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Comments 26501 to 26550:

26501. wili at 14:14 PM on 1 December 2015
       How much does animal agriculture and eating meat contribute to global warming?
       

       Another thing that this piece overlooks is the degree to which people can alter their ghg emissions of one sort or another. Many people are stuck with, say, long commutes to work, required trips to conferences, appartments where they can't completely control the heat...

       But diet is something that pretty much everyone has some ability to control by themselves. If it is one or one of the few things someone has control over, then it doesn't really matter how it stacks up against other contributors. If you can't change those, but can change your diet, everyone who can should be encouraged to do so.

26502. scaddenp at 13:06 PM on 1 December 2015
       How much does animal agriculture and eating meat contribute to global warming?
       

       TomR - this 2014 study attempted to estimate GHG emissions of various diets, standardized to 2000kcal/day. Their conclusion was that meat-eaters produced about twice as much GHG as vegan diets.

26503. TomR at 11:24 AM on 1 December 2015
       How much does animal agriculture and eating meat contribute to global warming?
       

       Your greenhouse gases for foods chart is grossly misleading since it lists by weight instead of by calorie and protein content.  

       For instance, one pound of dry beans contains five times as much protein and calories as tofu and costs much less, yet your graph makes them equals in global warming gases. Milk and yogurt have many fewer calories per pound and grams of protein per pound than nuts. Fat free, sugar free yogurt has only 200 calories per pound while nuts come in at roughly 1900 calorie. Thus, on a per calorie basis, yogurt is ten times more polluting than nuts and seven times world than rice or beans/lentils. That's huge.

       Many vegetables don't do well on a per calorie basis, but to have some health benefits, while beef and pork definitely do not. Canned foods also have a much higher footprint due to the canning, so dry beans are several times less polluting than canned and, of course, have no BPA. Medical care has a carbon footprint, too.

26504. wili at 11:06 AM on 1 December 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       Thanks, Tom. Was the other study you were thinking of the one discussed here?: www.skepticalscience.com/Macdougall.html

26505. wili at 10:55 AM on 1 December 2015
       How much does animal agriculture and eating meat contribute to global warming?
       

       (About 10 million pounds of beef from Brazil per month, for example.)

       www.ers.usda.gov/data-products/livestock-meat-international-trade-data.aspx

26506. wili at 10:51 AM on 1 December 2015
       How much does animal agriculture and eating meat contribute to global warming?
       

       I'm wondering about the country-by-country comparison. Specifically, when the claim is made that "in the USA, fossil fuels are responsible for over 10 times more human-caused greenhouse gas emissions than animal agriculture," does that include all the cattle that are imported from other countries where forests are being destroyed to support them?

26507. Tom Curtis at 08:04 AM on 1 December 2015
       Welcome to Skeptical Science
       

       Bobbi @4, if you don't mind my saying so, you have made two of the classic errors of AGW denialism.  The first is that you assume existing rates of a natural process represent the change in rates of the natural process.  That is important in that we are trying to explain not the long term stable background concentration of CO2 (280 ppmv) but the recent rapid increase of the CO2 concentration by 120 ppmv.  Background rates of processes in the CO2 cycle clearly cannot change the current rapid rise, for if they did there would also have been a rapid rise at similar rates over the whole of the holocene.  It follows any background emissions of CO2 from wild fire are matched by background sequestration of CO2 so that the net longterm change in CO2 concentration in the atmosphere is zero.  So, before taking your argument any further, you need to indentify the increase in CO2 emissions due to wildfire relative to background rates.  As wildfire and controlled burnoffs due to Land Use Change (LUC) are already included as anthropogenic emissions in IPCC calculations, you also need to specifically identify how much of the increase in wildfire is not due to LUC. 

       The second classic error is to ignore the fact that any biological emissions of CO2, including by wildfire, comes from CO2 originally drawn down from the atmosphere by photosynthesis.  That does not mean automatically that an increase in wildfire will not result in an increase in atmospheric CO2.  Such an increase, with no matching increase in photosynthesis and with no matching decrease in respiration (either by animals eating the plant matter, or through natural decay of plant matter) could result in a decrease in carbon stored in plant matter and a consequent increase in CO2 in the atmosphere.  But because of the close connection between photosynthesis and combustion, you need to look at the relative rates of each (and respiration) to determine what the net effect is.

       As it happens, combustion of plant material from all sources including as a fuel, only accounts for about 2.4 PgC/yr emissions.  Further, not only has the combined emissions of combustion of plant material plus respiration increased, but so also has photsynthesis by a larger amount (see chart below):

       

       As a result the combined effect of photosynthesis plus respiration/combustion is to take 2.6 PgC/yr out of the atmosphere if we ignore LUC (ie, the natural effects only), or 1.5 PgC/yr including anthropogenic LUC.  Both are a relatively small fraction of the 7.8 PgC per year from industrial emissions (fossil fuels pluc Cement) or 8.9 PgC/yr from all anthropogenic sources.

26508. InnocentSmithReturns at 07:59 AM on 1 December 2015
       Murry Salby finds CO2 rise is natural
       

       What I am about to ask may seem unfair, but it would be very helpful to me.  As a former Process Control engineer I am very interested in where you see a mistake or error in the presentation at https://www.youtube.com/watch?v=K_hBOU26F5o   I know you have posted arguments against Salby in the past, but what I am looking for is not counter arguements, but rather something like "At time frame 50:45" his math is wrong as follows..."  or "At time frame 50:45, the assumption he makes is wrong based on the following research data [with reference to study data ]   I want to keep the arguement tight and specific.  I realize this is a lot of work, but you might gain a convert (me) if you can show me specifically where he goes wrong in this presentation.  I am putting questions to Salby as well.   Thanks!

26509. scaddenp at 07:55 AM on 1 December 2015
       Welcome to Skeptical Science
       

       Since you dont supply link for forest fire Co2 release nor show us your calculation, I cant comment except that your numbers seem at odds with other sources. The isotopic composition of excess CO2 in our atmosphere is consistant with FF (which have no C14 whereas forest do).

       Forest fires dont produce long term change in CO2 concentration unless the forest is not replanted in something with similar carbon capture rates. Land use changes are an issue of course and you will see the accounting for that in IPCC reports.

       Cutting CO2 emissions significantly means switching energy use to non-carbon sources. Using less also helps. The best way to make the cut is simply to ban building new power stations that emit CO2 - let the market figure out the best replacement technology as FF stations age out. That doesnt go well with right-wing "govm't restricting freedom" types so second best way is Friedmann economics and impose cost on the externality (the effect of CO2 emissions). In practise this is some sort of carbon trading or carbon tax which prices FF-generated power more expensively than non-carbon sources.

       You dont need to reduce CO2 to pre-industrial age. You only need to slow climate change to a rate at which economic and human systems can adjust.

26510. Tom Curtis at 07:41 AM on 1 December 2015
       How much does animal agriculture and eating meat contribute to global warming?
       

       CBDunkerson @2, here is the CH4 cycle as estimated in AR5:

       

       The important factors are the annual increase (17 Tg CH4/yr) and the cumulative increase (2970 Tg CH4/yr).  As each molecule of methane (atomic weight 16) gets converted to a molecule of CO2 (atomic weight 44), these need to be multiplied by 2.75 to get the decay emission at Tg CO2, or by 0.75 for Tg C.  To convert to Petagrams, we need to multiply by 0.00275 and 0.00075 respectively, giving a cumulative emissions after decay of 2.2275 PgC, and 0.01275 PgC/yr.

       For comparison, here is the CO2 cycle from AR5:

       

       The cumulative emissions after conversion amounts to 0.9% of CO2 emissions, and is well within error.  The annual emissions amount to 0.3% of annual CO2 emissions and again is well within error. 

       The upshot is that methane can in fact be ignored for longer term planning (>200 years).  Its decay time of 12.4 years, however, means it will take approximately 50 years to effectively remove the excess CH4 with no further emissions, meaning it is a very substantial player over the coming century.

26511. ECLife at 06:48 AM on 1 December 2015
       Sea level rise due to floating ice?
       

       Thanks for pointing out my quick assumption.  I repeated the experiment with a balloon floating in 5% and 15% salt solutions and because it wasn't frozen, less dense, the balloon almost appeared neutrally buoyant in the 5% but more so in the 15% but the mass would be the same, displacing it's mass.  When I popped the balloon, the change in the 5% was not really noticeable but was in the 15% solution.  

       Conversely, I would say that as sea ice is formed, the ocean will get more briney and levels would drop.  It helps to think it through and realize our level is due to the floating and subsequent melting of ice, not the addition of 2 liquids.

26512. Andy Skuce at 04:27 AM on 1 December 2015
       How much does animal agriculture and eating meat contribute to global warming?
       

       Thanks for putting this in perspective, Dana.

       I think that the point of focussing in on beef and dairy is not so much that we can solve the climate crisis this way, but that avoiding beef or just cutting down is something that everyone can do that will make a small difference to emissions, a significant improvement to personal health and a reduced impact on the land.

       I should admit at this point that I am a non-observant vegetarian.

       XKCD has a cartoon that nicely illustrates the disproportionate mass of the world's cattle, with the implication that they have an outsize ecological hoofprint. George Monbiot also has a recent article on what species is causing the biggest contribution to the population crisis.

       

26513. Andy Skuce at 04:07 AM on 1 December 2015
       The Road to Two Degrees, Part One: Feasible Emissions Pathways, Burying our Carbon, and Bioenergy
       

       I didn't include any discussion of biochar because I have yet to see a proposal that can scale up to the problem we face. ELIofVA, if you can provide a link that quantitatively lays out a program to solve the climate crisis through mixing charcoal into the soil, I would be happy to read it.

       I don't doubt that biochar is a useful and sustainable practice in organic farming. It should improve the soils and it will help reduce emissions a little.

       Perhaps I have been too much influenced by George Monbiot's assessment.

26514. CBDunkerson at 03:45 AM on 1 December 2015
       How much does animal agriculture and eating meat contribute to global warming?
       

       Given that methane in the atmosphere breaks down to carbon dioxide and water (CH4 + 2O2 -> CO2 + 2H2O) fairly quickly, shouldn't increased methane levels be considered as increased CO2 levels for longer term planning?

       Basically, it seems to me like that whole '20 times more potent' bit on methane may inflate it's relative importance. Yes, in the short term one molecule of methane may be 'as bad' as 20 molecules of CO2... but the short term impacts are miniscule. In the long term that one molecule of methane is going to be one molecule of CO2... and thus methane emissions are, for practical purposes, equivalent to CO2 emissions.

       Put another way... should the 14% global GHG impact from methane be viewed as a short term mathematical construct, with the actual long term impact actually more like 0.7% (14% / 20) once that methane becomes CO2?

26515. ELIofVA at 03:34 AM on 1 December 2015
       The Road to Two Degrees, Part One: Feasible Emissions Pathways, Burying our Carbon, and Bioenergy
       

       Why is there no discussion of biochar as Carbon Capture and Store technology.  Making charcoal has been proven to capture carbon for at least thousands of years as proven by precolumbian cultures that made marginal rain forest land highly productive for growing foods.  This technology creates charcoal by burning organic material in the absence of oxygen.  The good part is that the charcoal has a great benefit in the short run increasing water retention, bio-organisms and micronutrients to improve food production and re-carbonize the soil.  This gets around the problem of where to put the sequestered carbon.  It still depends on plants sequestering the carbon from the atmosphere.  However, unlike reforestation alone, it prevents much carbon from re-emitting co2 from decomposition in a short time frame.  Finding immediate benefit for the uses of biochar gives a short term economic incentive that could eventually be of measurable benefit to the atmosphere.  Just like a bleeding patient, stopping the bleeding (burning) is the most critical.  However, the nurturing the conditions to increase new blood (sequestration) is a much slower but important process.  

26516. Bobbi at 02:16 AM on 1 December 2015
       Welcome to Skeptical Science
       

       I've done two calculations to determine the contribution to atmospheric CO2 from wildfires, compared with burning fossil fuels.  I did not include Volcanoes or other natural CO2 sources.  When I estimated forest density, I came up with wildfires producing 88 times fossil fuel CO2 production.  When I found pre-computed numbers, I found that wildfires and fossil fuel burning are comparable.

       Assuming that forest fires produce the same amount of atmospheric CO2 as burning fossil fuels, and the half-life of atmospheric CO2 being 500 years, even if the entire WORLD shut down all fossil fuel burning (impossible!), the reduction in atmospheric CO2 would take centuries. And, since making more than a 25 cut in global fossil fuel use is unlikely, we are in this mess for the long haul.  So, my questions to you are:

       1. What do you propose to realistically cut CO2 significantly?

       2. How long will it take to reduce CO2 levels to pre-industrial age amounts?

       Thank you in advance,

       Bobbi

       Moderator Response:

       [RH] Changed all-caps to italics. Please avoid all-caps, per commenting policies.

       [edit] Also, please show us your calculations that estimate forest fires produce 88 times the CO2 as FF emissions. 

26517. Cooper13 at 01:34 AM on 1 December 2015
       How much does animal agriculture and eating meat contribute to global warming?
       

       Excellent post.

       The flow charts are a fantastic visualization of the ratios for various energy uses and related emissions. This really points to the core targets that Americans can work on for overall emissions reductions, and where they can make the biggest impacts.

26518. Miriam O'Brien (Sou) at 01:25 AM on 1 December 2015
       A Buoy-Only Sea Surface Temperature Record Supports NOAA’s Adjustments
       

       A big thank you to you both, Zeke and Kevin. This is really useful and not a surprise, given the work I know went into preparing ERSSTv4. I like it that you've now included a comparison with Argo data, which contradicts what some people have been claiming. I'll be referencing this article from time to time.

26519. Tom Curtis at 00:29 AM on 1 December 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       RickG @31, unlike CO2, aerosols do not become well mixed in the atmosphere.  As a result the negative forcing in relation to US/European aerosols was largely confined to the North Atlantic region, while those from China are largely confined to China.  That is significant because there is evidence that the North Atlantic region is more sensitive to forcings than most other regions of the globe.  This is most obvious with the impact of the milankovitch cycles forcing the glacial cycle due to strong NH summer insolation despite near zero global forcing.  (Note, nearly all the major glacial ice sheets are associated with the North Atlantic.) 

       The upshot of this is that it is not a given that a given aerosol concentration over China will have the same masking effect as the same aerosol concentration over Europe/NA.  So while increases aerosol emission will mask some warming, it is difficult to determine how much.

26520. RickG at 00:22 AM on 1 December 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       I wonder, with respect to the cooling period from 1940 to the mid 1970s, which masked actual warming due to sulfate emissions; are there any projections as to what increased sulfates in Asia may be masking?

26521. Tom Curtis at 00:20 AM on 1 December 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       wili @28, no we have not.  The reason is that, with zero net emissions, CO2 concentrations in the atmosphere will be drawn as excess CO2 is taken up by the ocean.  This process is fairly rapid and occurs on approximately the same timescale as the rise in temperature from the Transient Climate Response to the Equilibrium Climate Response.  It follows that, with zero net emissions, temperatures will remain approximately constant, as shown in this graph from Matthew's and Weaver (2010):

       

       Although Matthews and Weaver show a constant or slightly declining temperature with zero net emissions, a more recent study (not to hand at the moment) has shown the possibility of a slightly rising temperature as well, although this is most probable with low ECS so the rise in that case would be gradual and restricted.  In any event, so long as we achieve zero net emissions before we reach 1.5 C, and possibly 1.9 C, we can prevent mean decadal temperatures rising above 2 C above the preindustrial average.

       That's the good news.  The bad news is that even continuing emissions as low as 5% of current emissions may (and certainly emmissions at 10% of current levels will) be enough to kick us into the constant CO2 concentration path (red line above).  In that case whether or not we exceed 2 C depends on whether the ratio of 2 C divided by current temperature above preindustrial is less than, or exceeds the ratio of ECS to TCR, which means even another 0.2 C rise will make us 50/50 to avoid 2 C at best.  Further, ongoing emissions at the 5% rate will in the long term (400 plus years) result in an ongoing gradual rise in temperature for up to tens of thousands of years into the future (or until we reach zero net emissions).

       Further, this analysis ignores the effect indicated @15 above.  That probably means we require slightly negative net emissions of CO2 to achieve zero net CO2eq emissions.  (Note, for the long term, multi-centenial temperature rise, it is zero net CO2 emissions that matter, not zero net CO2eq emissons, due to the relatively short atmospheric lifetime of WMGH gases other than CO2.)

26522. wili at 23:19 PM on 30 November 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       On feedbacks, see most recently this: GW will be faster than anticipated (because of methane feedbacks from lakes)

26523. wili at 23:15 PM on 30 November 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       Here's another question to pose to Kevin Anderson (or anyone else who want to take a shot at it):

       Given the lag time for full equilibrium effects of CO2, and given that we have been emitting at by far the highest rates over the last few years and decades, and given that we are already at about 480 ppm CO2 eq...isn't it likely that we are already locked in to about a 2 degree rise over preindustrial times, even if we were to stop all further emissions today?

       (This is of course assuming that we won't suddenly come up with a way to massively sequester atmospheric CO2, and that there is not some massive, unknown negative feedback waiting in the wings to save us--the potentially massive and quick feedbacks all seem to be positive, and you could add those to my 'given's above.)

26524. bozzza at 17:18 PM on 30 November 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       @ 22,

         Yes: but that is the exact politics of the matter- "..what is an excessive amount?"

         You are talking about the invisible hand of free market theory that is of course corrupted by any, and all, form(s) of Government intervention. The difficulty you talk of is often referred to as being, "..when Governments pick winners!"

26525. bozzza at 17:07 PM on 30 November 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       @ 24, 

        This is the argument that makes 'baseload' power largely a myth. If the elite want bespoke industry that makes profits while they sleep then they need to find a way to subsidise it and at the moment it is done through the sheeple consumer being too distracted by Hollywood to care enough about their kids to complain about the externalities of a globally manifest 24 hour working day.

        The definition of 'efficiency' is worth looking at. Methodical thought implies that a problem is first well defined.

26526. Tom Curtis at 16:06 PM on 30 November 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       michael sweet @16, methane decays as a function of the concentration of OH radicals in the atmosphere.  Therefore increasing the quantity of ozone (thus preventing the photodissociation of H2O) and of methane will increase the average decay time of CH4 (currently about 12.4 years to reduce to 36.8% of the original concentration).  NO2 decays by photodissociation, so the rate is controlled by insolation and hence is fairly stable (decay time 121 years).  In either case, the effect is that at a given emission rate, there will be a equilbrium concentration such that 63.2% of the concentration equals the emisisions of the decay rate.

       For NO2, that concentration is significantly greater than the current concentration, even if NO2 emissions were halved.  As a result sequestration to avoid increased forcing from NO2 will certainly be required.  Because of the high natural rate of CH4 emissions and short decay time, that is not necessarilly the case.  Therefore it is possible that sequestration will not be needed for CH4.  On the other hand, increases in arctic CH4 emissions as a feedback, in addition to ongoing agricultural emissions will likely require ongoing sequestration.  In neither case will sequestration need to continue in perpetuaty, only until atmospheric concentrations stabilize.  That, however, is likely to take more than 50 years for methane and several hundred years for NO2.

       Beyond those points, RustNeverSleeps @18 makes excellent points.

       I am not aware of any particular research on this.  It is just a point that follows logically from the difficulty in reducing direct agricultural emissions combined with the at least doubling of human population over the coming century (with consequent increase in the need for intensive agriculture).  It is, however, a point that can slip by unnoticed by treating all emissions as just CO2eq for emissions pathways.

       Finally, my final conclusion was not that a small multiple of sequestration made necessary by agricultural emissions will also sequester the emissions from an ongoing fossil fuel industry.  That is certainly not the case, and it is dubious IMO that even 50% of current fossil fuel use can be reconciles with net zero emissions by sequestration.  However, some small level of sequestration will be necessary regardless, and that small level can be increased to reduce overshoot at a slow rate.  We are still best of keeping that overshoot as low as possible. 

26527. Tom Curtis at 15:41 PM on 30 November 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       Digby Scorgie @22, the product of air transport is not air transport itself, but efficient transport of people and goods.  One of the cheapest competitors of air transport is sea transport (or rail transport, or blimp transport) and in some cases simply telecomunications.  Therefore, even if no adequate substitute for jet fuel can be found, there will still be reasonably prices substitutes for the actual services provided by modifying our social expectations or rapidity of delivery.  Indeed, much of the "expense" of converting to a low emissions economy is simply social inertia in the form of expecting the bundle of goods and services we currently have, ie, optimized for delivery using fossil fuels, to remain unaltered when we could instead optimize for delibery with renewables with no loss of utility.

       That leave aside the fact that jet fuel can be synthesized direcly from biological fuels, and/or jet fuel exhaust can be captured and sequestered, in either case providing a zero net emission substitute at far below infinite cost.  Indeed, I included these possibilities in my estimate of US$200 carbon price for complete subsitution (although early schemes in this direction may be more expensive).

26528. Tom Curtis at 15:32 PM on 30 November 2015
       Heat from the Earth’s interior does not control climate
       

       Maark @41, you should more carefully read the post above as it contains enough information to refute your theory as is.  Further information is available here.  On top of that, the rate of spread over time at ocean ridges is well known by dating the ocean floor.  That rate of spread is in turn correlated with amount of magma ejected, and hence the rate of heat flux at the ocean ridge.  This data does not support your theory.

       Finally, looking at things differently, the key question is not the absolute rate of energy release from the interior, but the rate of change in that energy release.  That allows us to consider the direction of that change by considering the sources of geohysical heat, which are two fold: friction from tidal interactions, and heat from radioactive decay.  The later necessarilly decreases with time because the radioactive elements are in fact decaying, ie, becoming inert elements by various combinations of radioactive emissions.  The rate at which that occurs is slow, being dominated by elements with half lifes in the billions of years - but it is one way.  The process cannot reverse itself.  Likewise, over time tidal forces reduce as tidal friction moves the interacting bodies further apart.  Again this is very slow.  There is a slight possibility of variation in that different continental configurations will result in more or less tidal friction, and hence more or less geothermal heat from tidal forces.  As it happens, the current continental configuration represents a near peak for tidal friction, but that peak will have been declining since the closing of the isthmus of panama as Australia, South America and Africa continue to drift north (thereby reducing friction by opening up the gap to Antarctica.  In any event, any change form this will represent a very small fraction of total geothermal heat over intervals of 100s of thousands of years.

       There is simply no physical basis to think geothermal heat could be increasing on a global level, and if anything it will be declining, at a far slower than glacial rate.

26529. Glenn Tamblyn at 14:37 PM on 30 November 2015
       Heat from the Earth’s interior does not control climate
       

       Maaark
       
       Use the search option at the top of the page to search for informaton about 'Milankovitch Cycles'.
       
       Essentially cyclical changes in Earths orbit and axial tilt that cause small fluctuations in how much sunlight is received by different parts of the Earth at different times of the year.
       
       This provides a small warming and cooling impetus. This then is magnified by changes in CO2 levels in the atmosphere as the oceans warm and cool, changes in methane levels in different climates and expansion/contraction of land and sea ice, altering how much sunlight the earth reflects to space.

26530. Maaark at 14:25 PM on 30 November 2015
       Heat from the Earth’s interior does not control climate
       

       I will pose this as a question because I am not an advanced scientist, just a college student in some basic environmental classes. If the earth's record shows 7 cycles of heat/cooling in past 650,000 years, then we should ask what is the common factor in all of these events. It is possible atmospheric C02 was the source, but then humans were not the source of the C02. Another common factor was the Earth's core and its heat. It is simple to observe earth's heat on any day in winter in our North American climate. When I pour concrete I must keep the ground below the concrete from freezing. We construction workers pile hay or straw in the ground and in a couple of days it is unfrozen. Does anyone disagree that there is constant heat radiating up from the earth core? This is basic right?

       My hypothesis, after reading the very basics of plate techtonics, is that warmer plates move closer to the surface heating water and soil. It is a fact that the plates are constantly moving so shouldn't this be considered? Where could I find evidence from core drill temperatures? Are there records kept as in sea temperatures?

       Some arguments above negate the potential for core heat to radiate this strongly on the basis that the change in temperature would need to be drastic. But my science book is saying that if air temperatures increase just one degree the results are drastic. Well then if an area under the Atlantic 1,000- square miles warmed by 4 degrees and the ocean conveyor belt brought that warm water to the equator it would certainly affect our huricane season and El Nino. It would also affect the glaciers. This hypothesis is at least consistent with warming in the pre-human historic past.

       If you have a simple expaination I sincerely want to know before I embarrass myself in class. Thanks

26531. TonyW at 14:11 PM on 30 November 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       Another example of how some scientists don't give the full picture (or even the correct one) is Schmidt's Carbon Brief interview where he gave completely inaccurate figures for US emissions, even praising them (claiming imaginary reductions). This leads to the notion that GDP can be decoupled from emissions, which I've read other scientists espouse. I've always felt that this idea is false as it likely didn't take into account exported emissions. This Monbiot article points to research that  there is no evidence that decoupling is taking place at all (and may even be the reverse). I think scientists are guilty of not thinking deeply enough about this stuff, even though they think deeply about their subject area.

       Anderson is absolutely right, IMO, to point to these failings of the scientific community.

26532. Tom Curtis at 13:06 PM on 30 November 2015
       It hasn't warmed since 1998
       

       AJC1973 @366:

       1)  You seem very confused about trends and variation.  The point about the final point of data is that it tells you nothing about any other data point.  In contrast, the trend sums up information about all the data, and does so in a way that usefully informs you about the next likely datapoint (see video below).  People who only want us to look at the first and last datapoint are really cherry picking - trying to blind us to the truth by the carefull exclusion of data contrary to their narrative.

        (Further comments)

       2)  Words to indeed have meaning, and expostulating about that fact won't lead us to ignore those meanings.  Thus, here are the four most recent annual temperature records for the three major surface temperature records:

       Year_____: _1998, _2005, _2010, _2014

       HadCRUT4: 0.536, 0.544, 0.559, 0.567

       NOAA____: _0.63, _0.66, _0.70, _0.74

       GISS_____: _0.63, _0.69, _0.72, _0.74

       As can easilly be seen, in each case 1998 < 2005 < 2010 < 2014.  You want to say that 2014 = 2010, but that is not true.

       Probably you have been confused by people inaccurately talking about a "statistical tie".  That is because in each case 2005 lies within the uncertainty interval of 2010.  Therefore, given the data it is statistically possible that 2010 was actually the warmest year, but the nominal value (or the mean estimate) places 2010 above 2005.

       Note, this is not a 'statistical tie' (or worse, a case where 2010 is 'statistically indistinguishable' from 2005).  That is because there are years which may have been (given uncertainty) warmer than 2005, but which could not have been (given uncertainty) warmer than 2010.  Put another way, the probability that 2010 was the warmest year given the data is greater than the probability that 2005 was the warmest year.

       Note, the same can be said of the relation between 1998 and 2005, and 2010 and 2014.

26533. Eclectic at 12:54 PM on 30 November 2015
       It hasn't warmed since 1998
       

       AJC1973 @366 : You will need to explain yourself more clearly ~ since your post [above] does not make much sense.

       Words ( even "Proffesor" ) can have meaning ~ but they need to be allied with commonsense thinking. Is the world warming . . . or isn't it? The evidence shows clearly that it is . . . and word-games cannot alter the physical reality of it all.

26534. Digby Scorgie at 12:48 PM on 30 November 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       Andy @20: I look forward to that, thanks.

       Tom @21:  That makes sense; the tax must make fossil fuels more expensive than the next cheaper alternative.  The only problem I then foresee is when it costs an excessive amount to get the alternative introduced — as perhaps with synfuels for aircraft and ships.  Anyway, it will be extremely interesting to hear what Kevin Anderson has to say about this, because he doesn't think an MBI such as a tax will work.

26535. AJC1973 at 12:11 PM on 30 November 2015
       It hasn't warmed since 1998
       

       2 things... 

        

       using a trend as an answer as to why the current data doesnt matter is crazy. you cant say it doesnt matter look at the other 10 data points they lead to this...  obviously they dont if they did there would be no cooling trend... lets break it down.. this is like a straight a student someone who had got 10 straight A's but on the final got an F..  The Proffesor then grades accordingly.. but the student says no... you didnt take into account the "Trend" my grade should be reflective of the past 10 measurements... would that really fly?

        

       Also come on guys words have meaning.. you cant say that 2010 was the highest temerature on record, it was tied with 2005.  if 2005 was just as warm 2010 cant be higher... 

26536. scaddenp at 10:53 AM on 30 November 2015
       There's no empirical evidence
       

       jl5501 - there are a number of approaches to this. On page 405 of IPCC WG1 (chapter 5),  you will find results of 9 studies with different methods summerized. The range of the ECS from these studies is still wide. Another recent study is discussed here. Accurately determining both past temperatures and particularly past forcings is not a trivial exercise.

26537. Riduna at 05:30 AM on 30 November 2015
       G R A P H E N E
       

       Graphene technology certainly does not - and can not - address the rapidly growing problem of population increase or the pressure this puts on the food supply required for their survival. However, it may provide clean water through its potential use as a membrane filter. Graphene technology is not claimed to be a universal panacea. It may slow but will not stop carbon emissions from a warming Arctic.

       Given the present state of technology, it is difficult to see graphene technology replacing aviation fuel with stored electric energy. On the other hand, pending this development, it is possible to replace fossil fuel with bio-fuel. Graphene does have potential to slow, possibly reduce, ocean acidification by reducing greenhouse gas emissions.

       The essay examines the potential for graphene technology to displace fossil fuel for electricity generation and storage, land transport and, eventually, on vessels now dependent on bunker oil for propulsion. It will be developed. If it is not, there appears to be no other candidate able to displace fossil fuels. The consequences of not displacing them may make large parts of the globe uninhabitable by our species.

26538. Eclectic at 21:24 PM on 29 November 2015
       There's no empirical evidence
       

       jl5501 @301 : The answer to your first question is multi-faceted, regarding past influences. In the short-term viewpoint of recent centuries, the biggest factor is atmospheric CO2 (plus its feedbacks). In the longer term i.e. megayears, you will find large influence from the subtle shifts of interaction between the gradually changing cycles of the planet's orbital shape and inclination of the axis, as well as continental drift [affecting ice-related albedo].

       Go to this site's Home Page, and check out the various Climate Myths ~ and in particular, Number 14 which addresses the recent cycling of Ice Ages. The chart there may give you the impression that a new ice age might be "expected" in 10,000 years or so . . . but in the text you will notice that the next [natural] deep cooling from orbital/tilt interactions will be a weak effect . . . and so the next "due" Ice Age might well be (hypothetically) due in 30,000 years or longer ~ yet in reality ( and owing to the the recent high levels of human generated co2 ) that due-to-arrive Ice Age will be scotched by the present higher than natural CO2 in the air and by the warmed-up oceans and by the dissipating North Polar ice. So . . . a long, long wait for new ice ages . . . and an unpleasant time for the next few centuries, from the overheating of our planet.

26539. reuns at 21:17 PM on 29 November 2015
       Discussing global warming: why does this have to be so hard?
       

       we are not playig nothing safe : humans are changing earth and that's a good thing, I like the scientific evolution of our society which makes us confortably discussing on the internet of possible climate in the future centuries. this is a huge progress and it can continue to evolve.
       
       BUT : it means we have to stop fighting for stupid questions. the most important problem is to have food, water, energy, houses.
       
       if we can produce and distribute that all other the planet, it will be good. clearly, the biggest fear is capitalism which makes all these things too expensive and forces us to work for silly reasons (and consume more and more CO2 for nothing !), much more than climate change which even with 4°C shouldn't imply wars and food problems because it will be very slow compared to our lifes.
       
       so fire the assholes which serve us of governement, and let's assist the climate change without fear.

       Moderator Response:

       [PS] Please take the time to review the Comments Policy and ensure future comments are in full compliance with it.

       You also make a number of eyebrow-raising assertions. eg "capitalism which makes all these things too expensive" and " 4°C shouldn't imply wars and food problems". If you are going to make assertions, especially contrary to mainstream thought, then you need to back these with supporting references.

26540. reuns at 21:02 PM on 29 November 2015
       CO2 effect is saturated
       

       so, where is the answer to the article ?
       
       the curve relating the CO₂ concentration in atmosphere and temperature of lower atmosphere ?
       
       it should be a simple thermodynamic equilibrium wich depends on absorption and emittance parameters,
       
       and yes even with 100% of CO₂ the temperature would be finite (because of the Stefan-Boltzmann black body rule which says the irradiance depends of temperature in T⁴ : the more a body is hot, the more it cools itself by irradiating around)

26541. jl5501 at 19:48 PM on 29 November 2015
       There's no empirical evidence
       

       We know that the climate was warmer in the geological past than it is now. What do we know of the factors ( particularly co2) that caused the decrease in temperature from the warmest time?

       
       From that, are we able to calculate how much the climate would be warming without human generated co2 emissions

26542. Tom Curtis at 16:22 PM on 29 November 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       Digby Scorgie @19, for a carbon price to eliminate the use of fossil fuels, it need only raise the cost of using the fossil fuel to greater than its next cheapest competitor.  As there is no use of fossil fuel where the next cheapest competitor has an infinite price, the cost of the carbon price need never rise to infinity to eliminate the emission of CO2.  It is dubious that it needs to rise even to US$200 in the long term, although with current technologies it would need to rise higher to completely eliminate CO2 emissions.

26543. Andy Skuce at 14:51 PM on 29 November 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       Digby, we are arranging one, maybe two, interviews with Kevin Anderson over the next little while, so I will make sure to put that question on the list.

       If you or other readers have anything else you would like an answer to, ask it here and I will pass it along.

26544. Digby Scorgie at 14:20 PM on 29 November 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       Kevin Anderson has an interesting article at his website about methods of inducing a decline in the burning of fossil fuel.  He contends that MBIs (market-based instruments) are inadequate to the task.  By MBIs is meant such methods as carbon taxes and cap-and-trade.

       (As an aside, I should mention that I've always wondered if instituting a carbon tax is like trying to divide by zero: for fossil-fuel use to tend to zero, the tax has to tend to infinity!)

       It would be interesting to follow up this Part Two article with Anderson's view of MBIs.  How about it, Andy?

26545. rustneversleeps at 07:42 AM on 29 November 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       michael sweet,

       N₂O has an atmospheric lifetime of about 120 years, and a global warming potential 300x that of CO2 over a 100 year timescale.

       Furthermore, the N₂O emissions do not come from "gasses already in the atmosphere" unless you consider the Haber-Bosch process as doing that. The fact is that we have disrupted and dominate the nitrogen cycle far, far more than we have the carbon cycle.

       Methane, while it does have a shorter atmospheric life, also has a GWP of 34x that of CO₂ at the hundred year timescale. Which is surely germane if we are talking about hittlng the 2C target.

       So I don't think your rejoinder to Tom really holds.

       (N₂O is also a powerful ozone depleting substance, just to ruin our days a bit more...)

26546. MA Rodger at 02:27 AM on 29 November 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       Leto @11.

       I am inclined to see the 'mugged old lady'analogy as not immediately applying to the full ΔTemperature resulting from AGW. There is obviously no bad stuff (no mugged old ladies) if AGW resulted in ΔT(full)=0.1ºC. So perhaps we should apply it to the ΔT(from now). Or better still apply it to emissions from now. But such meddling probably is too much of a strain on the analogy.

       Howver, I do rather like the idea of David Lewis @13 who likens present AGW policy to the 1939-40 Phoney War. A lot is being done (the UK was re-arming big-time well before Munich) but there is so far no sanction to properly begin doing what is inevitably needed to be done. In the greater public consciousness, the bad stuff has yet to be seen as that bad. Mind, comparing the available perspecive of Nazi malevolence in 1939-40 and the available perspecive of AGW today, playing a Phoney War with AGW is far less excusable.

26547. michael sweet at 21:29 PM on 28 November 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       Tom,

       Can you post a link to support your claim that agricultural emmisions must be countered by sequestration to keep temperatures stable?

       It seems to me (without citations) that agricultural emissions will not need to be sequestered for two reasons:

       1) Methane and NO2 are shortlived in the atmosphere and after a decade or two decompose into CO2 and harmless gasses.  This is different from carbon dioxide which is essentially permanent once it is emitted.

       2) All agricultural emissions come from gasses already in the atmosphere. Therefore if agriculltural emissions are stable after a period of time the concentration of agricultural methane and NO2 will stabilize. (The resulting CO2 came from the atmosphere so it would not increase CO2).

       Lowering CO2 emissions from deforestation is necessary for long term stability of the atmosphere and may be difficult.  Some sequestration may be necessary but the scale required might not be as large as you suggest.

       This summary reviews many methods of reducing agricultural emissions by altering farm practices.  Greater farm efficiency and choice of crops that emit less greenhouse gases can help.  Managed forrest produces substantial income in many locations as long as enough food is produced.

       The required use of a technology as difficult as sequestration that has not yet been developed at any price is extremely risky.  

       I find it interesting that the IPCC declines to estimate sea level rise from the decline of the great ice sheets because it is not well understood while at the same time relies on unknown technology for sequestration.

26548. denisaf at 13:43 PM on 28 November 2015
       The Road to Two Degrees, Part One: Feasible Emissions Pathways, Burying our Carbon, and Bioenergy
       

       There are two relevant issues missing from this discussion. Firstly, the greenhouse gas emissions are already causing irreversible ocean acidification and warming, with a consequential deleterious impact on the operation of the marine ecosystem. Secondly there is the fallacious presumption that technological systems can be installed that will rapidly emulate what it has taken natural forces eons to do. Additionally, these techological systems naturally age despite the use of energy and materials for their operation and maintenance. Systems providing negative emissions may turn out to be worthwhile for a while but they cannot possibly offset the positive emissions. In addition, no realistic alternatives to the jet fuel used by the many thousands of aircraft, including airliners, or for the fuel oil used by the many thousands of ships, including cargo vessels, have been identifies despite research over many decades.

26549. Tom Curtis at 11:52 AM on 28 November 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       The long term maintenance of a stable temperature requires zero net emissions.  Further, to bring emissions down sufficiently for a 2 C target requires western nations to reduce to zero net emission by 2050 or there abouts, even if we do not set national emission quotas on an equal per capita basis (the only truly fair way to tackle climate change).  That presents a major problem.  From 10-20% of total emissions are a direct product of agriculture.  That rises to about 30% if fossil fuel use in agriculture is included.  Of the direct emissions from agriculture, about 50% is in the form of nitrous oxide from fertilization of crops, and an approximately equal amount is from methane production either from rice production or from enteric fermation from cattle.  

       While studies have been undertaken as to how these values can be reduced, it would be foolish to think they can be eliminated.  Nor can we draw down from current levels of agricultural production without guarantteeing a global famine.  Ergo, for the forseeable future (ie, for several centuries down the track) we can expect NO2 and CH4 emissions from agriculture to equal at least 10% or current CO2eq emissions.  That is, absent carbon sequestration CO2 emissions cannot be reduced below approximately 10% of current values.

       Ergo, any viable future pathway must include carbon sequestration of at least 10% of current CO2eq emissions.  That is in addition to any carbon sequestration of continuing standing energy supply from fossil fuels, or from transport (some of which may be impossible to eliminate).

       The key point is that large scale sequestration is going to have to be deployed withing 30-40 years regardless of whether or not total emissions ever go negative or not.  That is, even the emmision reduction curves in the first figure above that "... assume no net-negative emissions technologies deployed ..." must in fact deploy large scale sequestration technologies to deal with agricultural emissions.  That being the case, we cannot consistently argue that we must follow one of those paths or fail to limit warming to a 2 C target.  If we can deploy sequestration technology that compensate for agricultural emissions, than we can deploy 50% more of that technology and generate substantial net negative emissions.

       This is not necessarily an optimistic point.  Such technologies may be unfeasible at large scales, in which case the view is very pessimistic indeed for in that case we will never reach carbon neutrality.  But more probably such technologies are achievable (though potentially with significant difficulty).  In that case the situation is not as cut and dry as Anderson suggests.  It is not, then, that we should not reduce emissions significantly faster than we actually are - but that it is not necessarilly cause for despair if we do not.  There probably will be a plan B, and must be if there is in fact a viable plan A.

26550. billdw at 04:51 AM on 28 November 2015
       The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
       

       Leto @9

       The truth is the solution is painful and always has been painful because it requires sacrifice for a future, that one can maybe foresee, but not see.

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