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Comments 126251 to 126300:

  1. Al Gore got it wrong
    why are errors by al gore acceptable just because he isnt a scientist? he is reading a script isnt he? hopefully, scientists wrote the 'script'. but, if 'scientists' did write the script, then why is it filled with so many glaring lies. sorry, i cant call them errors or untruths. the included 'information' was clearly deliberate for causing alarm. so, then, back to my original question. why are errors acceptable in the global warming but so aggressively belittled and attacked when skeptics raise a legitimate question? i am very curious about the bias attitude of error forgiving/overlooking nature of global warming vs strike down global warming skeptics. heck, i would rather be a ufo believer. at least i will just get laughed at instead of being vehemently attacked!
  2. Can you make a hockey stick without tree rings?
    DeNihilist, here is a short page with links regarding Loehle. There is a lot of material here on Skeptical Science, too, if my fuzzy memory serves.
  3. Can you make a hockey stick without tree rings?
    Well, i found some time today to look over those papers, now realize that i am not a scientist but do have a capacity to understand technicalities. Chris, the Moberg paper in my opinion is top drawer, the only critique I have, is I wish that they would not lay the instrumental on top of the original data. My eyes are not as good as they use to be. Tom, the second paper you put up was to me what science should be, a constructive argument about anothers' work. thank-you. Since you don't seem to have much respect for "my friend" JoNova, how this paper then, by Loehle... http://www.ncasi.org/publications/Detail.aspx?id=3025 any hidden agendas here that I should know about? Thanx
  4. Models are unreliable
    The above article attempts to debunk the "skeptic argument." However, the attempted debunking rests upon the abnormal semantics which the article attaches to the word "prediction." As normally defined, a "prediction" is a logical proposition about the outcome of a specified statistical event that is made at a specified interval in time in advance of the occurrence of the event's outcome. As it is an example of a proposition, a prediction is true or false. I understand that the climatologist James Hansen once predicted that the highway outside his office in Manhattan would be underwater 20 years later. Hansen had made a prediction. In the event, Hansen's prediction proved false, invalidating Hansen's hypothesis. All of the article's examples of "predictions" are computed temperatures. They provide the basis for comparison of computed to measured temperatures. However, by itself such a comparison neither validates nor invalidates the associated model for the events are unspecified. With the events unspecified, the model lacks the property of "falsifiability" that is possessed by every model that is "scientific" in nature. To render one of the IPCC's models falsifiable, the builders of this method would have to specify the statistical event that is associated with each prediction. According to authorities that include the IPCC itself, this task has not yet been accomplished. In its most recent report, the IPCC states that its models do not make "predictions" but rather that they make "projections." While predictions support the validation of a model, the IPCC's "projections" support only "evaluation." The distinction is an important one, for to control any sort of system, one must have the capacity for predicting the outcomes from movement of the control system's actuators. Whether the IPCC's models have the capacity for doing so remains unknown pending the definition of the events and conduct of a validation exercise. Thus, whether regulation of carbon dioxide emissions would have the desired effect of controlling global temperatures is also unknown. Associated with confusion over the differing meanings of "prediction" and "projection" in the language of climatology is a mistake repeatedly made by people who are interested in climatology but unfamiliar with the methodology of science. This mistake is to confuse a model built by scientists with a scientific model. A scientific model makes predictions. A model that makes no predictions is not a scientific model even when built by scientists.
  5. Can you make a hockey stick without tree rings?
    i find that most of the cynic blogs are a complete waste of my time , the inhabitants therein seek only to spread denial they are not interested in fact, the best way to help is to answer their letters to the editor garbage in your local paper.remember though to make your reply interesting and use lay terms . the use of logic rather than ad infinitum scientific opinion also can be very usefull. simple and to the point ,,,
  6. Measuring Earth's energy imbalance
    guinganbresil, the bucket analogy is only that--an analogy. It's not nearly a perfect one. I'm not going to try to improve it, because that will yield diminishing returns. But consider what I wrote in #24. The real atmosphere behaves on a continuum, but with a delay. Insulation causes energy accumulation which increases temperature which increases outgoing radiation. That takes a little while, but not very long. Blackbody radiation laws that fit really well to nearly all condensed matter. Of course, a portion of that outgoing radiation gets absorbed and re-emitted, which raises the temperature, and so on.
  7. Measuring Earth's energy imbalance
    Riccardo, Look at #23-#29 (Tom and canbanjo)... I didn't see them before. I like the analogy, but the bucket should have two holes - one representing the CO2 band at 15um and the other the other represents the much larger non-CO2 OLR. As the CO2 "hole" is made smaller, the rate of water exiting the bucket is reduced (i.e. OLR goes down) and the water level starts going up. The increased pressure causes more water to exit the non-CO2 "hole". There is less water exiting the CO2 "hole" (has to be, since when the CO2 "hole" is completely closed, no water will be exiting! You don't get more water exiting a smaller hole.) The total water exiting the two holes will only start going up again when you STOP shrinking the CO2 "hole" - then it will go up until it equals the input and you are back in equilibrium. Moral of the story: OLR should be going down with increasing greenhouse effect.
  8. How do we know CO2 is causing warming?
    Riccardo, I think the confusion is in the definition of the system - if you consider the boundary at TOA, the OLR must go down to cause the radiative imbalance as described by the greenhouse effect. To say that the CO2 absorbs long wave from the surface and re-emits it back down causing a temperature increase and subsequent temperature rise that causes total OLR to increase does not conserve energy. Look at a block of CO2 at TOA - that reasoning would have it emitting more IR downward AND more IR upward! Unless it is creating energy (which it is not) or converting short wave (which it is not) or is being warmed by some other source (of which I am unaware...) this scenerio is non-physical. I fully agree with your point on increasing OLR due to a drastic imbalance in the past that we are still moving back toward equilibrium. As I understand historical CO2 concentrations, they have been much lower than present for 100K's of years, so this rapid CO2 event you mentioned did not happen in the recent past. Please take a much closer look at the behavior of a system with the step function response (as described by Murphy) driven by a ramp instead of a step. You can get a feel for it by looking at a series of small steps (like a staircase) and add up the step responses. The OLR should go down while the CO2 is going up. The OLR will go up only after the CO2 increase has stopped (or the rate has gone down significantly.) All of the complications and nonlinearities you mentioned should be buried in the step response and as long as you are in a quasi-equilibrium condition, the general behavior should hold. This is pretty basic stuff in electrical engineering (charging capacitors etc.) Concerning Venus - I found a great paper describing the atmosphere - very interesting! I thought it resembled a baked potato wrapped in aluminum foil. In fact, Venus looks cooler at TOA than Earth! This is completely consistant with the decrease in OLR with increasing CO2 I mentioned earlier. Also, a large portion of the high surface temperatures on Venus are due to the high atmospheric pressure via adiabatic lapse rate. http://yly-mac.gps.caltech.edu/Z444/Flash4/Venus_greenhouse/RT_in_Venus_Atmosphere_AGU_GM01301CH08.pdf
  9. What do the hacked CRU emails tell us?
    Also, I'd like to add that when proposing a theory, the onus is on those that aim to prove the theory correct, not on the skeptics. The skeptics provide very useful information in keeping all the scientific avenues open for exploration, and gradually theories that contradict the hypothesis may be brought down with carefully investigated evidence and with the utmost consideration... absence of politics.
  10. Can you make a hockey stick without tree rings?
    Just for the record, there are plenty of ways ocean heat redistribution can potentially impact how much heat is kept and/or brought into the system. For instance, changes in the SOI can cause changes in precipitation, increases in precipitation cause cooling and increased precipitation means (see Wentz et al. 2007 How Much More Rain will GLobal Warming for a discussion of the precipitation, temperature and WV effects of El Ninos. Cheers, :)
  11. Can you make a hockey stick without tree rings?
    #31 sgking sgking: As you seem to accept Jo Nova as an authority on this, maybe you would care to get an explanation from her why she uses the 1997 Huang/Pollack paper in the post, with no mention of their later work? If she has found errors in those later papers, it would be very interesting to know. I would also like to know your own reflection on this. Since you are referring to that blog post here, you must have made some assessments.
  12. Can you make a hockey stick without tree rings?
    Thanks, chris!
  13. Can you make a hockey stick without tree rings?
    sgking, unfortunately the person who created the stuff you linked to is misrepresenting the science. Their misrepresention of the Moberg’s paleotemperature reconstruction is described above (see my post: chris 07:25 AM on 5 December, 2009) Their misrepresentation of the 1997 Huang/Pollock/Shen (HSP1997) borehole data is a truly dismal piece of cherrypicking; the misrepresenter has declined to point out that Huang/Pollock/Shen (HPS) have already pointed out that their 1997 data is completely unsuitable for comparing the temperatures of the MWP with current temperatures[**]. They have recently concluded that their borehole reconstruction indicates that the MWP was around 0.5 K cooler than current temperatures.[*] So the borehole data is entirely consistent with all the other scientific data and analysis. [*]S. P. Huang and H. N. Pollack P.-Y. Shen (2008) A late Quaternary climate reconstruction based on borehole heat flux data, borehole temperature data, and the instrumental record Geophys. Res. Lett. 35, L13703, doi:10.1029/2008GL034187 Abstract: We present a suite of new 20,000 year reconstructions that integrate three types of geothermal information: a global database of terrestrial heat flux measurements, another database of temperature versus depth observations, and the 20th century instrumental record of temperature, all referenced to the 1961–1990 mean of the instrumental record. These reconstructions show the warming from the last glacial maximum, the occurrence of a mid-Holocene warm episode, a Medieval Warm Period (MWP), a Little Ice Age (LIA), and the rapid warming of the 20th century. The reconstructions show the temperatures of the mid-Holocene warm episode some 1–2 K above the reference level, the maximum of the MWP at or slightly below the reference level, the minimum of the LIA about 1 K below the reference level, and end-of-20th century temperatures about 0.5 K above the reference level. ------------------------------------------------- [**]HSP describe carefully in their 2008 paper why their 1997 paper (HSP 1997; used by the misrepresenter that you linked to) can’t be used to compare MWP with current temperatures. The data in HSP 1997 contains no data for the 20th century, because of concern in the large number of boreholes analyzed that the top 100 metres of depth might be contaminated by non-climatic influences. The end of the record in HSP1997 defines the estimated temperature around the turn of the end 19th century. The data in John Cook’s Figure 1 (Huang 2000) is from a set of boreholes that have passed a quality control for eliminating non-climatic contributions, and this approaches is extend much further in HSP2008 cited just above.
  14. What do the hacked CRU emails tell us?
    So Jones has resigned. UEA is conducting an enquiry into data 'misuse' The head of the world climate forum is also launching an enquiry. For an overview of the situation go here.... http://mensnewsdaily.com/sexandmetro/2009/12/01/top-global-warming-scientist-resigns-over-allegations-he-overstated-the-case-for-man-made-climate-change/
  15. Can you make a hockey stick without tree rings?
    Here are some graphs that seem to suggest something different than those above: http://wattsupwiththat.com/2009/12/04/jo-nova-finds-the-medieval-warm-period/
  16. Can you make a hockey stick without tree rings?
    John 27 response does last glacial maximum = LIA ?? If you set out to find the LIA in the borehole, stalagmite and glacial data presented above you really couldn't find it. If that data can't identify this 'period of dramatic climate change' why should we trust it to identify any period of dramatic climate change. I don't see how we can defend this data as a climate proxy and believe in the LIA. We have to throw away one or the other.
  17. Was there a Medieval Warm Period?
    I am even more perplexed now. Fig 3 and Fig 4 span 10 years of data. Fig 1 and Fig 2 span 300 years of data How can you compare 300 years of data to 10 years of data (what's more the hottest). I hope you realise that some of your detractors are accusing your side of cherry picking the data. Please don't do it on the site intended for the general public.
  18. Was there a Medieval Warm Period?
    I am a bit perplexed when i look at Fig1 and Fig2 for MWP and LIA. Why do we have this remarkable anomaly over GreenLand?
  19. Can you make a hockey stick without tree rings?
    WeatherRusty - the simplest method of getting the word out is just to post, post, post - on your blog, on Facebook, and especially on the comments sections of news sites which run the misleading stories. Link them here so they can read the info for themselves. Sure, you run the risk of more uninformed commentary, but maybe some minds will be changed.
  20. The growing divide between climate scientists and public opinion
    The challenge for objective people is to remain skeptical while not becoming drawn into the blind faith that is becoming increasingly a feature of the deniers (people who claim to be skeptics). It is important to question things but, not in the process of doing so, to deny evidence or indicators that do not reinforce a particular theory. Sadly, a significant number of people are latching on to points of view that are more driven by inverse intellectual snobbery than a considered point of view that is soundly based. My biggest concern is that points of view that reinforce our deep seated human desire to do nothing are quite appealing.
  21. Water vapor is the most powerful greenhouse gas
    Just a thought, are any of you familiar with global dimming. The article states that there has been an increase in WV in the atmosphere which has been recorded since 1988. If this is true then in essence there should be greater cloud cover which acts as both a negative feedback mechanism and a positive feedback. I cant remember where but i read that the suns rays have a greater impact on the evaporation of water than a rise in temperature alone. Something about the excitement of water molecules. So the increase in cloud cover and aerosols act as both a positive and negative feedback mechanism not exactly canceling each other out though. Apparently global dimming is half as strong as global warming. I'm sure that if i have made an error some where in my logic you will correct me.
  22. Can you make a hockey stick without tree rings?
    Just back from work Tom, will review the papers in the next couple of days, as Christmas is coming up rather quickly, and being a typical guy, haven't started the "shop" yet. Phillipe, point taken. Bad use of grammer. Should have been a bit more precise. One of the papers that Tom pointed to, if my quick look was somewhat close to right, seems to show a new way to analyze the data. This is what I meant, science grows with every new discussion. Sometimes the new ways are right, sometimes wrong, but from this we gain valuable knowledge. Will try to slow down my thoughts in the future to be more clear. LOL Chris, my friend Jo! Not quite, but I would bet that you would have a great discussion with someone that seems that passionate! I visit about 12 different blogs during the week, and try to keep them even - yes/no/maybe-so. The main thing is to have a bit of time to let your critical thinking sift through the "junk" from all sides. I found it interesting that Prof. Mann has "allowed" the MWP to at least be shown in his latest paper. His explanation is intriquing to say the least. But again, I have not had time to go as deep as my depth of understanding will allow me. This silly thing called life keeps getting in the way! Thank-you for the link to Moberg and your explanation. I can see a BIG pot of coffee is going to be consumed in the near future.
  23. Can you make a hockey stick without tree rings?
    What you show doesn't cover the MWP but does extend over the LIA. Do we believe in the LIA? My understanding is there is evidence ice/glaciers reached their maxima around 1700's (may be some variation based on location) and that things have been warming since and glaciers retreating. Lets look at the different methods 1) Boreholes show on evidence of LIA. 2) The stalagtite graph shows a temperature peak in 1700's. 3) The glacier record shows no 1700's temp minima (glacier maxima) followed by slow climb to 1900's. This is very strange as one method used to confirm the LIA (glacier treat) now seems to be refutting it's existence. Do we have to abandon the LIA idea to accept this data?
    Response: Mann's graph does go back 2000 years well past the MWP but I included just part of that graph in the interest of keeping the presentation as simple and clear as possible - extending the graph doesn't change the end result (that the last few decades are the hottest in the last 1000/2000 years). Anyhoo, here is the complete graph:



    Re "abandon the LIA", there seems to be a common notion kicking around that climate scientists are trying to talk down past climate change. This is decidedly not the case. On the contrary, as Dana Royer puts it: "the geologic record contains a treasure trove of 'alternative Earths' that allow scientists to study how the various components of the Earth system respond to a range of climatic forcings." For this reason, periods of dramatic climate change like coming out of the Last Glacial Maximum are of strong interest to climate scientists. These periods indicate that the climate is sensitive to radiative forcing which in turn tells us that the climate is sensitive to the current very strong radiative forcing from CO2.
  24. The hockey stick divergence problem
    Chris #18 Some issues with the instrumaent data 1) there has been a bit of a divergence between the HADCRUT and GISS data, the two main global records, over the past decade. THis has lead to the arguement about whether the last decade has shown cooling. 2) What is presented is not what has been noted down from the thermometer. The data goes through manipulation to account for changes in instrument, position, local changes, urbanisation etc. This process can be contraversial. As an example you can read about how this process upset some sceptical scientists in New Zealand if you wish. http://nzclimatescience.net/index.php?option=com_content&task=view&id=550&Itemid=32 I'm sure I could list more. As an aside. If people like little gizmo's to play with online then NOAA have graphs on there front page where you can play with a slider. Hours of fun. www.climate.gov
    Response: The divergence (word du jour) between HADCRUT and GISS is largely due to the fact that HADCRUT doesn't include the Arctic when calculating the global temperature. As the Arctic is warming faster than other areas due to polar amplification, this means the HADCRUT time series underestimates recent warming trends.
  25. The hockey stick divergence problem
    In what sense has "the land-based record has been fraught with problems in the last few decades", Heidi? The temperature record is consistent with the broad rsnge of real world warming consequences (sea level rise, sea ice retreat, polar and mountain glacier recession, biologicsl cosequences etc.). I haven't read any analysis that indicates that there is a problem with "the land based record". What did you have in mind?
  26. Can you make a hockey stick without tree rings?
    DeNihilist, your friend “Jo” on that odd web site is being rather naughty! It’s easy to download Moberg et al’s data, e.g. from the NOAA paleodata repository here: http://www.ncdc.noaa.gov/paleo/globalwarming/moberg.html If one plots the data (try it yourself), you’ll see that your friend “Jo” has done some odd things to it. S/he has applied some unspecified smoothing that has accentuated/broadened some of the spikes in the earlier part of the record and attenuated the spike in the mid 20th century, and shifted all the data upwards by a few tenths of a degree for some reason. In fact the spikes are simply noise. The major spike around 990 AD lasts only for about 7 years, up and down, and is obviously noise. Likewise with the spikes around 1020 and 1110 AD, although the reconstruction is consistent with a real N. hemisphere MWP that slowly reached a temperature around 0.2 – 0.3 oC warmer than the preceding and following period, but quite a bit cooler than now. Moberg’s reconstruction puts the MWP temperature at around the same temperature as the mid 20th century global temperature. Remember that Moberg et al is a Northern hemisphere reconstruction. One needs to be careful in comparing a smoothed record with a real, unsmoothed instrumental record. However we know that the earth surface really has warmed by around 0.5 oC since the middle of the 20th century and by around 0.7 oC in the N. hemisphere (if one thinks it’s appropriate to compare like with like).
  27. Can you make a hockey stick without tree rings?
    The problem with that scenario Mizimi, is that the mechanisms that you speak of (ocean heat redistribution due to cyclical shiftsd in ocean dynamics) simply can't add significant heat to the earth system. Tsonis et al have recently pointed that out [*] So Tsonis et al have converted the qualitative suggestions of their 2007 paper into a quantitative analysis of the contribution of these effects to 20th century warming [*]. They conclude that these effects made a significant contribution to early 20th century warming, and a small contibution to warming since 1960 (perhaps 0.1-0.15 oC) with zero contribution to warming since around 1985. The nett contribution to 20th century warming from the effects you are describing is (according to Tsonis et al) close to zero (perhaps 0.05 oC). So the scientists whose earlier work you are rather over-embellishing to support a notion, simply don't agree with you. Their earlier qualitative analysis idicates that cyclic ocean regime changes can have temporary small effects on surface temperature. A quantitative analysis establishes that the nett effects of these are small, and that their contribution to the marked warming since the early 80's is close to zero. [*] K. L. Swanson, G. Sugihara and A. A. Tsonis (2009) Long-term natural variability and 20th century climate change Proc. Natl. Acad. Sci. 106, 16120-16123 (see Figures 2 and 3 and text).
  28. Can you make a hockey stick without tree rings?
    JoNova makes many, many false claims. Her Skeptic's Handbook is filled with claims that have been debunked countless times. 1) Joanne Nova did not do her research or did so without due diligence. or 2) Joanne Nova is intentionally misleading the general public.
  29. Philippe Chantreau at 06:46 AM on 5 December 2009
    Can you make a hockey stick without tree rings?
    DeNihilist says "And that Tom , is what science is about! Point - counterpoint." No. That's what rethoric, politics or court room arguments are about.
  30. Can you make a hockey stick without tree rings?
    DeNihilist: Those two pages I pointed you to are appropriate not just to the JoNova page, but also to the co2science page you pointed to.
  31. Water vapor is the most powerful greenhouse gas
    Riccardo - thanks for the PS pointer. I recently read a paper ( which I seem to have lost) showing that there has indeed been an unexpected increase in convective turnover in the tropics...must try and relocate it. Just as a side issue... the amount of WV is not just T dependant - you have to have a source. No source in the Sahara so it's dry even tho' T is high. Lots of water in the tropics so it's humid. Also, in general terms, the atmosphere could hold a lot more WV -if the contact surface area between air/water was increased - without an increase in T. Air conditioning spray humidifiers do just that.
  32. Can you make a hockey stick without tree rings?
    #6...no I don't think it is just the sun, although solar fluctuations have an effect. I think it is the resultant of a lot of chaotic behaviour from a variety of events ( El Nino/a. PDO,NAO, TSI etc) which when synchronised cause a pronounced shift in climate. "The above observational and modeling results suggest the following intrinsic mechanism of the climate system leading to major climate shifts. First, the major climate modes tend to synchronize at some coupling strength. When this synchronous state is followed by an increase in the coupling strength, the network’s synchronous state is destroyed and after that climate emerges in a new state. The whole event marks a significant shift in climate. It is interesting to speculate on the climate shift after the 1970s event. The standard explanation for the post- 1970s warming is that the radiative effect of greenhouse gases overcame shortwave reflection effects due to aerosols [Mann and Emanuel, 2006]. However, comparison of the 2035 event in the 21st century simulation and the 1910s event in the observations with this event, suggests an alternative hypothesis, namely that the climate shifted after the 1970s event to a different state of a warmer climate, which may be superimposed on an anthropogenic warming trend. from: "A new dynamical mechanism for major climate shifts" GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L13705, doi:10.1029/2007GL030288, 2007 (Tsonis et al 2007) which describes the results of treating climate as a chaotic networked sytem using observed data for such events and modelling the results. The model indicates a synchronisation roughly every 10yrs...1910..20..30..40..50.. but shift in climate state occurs only if the result is an increase in coupling strength - which happened in 1910, 1940 and 1970 - and in each case the result was an increase in temperature.
  33. Can you make a hockey stick without tree rings?
    And that Tom , is what science is about! Point - counterpoint. Brilliant reply. I will delve deeper into those two pages later, Thanx! PS - just to let you know, I find the volume on MOST of these blogs a bit to loud. Like panning for gold, you have to dump about 99.7% of the raw material to filter out the gold. Though both sides do have some funny ad hommien attacks, in my experience, the truth is found in the quieter moments.
  34. Can you make a hockey stick without tree rings?
    DeNihilist: "Excellent post" by JoNova? Really? Have you seen this or this?
  35. Can you make a hockey stick without tree rings?
    Leto, try here - http://joannenova.com.au/2009/12/fraudulent-hockey-sticks-and-hidden-data/ an excellent graphic representation of the MWP. Warning, Jo is a strong sceptic, so though the graphic is of immense value, her writing style is quite brunt
  36. Can you make a hockey stick without tree rings?
    Whoops - :)~ http://www.co2science.org/data/mwp/regions/nhemis.php
  37. Can you make a hockey stick without tree rings?
    John, you might want to check out JoNova's site for an excellent post on the MWP. She got her info from this site, all peer reviewed. Peace
  38. Was there a Medieval Warm Period?
    This is more or less n topic, thanks mostly to TruthSeeker going off topic. TS, please read the detailed expose made by deepclimate.org. They have shown that it was Chris de Freitas (and others) who were in fact manipulating and subverting the peer-review process, not the other way round! The papers in question are all pseudo-science and should have never made it through peer review. The same culprits now often publish at Energy and Environment with other "sceptics" because contrarians have allegedly infiltrated that peer review and editorial process. PeterPan, in figures such as those shown above, the hatching is typically used to indicate statistical significance. Maybe John Cook could change the captions to specify exactly what the hatching means?
  39. How do we know CO2 is causing warming?
    I don't believe any of these studies are meanigful any sense to come to any conclusions on AGW. Otherwise serious scientists would have made those conclusions already based on these theoretical results. Its more or less a theoretical excercise in exploring current limitations in regards to piecing together how the climate system works. The data discussed is over the region with the highest OLR anamolies, not to mention during opposing seasons for the regions with ~4% humidty and 10F differences. Change in CO2 bands in clear sky mostly indicates change in the stratospheric temperatures. This says nothing about the earths energy balance and its system, and certainly not anything about the final number of that energy balance in regards to CO2. Cheers.
  40. What do the hacked CRU emails tell us?
    @Ricardo--So, we are left with a highly personal opinion (based on ?) of "useless", but in this case I agree with you: The dropped data was indeed "useless" if one's objective is to create a hockey stick graph and "hide the decline" evident in the dropped data. In any event, how could Jones have known the data was "useless" if he couldn't explain WHY the tree rings no longer served as a useful proxy for temperature. Perhaps they never did? Perhaps tree ring width correlates more closely with some other variable related to but independent from temperature such as...I don't know...rainfall/humidity?
  41. Can you make a hockey stick without tree rings?
    Nice post. John, where do you find the time? You are prolific! Here is another good source for what may have caused the warming in the early part of the 20th century: http://tamino.wordpress.com/2008/10/19/volcanic-lull/
    Response: Where do I find the time? The key is realising that sleep is a luxury item.
  42. Heide de Klein at 01:05 AM on 5 December 2009
    The hockey stick divergence problem
    Your statement that the instrumental evidence must always be preferable doesn't hold water. The land-based record has been fraught with problems in the last few decades. Either you question it, or you bury your head in the sand declaring CO2, warmth and light stunts tree growth. Now, perhaps you can point me to other independent proxies that don't exhibit the decline. I know for sure that speleothems and the Tijlander series (used upside-down) do!
  43. Heide de Klein at 00:52 AM on 5 December 2009
    Can you make a hockey stick without tree rings?
    The speleothem record exhibits the divergence problem. Is that why it was truncated?
  44. Heide de Klein at 22:47 PM on 4 December 2009
    The hockey stick divergence problem
    It seems to me that you either believe the trees or the instruments. Either some unknown agent is affecting the trees, causing them to stunt their growth - perhaps it is a heady mixture of more warmth, CO2, and sunlight. Or, the quality of the instrumental record has become compromised in some way, for some reason, by someone.
    Response: Direct instrumental evidence is always preferable over proxy methods of determining temperature changes. The fact that tree-ring proxies have also diverged from other independent proxies is a strong indication that it's the tree-ring sensitivity to temperature that has changed. This is also borne out by the fact that tree-ring divergence isn't universal but is concentrated in high latitude northern sites.
  45. The physical realities of global warming
    Berry, you're definitely right and it is exactly what i said should be avoided in that comment. I said "almost flat" because i was going to compare with the developed nations numbers, of the order of 10 or more tons.
  46. The physical realities of global warming
    24 Riccardo: In the last decades global per capita emissions has been almost flat globally.(...) According to a recent article in Nature Geoscience (17th Nov) "Trends in the sources and sinks of carbon dioxide" (Corinne le Quéré, et al.), the per capita emissions has actually risen the last decade: "The growth in emissions since 2000 was also accompanied by an increase in the world per-capita emissions from 1.1 metric tons of carbon in 2000 (Fig. 1d) to an all-time high of 1.3 metric tons of carbon in 2008" (...).
  47. Can you make a hockey stick without tree rings?
    Leto, CRU controversy or not, we all (and the scientists in first place) always try to have more evidence. The more the evidences the more we trust the findings. But even if one thinks that there's not enough evidence, one is not scientifically allowed to ignore (or worst throw away) what as already been done.
  48. Can you make a hockey stick without tree rings?
    Leto, what you are asking is strange. Scientists tried hard to collect as many different proxies as possible to avoid problems any single proxy type may have. Different proxy types also tend to be geografically located in different environments, so using more proxy types guarantee a better coverage. If you for some reason do not trust tree rings, i'd suggest to look at reconstructions where just tree rings have been dropped while keeping all the other. If you look, for example, at the data of the Arctic from the paper linked by John in comment #5, they used 4 tree rings data sets out of 23 total. One might anticipate that their influence will be modest. I've seen somewhere the comparison of reconstructions with and without tre rings, but i can't remember where; i can't help you more.
  49. Was there a Medieval Warm Period?
    In Mann's graphs, why are there cells with a grey X and others without it? What does the grey X mean? (I don't have access to the full document, so I cannot look it up). Thanks.
  50. How do we know CO2 is causing warming?
    guinganbresil, not true that that if CO2 increases OLR must be dropping, as the step change example shows. It's a matter of when and how it all occurs. Working out realistic details is not at all easy. Crudely speking, CO2 concentration is quadratic with time, the associated forcing is logarithmic with CO2 concentration, temperature variation is linear with forcing and has it's own time response, thermal emission goes with the fourth power of temperature. But physics helps us if you immagine a quasi-equilibrium situation (small deviation from equilibrium), which is not far from the reality of the earth system. The increasing CO2 concentration produces warming. Thermal emission must be increasing, more rapidly so the more the system is out of equilibrium; consider also that it is generally stronger than the forcing due to it's 4th power dependence on T. In the assumption of small deviation from equilibrium, you will reach a balance between the two opposite tendencies so that OLR would be roughly constant in time a little below equilibrium. It is then this departure from equilibrium that goes with the rate of CO2 increase. Here you can also appreciate why it's so hard to observe it experimentally, it's intrinsically small. Now, if you observe the OLR increasing with time it means the CO2 has increased (some times in the past) so rapidly that the earth system is still keeping up trying to reach the new equilibrium. You will see a decrease only if CO2 increases very rapidly; after a while the system will reach again a quasi-equilibrium or it will all end up in what climatologists call a runaway warming. Venus is always quoted as an example of the latter.

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