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Comments 45901 to 45950:

45901. Gingerbaker at 04:33 AM on 23 April 2013
       Global Warming: Not Reversible, But Stoppable
       

       According to Aradhna Tripati, a UCLA assistant professor in the department of Earth and space sciences and the department of atmospheric and oceanic sciences:

        

       “The last time carbon dioxide levels were apparently as high as they are today — and were sustained at those levels — global temperatures were 5 to 10 degrees Fahrenheit higher than they are today, the sea level was approximately 75 to 120 feet higher than today, there was no permanent sea ice cap in the Arctic and very little ice on Antarctica and Greenland,”

        

       This does not seem to jive with the Science article which asserts that if CO2 emissions were to stop today, the global temperature would not go up. Every CO2 vs global temp graph I can remember seeing indicates that that there is a significant time lag between CO2 concentration and global temp.

        

       We now know that 90% of the heat imbalance caused by AGW is in the deep oceans.  This heat, along some time scale, will eventually become unsequestered and actually increase temperatures, yes?

        

       Every report I remember reading has implied that the 0.8C global temperature increase we have seen is by no means all that we can expect 400 ppm CO2 to deliver.

        

       Now, one article in Science comes out, and we are supposed to believe its assertions?  This is not making sense to me.

45902. shoyemore at 04:09 AM on 23 April 2013
       Major PAGES 2k Network Paper Confirms the Hockey Stick
       

       Roger D #3

       the point is that the flatish average annual surface temperatures mislead the willing-to-be-misled into thinking that no damage is being done between up-ticks in avg. surface temperature.

       A very good description of boiling frog syndrome.

       The premise is that if a frog is placed in boiling water, it will jump out, but if it is placed in cold water that is slowly heated, it will not perceive the danger and will be cooked to death.

       http://en.wikipedia.org/wiki/Boiling_frog

45903. keithpickering at 02:54 AM on 23 April 2013
       Major PAGES 2k Network Paper Confirms the Hockey Stick
       

       Not just the Arctic. The world as a whole is a whopping 0.2°C warmer during the most recent 30-year period (1983-2012) than during 1971-2000, in spite of a 60% overlap in dates.

45904. Bob Loblaw at 02:33 AM on 23 April 2013
       The science isn't settled
       

       engineer:

       I don't think it is correct to just call it a technical problem. To follow on Glenn's comment, when you are trying to model today's climate, you can get away with saying "this is what the vegetation is", or "this is where the ice sheets are", etc., and simply measure the required input parameter for the climate models. You can even do that to a certain extent for past climates, as there are proxies that will give you an indication of vegetation cover, ice cover, etc. Understanding why the vegetation, ice, etc. are the way they are is a help, but not an absolute necessity to be able to develop a good understanding and a reliable model of current climate.

       Contrast that with the future: we can't measure the vegetation cover or ice sheet distributions - we have to model them. But uncertainties in how vegetation responds to a changing climate is not a problem that necessarily requires increased understanding of climate dynamics - it is a problem of understanding vegetation dynamics. Predicting something like future aerosols not only requires estimating future levels of existing emission sources (which requires economic modelling), it also requires assumptions of what future combustion technology might produce, and what social policy choices might be made. You can start by assuming they won't change, but proper policy decisions require that you also evaluate what might happen if they do change (using realistic ranges of possibiliites).

       It's a classic multi-disciplinary issue.

45905. jdixon1980 at 02:27 AM on 23 April 2013
       The History of Climate Science
       

       Neilrieck @ 15, I would point out to those friends and relatives that Weart's interactive html history is divided into subtopics addressed in many bite-sized "essays" (his term) that can easily be read in a single sitting and don't have to be read in any particular order, and the writing is excellent.  I find the Weart essays (which I downloaded as PDF's to my e-reader for reading on my daily commutes) to be page-turners, albeit speaking as someone who was already interested in this subject.  Still, this post adds something in that, as a comprehensive treatment, it is far more condensed than the entirety of Weart.  

45906. John Hartz at 02:24 AM on 23 April 2013
       The science isn't settled
       

       @engineer

       Here's a concise descpriton of how global climate models evolved and function.

       By the mid-1990s, it was possible to investigate the causal mechanisms behind changes in Earth's climate using relatively sophisticated mathematical models of Earth's climate. These models solved the same complex equations of atmospheric physics that numerical weather prediction models did. But they also took into account components of the climate system other than the atmosphere, including the oceans, the continental ice sheets, and even life on Earth (collectively known as the "biosphere"), and they attempted to account for the physical, chemical, and biological interactions among these components. Of course, no theoretical model is ever perfect; even the best model is only an idealization of the actual world. There are always real-world processes that cannot be captured—for example, in the case of a numerical climate model, individual clouds or small-scale air currents like dust devils—that are simply too small for the model to resolve. The key question is, can the model be shown to be useful? Can it make successful predictions?

       Source: How Do We Know Humans are Responsible for Global Warming? by Michael Mann, WeatherUnderground, April 22, 2013

45907. jdixon1980 at 02:17 AM on 23 April 2013
       Global Warming: Not Reversible, But Stoppable
       

       Small typo: I think there was supposed to be a "(C)" after temperature change in the Figure 1 description.

       Moderator Response:

       [AS] Thanks, fixed.

45908. Martin Lack at 02:08 AM on 23 April 2013
       Carbon Dioxide the Dominant Control on Global Temperature and Sea Level Over the Last 40 Million Years
       

       Bill Everett @22, 52, and 74.

       I am 100% with you on your persistent advocacy for use of the 'thermostat' analogy (rather than 'control knob').  As you have pointed out, promoting the view that atmospheric CO2 acts as a thermostat reinforces the reality that there is a great deal of inertia in the climate system.  Without this, 0.8 Celsius for 40% increase would imply 2.5 C for double. However, since there is inertia in the system, we are heading for 3 to 6 C for double pre-Industrial CO2 levels.  Therefore, given the disruption being caused by 0.8 C, I really do not understand how anyone can remain complacent about where humanity is taking this planet...  To mark Earth Day 2013, Michael Mann has posted an excellent extract from his book, The Hockey Stick and the Climate Wars, on the Weather Underground website today:

       http://www.wunderground.com/earth-day/2013/how-do-we-know-humans-are-responsible-for-global-warming

45909. dana1981 at 01:55 AM on 23 April 2013
       Major PAGES 2k Network Paper Confirms the Hockey Stick
       

       Roger @3 - bear in mind that the Arctic is now considerably warmer than the 1971–2000 average.

45910. Roger D at 01:49 AM on 23 April 2013
       Major PAGES 2k Network Paper Confirms the Hockey Stick
       

       Thanks for the post. The study's finding that "The Arctic was also warmest during the twentieth century, although warmer during 1941–1970 than 1971–2000 according to their reconstruction." is not what I would have expected. However, looking at the natural climate/ temperature indicator of July sea ice extent reconstructed back to 1870 a smoothed-line fit starts to curve downward at about in the 1941-1970 period. The ongoing loss of ice in a region that is on average not wamer in the latter part of 60 years (1941-2000) seems like a good reminder that it does not take a constant yeaer on year increase to cause pronounced natural response over large areas. Arctic sea ice is an easy to visualize indicator but as Sks and others have shown there are numerouse others. For me as a layman the point is that  the flatish average annual surface temperatures mislead the willing-to-be-misled into thinking that no damage is being done between up-ticks in avg. surface temperature.

45911. John Hartz at 01:43 AM on 23 April 2013
       2013 SkS Weekly News Roundup #16B
       

       @jyushchyshyn:

       If Canadians are truly concerned about the global environmnet, they will demand that the mining of the tar sands bitumen be stopped.  

45912. Glenn Tamblyn at 20:47 PM on 22 April 2013
       The science isn't settled
       

       engineer

       There are a range of potential feedbacks that are hard to quantify because each one of them is an entire field of study in its own right. For example:

       Vegetation response. Will the Amazon for example remain a rainforest? Become a drier forest? Grassland? Each has different implications for carbon cycle sinks and sources, surface albedo and evapotranspiratioin patterns.

       Ice sheet retreat. What are the dynamics of any decline in Greenland ice sheet cover, WAIS, EAIS? Timing and extent of this for any particular level of GHG forcing again has significant impacts on albedo.

       Ocean Circulation. Major ice sheet melt might impact on the Thermo-Haline circulation that drives ocean currents - there is some evidence this was a part of what happened during the warming from the last Glacial Maximum. If ocean currents change, this can alter the distribution of where heat is transported to. Thus cloud patterns, climate zones, all sorts of things.

       Methane release from Permafrost. How fast will permafrost melt and where? Will this produce more aerobic or anaerobic decomposition of the defrosted organic matter, influencing whether carbon outgasses as Methane or CO2. Higher rates of methane release will have a greater short term warming effect than if it is released as CO2 even though the longer term impact will be the same as ultimately the methane is oxidised to CO2

       This stuff is too hard to do at a theoretical level and even modelling involves stacking models on models. Thats why paleo climate studies are an important reference point. That is what climate has actually done in other circumstances.

45913. Miriam O'Brien (Sou) at 17:09 PM on 22 April 2013
       Major PAGES 2k Network Paper Confirms the Hockey Stick
       

       It's great that we are now getting more detailed information about past conditions at the regional level within the context of the whole world.  Paleo research seems to be progressing exponentially.  It will help us better understand what humanity is facing now, even though we've never faced conditions like this before.

45914. engineer8516 at 14:17 PM on 22 April 2013
       The science isn't settled
       

       @ Bob, It's just a miscommunication on my part. I couldn't think of how to word my question that's why I ended up asking that subjective question in the beginning.

       I'm not questioning the reliability of models...models are used all the time like CFD. The limitations in CFD is due to budget and computer power. I was wondering where the uncertainty in climate was mainly coming from like the uncertainty in equilibrium climate sensitivity from double co2. was it because of theory or tech? but you guys already answered my questions that the it's due to limits on current tech. thanks.

45915. jyushchyshyn at 14:04 PM on 22 April 2013
       2013 SkS Weekly News Roundup #16B
       

       If Canada wants people to accept Keystone XL and the oil sands, it must show the world that it takes the environment seriously. The carbon pricing deadlock is indeed hurting Canada's economy.

45916. Maggnum at 13:46 PM on 22 April 2013
       Major PAGES 2k Network Paper Confirms the Hockey Stick
       

       I look forward to seeing the results of the ocean temperature recreations. I hope they are able to include and take into account the deep ocean warming, especially as it relates to the paleo-climate of the past 2000 or so years.

45917. scaddenp at 13:39 PM on 22 April 2013
       The science isn't settled
       

       There can be quite a gap between a qualitiive description of a process (eg think ENSO) and a computer model able to capture it, but a big factor is limitations on the measurement system and time length of good data. (eg for Argo we have only 10 years so far). If you want quantitive models, you need accurate measurements. As far as I know, aerosol measurements are still short of modellers hopes.

45918. Bob Loblaw at 13:36 PM on 22 April 2013
       The science isn't settled
       

       engineer:

       ...it is odd that you interpret my somewhat-rhetorical questions as "defensive", when you yourself began with somewhat-rhetorical questions. Granted, it can be difficult to read tone into a written comment, but you started off with what semed like a "gee, this should be so simple if it is well-understood" sort of comment. It reminded me of the following XKCD comic:

       

        

       Perhaps a better start would have been to pose the question something like "What part are understood, and where does uncertainty in this value come from?" (as you are beginning to ask now) rather than implying it can't be "well understood" because it can't be predicted as easily or accurately as the simple examples you gave. The question relates to the How reliable are climate models? discussion, where you can find out much more about how the reliability is examined.

       In a system as complex as global climate, you can have uncertainty in predictions due to uncertainty in the measurement of input variables, even if the physics of those portions of the system are well understood at a theoretical level. For example, consider the effect of aerosols. The radiative effect of a specific aerosol can be modelled quite well, given sufficient data about the size distribution, physical, and optical properties of the aerosol, etc., but getting detailed measurements of those physical properties over huge swaths of the atmosphere over sufficient time can be extremely difficult. Even if the technology exists (e.g AERONET), budgets aren't infinite and measured data is incomplete.

       Then take that difficulty into the future, and try to predict exactly what the future aerosol state will be. It's not that it's hard to predict what a particular aerosol will do - it's hard to predict exactly what will be up there.

45919. engineer8516 at 13:23 PM on 22 April 2013
       The science isn't settled
       

       scaddenp, last question. when you say "a lot less confidence quantifying some of those processes accurately" is that due to technology limitations (computing power) or theory? thanks

45920. engineer8516 at 13:05 PM on 22 April 2013
       The science isn't settled
       

       thank you. that explained a lot.

45921. scaddenp at 13:04 PM on 22 April 2013
       Climate's changed before
       

       Kristjan, I think it is expected to be more or less constant within a particular range of temperature/states. Ie once all the ice is melted, then the albedo feedback becomes a lot more subtle. Ditto, on an iceball earth, you would expect sensitivity to be high at point where ice melts at tropic.

45922. scaddenp at 13:00 PM on 22 April 2013
       The science isn't settled
       

       Good question. As far as know, for ECS you need to know where feedbacks will stabilize. Ie if you perturb CO2, where does T settle when all feedbacks are in equilibrium. Now I think you could say there is a lot of confidence about what the feedbacks are, a lot of confidence about how the feedbacks work, but a lot less confidence about quantifying some of those processes accurately. (eg the complex dance of aerosol, water vapour, temperature and clouds).

45923. engineer8516 at 12:36 PM on 22 April 2013
       The science isn't settled
       

       @ bob, relax man. I'm not sure why you're so defensive.

45924. engineer8516 at 12:33 PM on 22 April 2013
       The science isn't settled
       

       so is the uncertainty mainly the result of the lack of theoretical understanding or the lack of more sophisticated technology (e.g. better satellites)? How much of the uncertainty in equilibrium climate sensitivity is from a lack of theoretical understanding?

45925. Kristjan at 12:16 PM on 22 April 2013
       Climate's changed before
       

       Is climate sensitivity a constant or dependant on other variables? Meaning, as the earth gets warmer (or cooler) does the climate sensitivity stay the same or increase/decrease (or maybe it's dependant on some other variables as well)?

45926. Bob Loblaw at 12:15 PM on 22 April 2013
       The science isn't settled
       

       engineer:

       I will answer the question with more questions.

       1) you are selecting some very simple examples from heat transfer (mixing two different quantities, at two temperatures, of the same fluid) and the properties of materials (a single Hookian spring). They are high-school "engineering", not engineering school engineering. How simple is it to calculate the peak spark plug tip temperature in an F-1 racing engine at the end of a straight-away on the 72nd lap of the race at [pick a course] on a hot summer afternoon - from first principles? Would you consider the design of racing engines to be an area that is not well understood?

       2) I would think that brige-building, slope stability calculations, etc. would be considered well understood engineering areas. Why does standard design practice often  use relatively large (e.g. 2 or greater) factors of safety? Surely any factor of safety greater than one will do? (For those not familar with the term, a design factor of safety of 2 means that the design strength is twice the needed strength.)

       3) a standard physics example of things that are difficult to calculate is the n-body problem. Does this difficulty in calcuating an exact answer mean that our understanding of gravity is not well understood?

       4) If you wish to continue the discussion, would it be better if we did so without rhetorical questions?

45927. scaddenp at 11:39 AM on 22 April 2013
       The science isn't settled
       

       Understanding the feedback processes well does not necessarily mean that crucial numbers can be extracted easily. Things like - amount of aerosol, full thermal description of ocean, cloud vapour response etc. The Argo network, better satellite measurement, GRACE and so on eventually allow for more precision.

45928. Bob Lacatena at 11:30 AM on 22 April 2013
       The science isn't settled
       

       engineer,

       I think that the problem is that you are trying to compare climate science with the hardest of hard sciences -- engineering sciences, like classical physics.  Many other sciences are not nearly so precise, including quantum physics, biology, neuroscience, medicine and more difficult chemistry (especially the state of chemistry before the development of the electron microscope).

       Would you consider all of these fields to be "not well understood?"

45929. barry1487 at 10:30 AM on 22 April 2013
       Climate Sensitivity Single Study Syndrome, Nic Lewis Edition
       

       Albatross,

       I often point out to people ('skeptics', usually) the error of relying on a single study, and most often it is with climate sensitivity estimates. It's good to see that caution explained here. I'm not trying to bait anyone. After reading at several places in the article that one should not lean on a single study, it simply leapt out at me that this had been done to make a point about uncertainty on climate sensitivity estimates from intermediate complexity models. Is it inappropriate to apply the same standard to this question as it is to climate sensitivity estimates?

45930. John Hartz at 09:00 AM on 22 April 2013
       2013 SkS News Bulletin #8: Alberta Tar Sands and Keystone XL Pipeline
       

       @jyushchyshyn:

       If the Keystone XL were to be approved, the refined product would be sold to the highest bidder -- most likely China.

       The primary cause of manmade climate change is the burning of fossil fuels. Keeping the reamaining deposits of fossil fuels in the ground ensures that they will not be burned. 

45931. engineer8516 at 08:50 AM on 22 April 2013
       The science isn't settled
       

       I have some questions related to this that have been bothering me for a while.

       This article isn't about equilibrium climate sensitivity from double co2, but I'll use that for my point. the IPCC report gives a value of 2 to 4.5 C with a likely value of 3C and confidence level of greater than 66%. Less than 1.5C has a confidence level of less than 10%.

       This is where I'm confused, for very well understood fields, such as heat transfer, equilibrium values can be calculated with a high degree of accuracy. For example, we can calculate the equilibrium temperature that a mixture of 1lb of 80F water and 1lb of 60F water would reach. Or in vibrations, how much a spring would stretch when it reaches rest from a hanging mass.

       Obviously these are simple examples, but the point is that equilibrium values can be calculated with a high degree of accuracy in well understood fields certainly. The 5% not understood in climate looks like it has a pretty significant impact on the calculation of an equilibrium value. So why is the topic of climate considered well understood? Thanks

45932. scaddenp at 08:45 AM on 22 April 2013
       The science isn't settled
       

       Thinking on this further - that statement is not "an essential part of AGW theory". It is an outcome of the current theory of climate. Falsifying climate theory is same as for any other theory - the theory must change if predictions derived from the theory do not match observation with both the limits of prediction and limits on observation. One of the problems with claims to  falsify climate theory is that they falsify predictions that climate theory does not make.

45933. jyushchyshyn at 07:29 AM on 22 April 2013
       2013 SkS News Bulletin #8: Alberta Tar Sands and Keystone XL Pipeline
       

       If you have a plan not to use the oil which Keystone would deliver, why do you need Obama to reject it? Why not let the market stop it. Global warming is caused by consumers, not suppliers.

45934. sidd at 06:56 AM on 22 April 2013
       Global Warming: Not Reversible, But Stoppable
       

       1)Byalko (2012) get the formula from a regression of T and CO2 for last 780Kyr

       2)The reference [19] to Byalko (2010)

       "...climate perturbations increase proportionally to the time derivative of temperature [19] ..." is a very general discussion of basins of stability, and does not convince me yet.
       

       That said, i do like Byalko (2012) teasing the 40Kyr periodicity out of a simple model.
       

       sidd
       

       
       

45935. scaddenp at 06:00 AM on 22 April 2013
       The science isn't settled
       

       Further to 6 - measure the change in surface radiation or OLR and then find that is inconsistent with calculated change due to increased GHG.

       You could also add - models based on AGW forcing would not reproduce past climate within the errors of model and forcing. You might think from arguments about paleo that this isnt a strong argument, but note that you can use this method to disprove alternative hypotheses like "the sun explains it all". "GHG changes have no effect".

       I think that the easy practical ways to disprove AGW were all tried long ago and failed with explains your problem with find them.

45936. grindupBaker at 04:48 AM on 22 April 2013
       Global Warming: Not Reversible, But Stoppable
       

       Bill Everett @26 equilibrium temperature "Teq =0.98(C - 280)" must have some elements missed, in life haste possibly. I just readily found "http://www.oocities.org/marie.mitchell@rogers.com/Climate_Notes.html" with a bunch of familiar looking numbers and formulae I recall from Drs. Randall, Trenberth, Hansen & others video lectures the last few weeks like the Watts m**-2 forcing (no feedback) = 5.35*LN(CO2/CO2<base>). I'd suggest searching each of those to find the agreement from expert sources before using, but that site doesn't seem to be pushing an agenda, no diatribes just some related quoting after the numbers.

45937. Tom Curtis at 03:53 AM on 22 April 2013
       The science isn't settled
       

       h-j-m @61, each of the following methods states a condition which has been experimentally tested and is known to be false, but which would falsify the theory if true.

       Method 1:  Warming of land surfaces equal warming of oceans, showing the change in temperature is caused by changes of SST rather than forcing.

       Method 2:  Stratosphere warming as troposphere warm showing the warming to be dominated by changes in solar radiance.

       Method 3:  Meso-sphere and thermosphere increasing in volume (showing that they are warming) as troposphere warms.

       Method 4:  Warming exists even though anthropogenic forcing factors remain constant.

       Method 5:  Known natural forcings are larger than known anthropogenic forcings.

       Method 6:  Width of anthropogenic GHG absorption spectra in outgoing LW radiation  unchanged over time.

       I am sure the list can be extended substantially, particularly once we start applying statistical tests rather than the crude method of simple falsification.  It should be noted that if there were reasonable doubt about the theory, competing natural explanations would not have been falsified (they all have been).

       Now, here is the real challenge.  Find a theory that contradicts the claim that is both falsifiable and has not already been falsified.  It is a challenge "skeptics" seem to avoid like the plague.

45938. Albatross at 03:52 AM on 22 April 2013
       Climate Sensitivity Single Study Syndrome, Nic Lewis Edition
       

       Hi Tom @33,

       Either Dana or I will respond to your post, but I for one would like to investigate this more closely before doing so.  Thanks for your patience.

45939. Tom Curtis at 03:36 AM on 22 April 2013
       Climate Sensitivity Single Study Syndrome, Nic Lewis Edition
       

       Albatross @32, Dana correctly describes Lewis as claiming that the mode (most likely climate sensitivity) of his result is identical to the mode of Aldrin et al, but then incorrectly calls that claim a simple misrepresentation.  It is not a misrepresentation.  The modes of the two studies are identical to the first decimal point.  It is, however, misleading in that it is an apples and oranges comparison.  Given that other studies report the mean, in comparing with other studies the mean should be reported, or it should be made absolutely clear that not only are you reporting the mode, but that the authors you are reporting on reported the mean.

       Dana then engages in his own apples and oranges comparison, stating (correctly) that  Aldrin et al reported a climate sensitivity of 2 C, without stating that it was the mean.  As the preceding paragraph mentioned only modes of the climate sensitivities, contextually that indicates that Aldrin reported the mode, which is false.  It thereby creates a misleading impression.  It further misleads because the requirement to be responsive is ignored.  It appears that Dana is contradicting Lewis, whereas he is merely reporting a different value.  As it is his clear intention to rebut Lewis, readers should be able to reasonably expect that his counter evidence will be responsive.

       Further, the claim that the 1.6 C modal value appears nowhere in the paper is at best an evasion, and at worst directly untrue.  The figures are part of the paper, and the information in the figures therefore appears in the paper.  As such, the modal value of the main analysis, which is easilly identified from the figures, appears in the paper.  Dana is welcome to show that the figure does not show a modal value of 1.6 C if he likes, but simply pretending it is not part of the paper is not appropriate.

       It would be easy to correct the article by removing these flaws.  The discussion could be replaced with an informative discussion of the reason climate sensitivity studies report means (or central estimates) and why reporting only the mode in making those comparisons is misleading.

45940. h-j-m at 02:47 AM on 22 April 2013
       The science isn't settled
       

       I take that this sentence

       "anthropogenic greenhouse gases are causing most of the observed global warming"

       is an essential part of AGW theory.

       Can someone please offer a practical method of how to disprove it?

       Unfortunately so far I failed to find one.

45941. Albatross at 01:42 AM on 22 April 2013
       Climate Sensitivity Single Study Syndrome, Nic Lewis Edition
       

       Barry@31,

       Dana might disagree with me, but the following text from Dana's post is correct:

       "Lewis's claimed value of 1.6°C appears nowhere in the paper itself. Rather, Lewis apparently ignored the authors' reported findings in favor of a value he estimated from graphs in the paper" 

       What Lewis did amounts to cherry picking and in turn being deceptive.

       As for your claim that:

       "It seems inconsistent to cite a single paper (Olsen et al 2013) to buttress a point, when citing single studies is repeatedly advised against."

       Nonsense. Please stop trying to bait people, your argument makes no sense in the context of the discussion.

45942. John Russell at 00:54 AM on 22 April 2013
       Global Warming: Not Reversible, But Stoppable
       

       Andy:

       The analogy I use with people is that of the 'climate flywheel', which we have gradually accelerated up over the last 200 years or so -- but particlualrly over the last 50 years at an ever increasing rate. So if we stopped emissions today the flywheeel would keep turning and would only very slowly lose speed over the forthcoming millenia. Only by actively removing greenhouse gasses from the atmosphere could we create a brake and actually begin to slow down that flywheel.

       Of course the real problem is that, as of the moment, we don't show any inclination to even consider reducing the rate of acceleration. 

45943. barry1487 at 18:32 PM on 21 April 2013
       Climate Sensitivity Single Study Syndrome, Nic Lewis Edition
       

       It seems inconsistent to cite a single paper (Olsen et al 2013) to buttress a point, when  citing single studies is repeatedly advised against.

       
       Dana, if Tom Cutrtis is right, and the modal value Lewis gives is consistent with Aldrin, you should update the article. You will need to revise your argument on that.

45944. Ger at 17:28 PM on 21 April 2013
       Global Warming: Not Reversible, But Stoppable
       

       @Bill Evert #26. The equotation is subtracting ppm (a ratio) from degrees celcius (a measurement of energy) multiplying by an unknown 0.98. That formula can not be correct.  

45945. Tom Curtis at 16:32 PM on 21 April 2013
       Global Warming: Not Reversible, But Stoppable
       

       Bill Everett @26, 0.98*(CO2 concentration - 280) represents a climate sensitivity of 274.4 C per doubling of CO2, a figure which is definitely wrong.  Are you sure you have not misquoted the equation?  If not, I would not be quoting Byalko as a guru on climate change. 

45946. grindupBaker at 16:01 PM on 21 April 2013
       Global Warming: Not Reversible, But Stoppable
       

       @Killian #11 James Hansen et al (many persons) do say in your reference "scenarios all assume a massive 100 GtC reforestation program, essentially restoring biospheric carbon content to its natural level". That 100 GtC (47 ppmv CO2) is 91% of a Brazilian rain forest (only +8% of the current land biomass so it's possible). 50 ppmv CO2 = 106,631,500,000 t carbon. Brazilian rain forest (10% of the Earth's carbon store) has 110,000,000,000 tC (52 ppmv CO2) on 3,375,413 sq. km. Hansen et al have the 100 GtC being bio-sequestered over 2031-2080. Since the data I've seen shows ~+1 ppmv CO2/yr from land use clearing, just stopping that would be really handy over 67 years. It would be great, and interesting, if we were some other species that might do those things that Hansen et al recommend but I think James Hansen might be confusing us with some superior species (a whole bunch of you maybe). A 2nd Brazilian rain forest or equivalent complex mix on our planet does not seem to mesh well with our actual interests that I see in the daily news.

45947. Ger at 15:58 PM on 21 April 2013
       Global Warming: Not Reversible, But Stoppable
       

       @ Doug #22, http://www.probos.net/biomassa-upstream/pdf/finalmeetingECN.pdf as an introduction to how biomass is torrefacted. Indeed is used in roating coffee beans but has more links with making charcoal

       BTW used coffee ground is an excellent fuel for gassification.

45948. grindupBaker at 15:56 PM on 21 April 2013
       Global Warming: Not Reversible, But Stoppable
       

       Shouldn't the "about 340 ppm by 2300, approximately the same level as it was in 1980. In the next 200 years" be the next 287 years ? I'm getting so old I'm losing track of decades so it might be me.

       Moderator Response:

       [AS] Oops. You are not the only one getting old! I changed it to "300 years". Thank you.

45949. BillEverett at 15:11 PM on 21 April 2013
       Global Warming: Not Reversible, But Stoppable
       

       I find the preceding comments extremely interesting and important. I looked at this post and the first few comments yesterday, printed the Matthews and Solomon op-ed, and resolved to read that short piece this morning, review any additional comments, collect a few resources, and formulate a comment of my own. I woke at 5:30, it is now 7:49, I have run out of time. I have scanned quickly the last half of the comments. I would like to be in e-mail contact with many of the commenters. Click on the author at http://www.degruyter.com/view/j/integ.2012.12.issue-2/integ.2011.101/integ.2011.101.xml and send me an e-mail if you agree.

       I am not a scientist of any sort. I am not a mathematician. But I think I can understand some science and some mathematics and some other things. It is critical to remove the "violence" (i.e., arguing to get others to adopt your view) from the "violent agreement" (Wyoming@19). That is, we need to convert argument to discussion. The reason is nicely put in two sentences in J.B. Calhoun's 1970 Ekistics paper: "Thus, in the presence of this increased exposure to value conflict, there will be required an augmented awareness of the necessity for others to maintain value sets differing from one's own. Furthermore, realizing one's own functional role requires expenditure of considerable effort in assisting others to fulfill the objectives of their value sets. [pp. 431-432]" This was in the context of describing his predicted conceptual revolution 7 in ~2018 AD (for context, revolution 2 was the Living-Agricultural Revolution of about 8157 BC; revolution 5 was the Scientific-Exploitive Revolution of about 1868 AD).  His simplistic model was originally presented in December 1968  at the AAAS annual meeting in Dallas (Frontiers of Science Lecture III). I can send a pdf format scan of that paper to those who contact me.

       I have some understand of systems dynamics. For example, in the spring of 1971, the local Sierra Club chapter asked me to give a talk on the "Limits to Growth" model. I prepared and gave a two-hour presentation. The first third was a basic introduction to systems dynamics, the second third was a description of Forrester's "World Dynamics" model and results of my study of multiple scenarios, sensitivities of various couplings in that model, etc., and the last third was on the current status of the work in progress in Dennis Meadows group at MIT and what might be expected from it.

       Much of the discussion here is great, but somewhat in the wrong place, in my opinion. This site is a "debunk denialism, explain the consensus science, and maintain an acquaintance with the real ongoing 'debate' about the fine points" forum in the broad sense of "forum." But we do need a serious discussions along the lines of the preceding comments so that we can (metaphorically) find our places in the choir and sing out in harmony sufficiently well and increasing loudly to cause the needed paradigm shifts (William@20; also see Makem & Clancy: A Place In The Choir).

       With regard to the temperature-CO₂ equilbrium and temperature change from the pre-industrial temperature, one suggestion is T_eq =0.98(C - 280), where T_eq is the equilibrium temperature change from the pre-industrial temperature in degrees C and C is the atmospheric CO₂ concentration in ppm, from Byalko, Phys. Usp. 55(1) 103-108 (2012). There, the estimated time of relaxation to equilibrium is 650-750 years. I quote the concluding two paragraphs from that paper:

           The practical consequences of the forecasts of the energy sector and the corresponding solutions of the relaxation equations are quite substantial. The main conclusion is as follows: all actions to 'correct' the atmosphere begin to affect the average temperature of the planet with a noticeable delay. Thus, in the radical scenario, the maximum CO₂ emission occurs in 2030, but its maximum concentration is attained only in 2042, and the temperature reaches some limit (possibly, a maximum) only by the end of the 21st century.
           The warming leads to one more unpleasant consequence, which is that climate perturbations increase proportionally to the time derivative of temperature [19]. A qualitative conclusion hence follows: weather anomalies will become maximal by the middle of the 21st century, when the CO₂ concentration passes its maximum. This statement relates to the radical scenario, while the inertial scenario is completely catastrophic both for temperature and for weather anomalies. The humanitarian consequences of global warming cannot be evaluated in the framework of a physical approach to climate problems.

       I apologize for my comment being somewhat disjointed (had less than three hours of sleep last night and am falling further behind schedule).

       -- Bill

45950. Doug Hutcheson at 10:38 AM on 21 April 2013
       Global Warming: Not Reversible, But Stoppable
       

       William @ 20, the Guy McPherson essay in turn links to a disgusting article by that doyen of the radical Right, James FishingDelingpole, which concludes;

       "Our culture deserves better than to have the terms of debate dictated by malign, politically motivated, professional offence-takers.

       Let's stop surrendering and start fighting back."

       I couldn't have put it better myself.

       After reading what Delingpole wrote (and subsequently disinfecting my monitor), I am amazed that he is given oxygen. Surely he is smart enough to know he is batting for the wrong side? Still, his rhetoric is so inflammatory, I'm glad he doesn't bat for us: stuff like that from this side would do untold damage to getting the message, about stopping AGW, out in a sane and rational way.

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