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Comments 126101 to 126150:

  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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?
  6. 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).
  7. 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).
  8. 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.
  9. 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.
  10. 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.
  11. 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.
  12. 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.
  13. 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.
  14. Can you make a hockey stick without tree rings?
    DeNihilist: "Excellent post" by JoNova? Really? Have you seen this or this?
  15. 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
  16. Can you make a hockey stick without tree rings?
    Whoops - :)~ http://www.co2science.org/data/mwp/regions/nhemis.php
  17. 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
  18. 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?
  19. 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.
  20. 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?
  21. 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.
  22. 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!
  23. 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?
  24. 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.
  25. 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.
  26. 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" (...).
  27. 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.
  28. 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.
  29. 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.
  30. 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.
  31. Can you make a hockey stick without tree rings?
    Hi there, It is somewhat disappointing that the examples you provide generally do not go back through the MWP (those that do seem to involve tree-rings, which I do not trust, or involve composites, which I do not trust). Could you point me to single-modality, non-tree-ring proxies that examine this period, and that do not suffer from a modern divergence problem? Preferably, they should be regional, to assess claims that the MWP was confined to Europe or the northern land mass. The ideal proxy would be one that matched historical accounts of the MWP. I am not making any point here - I am genuinely curious, and just starting to look at the evidence in view of recent CRU controversies. Regards, Leto.
  32. How do we know CO2 is causing warming?
    Riccardo, I think I am beginning to understand. The step response graphic in Murphy gives the impression that OLR should be going up - I don't think that is true in reality. The step response of a system is very useful in understanding how the system responds to changes but it does not represent the reaction to a real signal (unless of course it is a step function!) If you imagine the vertical increase in CO2 as actually having an upward slope (which it does in reality), then the vertical drop in OLR will also have a slope - going down. We are really in a condition where CO2 is still rising so the the OLR should be dropping - not rising. This is VERY important. I will see if I can find a reference, but I have seen plenty of step response problems (charging capacitors etc.) when I studed EE to know that a system with this step response will have a decreasing OLR if CO2 is still increasing. The return to equilibrium (an increasing OLR) occurs when the CO2 stops increasing. --- I am of course ignoring saturation and other non-linear effects. I am just trying to sort out whether it is supposed to be going up or down!
  33. How do we know CO2 is causing warming?
    Riccardo, I think I am beginning to understand. The step response graphic in Murphy gives the impression that OLR should be going up - I don't think that is true in reality. The step response of a system is very useful in understanding how the system responds to changes but it does not represent the reaction to a real signal (unless of course it is a step function!) If you imagine the vertical increase in CO2 as actually having an upward slope (which it does in reality), then the vertical drop in OLR will also have a slope - going down. We are really in a condition where CO2 is still rising so the the OLR should be dropping - not rising. This is VERY important. I will see if I can find a reference, but I have seen plenty of step response problems (charging capacitors etc.) when I studed EE to know that a system with this step response will have a decreasing OLR if CO2 is still increasing. The return to equilibrium (an increasing OLR) occurs when the CO2 stops increasing. --- I am of course ignoring saturation and other non-linear effects. I am just trying to sort out whether it is supposed to be going up or down!
  34. There is no consensus
    angeloftheknight, you might want to also read cce's The Global Warming Debate site, because it gives a broad overview. That background would help you better select which topics on this most excellent Skeptical Science site to focus on.
  35. Can you make a hockey stick without tree rings?
    It seems to me that if we are trying to decipher which proxies are actually good proxies for temperature this thread doesn't really help very much. While the borehole and glacier reconstructions for the last 100 or so years(when we supposedly have good temperature measurements) are more or less consistent with one another, the actual temperature measurements (at least as referenced in Mann above) are much higher ~0.5C increase as opposed to closer to 1C for the temp reconstructions(the two of which don't agree with one another too closely incidentally). Unless you think that the temp reconstructions are badly biased, you are then forced to conclude that the proxies are(they can't both be right). If the proxies are biased, then reconstructions based on them can't be relied on. Cheers, :)
  36. Water vapor is the most powerful greenhouse gas
    Mizimi, unfortunately who wrote that page failed to notice that using the very same ESR utility it can be easily found that the upper troposphere has indeed warmed. An obvious question then arises as to how can specific humidity drop while temperature rises. It looks more like a convection issue. P.S. The first graph shown in you link has been demonstrated to be wrong quite a while ago. But you know, things keep hanging around forever over the internet ...
  37. angeloftheknight at 10:37 AM on 4 December 2009
    There is no consensus
    Long ago, in post #150, hrnsoftware asked about the ozone layer. No one replied, so far I could tell, so I offer this site: www.themonitor.com/opinion/ozone-5103-depletion-protocol.html This might provide an answer to his/her question regarding recovery of the ozone hole and what effect the Montreal protocols had, or did not have, on it. I just stumbled on this site today, and I think it's marvelous. I'm not a scientist but I consider myself a logical thinker and I like a good argument. In the interest of transparency I acknowledge I'm a "denier" (some of us prefer "realist" per Frank Beckmann, WJR-Detroit). I like hearing opposing views. I'll check in as often as possible, but If I'm not careful, I could become addicted to the pheromones my brain produces by reading this site! Thx
  38. Can you make a hockey stick without tree rings?
    nofreewind, the problem with "historical anecdotes" is that they are just that...anecdotes. An anecdote almost by definition relates to a personal or localised observation, and it's usually qualitative...and "common sense" can often lead one smartly to the incorrect conclusion! A case in point is glacier recession. There's little doubt that Alpine glacier maximum was in the mid 18th century as you indicate. The earth (at least the Northern latitudes, and especially Europe, where most anecdotal, and more scientific observational evidence, comes from) was coolish in the so-called Little Ice Age. This was a prolonged period of low solar activity and highish volcanic activity. Glaciers advanced. Some of the recovery from the LIA was natural recovery from natural negative forcing (sun returned to "normal", volcanic activity lessened). Quite a bit of it was anthropogenic resulting from a rather significant rise in atmospheric CO2 from ~280 ppm in the late 18th century to 300 ppm by 1900 and 320 ppm by 1960. It's easy to determine (knowing what we know about the quantitiative relationship between atmospheric CO2 change and earth temperature change) that this will have made a large, and likely dominant contribution to the warming from the early 19th century to the mid 20th century. And after that it's a question of degree and quantitation that can only be addressed by a non-anecdotal analysis. You mention the Alps, so we could look at those beautiful mountains. A detailed study of Alpine glaciers was published by the World Glacier Monitoring Service in Zurich a couple of years ago. This shows that the rate of Alpine glacier retreat has followed the temperature trend with rather slow glacier retreat as the N hemisphere warmed v. slowly following the LIA, and then faster as the anthropogenic contribution to warming kicked in. The latest (post 1970's) bout of warming has seen Alpine glacier recession retreat rather remarkably. I know this from first hand since I try to spend a holiday each year in the Alps or the Pyrenees. The changes can be rather remarkable, even in the anecdotal sense of a personal observation... Haeberli W et al. (2007) Integrated monitoring of mountain glaciers as key indicators of global climate change: the European Alps Annals of Glaciology 46,150-160 Abstract: The internationally recommended multi-level strategy for monitoring mountain glaciers is illustrated using the example of the European Alps, where especially dense information has been available through historical times. This strategy combines in situ measurements (mass balance, length change) with remote sensing (inventories) and numerical modelling. It helps to bridge the gap between detailed local process-oriented studies and global coverage. Since the 1980s, mass balances have become increasingly negative, with values close to -1 m w.e. a(-1) during the first 5 years of the 21 st century. The hot, dry summer of 2003 alone caused a record mean loss of 2.45 m w.e., roughly 50% above the previous record loss in 1998, more than three times the average between 1980 and 2000 and an order of magnitude more than characteristic long-term averages since the end of the Little Ice Age and other extended periods of glacier shrinkage during the past 2000 years. It can be estimated that glaciers in the European Alps lost about half their total volume (roughly 0.5% a(-1)) between 1850 and around 1975, another 25% (or 11% a(-1)) of the remaining amount between 1975 and 2000, and an additional 10-15% (or 2-3% a(-1)) in the first 5 years of this century.
  39. Can you make a hockey stick without tree rings?
    nofreewind, if you click on the link to Oerlemans 2005 associated with Fig. 3 above, you'll see that the number of glaciers for which quantitative data are available is extremely limited prior to the late 1800s. The earlier data are completely dominated by Alpine glacier records. Despite this Alpine dominance, Oerlemans' Fig. 3A does not show more than a modest decline in reconstructed temperature prior to about 1850. So I would conclude from this that the information you cite from Fagan's book is largely anecdotal, and the data as shown by Oerlemans are not consistent with it. *Global* warming as determined from globally distributed glacial records appears to begin around 1900, with the usual pause around the 50s. This is yet another proxy record that suggests some past climate variability that is overwhelmed by changes in the last 40 years. Climate appears to be sensitive to even modest forcing (as the proxy records show), and there is no denying that CO2 results in a significant net radiative perturbation. Certainly this is a cause for concern.
  40. What do the hacked CRU emails tell us?
    sgking, the facts speak for themselves, indeed; they just dropped the (know for years) useless data to make the graph. Period. Simple enough, unless one is trying to see the evil in any case and can always come up with specious accusation of some sort. P.S. The first sentence on McIntyre was just a joke, i apologize if i didn't make it clear enough.
  41. Can you make a hockey stick without tree rings?
    John, of course the planet is warming? According to Fagan's book the Little Ice Age, the glaciers in the Alps reached their maximum in 1750. They have excellent historical accounts of how the ice buried various towns. Since that time, most glaciers around the world have been receeding, for >200yrs. Yet even in the CRU emails the scientists admit they only account for mans hand since the 1970's, their own data shows no temp rise from mid 40's on. (I know we can find the reason it was mans hand causing the cooling - which in reality was just a pause) We have glaciers melting for 250 yrs, yet AGW caused them to melt the last 35 yrs? As a rational person I say if they receded for 200 yrs w/o AGW how can we possibly even mention AGW as a cause of glacier melting, and sorry, I get very skeptical of anything you would say, if you blame glacier melting on AGW. (although soot contamination as a real factor makes good sense to me for both glaciers and the artic) Is this the kind of "direct observation" you are talking about? Same thing goes for African droughts, etc etc etc. In fact, every nook and cranny I look into, I usually find the same natural variability and historical anecdotes to prove my "common sense". http://www.appinsys.com/GlobalWarming/GW_4CE_Glaciers.htm Of course other people might look at things differently when they START with the premise that man is at fault and then work backwords, as the IPCC clearly state in their founding mandate. Proud to Be A Skeptic, but I'm no Denier.
  42. What do the hacked CRU emails tell us?
    @Riccardo--Do you dispute McIntyre's summary of the steps involved in "the trick"? And do you claim that Jones disclosed his methodology in the IPCC report? If so, then please be specific and set me straight. If not, then it shouldn't matter to you you whether I cited McIntyre's summary or someone else's. The facts speak for themselves. Res ipsa loquitur.
  43. Water vapor is the most powerful greenhouse gas
    "The specific humidity has been increasing over the last few decades near the Earth’s surface (as shown by the 1000 mb data), while it has been decreasing in the upper troposphere (as shown by the 300mb data). The increase in specific humidity at the Earth’s surface (1000 mb) is related to surface temperatures. For all except the far southern hemisphere bands, the effect of the 1997/98 El Nino can be seen in the specific humidity graphs. The decreasing specific humidity in the upper troposphere (300 mb) indicates that the warming at the Earth’s surface does not match the CO2 based warming theory. This is especially so in the northern hemisphere, which has experienced most of the warming in recent decades.....This is a major area of contention in the climate science area, since without the water vapor feedback the CO2 based theory loses its significance." http://www.appinsys.com/GlobalWarming/WaterVapor.htm
  44. The hockey stick divergence problem
    This is the first webpage I've come accross that actually seems to understand the divergence problem. Cheers to post #14 for plainly stating the three possible outcomes. I have a question regarding the Cook paper (I would read it myself if I had more money or were a computer hacker). The phrase thrown about is "before the 1960s, the groups tracked each other reasonably well back to the Medieval Warm Period." Does this mean back to the *end* of the MWP or back into the middle or beginning of it? The reason I ask is some of the tree ring proxies might respond non-linearly to temperature as a simple natural matter of fact. If the agreement between tree rings and other proxies is only between the end of the MWP and the beginning of this most recent warm period, then there is a real possibility that the proxy is only valid under a certain (low) temperature range and beyond a cuttoff growth rate becomes a proxy for precipitation and not temperature. If the response to the high temperatures of the MWP was linear as expected, while the response to current high temperatures is not, then there's good reason to think some recent phenomena is causing the divergence problem.
  45. Can you make a hockey stick without tree rings?
    So what happened in 1900 to trigger the steep rises in T ( 0.6C in 45 years)that the graphs depict? "Using modelling techniques, the Finnish team was able to extend data on solar activity back to 850 AD. The researchers found that there has been a sharp increase in the number of sunspots since the beginning of the 20th century. They calculated that the average number was about 30 per year between 850 and 1900, and then increased to 60 between 1900 and 1944, and is now at its highest ever value of 76." http://physicsworld.com/cws/article/news/18692 commenting on: #I G Usoskin et al. 2003 Phys. Rev. Lett. 91 211101 # Since the peak in sunspots circa 2000 there has been a steep and lasting decline in solar activity and an observable decline/flatline in T trends.
    Response: Be wary that you don't fall into the "it's the sun" trap (you wouldn't be alone if you do). The same study that found "the sun has been more active in the last 60 years than anytime in the past 1150 years " (Usoskin 2005) also found the correlation between solar activity and temperature ended in the mid 1970s. At that point, temperatures rose while solar activity showed no long term trend (in fact, independent methods indicate a slight cooling trend). Their conclusion:
    "during these last 30 years the solar total irradiance, solar UV irradiance and cosmic ray flux has not shown any significant secular trend, so that at least this most recent warming episode must have another source."
  46. What do the hacked CRU emails tell us?
    Steve McIntyre ... ipse dixit. (Sorry for the two out of maybe three latin words i know) :) Seriously, now thanks to McIntyre we know that there's nothing wrong in "hiding" the data when they are obviously not representative of the temperature. This is a small step back and good news indeed. We are left with a highly personal opinion (based on?) of "not evident" and "not adequately disclosed". Just a little effort away from "there's nothing relevant to us in that email".
  47. Measuring Earth's energy imbalance
    sgking, that email has absolutely nothing to do with models, it's about data on energy balance. Then the first three points you made have nothing to do with it. (No comment on the fourth point). One thing I do not understand of you comment. What you mean by "science isn't settled"? That we do not have numbers for all the quantities we like with a precision to the tenth decimal digit? Or, instead, that the basic physical processes involved are understood and we are able to quantitatively describe the real world with a good aproximation? There's a sea of difference between the two, the former being true just for a small set of the physical constants we know. We'd have to throw away maybe 99% of the known physics ...
  48. Can you make a hockey stick without tree rings?
    I'm wondering where this article fits into this: http://news.mongabay.com/2009/1019-hance_sediment_core.html Sediment Cores from a lake in the arctic show unprecedented 20th century warming and indicated that cooling should have continued... Can a hockey stick also be made out of this? Also, is this not independent evidence for rapid 20th centuring warming in the norther hemisphere that has nothing to do with tree rings? AL
    Response: In preparing this post, I nearly did include one paper Kaufman 2009 which combined proxies of tree-rings, ice cores and lake sediment. I only decided not to include it because the study did include tree-rings and only covered the Arctic region. I'm not sure if this is the same study as the one you mention but they do seem to come out around the same time.


    Figure 4: The long-term cooling trend in the Arctic was reversed during recent decades. The blue line shows the estimated Arctic average summer temperature over the last 2000 years, based on proxy records from lake sediments, ice cores, and tree rings. The shaded area represents variability among the 23 sites use for the reconstruction. The green line shows the long-term cooling trend. The red line shows the recent warming based on instrumental temperatures (Kaufman 2009).
  49. How do we know CO2 is causing warming?
    guinganbresil, referring to fig 1 of Murphy et al. 2009, if you have a step increase in greenhouse gas you'll initially have a step decrease of OLR. Then temperature will start rise and OLR will progressively increase toward the original value to restore balance. Remember that thermal emission typically has a much stronger temperature dependence than the other factors and tends to dominate the OLR.
  50. Can you make a hockey stick without tree rings?
    You may also want to consider wine harvest dates as was once published by a French group who went through their church books dating back to 1300. Presently the wine harvest dates occur later in the autumn compared to medieval times, and it is all about temperature of course.

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