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Comments 26701 to 26750:
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saileshrao at 20:10 PM on 4 December 2015How much does animal agriculture and eating meat contribute to global warming?
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 at 19:53 PM on 4 December 2015How much does animal agriculture and eating meat contribute to global warming?
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. -
RedBaron at 12:16 PM on 4 December 2015How much does animal agriculture and eating meat contribute to global warming?
@scaddenp #53 In ref to my post #52
I was specifically refering to Managed Intensive Rotation Grazing, not other forms of agricultural intensification. MIRG
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scaddenp at 12:15 PM on 4 December 2015How much does animal agriculture and eating meat contribute to global warming?
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.
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Jim Eager at 12:02 PM on 4 December 2015How much does animal agriculture and eating meat contribute to global warming?
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.
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scaddenp at 11:51 AM on 4 December 2015How much does animal agriculture and eating meat contribute to global warming?
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?
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RedBaron at 10:46 AM on 4 December 2015How much does animal agriculture and eating meat contribute to global warming?
@ 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.
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OnceJolly at 10:35 AM on 4 December 2015How much does animal agriculture and eating meat contribute to global warming?
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."
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KeenOn350 at 10:22 AM on 4 December 2015New research finds that global warming is intensifying wildfires
Typo needs fixing - in quote from the summary -
2014 was the second longest largest in
DaveW
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denisaf at 09:09 AM on 4 December 2015Deep Ocean: Climate change’s fingerprint on this forgotten realm
This discussion of what is irrevocably happening in the oceans due to the unintended, deleterious consequences of industrialization is just one of the symptoms of what has gone wrong. However, the efforts of the likes of Levy can well contribute to society slowly waking up to making sound adaption and amelioration decisions. Hopefully, the Paris talks will see a little progress in that direction.
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saileshrao at 08:16 AM on 4 December 2015How much does animal agriculture and eating meat contribute to global warming?
Jim Eager @46:
Please see, e.g., Anthony Barnosky's paper in PNAS,
http://www.pnas.org/content/105/Supplement_1/11543.full
and Vaclav Smil's book, "Harvesting the Biosphere: What We Have Taken From Nature":
http://www.amazon.com/Harvesting-Biosphere-What-Taken-Nature/dp/026201856X -
scaddenp at 07:23 AM on 4 December 2015How much does animal agriculture and eating meat contribute to global warming?
Redbaron - please see this paper. Soil carbon loss under intensive dairying is a substantial issue here in NZ and the subject of research eg (here). It looks like intensification of agriculture is not good for carbon soil stocks.
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Reason_4 at 06:55 AM on 4 December 2015How much does animal agriculture and eating meat contribute to global warming?
@Jim Eager @47
Not sure how I can explain this better, but lets make it even simpler.
If I release 1 ton of methane (yes regardless of source) that results in a certain amount of forcing ... right?
If I release 1 ton of methane AND at the same time sequester 5 tons of CO2 there is still some NET forcing ... but not as much as in the first example ... right?
This net result is why we (of course) don't count CO2 emissions from respiration (not just because CO2 is a less potent GHG than methane, but because the net result is zero)
This is my very simple question regarding emissions from livestock. Why do we not look at the emissions AND the source of the carbon in those emissions AND any associated sequestation that arises as a result of raising livestock - and then arrive at a net figure for the whole operation.
Fossil fuel sourced methane is simple - we know the source, so no short term carbon cycle to allow for there ... right? and until there is finally some actual commercial CCS projects run in association with extraction, there is no sequestration adjustment necessary to arrive at a net forcing either ... right?
If we don't examine the net forcing arising from 'animal agriculture', how can we say that we are addressing the question raised by Dana in the title of this article ... accurately?
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One Planet Only Forever at 02:08 AM on 4 December 2015Uncertainty is Exxon's friend, but it's not ours
A clarification of my comment@11.
The event that flooded Calgary ion 2013 included large amounts of rain falling at higher elevations in the mountains that would have been a snow acumulation at that time of year if it was just a bit cooler. Also, the ground at higher elevations was still frozen which is not uncommon in the late spring but may have been due to a lower than normal thickness of snow insulating the ground from freezing during the winter (thicker snow will reduce the depth of freezing in the ground it covers) ... Lots of added uncertainty with rapid rates of climate change, including the interactions between different factors.
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One Planet Only Forever at 01:33 AM on 4 December 2015Uncertainty is Exxon's friend, but it's not ours
knaugle@9
The example you presented can be repeated for every climate related weather behaviour that affects a built item. But it is important to understand that there is even more involved in a dam design than how much total volume will end up being held behind the dam.
In addition to the basic design rule of a once in 100 year rain event volume being the 'regular upper limit on water levels', every dam is also evaluated for its ability to hold back more than a one in 1000 year event without being 'overtopped'. Associated with the evaluation of the overtopping is the rate of safe by-pass through the feature designed to safely allow flow to by-pass the dam to avoid catastrophic over-topping.
The 2013 flooding of Calgary was the result of a very intense rain event in the mountains upsteam of Calgary early in the spring. The result was an impossible to respond to rate of water trying to pass through the Calgary waterways. The many dams upstream of Calgary were not able to mitigate the event. Scientific evaluations have been performed to try to determine what run-off events could occur and what features may best mitigate those potential events, and rapid climate change adds significant uncertainty to those evaluations.
There have also been cases in Calgary of very recent wind events resulting in parts of buildings, including window panels, being blown off of already completed buildings that have been standing for many decades.
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Jim Eager at 00:50 AM on 4 December 2015How much does animal agriculture and eating meat contribute to global warming?
Reason_4: "I am still mystified why fugitive CH4 from fossil fuel extraction or transport seems to be treated in the same way that CH4 from ruminant livestock is treated or accounted for."
Simply because the atmosphere does not care where the CH4 comes from, the additional forcing is the same regardless. -
Jim Eager at 00:46 AM on 4 December 2015How much does animal agriculture and eating meat contribute to global warming?
Saileshrao, sorry, but simply asserting that livestock respiration is anthropogenic does not make it so. It is still atmospheric CO2 in, atmospheric CO2 out. Overgrazing degradation of range land and desertification are serious but separate issues.
saileshrao: "biomass of livestock megafauna today is 5.5 times the biomass of ALL megafauna from prehistoric times!"
Citation please. The pre-European population of North American bison alone was in the order of 20-30 million.
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bjb11213 at 00:19 AM on 4 December 2015Uncertainty is Exxon's friend, but it's not ours
In most legislations, ignorance is no defence.
I wonder if there is a case in US or world courts for suing Exxon for their share of the climate damage done since 1980, when they became aware of the consequence of their actions. I say this with some reluctance as I'm well aware that the primary beneficiary of any action would be lawyers hired by both sides of the argument.
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Tom Curtis at 00:18 AM on 4 December 2015How much does animal agriculture and eating meat contribute to global warming?
CBDunkerson @44, an excellent summary. It is, however, a little over pessimistic. Research is being undertaken into how to reduce methane from enteric fermentation and from rice cultivation. Further, given that amospheric methane concentrations must be near the equilibrium value for current emissions (else the plateau of concentration over the 1990s would not have occured) such measure may feasibly limit future growth in CH4 concentration - although it is dubious, in the face of the need to feed a more than doubling of the human population, that they will permit a decease in concentration. Of greater concern in that regard is NO2, whose longer residence time means it is nowhere near equilibrium, and where reduction of agricultural emissions is more limited in potential scope.
The point remains, however, that the key task in to reduce CO2 emissions. That is not only because it is CO2 emissions alone that will cook us long term, but also because tackling CO2 emissions is likely to lead to the technology to generate slightly negative net emissions of CO2 as a compensation of whatever persistent forcing from CH4 and NO2 exists.
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knaugle at 23:19 PM on 3 December 2015Uncertainty is Exxon's friend, but it's not ours
@One Planet Only Forever
Another way to explain your point would be to consider dam construction. In my area, state law requires dams to be able to withstand a 100 year flood. That would be something like what Hurrican Camille did to Virginia back in the 1960s. However, if climate change makes the 100 year flood more like whatis now a 1000 year flood, then everything we build is rather underdesigned. Even in this case, there well always be someone who thinks a 50 year flood is plenty.
It is not that there is uncertainty in climate, weather changes one year to the next, but that climate change itself quantitatively changes the uncertainty in weather parameters that must be assumed in the design process. It may well be that today's robust design in 50 years is woefully inadequate.
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CBDunkerson at 22:48 PM on 3 December 2015How much does animal agriculture and eating meat contribute to global warming?
I think we have established that the long term impact of livestock methane emissions is likely to be very low (when we consider that it will decay to CO2), zero (when we consider that the emitted carbon is essentially re-cycled from the atmosphere to begin with), or even negative (when we consider carbon sequestration from waste).
Given this plausible range of 'very little harm' through 'some benefit' it seems clear that we can pretty much ignore the issue. Long term, methane from livestock isn't going to be a problem. The same can probably be said, for similar reasons, of methane from rice production and even landfills. Methane from fossil fuels doesn't have the 'recycling' and 'sequestration' conditions, but it still decays to CO2 and thus will have a small long term impact... especially as it will inherently decline if/when we get the much larger direct CO2 emissions from fossil fuels under control.
Ergo, I would argue that we can all but ignore methane for long term planning purposes. We need only look at its 'short term' (e.g. through 2100) impact. Unfortunately, given Tom's analysis and IPCC flow diagram, there I do see a problem. So long as the human population continues to grow I see very little chance of preventing methane emissions from livestock, rice, and landfills from also growing in response. That will mean continually increasing emissions and atmospheric levels. In one sense, these human activities which temporarily convert some of the CO2 to methane are one of the 'sinks' slowing the growth of atmospheric CO2 levels... which unfortunately results in a net warming increase. That means, short of radical changes to the global food supply and/or waste handling, the 'short term' warming from methane will continue to grow so long as the global population does.
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Dikran Marsupial at 22:17 PM on 3 December 2015Murry Salby's Correlation Conundrum
BTW from figure 1, you can see that the net natural sink has been growing over time, which suggests that the net natural sink is a response to increasing anthropogenic emissions. If you extrapolate backwards I suggest you will find that the net natural sink would hit zero sometime in the 19th century. In reality a small net natural sink has been in existence for rather longer, but the rate of increase isn't exactly linear, so the extrapolation doesn't give a precise estimate.
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Dikran Marsupial at 22:08 PM on 3 December 2015Murry Salby's Correlation Conundrum
"If the earth system is a net sink for CO2, and if human contribution prior to the industrial revolution was insignifigant, then shouldnt the long term trend of atmospheric CO2 prior to that point in time be headed towards zero ? "
No, the carbon cycle has feedback mechansims that tend to increase the amount of CO2 in the atmosphere and others that tend to decrease it. So if you leave the carbon cycle to its own devices, it eventually finds an equilibrium atmospheric concentration and stays fairly constant (which is what we observe in the ice core records, during interglacials, the level returns to more or less the same level each time). However, if you do something to upset the balance (e.g. fossil fuel emissions), then the various feedback mechanisms tend to act to try and return the atmospheric levels back to normal (this is apparently known as LeChatellier's principle). The reason natural emissions and uptake are out of balance is because anthropogenic emissions have perturbed the previously stable equilibrium. In pre-industrial times, natural emissions and natural uptake were approximately balanced, and so atmospheric CO2 levels were relatively stable.
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Reason_4 at 22:01 PM on 3 December 2015How much does animal agriculture and eating meat contribute to global warming?
@scaddenp and Jim Eager @ 34 and 35
I'm well aware of the difference in warming/forcing potential between CO2 and CH4.
I am still mystified why fugitive CH4 from fossil fuel extraction or transport seems to be treated in the same way that CH$ from ruminant livestock is treated or accounted for.
Yes, both have the same forcing potential, but one is at least carbon (not forcing) neutral while the other ... isn't.
Let me try another way. We have yet to raise ruminant animals on our mini farm, but more from lack of knowledge and unwillingness to be tied to the property 365 days a year than for any environmental concern. But it is in the long term plan.
When we do I want to be well armed to defend our choice against those that say we are destroying the planet by keeping cattle or sheep. I will hopefully convince someone from the local Uni to take some before and after soil samples to demonstrate the increased carbon sequestration nutrients from large animal manure helps create. If we can point to greater carbon sequestration than is likley to be emitted, and there is no need for externally sourced feed or fertilisers, we would be justified in stating the meat we produce is carbon negative ... right?
If we can justifiably make that claim ... again, just why is fossil fuel sourced methane treated exactly the same as livestock sourced - because if that is all that is counted, our carbon negative cattle ... are anything but. Right?
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Dikran Marsupial at 21:53 PM on 3 December 2015Murry Salby finds CO2 rise is natural
The first factual error he makes is at 1:15 and is the first piece of scientific information given in the talk. He says:
"The IPCC position is exclusive; the increasing CO2 results from anthropogenic emissions entirely"
This isn't actually true, in AR5 says (page 493)
"With a very high confidence, the increase in CO2 emissions from fossil fuel burning and those arising from land use change are the dominant cause of the observed increase in atmospheric CO2 concentration"
The reasons they say "only "dominant" is because there are also emissions from cement production, but also to allow for the possibility of some component due to ENSO (I know this because I asked for clarification). So Salby misrepresents the IPCC in the very first statement. Not a good start.
The fact that the natural environment is a net carbon sink is, somewhat ironically, established by the equations he gives on the slide from 5:12. If instead of plugging in the IPCC estimates for natural fluxes, you use the observed growth rate to infer the difference between natural emissions and natural uptake, you find that natural uptake is always greater than natural emissions. This directly refutes Prof. Salby's conclusions, and he has been informed of this, but he contines to ignore that and doesn't mention in in his talks. You can find an explanation of why in my article on an earlier talk (I sent him a copy for comment before publishing it, but recevied no reply).
My article also explains his mathermatical error that starts with the following slide (note he never states exactly how he gets the data for that graph, and ignored my request for clarification).
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saileshrao at 20:08 PM on 3 December 2015How much does animal agriculture and eating meat contribute to global warming?
Jim Eager @ 35,
Livestock is NOT in equilibrium with the environment as the accelerating desertification of grasslands and pasture lands clearly shows. Indeed, the biomass of livestock megafauna today is 5.5 times the biomass of ALL megafauna from prehistoric times! Therefore, the breathing contribution of livestock is an anthropogenic contribution to the imbalance in the Earth's carbon cycle.
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saileshrao at 20:00 PM on 3 December 2015How much does animal agriculture and eating meat contribute to global warming?
Tom Curtis @28, HK @ 33,
Pierrehumbert's argument is that methane concentrations in the atmosphere will decay exponentially with a short half-life of 12.4 years. That is clearly not the case in reality as we continue to pump fresh methane into the atmosphere year after year, while pretending that methane is benign compared to CO2.
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RedBaron at 19:53 PM on 3 December 2015How much does animal agriculture and eating meat contribute to global warming?
@scaddenp #39
That is an excellent point. Sometimes people, even great scientists, get so wrapped up in the minutia of detail, they overlook the the bigger picture. The same thing that can be asked about rice paddys can be asked about meat production. How is it that the grassland/grazer biome responcible for long term global cooling on the planet, is now contributing to warming? (see post #21) What has changed since the industrial era? If you approach the problem from that perspective, I think the science is where the change in production methods might change the fundamental balance in the carbon cycle. That's where your interesting research can be found. What are the differences between a grassland/grazer biome and a cropland biome where the animals have been removed and instead raised in CAFOs? Rather than blame the animals themselves for AGW, I personally think the only conclusion anyone can make is the production methods have changed.
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bozzza at 16:05 PM on 3 December 2015Uncertainty is Exxon's friend, but it's not ours
@4, uncertainties change. The problem is no one can put their finger on any solid numbers with enough certainty to warrant investor panic.
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bozzza at 16:00 PM on 3 December 2015Uncertainty is Exxon's friend, but it's not ours
@1 the point you raise is, I suspect, even more poignantly significant, if not terribly ironic, than you first thought.
Ignorance of the law is no excuse: but of the moral law apparently not so!
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scaddenp at 12:12 PM on 3 December 2015How much does animal agriculture and eating meat contribute to global warming?
What matter with paddy production though is how much is it changing? Absolute emissions arent as interesting as how much change has occurred in 20-21 century.
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Digby Scorgie at 11:01 AM on 3 December 2015The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
Tom Curtis, I think your final paragraph is the one that's really relevant. It relates to the very first graph in the above article, from which we see that we only have about two decades in which to make drastic reductions in fossil-fuel use. And there are some parts of the fossil-fuel system that are built to last quite a bit longer than two decades — ships, aircraft and coal-fired power stations are some that come to mind.
Anyway, Tom, I don't know about you, but I find myself in the position of someone having an interesting philosophical discussion on the deck of the Titanic — after the ship has hit the iceberg. But then, being an old man, I can afford to take a dispassionate view of the whole catastrophe.
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Mal Adapted at 10:47 AM on 3 December 2015How much does animal agriculture and eating meat contribute to global warming?
Thanks to scaddenp for the reference to table 6.8 (not 5.8, sorry), on page 507 of the AR5 WG1 report. It shows that in the interval 2000-2009, rice cultivation contributed 36 Tg/year to the total 331 Tg/year of anthropogenic methane emissions, compared with 89 Tg/year for ruminants. I'm not surprised that vegans aren't calling for an end to rice production, however.
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scaddenp at 10:22 AM on 3 December 2015How much does animal agriculture and eating meat contribute to global warming?
RedBaron, i am in no way claiming that ruminants are only source of biological methane. I am really claiming that if you increase the number of ruminants (in particular since pre-industrial benchmark), then you are getting more methane into the atmosphere than if you had left them at preindustrial level. Increase in methane from any source is a concern, but the to-date, increase in ruminants is a major source. Numerous papers on this cited in IPCC report and working groups on methane. A review paper here could be starting point. Other sources of anthropogenic methane including paddy agriculture, landfills, manmade lakes/wetlands and waste treatment are considered in CH4 inventories. Table 5.8 in IPCC AR5 WG1 report lists source of methane with references. (Ruminants contributing 89 Tg/year of the total anthropogenic source of 331). The same table also lists natural sources but for consideration of change in methane level (and hence warming), it the change from pre-industrial at matters.
Note also that 2/3 of methane production from cattle is enteric rather than from manure.
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RedBaron at 09:48 AM on 3 December 2015How much does animal agriculture and eating meat contribute to global warming?
@scaddenp #34
Please supply some citation showing that this statement "there is more GHG effect than you would have if you had no animals (or no ruminants)." has been properly analysed and is true. Methanogens are microorganisms that produce methane as a metabolic byproduct in anoxic conditions. That certainly is true. But they are certainly not unique to ruminants. In fact methogen archaea are ubiquitous in the environment and soils. In some areas for example termites far exceed the methane production of any ruminants. Nor are methogen archaea the only source of methane produced by decomposition and incomplete oxidation of the products of photosynthesis. Nor is methane oxidation in the atmosphere the only way to reduce methane to CO2 as methanotroph prokaryotes are also ubiquitous in many environments. I have yet to see any documentation of any analysis of methane production that proves ruminants increase atmospheric methane over other forms of decomposition or incomplete oxidation of organic material except in the artificial feedlot/cess pool production model. And even then the methane can be collected and used as a biofuel.
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Jim Eager at 08:52 AM on 3 December 2015How much does animal agriculture and eating meat contribute to global warming?
Reason_4, CO2 from respiration is not counted because it is 100% carbon neutral: the C respired into CO2 came from the plant matter eaten by the livestock, which came from CO2 in the atmosphere. There is no new CO2 and thus no additional forcing.
The methane emitted by ruminants also came from the same source (atmosphere CO2 > C in plants), but it is counted because it is emitted as CH4 rather than as CO2, which produces a greater forcing than the original CO2 until it is oxidized into CO2.
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Riduna at 07:40 AM on 3 December 2015G R A P H E N E
MA Rodger @ 18 suggests that graphene technology has yet to leave the lab. However, graphene technology is leaving the lab and being commercialized. Evidence of this is provided by the decision of Grapheno to produce batteries using graphene polymer in electrodes at a new 7,000 m2 factory in Spain(1). The batteries are reported to be ~5 times more efficient than existing batteries.
(1) http://www.graphene-info.com/graphenano-announces-launch-manufacturing-plant-graphene-based-batteries
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scaddenp at 07:07 AM on 3 December 2015How much does animal agriculture and eating meat contribute to global warming?
Reason_4. Carbon is cycling all the time. Plants absorbs it CO2, plant decays and returns CO2 to atmosphere. Animals/humans eating plant and emitting CO2 is slight variation from this schedule. Breathing by any animal is carbon neutral -none of this changes net CO2 in atmosphere (unlike releasing fossil carbon). Ruminants are slightly different. A portion of plant carbon is released as CH4 instead of CO2 and it takes time for the CH4 to be oxidized to CO2. Over the time period before oxidization, there is more GHG effect than you would have if you had no animals (or no ruminants). The calculation of greenhouse gas potential for agricultural emissions is not a trivial calculation.
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scaddenp at 06:50 AM on 3 December 2015Models are unreliable
Model predictions for a parameters with a huge amount of unpredictable internal variability like surface temperature do take time to validate. However, the models predict a great many other variables with far less internal variability (eg OHC, clear sky surface radiation etc) and can be tested on that. Have you read the IPCC chapter on model validation?
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How much does animal agriculture and eating meat contribute to global warming?
Saileshrao #26:
"....where methane concentrations in the atmosphere have been monotonically increasing year after year."Really?
Not between 1999 and 2007, and much less after 2007 than before 1992!
Also note that the forcing growth rates from GHG’s other than CO2 decreased rapidly in the 1990’s.
So, when it comes to methane, I’m more worried about emissions from thawing permafrost and other possible feedbacks than directly from human activity that we can control.
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Tom Curtis at 06:02 AM on 3 December 2015There's no empirical evidence
blue65 @304:
1) The incoming radiation is for the most part, Short Wave radiation to which CO2 is transparent. Hence there is not significant redirection of "... energy by the increased CO2 before it reaches the lower atmosphere". It is the contrast between transparency to incoming radiation, and relative opaqueness to outgoing radiation that it is the key feature of greenhouse gases, and which makes them greenhouse gases.
2) Changes in the landscape are a factor, and are itemized by the IPCC as Land Use Changes (LUC). Overwhelmingly the effect of LUC is to reflect more solar radiation back out to space (increase albedo), thereby cooling the planet. However, the effect is small relative to the effect of changing concentrations of greenhouse gases and aerosols. The effect is itemized on the chart below as "Albedo change due to land use":
3) The temperature effects of cities relative to countrysides are a combination of changes in albedo but that is variable (concrete has reduced albedo but ashpalt has increased albedo); changes in thermal inertia, with most modern construction materials having low thermal inertias relative to plant matter (probably due to limited water content); and a large number of sources of industrial waste heat in cities (the "urban heat island effect"). Changes in albedo from cities also result from increased aerosol production which also effects countryside downwind from cities (an effect that has been detected). The net effect can be to warm or to cool cities relative to the local countryside. The total globally averaged effect is small relative to the forcing from greenhouse gases.
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John JMesserly at 05:53 AM on 3 December 2015How much does animal agriculture and eating meat contribute to global warming?
TomR was spot on about the weight mistake the EWG chart makes. Consider the FAO report "Tackling Climate Change through Livestock" (2013), page 16, figure 3 where you will find a chart graphing against protein content. What may surprise some vegetarians is that Milk is hardly one of the lowest as indicated in the EWG graph, but actually is higher in CO2e per kg of protein than some meats like pork or chicken. This is due to the previously discussed massive amount of methane produced by ruminants- a byproduct of cellulose breakdown by methanogen microbes in their guts.
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Reason_4 at 05:44 AM on 3 December 2015How much does animal agriculture and eating meat contribute to global warming?
Dana @29
I appreciate that, although as a permaculturalist I also understand the reverse is also possible (you can take already degraded land and dramatically improve carbon sequestration in a system that may well integrate raising animals to further enhance this aspect).
But I'm still curious about the first point - why some animal emissions are tallied (eg methane from ruminant animals) and others not (CO2 respiration from any animal) and then listed as equivalent to the same emissions from fossil fuels (either burnt or fugitive) when one is effectively carbon neutral in the short term carbon cycle ... and the other definitely isn't.
We (of course) dismiss deniers who suggest humans need to stop breathing/belching/farting ... why are some livestock emissions treated differently?
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Models are unreliable
reuns - You open your comment with an incorrect statement: "the best model is a will stay for a long time the linear interpolation of past observations". This is completely wrong when looking at non-linear forcings applied to (in this case) climate. If the behavior is non-linear, a linear projection will be wrong.
'Signal processing', or more appropriately statistics, is fine for analyzing past behaviors of a system. But projecting ahead in a SP approach requires (gasp) actual physics, and looking at the input/output relationships involved.
The rest of your comment is essentially a claim that the climate is too complex to model and project, which I believe has been sufficiently addressed by the fact that observed temperatures and for that matter regional patterns are indeed reproduced within expected variation by GCMs.
It's physics all the way down - if modeling does a reasonable job of reproducing the physics, we don't need to test an infinite variety of cases. That's just a call for delay, which turns into a continually moving goalpost fallacy where there will never be enough information (in the opinion of the delayers) to make any kind of decisions...
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blue65 at 05:33 AM on 3 December 2015There's no empirical evidence
The problem I see with this theory is that it seems to discount the effect of redirected energy by the increased CO2 before it reaches the lower atmosphere. Insulation works both ways. Put a dark background behind a 2 way mirror and almost light is reflected: put a light source behind it and it becomes see through. Changes to landscape are as much a factor as any in my belief. My imperical evidence is easier to prove; just check out the daily high and low temperatures of any metropolitan area and the rural areas next to them and see the contrast.
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Tom Dayton at 05:14 AM on 3 December 2015Satellites show no warming in the troposphere
Eli has a great post on UAH's flaws, by a satellite engineer who gives lots of details: UAH TLT Series Not Trustworthy.
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foolonthehill at 04:41 AM on 3 December 2015How much does animal agriculture and eating meat contribute to global warming?
RedBaron @27 - Re: Savory - plausability is nice but reproducability is better.
'Holistic management does not permit replication. Because of this fact we can only validate the ‘science’ used and monitor or document ‘results achieved’. Note: This point is critical to understanding the great difficulty reductionist scientists are experiencing trying to comprehend holistic planned grazing – because no two plans are ever the same even on the same property two years running, planned grazing cannot be replicated which reductionist scientists do to try to understand the ‘science.’
If one replaces 'holistic management' with 'homeopathy' then maybe you can understand my scepticism.
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Rob Painting at 04:29 AM on 3 December 2015Satellites show no warming in the troposphere
We will know if the current super El Nino is affecting the satellite record like the super El Nino of 1997/1998 when the December & January data come in - assuming the behaviour is similar to past El Nino.
As for Kevin Cowtan's Skeptical Science calculator - note the error bars are orders of magnitude larger than the trend, so there is no statistical basis for any claim that it has cooled. The time period is too short and the interannual variation (standard deviation) too large. We would need a longer time period in order to establish statistical significance. Note that contrarians never attempt this, they simply make a claim without supporting evidence.
It would be interesting to find out why the satellite data 'overreacts' to El Nino and La Nina though. Is this a real phenomenon occurring in the lower troposphere? Or is this an artefact which all the processing fails to remove from the microwave soundings?
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dana1981 at 01:43 AM on 3 December 2015How much does animal agriculture and eating meat contribute to global warming?
Reason_4 @ 23 - you have to consider what the land would be used for if it weren't being used for livestock pasture land. For example, when forest land is replaced by pasture land, that's actually a decrease in natural carbon sequestration.
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One Planet Only Forever at 01:11 AM on 3 December 2015Uncertainty is Exxon's friend, but it's not ours
ryland@4
Thinking a little more about your question the following may be the answer you were asking about.
The typical design basis for structures and water run-off is not the range or variation of weather conditions for a location, it is the statistical expected extreme of a design condition such as the maximum large-field wind speed expected to occur once in a 50 year period. My use of the term large-field is meant to differentiate the wind speed experienced concurrently by all of a large structure vs. the faster wind speed and resulting larger local forces a structure.
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