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Comments 25951 to 26000:

25951. Tom Curtis at 12:31 PM on 11 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       Glenn, I more or less agree with everything you write @168, except as regards nomads.  Nomads to not typically move continuously.  Rather, they will move to a campsite (often frequently revisited), set up camp and stay for a period from a few days to a few months, then move on again.  Given that meat can be sun dried in three days, and pemmican made in 3 to 6 weeks, that presents no major obstacle to the manufacture of dried foods.  The advantage of the dried food is that it can provide food while on the move, when it is inconvenient to slaughter, or provide food over periods with low fodder (such as winter).  The later allows stock levels to be reduced increasing the chance of getting the remainder of the herd through the period of low fodder.  Consequently it is no surprise to find that Mongolian cuisine features dried meat, and heavily features 'dried milk' in the form of cheese. 

25952. Glenn Tamblyn at 11:22 AM on 11 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       True Tom but there are nutritional reasons 'fresh is best' still applies to some extent where possible. However an important aspect of the 'living food storage' concept links 1 & 2. Animals can harvest low grade land through foraging on it.

       However this takes time; it takes time to raise cattle, sheep etc to slaughterable size; time for them to slowly harvest the poor forage that is no use to us. Since we can only incrementally 'harvest' a cow or a chicken each day through milk and eggs as they in turn harvest the land, they act as an temporary storage system for the forage that has already been 'harvested' that we cannot get quick access to - meat. Without that we would get no benefit from having them.
       
       And while there are variious low and high tech food preservation technologies, you then need to physically store the preserved food somewhere. Living storage is a part of the mix. Drying food for example isn't much use to nomadic people if they have to transport all that dried food. Living storage can walk with them as they travel.

       So what the mix will be at any location depends on local climate, soil fertility etc. technology, culture, all sorts of things. Meat animals are a necessary part of a balanced food supply system, filling in gaps that a pure vegetarian food supply can't.
       
       Feedlots of grain feed cattle just so we can have lots of steaks that are marbled 'just so' aren't. That is a wasteful indulgence.

       But trying to project a pure vegetarian ideal as some do onto a world that doesn't always have land that can support a pure vegetarian diet is a sentimental indulgence.

25953. ClimateBruce at 07:08 AM on 11 January 2016
       Myles Allen: Can we hold global warming to 1.5°C?
       

       1.5 degrees is technically possible but likely way to costly.  

       Assuming that we will be able to stabilize the non-CO2 greenhouse gases (CH4, NO2, etc.) at their current levels (because reducing them will be really difficult in a more affluent and more populous world) and assuming that we can eventually phase out coal, it looks to me like we are already close to seeing a 2°C world this century based on current greenhouse gases in the atmosphere (not that 2°C is a meaningful target):

       
       1. The aerosols from burning coal significantly dampen the temperature increase caused by CO2 emissions. According to Dr. Michael Mann, since the burning of coal must be ended to meet any meaningful temperature increase target, a more realistic target of atmospheric CO2 is 405 PPM, which will be reached in a few years (http://ecowatch.com/2015/12/24/dangerous-planetary-warming/2/)

       
       2. We are already at 400 PPM for CO2, 450 PPM CO2e if the Kyoto greenhouse gases are included, and 480 PPM CO2e if all IPCC greenhouse gases are considered (http://globalchange.mit.edu/files/2014%20Energy%20%26%20Climate%20Outlook.pdf

       
       3. The temperature increase at the end of 2015 was about 1.0°C and an additional .1°C increase is expected for 2016. In addition, the aerosols from the burning of fossil fuels are masking another .5°C of temperature increase. And the Earth’s current energy imbalance will likely lead to another .5°C increase over the coming decades based on the greenhouse gases already in the atmosphere. (If we can reach “net zero” anthropogenic CO2 emissions, the oceans will absorb significant amounts of CO2, but this will likely offset by natural emissions from global warming feedbacks (permafrost thawing, etc.))

       
       4. With all of the weird weather that we have been getting from 1.0° C temperature increase and with another .5°C to 1°C “baked in”, it would seem that current atmospheric concentrations of greenhouse gases are already too high

       If we are already close to seeing a 2°C world this century based on current greenhouse gases in the atmosphere, then in order to keep the global temperature rise this century to well below 2 °C above pre-industrial levels (per the COP 21 agreement) we need to remove the CO2 equivalent of all future greenhouse gas emissions from the atmosphere.

       ------------------------------------------------

       Greenhouse gas sources and sinks from 2015-2100 (GTCO2e):

       1522 - Net of all of the greenhouse gases emitted after 2015, assuming they peak in 2025 and are reduced linearly at 3 percent per year (net zero in 2058) (because we are very close to the atmospheric concentrations of CO2 and CH4 that will result in a 2.0° C temperature increase) (=580+942) (There will likely need to be significant CCS to meet the “net zero” goal, but the associated costs are not included here)

       
       320 - Greenhouse gases emissions from 2058-2100 that need to be captured and sequestered (8*40) (IEA – https://www.iea.org/publications/freepublications/publication/technology-roadmap-carbon-capture-and-storage-2013.html – assumes the annual amount of CCS needed is stabilized in 2050, whereas it is likely to increase)

       
       500 - GHG equivalent emissions from climate feedbacks from 2020-2100 (440 GTCO2e from permafrost and 60 GTCO2e from other sources)

       
       -450 - CO2 absorbed by the oceans from 2050-2100 as net CO2 emissions approach zero. Oceans currently absorb 30-50% of CO2 from fossil fuel emissions (http://www.gdrc.org/oceans/fsheet-02.html). Assuming that there are “net zero” fossil fuel emissions in 2058 and using a 40% absorption rate of 2010 emissions in 2050 of about 12 GTCO2, which would be reduced in half by 2100, the total CO2 absorbed by the oceans from 2050 would be 50 * (12 + 6) /2, or 450 GTCO2 (this is just a “swag” but is probably in the right ballpark)

       
       1892 - Total CO2 to be sequestered for a 2 degree world

       ------------------------------------------------

       To get an idea of the costs involved, simply multiply an optimistic lower bound of the expected dioxide removal costs for CO2 in 2050 ($100/ton – about ¼ of what the Natural Resource Council predicts for direct air capture (DAC) (http://www.nap.edu/catalog/18805/climate-intervention-carbon-dioxide-removal-and-reliable-sequestration) times the 2010 greenhouse gas emissions (about 50 GTCO2e). The result shows future generations would need to spend about $5 Trillion ($100 * 50 / 1000) to remove the CO2e for just one year of current emissions. Since emissions will not come down any time soon, we can expect that future greenhouse gas emissions that need to be captured and sequestered will be likely more that 2,000 GTCO2e, resulting in CDR costs likely in excess of $200 Trillion in this century for a 2° C world and likely more than $300 Trillion for a 1.5° C world.

       Moderator Response:

       [PS] Activated Links. In future please use the link button in the comments editor to do this yourself.

25954. Rob Honeycutt at 00:29 AM on 11 January 2016
       Tracking the 2°C Limit - November 2015
       

       angusmac @23...  The question of what the drivers were for the MWP is unrelated to baselining preindustrial temperature. The question of what global mean temperature would be without the effects of man-made forcings is relevant and is a far more interesting approach. Based on the modeled data I posted @16 it looks like the 1880-1909 baseline would be pretty close. It would be interesting to get actual figures for that modeled data for more accurate comparison.

25955. Tom Curtis at 21:09 PM on 10 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       Glenn Tamblyn @165, red meat, fish, and various vegetables and fruits can all be dried as an effective low tech storage option, which has the further advantage that you do not need to find feed for dried meat and (in appropriate locations) it is easier to protect dried meat from rats than to protect live animals from predators (including human predators).  A far more important factor for keeping livestock would be the constant supply of milk and eggs.  Consequently I consider your first and third points far more important than your second.

25956. Eclectic at 19:54 PM on 10 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       Glenn @ 165,  you make a very good point, on the low-tech "food storage technology".   I hadn't given it sufficient thought ~ and am obviously guilty of First World bias in my thinking, there.

       Cassava, I hear, is a subsistence crop that can be left unharvested for an extra year (if not immediately needed) . . . but I had been picturing the commonality of crops otherwise as being very vulnerable to vermin, during storage.

       Iron and high-quality protein [the essential amino acids] make livestock-sourced food a high-value food.   So we have to compare livestock with the very premium end of the vegetable-based foods, when we compare costs [both dollar costs, and environmental costs].

25957. SirCharles at 18:59 PM on 10 January 2016
       Hockey stick is broken
       

       Also => List of large-scale temperature reconstructions of the last 2,000 years

25958. Glenn Tamblyn at 18:04 PM on 10 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       Further to Tom's point. Some general considerations wrt meat animals.

       • They can forage on ground that can't support meaningful food crops. Don't just think cattle. Think shhep and goats. That land may actually support significant biomass but it isn't human consumable - unless we plan to genetically engineer humans to have multiple stomachs and chew cud. So animals can give us a significant yield from an otherwise indigestible but substantial calorie source.
       • They also act as a food storage technology - harsh to think but true. It isn't enough to grow food. You need to store it. One might, just, survive on a diet of lettuce but it's shelf life is terrible. The major grain crops constitute a storable food supply. Livestock do as well. As long as they don't die, their metabolism is actually a food storage mechanism. It ain't enough to just grow food. We need to deliver it to our bodies in a steady measured way. Storage is key.
       • They can concentrate many key nutrients and deliver them to us in useful forms - milk and eggs particularly.
25959. Eclectic at 14:46 PM on 10 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       Bother . . . it should have been: unrepentant.  So much for my prof reading!

25960. Eclectic at 14:29 PM on 10 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       Tom Curtis @ 162,   thank you for your kind comments.

       On the Major Issue : us Speling Nazzis are deeply concerned that you are an unrepentent spelling denier.   Rather than wrangle with you, I would simply refer you to the excellent website of the N.A.S.  [ National Academy of Spellings ] which makes all clear, on the science of modern spelling . . . and which also provides a useful overview of mainstream pronunciation [ as agreed by a consensus of over 97% of Academician pedants ] including a full summarization of the importance of Anthropogenic Glottal Warbling.       Sigh . . . I guess I should just be thankful you don't spell superçede with the French cedilla.    ;-)

       On the Minor Issue ( Climate Change ),  I am in accord with you on the matter of "grass fed" livestock pasturing on "poor land".   Certainly I am not advocating vegetarianism.   Whatever the merits of that case may be, I cannot think it likely that the human race could achieve an overwhelming change of preference (to meatless diet) in anything less than many generations . . . by which time, the world will have gained 3 or 4 degreesC, and by when the meatless diet may have become moot.

       A still smaller point : in Third World conditions, the meat in an omnivorous diet provides a useful iron source for those many citizens afflicted with iron-deficiency anaemia caused by high parasite loads.  Though unfortunately, in many such cultures, the children & pregnant women having greatest need of meat are often rather low in the pecking order for receiving meat & eggs.

       Finally, let me assure you of my goodwill & admiration of your energetic and scientific posts ~ which always make good reading.   Mon camarade, I do not possess the influence to get you awarded the Légion d'honneur . . . but I certainly vote for you to receive the Order of Learnin' : First Class.

        Two "esses" in Class   ;-)

25961. Tom Curtis at 13:55 PM on 10 January 2016
       Tracking the 2°C Limit - November 2015
       

       angusmac @21, the map you show from Renssen (2012) does not represent any specific time period.  Renssen states:

       "To address the questions raised in the introduction, we analyzed the monthly mean simulation results to establish for each grid cell the maximum positive temperature anomaly relative to the preindustrial mean (see example in Fig. 2). The analysis resulted in global maps of this anomaly (Fig. 3aeb), which we consider to represent peak HTM conditions in the model. It is important to note that the anomalies on this map do not represent “real” climatic conditions, as they originate from different months in the year and from different times within the last 9000 years. In addition, we also mapped the timing of this anomaly in ka BP (Fig. 4a-b) and the month of the year in which this anomaly occurred (Fig. 5). This was done for both ORBGHG and OGMELTICE. The latter experiment is used here as the standard simulation, as it contains the impact of all considered forcings."

       (My emphasis)

       In fact, consulting figure 5, we see that the maximum temperatures are drawn from every month except May, and the consulting figure 4a, that while most occure in the three millenium span, 6-9 kya (with approximately equal portions from each of those three millenia), some occur as recently as the last millenia.  

       Further, consulting Figure 2, we see that temperature trends in different seasons may be exactly opposite each other.  Indeed, given the insolation history in high NH lattitudes, that is exactly what we would expect.  It follows that the maximum temperatures shown by Renssen are not annual averages for any year.

       Given these strictures on the data, your use of it can only be called an abuse of data.  If I had any confidence you knew what you are talking about, I would call it fraudulent.  That is because the rise in temperatures for the 2 C guideline is a 2 C rise in the annually averaged Global Mean Surface Temperature (GMST).  It is expected that:

       • The increase in land temperature will be greater than the increase in sea surface temperature;
       • The increase at higher latitudes, particularly higher northern latitudes, will be greater than in tropical regions; and
       • The increase in winter will be greater than the increase in summer.

       All these features have already been observed.  The consequence is that a map of temperature maximums on the same line as that in Jenssen (2012) at a 2 C increase, even if constrained to the same year, would show significantly greater than a 2 C increase in temperature.  In fact, from Marcott et al, which you frequently cite, we know the increase in annually averaged GMST in the Holocene Thermal Maximum to have been approximately 0.5 C relative to preindustrial values.  Consequently, your argument @21 amounts to the claim that, because we surived temperatures 0.5 C above the GMST it is patently clear that temperatures 2 C above the preindustrial average will be without "any dangerous consequence".

       I will further note that your assumption that the HTM was "without any dangerious consequence" is as faith based as your prior, similar assumption about the MWP.  It is plausibly argued that in some areas of the world those conditions were very beneficial, as evidenced by the invention of agriculture.  Agriculture, however, was invented in low latitude regions close to water (The middle east, the Indus delta, southern China, and Central America).  Those are regions with low temperature increases, even on Jenssen's map.  They are not the regions which you highlight.

       Finally, here are model projected temperature anomalies for the 2050s (approximately 2 C warming) relative to the 1971-2000 mean:

       

       Please note the archaic units to avoid confusion.  As you can see, regionally in that situation, we will be facing temperatures as high as 10 C above the 1971-2000 average.  Clearly even if Jenssen 2012 was an annually averaged map, it would be considerably cooler than what we are facing with BAU.

25962. angusmac at 13:32 PM on 10 January 2016
       Tracking the 2°C Limit - November 2015
       

       Rob Honeycutt@16

       I did not state that current warming, "would be similar to the MWP without the assistance of man-made CO2." I only stated (and cited references) that showed that temperatures in the MWP were similar to 1961-1990 mean tempratures.

       Nevertheless, I do agree that computer models only show current warming if anthropogenic forcings are included. However, my question is what caused the previous warm periods when the human contribution was negligible?

25963. TonyW at 13:20 PM on 10 January 2016
       Carbon Brief’s 15 numbers for 2015
       

       I can't really see the point of a study proclaiming that the apparently impossible is actually possible, however improbable. 1.5C requires something we don't have, working scaled carbon negative technologies and, even then, shows warming going above 1.5C at some point. Every time you get a study showing some target is technically achievable, more people will switch off - "we're saved". Much of the AR5 is couched in terms of likelihood. Let's have reporting on studies that have the same language. Limiting to 1.5C is not possible (high confidence).

       188 pledges mean nothing unless the pledges are met. We have to wait another 5 years for that.

       331 seats. Good point. It's sad that so many countries don't have genuine democracies. A comfortable majority with 39% (or thereabouts) of the vote is hardly democratic.

       Zero emissions firmly based on science? I didn't see that from the linked article. Rather, it seemed to be firmly based on wishful thinking. I doubt that science could ever say it's possible (at least not with an industrial technolgical global society).

       For years, we've been told that we have to start taking mitigation actions "now". It's starting to wear a bit thin. Surely we're past that point now and we're not going to limit warming to even 2C. Let's aim to limit below 3C, whilst acknowledging that some countries will dissappear, others will have drastically altered coastlines and all sorts of climate catastrophes will be visited on us. But 3C would be far worse.

25964. sailingfree at 13:10 PM on 10 January 2016
       Temp record is unreliable
       

       Here is a link to the Karl paper: http://www.sciencemag.org/content/348/6242/1469.full

       See fig.2

25965. angusmac at 13:01 PM on 10 January 2016
       Tracking the 2°C Limit - November 2015
       

       angusmac@21 was my resonse to Rob Honeycutt@15

25966. sailingfree at 12:54 PM on 10 January 2016
       Temp record is unreliable
       

       Please show Karl's science paper, which puts the deniers' arguement to bed.

       1. The corrections to the data from the last 70 years are small and hardly noticable on his plots.

       2. Overall, the raw data shows MORE warming than the corrected data. That is correct: the corrections act to lower the warming.

25967. angusmac at 12:25 PM on 10 January 2016
       Tracking the 2°C Limit - November 2015
       

       I agree that the Holocene peak is preindustrial but I chose to use the MWP because there is more data available for the MWP.

       Notwithstanding the above, Renssen et al (2012) estimate the spatial distribution of the Holocene Thermal Maximum (HTM) temperature anomalies as shown in Figure 1. Figure 1: Global Variation of Holocene Thermal Maximum Anomalies (Source: Renssen et al, 2012)

       Renssen et al (2012) use a pre-industrial mean of (1,000 to 200) BP and it is evident from Figure 1 that most of Europe and North America experienced an anomaly of 2-3 °C during the HTM. Renssen et al (2012) is cited in 5.5.1.1 of AR5 WG1and they offer the following conclusions their paper:

       1. "At high latitudes in both hemispheres, the HTM anomaly reached 5 °C."
       2. "Over mid-to-high latitude continents the HTM anomaly was between 1 and 4 °C."
       3. "The weakest HTM signal was simulated over low-latitude oceans (less than 0.5 C) and low latitude continents (0.5-1.5 °C)."

       I conclude from the above that many parts of the world exceeded the 2 °C limit without any dangerous consequences and that these temperatures occurred when CO2 was at ≈ 280 ppm.

25968. Tom Curtis at 11:56 AM on 10 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       Eclectic @161, that is a very valid point although not, perhaps, as strong as you think.  Specifically, animals are very inefficient at converting vegetable matter to flesh.  Consequently, in calory terms you lose 90% of the nutrition in animal feed relative to the case when humans eat the feed directly.  Against that, the gain is not so much when protein requirements are taken into account.  Further, animal manure does increase plant growth, so that there are efficiencies lost by going to a vegan diet.  Never-the-less, a switch to a pure vegan diet would substantially decrease emissions.  Just not by 100% of the total livestock emissions.

       Despite that, I think it is worth preserving a meat supplemented diet.  That is partially because, while the nutritional requirements provided by meat can be provided by plants, that cannot be done cheaply on a global scale.  I feel the inevitable consequence of eliminating meat from the diet will be a return to the deficient nutrition that has been the lot of the poor over most of history, for most of the world - and in many cases falling below that level.

       Further, some locations are suitable for rearing cattle, but not at all suitable for horticulture.  I have in mind locations such as those near Mount Isa (where I grew up):

       

       That is cattle country, but you could not raise vegetables or wheat without unrealistic and unsustainable expenses for irrigation.  Many locations in Africa are also suitable for grazing but marginal at best for grain.  Going vegan simply means that a large amount of food raising capacity is lost without suitable replacement.  In Africa, it may be simply lost without replacement at all.

       Having said that, I dislike the idea of fattening lots (even grass fed fattening lots) on land suitable for horticulture - something that happens a lot, and increasingly so in recent times.

       With regard to the matter of the spelling of "supercede", I am a poor speller and probably cannot achieve a consensus with myself, let alone anyone else.  As it happens, "supersede" is the preferred spelling, but that is just an example of frozen fashion.  The linguistic roots are from middle english (superceden) and middle french (superceder), both with the c variant.  It follows that in this case my spelling has merely failed to keep up with the arbitrary dictates of grammar nazis - on which basis I have no inclination to merely conform.

25969. Pete Wirfs at 10:19 AM on 10 January 2016
       2016 SkS Weekly News Roundup #2
       

       Today, 1/9/2016, I found a flyer on my front door that contains a gish gallop of reasons to not support a carbon tax.  It goes on to recommend several climate denial web sites and youtube videos.  There are no indications on the flyer of who sponsored it.   I would love to have someone publish a response in the local newspapers, or help me in doing so.   Please contact me if you'd be interested in taking this on.  I'm in Oregon.

25970. angusmac at 09:49 AM on 10 January 2016
       Tracking the 2°C Limit - November 2015
       

       Images in angusmac@13 fixed Figure 2 Kaufmann et al (2013) Figure 5.7 WG1 AR5

25971. One Planet Only Forever at 09:01 AM on 10 January 2016
       AGU’s Sharing Science is helping scientists talk to the rest of us
       

       PaulG,

       I am pretty sure BobH was referring to the current undeniable episode of rapid global warming (far more rapid that non-human induced processes would be) that is undeniably connected to the current rapid increase of atmospheric CO2 to levels well above the highest level that occured during the past 800,000 years (and the increase of CO2 can only be explained as being due to humans dredging up and burning fossil fuels).

       What you described does not excuse a denial that recent human impacts are siginicant and a serious concern. And I agree with BobH that there is a strong tendancy for the Geophysicists among the scientifically trained to have that denial.

       As a member of APEGA (Association of Professional Engineers and Geoscientists of Alberta) I am aware that most of the Geoscientists working in Alberta (and there are many) have decided to try to personally benefit from the burning of fossil fuels. And many of them have specialized to the point of having no viable employment in any other endeaviour. That would explain the motivation of many of them to deny the developing undeniable better understanding.

       And many of them have written letters that get published in the APEGA publication that highlight their deliberate desire not to properly understand this issue. However, to be fair, many Engineers in Alberta are similarly biased regarding the issue of climate science.

       Things have been so distorted by pursuit of profit, tax revenue and employment any way hat can be gotten away with in Alberta (the result of global competition in a free-for-all market) that at one point the elected President of APEGA actually personally declared (on behalf of all members) that an APEGA member's responsibility was to maximize the profit that could be earned and to defend the developed pursuits of profit, rather than the 'protection of the public interest from unacceptable pursuits of profit so that a sustainable better future is developed' which is the truer 'public interest' that APEGA members have the responsibility to protect.

25972. Eclectic at 09:00 AM on 10 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       Tom @ 157 and 158 et seq.,   Thank you for the excellent presentation.   Seven billion people have to be fed, one way or another . . . so I should still like to make the point ( in the "opportunity cost" sense ) that, even if we all became Vegan vegetarian, then the increased nett CO2 emission from the extra "vegetable" production (sector) would need to be offset against the current high CO2-equivalent emissions of animal agriculture.  This point seems to have been lost, in the welter of world statistics that you and Ryland (and others, earlier in this thread) have been discussing.

       Also, can we come to a consensus on the spelling of supersede ?    ;-)

        

       Ryland @ 156,   Sorry to see you "have no more to say".  

       Better, if you had more to say : such as correcting the wrong inferences you have made, regarding livestock GHG emissions affecting global warming.

       Whether you meant livestock in the narrow sense of animal organic emissions, or you meant livestock sector (including all its transport, processing, and infrastructure usage of fossil fuels) . . . either way, you have come to an erroneous conclusion about the AGW effects of that particular food-production sector.

       And Ryland, you have failed to address the several points I raised in post #155, about the relativities and real long-term outcomes on Global Warming from (non-vegetarian) food production emissions of all sorts.   

25973. Tom Curtis at 08:25 AM on 10 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       I notice the OP states:

       "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%)."

       Given the facts laid out above, I believe this should be modified to state that animal agriculture is responsible for 14.5% including indirect emissions from feed production, transport and processing, and LUC, and that using a similar measure including indirect emissions, the transport sector emits as much as does the livestock sector.

25974. Tom Curtis at 08:19 AM on 10 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       Actually, I did make a mistake @158.  A direct comparison using the chart below shows the FAO 2013 estimated 3.45 GtCO2eq/yr for enteric fermentation and manure management.  That is directly comparable to the IPCC's 3.3 GtCO2eq/yr.  The difference probably due to the difference in time frames (2005 vs 2000-2010).  Any further difference is due to the inclusion of indirect emissions by FAO 2013.

       

25975. Tom Curtis at 08:12 AM on 10 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       Just a brief note re the IPCC chart I showed @157, the indirect emissions shown are for heat and electricity only.  That reduces total transport emissions to 7.007 GtCO2e per annum rather than the 7.1 indicated in the report - the difference no doubt coming from indirect emissions in manufacture (industry) and possibly other areas.  Likewise, indirect emissions from transport and processing (20%, FAO 2013), and from LUC (9.2% according to FAO 2013) are not included.  Further, emissions for feed (24.5%, FAO 2013) will be attributed to horticulture in the IPCC (though not shown seperately on the chart).  That brings the FAO direct emissions down to 5 GtCO2eq/yr, compared to the 6.4 GtCO2eq/yr for total direct emissions from the agricultural sector according to the IPCC.  The IPCC states:

       "If all emission categories are disaggregated, both EDGAR and FAOSTAT agree that the largest emitting categories after enteric fermentation (32–40% of total agriculture emissions) are manure deposited on pasture (15%) and synthetic fertilizer (12%), both contributing to emissions from agricultural soils. Paddy rice cultivation (11%) is a major source of global CH4 emissions, which in 2010 were estimated to be 493–723 MtCO2eq/yr."

       Combining the 36 (32-40)% from enteric fermentation with the 15% from manure leads to an estimate of 51% of direct agricultural emissions being from livestock, leading to a 3.3 GtCO2eq/yr estimate from the IPCC compared to the 5 GtCO2eq/yr equivalent estimate from FAO 2013.  Unless I have made a major error in tracking down equivalencies, the FAO 2013 estimate is significantly higher - a surprising fact given that the IPCC 2013 is based primarilly on FAO statistics. 

25976. Tom Curtis at 07:23 AM on 10 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       ryland @156, a seminal paper is one that first expresses a key idea.  There is nothing about being 'seminal' that guarantees geting the numbers right, particularly when the numbers can change through time.  Despite this you quote the 2006 paper as indicating "the livestock sector generates more greenhouse gas emissions as measured in CO2 equivalent – 18 percent – than transport".  As it happens, the 2013 paper says:

       "With emissions estimated at 7.1 gigatonnes CO2 -eq per annum, representing 14.5 percent
       of human-induced GHG emissions, the livestock sector plays an important role in climate change."

       (My emphasis)

       As I have already shown, the 7.1 gigatonnes, at best, equals the transport sectors 7.1 gigatonnes including indirect emissions, and even that most favourable comparison to your argument double counts 1.4 gigatonnes of CO2 equivalent transport emissions from the livestock sector.  Further, that 14.5% is as clear cut as the 2006 18%, and clearly supercedes it.  You ask why I ignore the 2006 values?  Because they have been superceded.  You, on the other hand, have no good reason for treating them as still current, but still want to do so.

       It is also superceded by the IPCC AR5 WG 3 report, published concurrently with FAO 2013, which shows:

       

       (Modified from AR5 WG 3 Figure TS.3)

       That shows transport sector contributions to be 14.3% of emissions when indirect emissions are included.  AFOLU includes emissions from agriculture, forestry and land use change, and as previously noted:

       "Annual GHG emissions from agricultural production in 2000–2010 were estimated at 5.0–5.8 GtCO2eq/yr while annual GHG flux from land use and land-use change activities accounted for approximately 4.3–5.5 GtCO2eq/yr"

       That means the entire agricultural sector generates 13.1% of human emissions (indirect emissions included).  It should not need saying that if the entire agricultural sector emits 13.1% of human emissions (including indirect emissions), that portion of the agricultural sector which constitutes the livestock sector emits less. The difference between IPCC AR5 and FAO 2013 may be due to the difference in reference period (2000-2010 for the IPCC, 2005 for FAO 2013), but in that case use of the IPCC figures on transport, which share the 2000-2010 reference period, makes for a very inexact comparison.  It is more likely due to the fact that the IPCC does not double count emissions from transport and LUC.

       To recap, you used three references.  The first has been superceded by the second, and therefore its figures are out of date and irrelevant, despite the reliance you place on them.  The third is an absurd work which treats CO2 from respiration as emissions, and (apparently) uses different Global Warming Potentials for CH4 emitted from livestock to that which they use for other industries.   I have comprehensively discussed the second, and only relevant reference that you cited; along with the equally relevant IPCC AR5.

       Finally, a slightly bowdlerised definition of LMAO.

25977. swampfoxh at 05:47 AM on 10 January 2016
       Why is the largest Earth science conference still sponsored by Exxon?
       

       Exxon is practicing the classic marketing philosophy of Playboy Magazine: bottle up your smut with an article written by a person generally respected by a large segment of the public (e.g. Ronald Reagan) and "nice people" will buy it with the justification that they must read Reagans' article while hiding their true motive to view the centerfold. Supporters for Donald Trump and Hillary Clinton exhibit this distinctly human behavioral trait:  Trump makes his money off the moral weaknesses and compulsiveness of people who gamble, but his supporters point out that he, "sells real estate".  Clinton's checkered past and present conduct is ignored because, "she is an intelligent and experienced woman". Playboy, Trump and Clinton are not too different from the Baptist Church deacon and pillar of the community who molests little girls in the sunday school restroom.  Exxon shares these characteristics, as do countless numbers of persons and institutions around the world.  Can AGU be condemned for pandering to Exxon while seeking scientific facts with which to conserve the planet, all the while knowing that Exxon is digging under their back fence?  Sure they can. Instead of it being all about the money, it could be all about the morals.

25978. swampfoxh at 04:59 AM on 10 January 2016
       Carbon Brief’s 15 numbers for 2015
       

       This site states that "balanc(ing) greenhouse gas emissions and sinks is zero to you and me."  But is it a zero we use to ignore the damage already caused or will be caused by the 400 ppmv world we now live in? 400 ppmv does not return the oceans to proper pH, unmelt the glaciers, bring back the multitudes of creature and plants already extinct, undo the peat fire in Indonesia, the drought in the midlatitudes, etc, etc, etc.  Making it back to balance zero is not my idea of a desirable future for any living organism. ..especially we humans.  What is your view?

25979. PhilippeChantreau at 04:58 AM on 10 January 2016
       AGU’s Sharing Science is helping scientists talk to the rest of us
       

       PaulG, for the purpose of ecosystem consideration, anything in the order of 5 million years without a major departure from a mean would be enough for me to consider equilibrium. There are longer periods in the record without major departures. I think you should substantiate your statement by first looking up what constitutes equilibrium when the term is used by climate science and then examining geological ages for periods that would be considered equilibrium. Did you do that? References?

       If there isn't any, then I guess you may be right, although, from the human civilization point of view, the horizon of 2 to 5 thousand years is more relevant. Then again it's not because climate has changed naturally that it is not now changing because of human activity. To visualize the effect of what we're doing now, one should imagine the current volcanic activity on Earth, then multiply it by 100. Sure, it could happen naturally. If it did, would we be concerned?

25980. Elmwood at 04:35 AM on 10 January 2016
       Why is the largest Earth science conference still sponsored by Exxon?
       

       i brought this issue up at a GSA section meeting last year to someone at their booth, that it's inconsistent to on one hand support science and the conclusions of climate scientists concerning AGW and on the other take funds from a corporation that actively has undermined climate change solutions and science.

       exxon name is mud up here and I wish people care but they largely don't, not even among many earth scientists. it's all about $$.

25981. PaulG at 03:27 AM on 10 January 2016
       AGU’s Sharing Science is helping scientists talk to the rest of us
       

       I'm not sure what you mean by GW denial. Most geologists I know would agree that either (1) the earth is warming, or (2) the earth is cooling, as it always has.  Many do accept Option (1).

       However, geologists are also familiar with earth's history. They have studied the evidence of past changes in earth's climate, and observed that often major climate change occurs quite rapidly.  And drastic (by human standards) climate change is the norm, it is natural.  Climate equilibrium has never existed.

25982. RobH at 01:13 AM on 10 January 2016
       AGU’s Sharing Science is helping scientists talk to the rest of us
       

       Geophysical Union?  Whenever I meet a scientifically educated person that is in GW denial, he (always a he) turn out to be a geologist. This leaves me wondering what is going on with geologists.  Any comment?

25983. ryland at 21:35 PM on 9 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       No I don't think the 2006 report superseded the report of 2013.   No idea what LMAO means.  Perhaps if you had  read what I wrote rather more carefully you might have  noted I did refer to and quoted from FAO 2013.  I wrote  "The UN Food and Agriculture Organization (FAO) estimates emissions attributable to the livestock sector amount to 7.1 GtCO2e per annum. This includes emissions associated with activities along the value chain, including feed production, livestock production, slaughter, processing and retail; see FAO (2013)". 

       I also wrote The IPCC estimates direct emissions from global transport amounted to 7.0 GtCO2e in 2010; see IPCC (2014).

       And perhaps the term "seminal" as applied to a paper or a report, is one with which you are not familiar.  To dismiss the 2006 FAO  as obsolete is to belittle its importance.in noting  emissions by the livestock sector were greater than emissions from global transport.

       I do regret that I did not use the term Livestock Sector rather than Livestock.  I had assumed my use of the term Livestock would be taken as encompassing the totality of the sector.  Clearly I was in error.  

       However, despite the shortcomings of my comment the fact remains that the livestock sector is responsible for a very significant part of total GHG emissions and I re-iterate I am surprised this was not overtly recognised by the economists.  I have no more to say

25984. Eclectic at 21:22 PM on 9 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       Ryland, you are wrong to use the UN FAO's figures at face value ~ i.e. without relating the livestock sector GHG-generation's impact on the Global Warming process that we ( you and I ) are so rightly concerned about.

       As Tom Curtis has pointed out, we must be careful to discount any double-counting of transport sector emissions of CO2 on the world scene.

       Next, we must separate that margin of transport/infrastructure CO2 emission (relating to livestock) which is over-and-above what would otherwise have been generated in the comparative (hypothetical) world where every human is Vegan-vegetarian.   I suspect (as you would also) that an "omnivore" world requires more transport & infrastructure, than would a purely vegetarian world society.  But how big is that margin?  I have not seen any analysis of that ~ yet it seems likely that such margin would be a minor fraction of the total emissions of CO2 deriving from fossil-carbon fuelling of that transport/infrastructure sector which feeds us humans.   Yet it is only that margin which can be realistically counted against the livestock industry.  And as we may expect, UN FAO has not quantified that margin of emissions.

       We should also very largely discount the livestock GHG emissions ~ they certainly exist but are very nearly in a plateau and are not cumulative  (unlike the fossil-fuel CO2 emission of transport etc.).  The livestock emits "recycled" organic CO2, to which we should add the other GHG methane emission ~ which has a steady-state or plateau level because there is only minor alteration of total livestock numbers worldwide.   Yes, there is some further deforestation-for-grazing, but again that has only limited scope to accumulate in the future before reaching a plateau level. 

       To summarize : the ongoing impact on global warming, from "total picture" livestock sector, is far from comparable to the impact of general world transport.   The UN FAO figures are misleading, because they are taken out of context.

       What hope for improvement in the future?  As I mentioned in the other thread :-    I reckon it will be very much easier to phase out carbon pollution from transport & agricultural machinery over coming decades, than it would be to change human dietary desires into the (almost) purely Vegan vegetarian.

        

25985. Tom Curtis at 20:01 PM on 9 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       ryland @153, are you suggesting that I consider FAO 2006 to supercede FAO 2013 (which I in fact rellied upon) rather than the reverse?  Or do obsolete references cease to be obsolete, in your opinion, if only they support your opinion more than the more up to date reference? LMAO

25986. ryland at 19:42 PM on 9 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       Tom Curtis You ignore the inital paper fron the UN FAO which states 

        

       Did you read the reference from the UN FAO which states “the livestock sector generates more greenhouse gas emissions as measured in CO2 equivalent – 18 percent – than transport"? That seems fairly clear cut I'd have thought.     

25987. tmbtx at 19:35 PM on 9 January 2016
       Latest data shows cooling Sun, warming Earth
       

       David Sanger - we talk about forcing values of around 2-4 W/m^2. Wouldn't then putting the solar irradiance plot on a scale with that level of variation make sense?

25988. Tom Curtis at 19:18 PM on 9 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       ryland @15, FAO 2013, the source of the Chatham House data, states:

       "Feed production and processing, and enteric fermentation from ruminants are the two main sources of emissions, representing 45 and 39 percent of sector emissions, respectively. 

       Manure storage and processing represent 10 percent. The remainder is attributable to the processing and transportation of animal products. 

       Included in feed production, the expansion of pasture and feed crops into forests accounts for about 9 percent of the sector’s emissions.

       Cutting across categories, the consumption of fossil fuel along the sector supply chains accounts for about 20 percent of sector emissions."

       (My emphasis)

       That makes it very clear that the emissions are not just direct emissions.  Indeed, direct livestock emissions account for just 65% of total emissions by the FAO estimate, or 4.6 GtCO2e/annum.  For comparison, the IPCC AR5 (WG 3 Chapter 11) reports 5-5.8 GtCO2e/annum for direct emissions from total agriculture, not just livestock.

       That is significant because the comparison used is to direct transport emissions, ie, emissions from fuel use on the road (or rail etc).  That is, it excludes the "...the indirect GHG emissions arising during the construction of infrastructure; manufacture of vehicles; and extraction, processing, and delivery of fuels." (IPCC AR5 WG 3, Chapter 8)  That is, the inflated value for livestock emissions relative to transport emissions is only accomplished by not comparing direct emissions to direct emissions, but rather, by including 1.4 GtCO2eq/annum of transport emissions in the "livestock emissions", along with other indirect emissions while excluding indirect emissions from transport.

       It follows that the best that you can claim, in an apples to apples comparison, is that livestock and transport have the same total emissions (direct plus indirect) emissions of 7.1 GtCO2eq/annum (see figure 8.1 of Chapter 8).  Even that, however, double counts 1.4 GtCO2eq/annum of emissions from transport in the livestock sector (most of which from the transport of feed).  So more properly we should compare the 5.7 GtCO2eq/annum from the livestock sector excluding transport to the 7.1 GtCO2eq/annum from direct and indirect transport costs.

       With regard to your third reference, do you truly wish to relly on a non-peer reviewed paper that insists respired CO2 should be counted as an emission for GHG accounting?  Or were you just adding that reference on for decoration?

25989. ryland at 17:08 PM on 9 January 2016
       95% consensus of expert economists: cut carbon pollution
       

       As suggested @6 I have posted to the appropriate thread giving references to support my comment @4.  The post on that thread is @151

25990. ryland at 17:03 PM on 9 January 2016
       How much does animal agriculture and eating meat contribute to global warming?
       

       This comment is posted in response to a comment from Moderator DB (@6) about a post (@4) I made to the thread “95% consensus of expert economists: cut carbon pollution"

       I expressed surprise that the economists had not commented on agriculture and stated that livestock are responsible for a bigger share of total global GHG emissions than is the whole of global transport. The moderator’s comment was:

       “This claim of yours is unsupported sloganeering and off-topic on this post:

       "livestock are responsible for a bigger share of total global GHG emissions than is the whole of global transport".

       If you wish to pursue that topic, bring credible evidence for your claims and present them on this thread."

       The following addresses those comments from the moderator.

       A report in 2006 (Livestocks Long Shadow-Environmental Issues and Options) from the UN Food and Agriculture Division stated inter alia:

       “the livestock sector generates more greenhouse gas emissions as measured in CO2 equivalent – 18 percent – than transport. It is also a major source of land and water degradation. Henning Steinfeld, senior author of the report also stated ““Livestock are one of the most significant contributors to today’s most serious environmental problems. Urgent action is required to remedy the situation.” The reference is  here 

       A report in December 2014 from Chatham House The Royal Institute for Foreign Affairs, reference here noted

        • Greenhouse gas emissions from the livestock sector are estimated to account for 14.5 per cent of the global total, more than direct emissions from the transport sector.

       In that report the following were referred to. 1 The UN Food and Agriculture Organization (FAO) estimates emissions attributable to the livestock sector amount to 7.1 GtCO2e per annum. This includes emissions associated with activities along the value chain, including feed production, livestock production, slaughter, processing and retail; see FAO (2013). The IPCC estimates direct emissions from global transport amounted to 7.0 GtCO2e in 2010; see IPCC (2014).

       More sensationally, the UK newspaper The Independent reported in November 2009 under the headline-"Study claims meat creates half of all greenhouse gases"  on a, non-peer reviewed, report from The World Watch Institute. This claimed that the UN figure of 18% of global emissions from livestock was a severe underestimate and that the true figure is 51%. The reference is here

       There are other references supporting the comments I made but I trust those given will both suffice and be accepted as “credible”

        

       Moderator Response:

       [GT] Cleaned up what appeared to be duplicated pastes in the comment.

25991. jipspagoda at 13:42 PM on 9 January 2016
       Why is the largest Earth science conference still sponsored by Exxon?
       

       wili,

       which posters do you believe are "Agents of Exxon"

25992. Big Oil at 13:35 PM on 9 January 2016
       Tracking the 2°C Limit - November 2015
       

       Too late. 415 ppm CO2 causes 3 to 4 C increase in temperature.

       scripps.ucsd.edu/programs/keelingcurve/2013/12/03/what-does-400-ppm-look-like/

        

       Global warming only became an issue in 1992 after the Cold War. By then it was too late. Too late. Too late.

       Moderator Response:

       [GT]
       
       Big Oil.

       Scattering so many comments over multiple threads so quickly isn't very helpful to the conversations. Each of your comments are reasonably on topic but perhaps confining yourself to one or two threads and elaborating a bit more might be more fruitful.

25993. Big Oil at 13:32 PM on 9 January 2016
       Carbon Brief’s 15 numbers for 2015
       

       The 1.5 C target might have been possible if global warming became in issue in the early 1900s. Only in 1992 after the Cold War did global warming become an issue. By then it was too late.

       Moderator Response:

       [GT]
       
       Big Oil.

       Scattering so many comments over multiple threads so quickly isn't very helpful to the conversations. Each of your comments are reasonably on topic but perhaps confining yourself to one or two threads and elaborating a bit more might be more fruitful.

25994. Big Oil at 13:31 PM on 9 January 2016
       Carbon Brief’s 15 numbers for 2015
       

       Too late. CO2 at 415 ppm causes 3 to 4 C increase in temperature.

       
       https://scripps.ucsd.edu/programs/keelingcurve/2013/12/03/what-does-400-ppm-look-like/

25995. Big Oil at 13:27 PM on 9 January 2016
       Why we need the next-to-impossible 1.5°C temperature target
       

       Actually, back in the Pliocene CO2 reached 415 ppm and caused 3 to 4 C higher temperature.

       https://scripps.ucsd.edu/programs/keelingcurve/2013/12/03/what-does-400-ppm-look-like/

25996. Big Oil at 13:26 PM on 9 January 2016
       Why we need the next-to-impossible 1.5°C temperature target
       

       Too late. Already passed 400 ppm. 3 C is locked in.

25997. Big Oil at 13:19 PM on 9 January 2016
       Carbon Brief’s 15 numbers for 2015
       

       Not a single signed the Paris agreement. It is a paper tiger.

25998. Tom Curtis at 12:54 PM on 9 January 2016
       Tracking the 2°C Limit - November 2015
       

       angusmac @17:

       2a)   The simplest climate effect of warm periods is to expand the Hadley Cells that exist on either side of the intertropical convergence zone.  That has the effect of causing tropical wet conditions to expand poleward, but also for the arid regions on either side of the tropical region to also expand poleward.  In European longitudes, that means nations bordering the mediterrainian become more arid.  Much of the middle east including Peria/Iran would also become more arid.  For Australia it means the southern states become more arid while the northern states become wetter.  This is not a beneficial change.

       Secondary effects can be more complicated.  The MWP was associated with megadroughts In eastern Africa (around Kenya), the South Western United States, Peru, and Northern Europe:

       

       The Northern European drought was complicated in that it was primarilly a reduction in summer rainfall, and was compensated for regions close to the Atlantic by increased winter rainfall.  That may explain why slavic populations (far from the Atlantic, and therefore significantly impacted) were less able to resist germanic invaders, who durring the time of the MWP pushed into formerly slavic areas in what is now Poland.  In either event, while the MWP was beneficial for germanic people in general, it was not beneficial for slavs.

       In short, there is solid evidence that the MWP was not beneficial for a large number of people, across the world, while being beneficial for others.  What does not exist is evidence tying together the sum of the effects.  We don't know whether or not the gains of the germanic people outweighed the losses of the slavs and italians.  Nor do we know whether gains by american plains indians compensated or exceeded the losses by the pueblo dwelling indians of what is now the SW USA.  And nobody has integrated the effect globally.  I doubt the information to do so exists.

       In short, your insistence that we know the MWP was beneficial amounts to an insistence either that only germanic people and their descendants matter (they being the only ones of which we can say this with confidence) or a fairly blind faith beneficial effects for those germanic peoples were universal.

       2b)  With regard to the CO2 fertilization effect, logically if it is beneficial (as seems likely), then the temperature which is most beneficial from Global Mean Surface Temperature alone will be less than the temperature which is most beneficial given GMST plus the CO2 fertilization effect.  The later is probably somewhere between 0.8 and 1.1 C above the preindustrial average for our current civilization.  The figure will differ with different technologies and population distributions.  If the CO2 fertilization effect is significant, that implies the ideal temperature for current populations and technologies absent the CO2 fertilization effect has already been exceeded, and my have been exceeded early in the 20th century.

       1)  First, choosing as a baseline the most recent period prior to major rapid human climate influence is not arbitrary.  It is certainly not a cherry pick.  It fixes a useful baseline without the question of the absolute peak of benefit from warming needing to be determined.

       In contrast, your baseline requires the unproven assumption that MWP warmth was net beneficial for humans, and the dubious assumption that without anthropogenic influence current temperatures would be equivalent to MWP temperatures (the mid-century solar maximum has gone, which together with recent volcanism suggests natural forcings would be back at early 20th century values) to justify it.  Of course, you give away the real justification when you write "this does not sound nearly as bad as 2 °C".

       In response to your final question, we are 1.095 C above the baseline used above, and probabily 1.3 C above the preindustrial baseline.  That puts us 0.905 C below the guideline used above, but probably 0.7 C below the 2 C above preindustrial guideline.  Adopting your convention, we would be 0.764 C above the baseline, and 0.905 C below the guideline used above, but probably 0.7 C below the preindustrial guideline.  The current twelve month running average is more than 1 C over the baseline used above.

25999. denisaf at 11:26 AM on 9 January 2016
       Why we need the next-to-impossible 1.5°C temperature target
       

       Reducing the rate of greenhouse gas emissions means closing down many of the current high emitters and providing sound alternatives.  This can only be a slow process for practical reasons regardless of the policies adopted by governments. And carbon capture and storage systems can, at best, only slow down the global rate of emissions slightly.

       There should be more focus on measures to cope with the irreversible rapid climate change and ocean acidification and warming that is under way. Proposed amelioration measures can only slow down the unintended deleterious consequences of using fossil fuels to provide energy to power technolgical systesm.

26000. angusmac at 08:17 AM on 9 January 2016
       Tracking the 2°C Limit - November 2015
       

       Tom@12
       3) Thank you for supplying the reference. I only looked at the references at the end of the Huang et al paper, not in-text. I also agree that land-only temperatures have greater variation than land-ocean but this does not change the logic of my post.

       
       2) I disagree that MWP was beneficial is a "statement of faith" – it is my perception that it is well-documented history.

       
       I am an avid reader of history and this shows that, since the last ice age, warm periods have usually been beneficial to the human race and cold periods are usually accompanied by crop failures and famine. Indeed, civilization occurred during the Climatic Optimum shown in Figure 2 (Kaufman et al, 2013) in my response to the Moderator@13.

       
       I make no comment on post-1980 CO2 fertilisation effects, I neither mentioned this subject nor alluded to it.

       
       1) Regarding pedantry, if people wish to use a pre-industrial temperature of 1750 and thus ignore warmer times in the past then they are entitled to their opinion. However, this ignores the fact that temperatures similar to the 1961-1990 mean did occur in the past without any documented dangerous effects on humanity. Consequently, “dangerous” should be measured from this or a similar baseline and not a very low period in the temperature history.

       
       My opinion is that the 1750 baseline is arbitrary and is akin to cherry picking as stated in my response to Eclectic@14 regarding the Dark Ages temperature minimum.

       Referring to your adjustment to the guideline of “1.669 °C” above the 1961-1990 mean, this does not sound nearly as bad as 2 °C. Additionally, does this adjustment mean that we are currently ≈ 0.67 °C above the guideline and not ≈ 1 °C ?

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