has been ultra conservative in it's communication of the science).
then you have scientist like Dr Elaine Ingham who claim vast potential for organic sequestration if we stoped killing our soils with synthetic fertilizers and exposeur to the sun. by vast she claims equivilent contemproaraeous to human emissions.
my understanding is that the ZCA Land Use Report was supervised within MSSI and peer reivewed, though its publication was by BZE and MSSI not in a journal.
ZCA Land Use Report specifically rejected this Alan Savory type argument. they found that dietry interventions can reduce methane emissions significant;y, but only can be used in lot feed systems, I've recently read that studies by diary industry have found that small amounts of grain feed eaten in the milking shed or afterwards can reduce enteric fermentaion by some significant amount but not entirely. Another thing they point out about Savory's assertions is that if you had farm workers moving temporay fences every day it would remove profitibility from the vast pasteral operations with large head counts that rarely see humans let alone get daily management in small mobile herds. Nobody has replicated the Savory assertions in a commercial livestock operation any place in the world in a study that can varify the claims around sequestration.
#69
I wonder if that's because you make a dubious anaolgy with ten fat cows and five skinny cows and make no attempt whatsoever to decribe any mechanism by which the overgrazing leads to fatter cows! Have they been there longer, were they rotated through fields, so many variables in farming and you talk of riddles. I assume you are attempting a paraphrasing of the Savory assertion, yet to confirmed with science in any commenrical farming system anywhere in the world.
#69
I would like a reference to that paper you refer to that demonstates ruminet ag is a net sink not a net source of emissions. Many permaculutralists repeat this assertion as an article of faith, so it's not like its a new one for me but I've never seen the convincing evidence and plenty to contradict it.
You make this assertion liberally but I can't find your citation 'up above', yet.
#78 foolonthehill
the technology to reduce the enteric fermentation in your cattle does exist, fed them some grain. various studies have looked at this and other inteventions. of course the grain also has emissions associated with it and if synthetic fertlizers have been used destruction of the soil biota and therefore short term carbon cycle is part and parcel their use.
I recommend you download the (free) Zero Carbon Australia Land Use Plan as it covers every aspect of Land Use emissions and sequestrations in what I would describe as great detail for anybody who doesn't study emissions in ag system.
@wideEyedPupil several posts
Your posts while thoughtful and well referenced do hilite the limitations of applying reductionist science to complex self regulating biological systems. Some of the things you talk about do partly take into account some of the unexpected emergent properties of the system, and some view it quite linearly. You really do need to be careful how you build back the reductionist science into a systems view.
Also you answered the riddle wrong, which means you haven't thought that out correctly either. So lets start with that. Overgrazed land produces less forage, less forage means it supports less animals, thus the correct answer is the overgrazed land is the one with 5 skinny cows. Properly managed land produces more forage. Much more. in the field we see 3X more forage, maybe 5X more forage, maybe more, it really depends how badly the land was overgrazed to begin with. The worse it was, the more improvement to be gained by proper management. So more forage means it supports more animals. The 10 fat cows are on the properly managed land in the riddle. I know it is counterintuitive, but once you think it through, hopefully you will understand.
Next, you said, "It's a while since I read it but because I was working with the principle authors I'm aware that they found sufficent evidence for them to reject the hypothesis often possed ... that oxidation of methane by water vapour above grass neutralises the effects enteric fermentation"
That's not the hypothesis, so rejecting that hypothesis doesn't really get you anywhere. That is describing abiotic oxidation. The hypothesis is the soil biota increases, including but not limited to methanotrophs. Increases in methane, in the right environmental conditions causes an explosion of methanotroph populations, and that is what biotically reduces the methane. Those environmental conditions that lead to the explosion of soil biota populations, including but not limited to methanotrophs, being enhanced in a properly managed grazing system. It's biotic, not abiotic.
Next you said, "Nobody has replicated the Savory assertions in a commercial livestock operation any place in the world in a study that can varify the claims around sequestration."
That isn't true. Maybe the ZCA Land Use Report couldn't find anything, but that doesn't mean it doesn't exist. I even posted one here that included several commercial scale ranches. At least I think I did. Just in case, here you go: [1] There are more even larger, but I don't think they have been published yet.
Next you said, "You make this assertion liberally but I can't find your citation 'up above', yet."
No problem. I repeated that citation and added some new in post #84, since people were having problems finding and/or understanding.
Next you said, "the technology to reduce the enteric fermentation in your cattle does exist, fed them some grain. various studies have looked at this and other inteventions. of course the grain also has emissions associated with it and if synthetic fertlizers have been used destruction of the soil biota and therefore short term carbon cycle is part and parcel their use."
This indicates to me you almost kinda understand. Just use that type of thinking, but expanded to include a wider array of emergent properties and interactions. More variables change than just the ones you mentioned and they all have interlocking interdependencies.
Michael Sweet, I looked at this quite a while ago and thought that for same amount of forage, production of methane per hectare was pretty similar between sheep and cattle. However, a review paper here suggest greater differentiation than this, with 10 sheep = 1 cow (and less CH4 from manure). This paper based on identical feed gives cattle lower, (8 sheep = 1 cow). I dont have figures for goats easily to hand but I remember them as being very similar to sheep. That said, there are very considerable differences in management of the 3 species for a small lot! Of course you could also look at rabbits or guinea pigs which are much better than ruminants ( but with completely different management and harvest issues).
RedBaron, firstly we talking about effect of farming. The effect of grassland expansion on climate in Cenozoic is not that relevant compared to even pre-industrial farming.
If I understand you correctly, you are now saying that CH4 production from increased ruminant density is offset not only by SOC increase (yet to be demonstrated) but also by changes to CH4 sources/sinks in microbial soil activity? My first reaction is to be highly skeptical since biogenic methane budgets are estimated both top down and bottom up. While there is imperfect closure which might be accounted for from microbial changes, this cant be very significant.
Assuming I have understood your argument correctly, I do not really see support for this in your papers. "Methane fluxes from differentially managed grassland study plots: the important role of CH4 oxidation in grassland with a high potential for CH4 production" looked at changes with different fertilizer and water but as you stated, it found no increase in flux due to oxidation in top layer. How does this support your thesis of "large enough to completely offset the CH4 produced"?
The fluxes measured in the experiment are tiny compared to enteric emissions (0.0017g CH4/day cf 140-160 dry cattle).
Methane uptake in upland soils is acknowledged as a sink but the paper suggests to me that this capacity would damaged by agriculture. Indeed, it references del Grosso which surveyed methane oxidation across upland soils and concluded: "The soils used for model testing showed a clear division in CH4 uptake rates among biomes. Grassland and agricultural soils had the lowest annual CH 4 uptake (<1.5 kg C ha-1 yr-1), coniferous and tropical forests showed intermediate CH 4 consumption (1.2-3.5 kg C ha -1 yr-1), and deciduous forest soils had the highest CH4 oxidation rates (4.5-10 kg C ha-1 "
Note also that enteric methane production is at least an order a magnitude greater than highest oxidation rate.
I dont want to be critical of MIRG, especially compared to grain feedlots, but certainly dont see this as answer to CH4 emissions.
Scaddenp and Fool on the Hill,
Thank you for your interesting comments and references. I will have to think about methane and see what I can do to minimize my emissions. I have about one hectare of land that would support one or two cattle without suplimentary feed (or a comparable number of smaller animals). Currently there is a sizable population of rabbits that the local coyotes eat.
@scaddenp
You are definately missing the boat on methane. The reference says even though there was a "dramatic" increase in methane produced, "none" was released to the atmosphere. So other studies that simply measured emissions failed to account for this emergent property. Also I am well aware that current methods of agriculture most commonly used do release methane to the atmosphere. The reason I showed that the natural ecosystem functions as a sink, is because ecoagriculture uses biomimicry to mimic that ecosystem function already evolved in a natural ecosystem (grazer/grassland biome) in order to change what is currently an emissions source into a sink as well. A sink that self regulates. ie when when production of methane increases, none releases to the atmosphere because the biotic reduction of methane also increases. Go back and read that a little closer please. "Nevertheless, no CH4 was released". This is the perfect example of an unexpected emergent property of the system. And do keep in mind we are talking about aerobic soils managed in a certain way. They exchange gasses with the lower levels of the atmosphere ie they "breathe". The CH4 goes into the soil, but none is released. That's why it can be viewed as a sink under those conditions.
RedBaron, I am not disputing the reference. The release of methane to the atmosphere from agricultural use is mostly a/ paddy fields (where there is no oxidizing layer) b/ Enteric emissions from ruminants (nothing to do with soil microbial activity) plus some from manure.
I am just failing to understand how you are linking this idea to position that increasing ruminent intensity even on MIRG isnt putting more methane into the atmosphere. If microbial activity is binding more carbon into soil, then it should show up in SOC measurements. Mostly, we see the reverse - intensity = less SOC, or that enteric emissions overwhelm increased SOC.
And dont forget that areas with increased SOC are counted in GHG inventories. It's not like GHG emission strategists have missed something.
Michael, I suspect the amount of time that you have available for animal management might be the overriding factor. Sheep need shearing (which is plus if you can get more for wool than cost of shearing), but fattening a few lambs might be good option. Goats climb and like eating things other than grass...
@scaddenp
I guess maybe where you are struggling is the concept of soil microorganisms as a controller of atmospheric trace gasses. Without that foundational understanding, any new studies lack the contextual relationship for you to understand. So to help you understand, I found an old review from 1996 that explains what we knew and didn't know about how soil biology controlls atmospheric trace gasses at that time. This maybe will give you the context needed to understand how new discoveries are unlocking the mechanisms by which the grazer/grassland biome taken as a whole functions as a methane sink and not an emissions source....managed properly of course.
Soil Microorganisms as Controllers of Atmospheric Trace Gases
(H2, CO, CH4, OCS, N2O, and NO)
@redbaron
thanks for the responce. I'm quite aware of emergent behaviors in complex systems (and the modeling of such phenomena in theoretical computational simulations), and the general complicatedness in addition to the complextiy of soil biota and any biological systems above the ground that might be active on it and therefore interacting with biota.
as someone challanging the dedicated work of the Land Use Plan that puts land use sector at 55% of emissions (and I've never heard that number challenged in the literature) i think the onus is on you to demonstrate any complexity that undermines 55% of total emissions with data and evidence — the rallying of phrases like emergence, complexity and reductionist science is no doubt music to my ears but data and specifics it is not.
you seem to find a way to build condencension into every second para but what I want to see is evidence, not defensive assessments of whether or not I 'get' your riddles. I understand the importance of soil biota and not destroying the surface vegetation in protecting the soil biota. I understand that your exmaple of ten fat cows and five skinny cows is designed to impress on one the problem of overgrazing (even though intensive over-grazing and recovery is exactly what Savory advocates so you gloss that detail too) but you forgot to I've read a tiny bit of everything from Masanobu Fukuoka's "The One-Straw Revolution" to Permiculture One to sitting in some of Dr Eliane Inghams (USA/Australian biota and fungi expert) online lectures and watched "One-Cow One-Planet".
I've visited many properties where overgrazing is a conceeded fact and others where the reverse is happening e.g. a biodynamic berry farm where the green manure crop of barley was reaching 8" high and still growing. It's clear increasing soil health increases 'carrying' capacity of the land when bio-diversity is encouraged in principle at a sytems thinking level rather than reductive Green Revolution type ag-disaster industrial farming.
But all that is not a substantive proof that methane is neutralised nor is it evidence that intensive grassing on rotational basis is vastly more productive, or indeed that animal intensive agriculture is a prefered responce to climate change. I'm reading a lot of commentary and philospohising in your posts and not much science. Thanks for the references I'l attempt to comprehend the work and get back to you on the science.
Redbaron, this still avoids the main points.
1/ microbial soil activity in changing CH4 is insignificant compared to enteric emissions. The very highest rates of CH4 soil oxidation measured by Del Grosso are still an order of magnitude less than ruminant emissions. 2 orders of magnitude for grassland. Are you disputing that measurment? Your reference appears to be hopelessly dated compared to modern sources (eg see the methane cycle in the IPCC from 3rd report onward and the references from which this table is based).
2/ If you want to argue for soils being significant in sinks, then SOC must be demonstrated to be increasing. No matter how complex the interactions going in soil/atmosphere, if SOC is decreasing, then soil is not a sink. Furthermore soil oxidization only accounts 5% of methane destruction so hardly a "controlling" influence.
@redbaron
8" —> 8 feet
you are climaing that in this study you refer to and I'm yet to read that all enteric fermentation dervived methane never enters the atmosphere because it is locked up in soil biota (given a particular pasture managmanet system). Methane being a gas that is lighter than many other gases in the atmosphere it's going to rise, to suggest that 100% is trapped in the soil when it's being breathed out ~1 meter above the soil is counter-intutative to me. I use that phrase because I'm sure it's music to *your* ears :-)