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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 126301 to 126350:

  1. Water vapor is the most powerful greenhouse gas
    villar, you can demonstrate non-runaway positive feedback in a spreadsheet: Cell A1: 0 Cell A2: 10 Cell A3: =A2+0.5*(A2-A1) Cell A4: =A3+0.5*(A3-A2) Now copy and paste cell A4 into cell A5 and on down the column for about 15 cells. The formula should automatically adjust to each cell, so each cell's value is the previous cell's value plus 50% of the increase that the previous cell had experienced over its predecessor. The feedback is an increase of each increase, not of the total resulting amount.
  2. Why is Greenland's ice loss accelerating?
    Thanks, Riccardo. Yes, I was referring to fig. 1 in this post. It seems that my English is worse than I thought :) I had read that sentence, but that sounds merely descriptive to me, kind of "there is a vertical difference compared to GRACE"... I'll check my dictionary when I'm back home this evening ;-) "If you look at anomalies the offset does not matter", unless those anomalies refer to the same reference period, isn't it? (eg. mass annomaly with reference to the 1980-1990 average) I realize I lack some education on the matter and this is just a small non-important bit in the whole post, so there's no problem if you don't feel like addressing this ;-). Thanks!
  3. Why is Greenland's ice loss accelerating?
    PeterPan, if you are referring to fig.1 in this post, it is stated in the caption "GRACE data is offset vertically". But anyway, if you look at anomalies the offset does not matter.
  4. The hockey stick divergence problem
    Thanks. This puts the "hide the decline" storm in a teacup into context, but isn’t it also relevant to the recent Yamal controversy that was whipped up by McIntyre? Was McIntyre simply unaware of or ignored the divergence problem? Seems to me that he did.
  5. Why is Greenland's ice loss accelerating?
    Why is there an offset of about 500 Gt between GRACE and van den Broeke et al 2009? To my unskilled view it would suggest that van den Broeke 2009 confirms the GRACE trend but not the amount of ice loss(?). Or is it shown this way just for clarity? Thanks! John, your great site is improving one post to the other. I think this is currently the best online resource on climate change for the lay public. Congrats and thank you!
  6. The hockey stick divergence problem
    I think the point here is that we should treat the data with appropriate caution but not throw it out altogether. If the pre-1880 data turns out to be consistent with proxies from other, completely independent methods (sediments / ice cores / whatever) then that should increase our confidence in the data (it would be unlikely that different proxies are wrong in the same way, at the same time, to the same degree). I think some people would like to just reject all proxy data and say we can't ever know anything about past climate, and therefore can't infer anything about the significance of current changes. The way to deal with such data is not to reject it out of hand but to publish it and make it open to challenge in the scientific literature.
  7. The hockey stick divergence problem
    Tree rings wouldn't be the first proxy thermometer doing something else than being the instrument we thought it was.
  8. Was there a Medieval Warm Period?
    Those of you interested in temperature reconstructions might want to take a look at this recent review I happened to notice.
  9. Water vapor is the most powerful greenhouse gas
    I really don'y buy the positive feedback model of water vapor. All positive feedback loops are unstable. The planet should have gone wildly hot millions of years ago in a positive feedback model. We have to conclude that water is in a negative feedback loop, either alone, as from the reflection of clouds alone, or in concert with other elements.
  10. The hockey stick divergence problem
    You would think drought conditions just might have accompanied warming periods in the past, (whether anthropogenic or not). Maybe all that is happening here is the discovery that the interpretation of tree ring data is not as simple as previously believed.
  11. The hockey stick divergence problem
    WAG I'm not sure what has been killed. Couple of quotes from Briffa 1998 "It seems clear that a major, wide-scale change has occurred in the ecology of Northern Hemisphere tree-growth and temperature. As yet, the cause is not understood, but a number of factors such as increasing atmospheric CO2, higher levels of pollutant (i.e. nitrates or phosphates) transport, other changes in soil chemistry or increased UV-B levels might be involved. There is also evidence that increasing atmospheric opacity has resulted in a notable reduction in the amount of solar radiation reaching the earth's surface since the middle of this century (Bradley & Jones 1992). Several factors could be acting together, and possibly interacting with changes in climate itself." And from the Q+A session at the end "K. R. BRIFFA. At this time, we do not know why maximum late-wood density declines in relation to large-scale changes (recent warming) in temperature." There are many possible explanations/suggestions put forward to explain the "divergence problem" but there appears no nailed explanation for it. In most cases the sorts of work that is required plant physiology, field ecology (as well as climatology) is not done by dendrochronologists. Until this sort of work is done it can only ever be speculation. In fact Briffa 1998 lists many possible factor this appears to be speculation (I count nine if you include ones in the first quote). "potential factors such as changing CO2, O3, and UV-B levels, and widely experienced alterations in the other atmospheric and soil balances, must be considered" "higher nitrate levels or perhaps tropospheric ozone"
  12. Was there a Medieval Warm Period?
    Truthseeker, re #50. You are being sarcastic, right?
  13. What do the hacked CRU emails tell us?
    Imo the use of the word skeptic in this context is misplaced. "skeptic" is a word that I find ambiguous. Skeptic toward science is not the same as being skeptic with in science, in where we associate skepticism with being rational as contrasted to a meaning of irrationality or ignornace. In the rational meaning all scientist are skeptics, even to their own ideas. What you describe/define I would not call skeptic, but dogmatic denial or irrational thinking.
    Response: We could get in the whole argument about whether global warming skeptics should be labelled skeptic, denier, denialist, etc. But that just gets us off the science. So I'll concede the term 'skeptic' if it allows us to discuss real issues and not get in an argument on what we should be calling each other (never a constructive topic).
  14. The hockey stick divergence problem
    Once again, John Cook kills it. If only every skeptic read Skeptical Science.
  15. Was there a Medieval Warm Period?
    Why do you post Mann and not Baliunas and Soon were authors of excellent work confirming the existence of the Medieval Warm Period (MWP) from a multitude of sources?
  16. The hockey stick divergence problem
    As I read it, John Cook did not conclude that the origin of divergence is anthropogenic. It's one possible explanation, as reported in the litterature. For the same reason you can not conclude that "tree ring proxies are not reliable during warmer periods". Here you're assuming that the problem is temperature; again, it's just a possible explanation. Also, you should consider that not all the trees in all locations show divergence, so you should have specified (like D'Arrigo did) tree rings affected by divergence. But whatever the reason of divergence is, if the reconstruction of MWP gives a temperature lower than the '60 of last century (or whenever divergence starts), there's no reason of concern.
  17. What do the hacked CRU emails tell us?
    I think this is the "divergence problem" John is refering to (hint: it's not a divergence problem): http://www.climateaudit.org/?p=7844
  18. The hockey stick divergence problem
    Just to add to my comments above, here is a quote from the D'Arrigo 2008 paper: "For example, reconstructions based on northern tree-ring data impacted by divergence cannot be used to directly compare past natural warm periods (notably, the MWP) with recent 20th century warming, making it more difficult to state unequivocally that the recent warming is unprecedented."
  19. The physical realities of global warming
    Or maybe CRU got their data from NOAA; I can't remember. Anyway, the organization from which CRU got their data still has those data, and anybody wanting those data need to ask those originators. You'd think skeptics would want to go to the original sources anyway, since apparently they don't trust CRU.
  20. The hockey stick divergence problem
    The only thing one can conclude from the verifiable, recent tree ring record is that tree ring proxies are not reliable during warmer periods, including possibly the MWP. This means that graps like Mann et al 1998 are not reliable indicators of T in eg the MWP. You can't conclude the cause of the decline is anthropogenic, either from Briffka 1998, or Cook 2004, as there is not enough reliable data to make a comparison prior to 1200 AD (most of the MWP) in Cook 2004 with the post 1960 records, and none in Briffka 1998 prior to 1880 to make a comparison with post 1960 records. Your inferance that the cause is anthropogenic does not come from tree ring science.
  21. The physical realities of global warming
    TruthSeeker, the raw data are safe and sound, and available, from the UK Meteorological Office that compiled the data set in the first place. CRU is merely one consumer of those data, and is prohibited by the Met Office from distributing the raw data anyway. That's the restriction that the Met Office places on all people/organizations to whom it gives those data. The Met Office's agreement is posted somewhere in the comments on one of the RealClimate threads, but I can't find it right now.
  22. The physical realities of global warming
    SNRatio I appreciate your suggestions, they are quality. I intend to take action on them. Along those lines, what are your thoughts that the CRU destroyed the raw data, it tends to undermine my or anyone else ability to really check into this?
  23. The hockey stick divergence problem
    Humanity, correct me if I am wrong, but are the papers to which you refer documenting the increase in NDVI over the Boreal Tundra? The Tundra has indeed greened in response to warmer temperatures and longer growing seasons, but the cores were not sourced from the tundra were they? The Nemani paper shows that growth in northern Eurasia seems to be primarily limited by energy/insolation-- so global dimming would likely have an impact there. Nemani et al's Fig 1 does show an increase in VPD which would decrease stomatal aperture (increase canopy resistance) which would reduce gross photosynthesis-- so it is perplexing that the NPP there has allegedly increased. Their Fig. 1C shows that N. Eurasia has cooled somewhat between 1982 and 1999. So this is clearly a complex problem. Fortunately, we have more reliable proxies for global temperature. Soil moisture is a limiting factor for tree growth. What is critical is whether or not the regional climate is such that water stress is an issue, certain regions are obviously more prone to frequent drought than others. In fact, you probably know that scientists also use dendrology data as a proxy for drought. That said, how do we know that historical regional droughts did not affect the tree growth in the past? Anyhow, I'm clearly not an expert, but perhaps someone in the know or John could address these issues. Thanks.
  24. CO2 is not the only driver of climate
    "The electrical power (Sun) heats the Microprocessor (Earth) just like the Sun heats the Earth." Gord, have you ever been wondering of the purpose of cooling paste put between a heat sink and the object which is to be cooled?
  25. What do the hacked CRU emails tell us?
    Comment to response in comment #30: "The whole approach of Skeptical Science is to point out that global warming skepticism misleads by focusing on narrow pieces of the puzzle while neglecting the broader picture - the job of Skeptical Science is to communicate the broader picture." I am a bit concerned about your polarization in "narrow" respectively "broad" pictures. I think you are hijacking the meaning of these words which may not be agreed on by everyone. I don't think such attitude will do no more good than deepen the cliff between you and others peoples that may not agree with you to the single letter and point. Modern science is about reductionism and with such tool exclude things as wrong and leave the rest as "possible". When deferring skeptical criticism to be "narrow" and "cherry picking" you are also denying the scientists themselves the very same tool they are supposed to use to strengthen the rest of the scientific communities confidence in a theory as "possible". Implicit, the statement carry the meaning that any scientist that does cherry picking is not doing proper science. This is a very strange position to hold because our confidence in a scientific theory ultimately relies on all the "cherry picking" criticisms a theory is exposed to and is able to withstand.
    Response: I appreciate your comments. Perhaps a more precise description would be that a common pattern in global warming skeptic arguments is to focus on narrow pieces of evidence while ignoring other evidence that contradicts their argument.
  26. The hockey stick divergence problem
    Step outside of dendrochronology and there is no evidence that Northern high latitude plants are struggling. Satellite data suggests that over the past couple of decades the planet has greened including the higher northern latitudes. Look at the references on this page. Read the first line on Nemani et al., 2003. Their figure4 also shows general improved plant growth in N. latitudes. Zhou et al., 2003 suggest improved growing conditions in N. latitude forest is primarily due to increased temperature and go further to say "Changes in stratospheric aerosol optical depth and precipitation have a smaller effect" The strange thing is these papers suggest the trees should be experiencing enhanced growth over recent decades not struggling. Maybe there is a flaw in the interpretation of tree ring data?
  27. What do the hacked CRU emails tell us?
    When working with a dataset it will always happen that data is contaminated in someway or the other. Many times data can be filtered before use, but when a dataset is large it is prone to happen that bad or even faulty data slips into an experiment. Researchers are aware of this and when a result - or a data point - turns up significant, part of the protocol is to do a double check. This is part of the scientific methodology: if something is a relevant factor, an experiment must be conducted to rule it out. What is of scientific methodology concern in the CRU report is not the fact that there exists bad data or the operator has a lot problem to get it working, but the fact that there seams to be a loss of traceability in the experiment and thus it is not possible to do the required double check. This should make us concerned. CRU has received critics for not releasing its data set – which is common practice in science after publication. Other scientist want and will do a double check because in science "my word" for something is not good enough. It's been stated that the dataset has been unavailable due to that it is not ready for release, and this is a valid point to make because if data is released it should be provided in such format that it is possible to replicate the experiment with traceability in the data set – for reason already mentioned. The conclusion I make from the report is that the data set is not in such format right now, and this should make us very concerned.
  28. Why is Greenland's ice loss accelerating?
    ubrew12, it is well know that in the arctic summer air temperature cannot be much higher than the melting point of ice; most of the heat goes to latent heat of melting thus limiting the increase in temperature. On the contrary, temperature fluctuations in winter are much larger because ice insulates the atmsophere from the warmer ocean. This is to say that atmosphere and ice are indeed strongly coupled. Ice and ocean couplig, instead, appears to be particularly relevant when the latter melts the floating ice shelves along the grounding line, speeding up the ice stream feeding the ice shelf.
  29. How do we know CO2 is causing warming?
    guinganbresil, OLR is indeed increasing which means postive energy imbalance; this is one of the (many) evidences of the warming planet. A good collection of papers on OLR can be found here. For the energy balance i'd suggest this Trenberth et al. in BAMS.
  30. Why is Greenland's ice loss accelerating?
    What if the ice-atmosphere system is more highly coupled than the ice-ocean system? Suppose we could assume the ocean was off doing its own thing, and that melting ice was mostly absorbing heat coming from the atmosphere? Perhaps then the ice melt could explain the (admittedly small) slowdown in air warming experienced in the last decade.
  31. Was there a Medieval Warm Period?
    Nevermind, just read: dhogaza at 05:51 AM on 29 November, 2009
  32. Was there a Medieval Warm Period?
    Is if possible that the divergence problem of tree ring anomalous proxies since 1960 is due to global dimming? I believe the earth DID dim during the period 1960-1975 and this shows up in the temperature record as falling temperatures, masking the global warming effect. Tree growth would have been affected by dimming to a degree much greater than just the effect of falling temperatures. Reduced photosynthesis would have led to narrow rings which might have been put down to temperature. Just a thought.
    Response: Yes, it certainly is possible global dimming is one of the causes of the divergence problem. A few studies explore this option. However, the issue is complex - there doesn't seem to be one smoking gun to explain the decline in tree ring growth. More onthe tree-ring divergence problem...
  33. Was there a Medieval Warm Period?
    nofreewind (#46), In your attempt to criticize Dr. Mann with some political commentary, you (or Tierney in this case) selectively quote him from a 2004 blog comment. Yet, left out is the rest of the paragraph: "...Most proxy reconstructions end somewhere around 1980, for the reasons discussed above. Often, as in the comparisons we show on this site, the instrumental record (which extends to present) is shown along with the reconstructions, and clearly distinguished from them (e.g. highlighted in red as here). Most studies seek to "validate" a reconstruction by showing that it independently reproduces instrumental estimates (e.g. early temperature data available during the 18th and 19th century) that were not used to 'calibrate' the proxy data. When this is done, it is indeed possible to quantitatively compare the instrumental record of the past few decades with earlier estimates from the proxy reconstruction, within the context of the estimated uncertainties in the reconstructed values (again see the comparisons here, with the instrumental record clearly distinguished in red, the proxy reconstructions indicated by e.g. blue or green, and the uncertainties indicated by shading)" This is the sort of thing being done as political goons eagerly parse through personal emails looking for dirt or the appearance of dirt. It certainly says more about Tierney and others doing the spin than it does about Dr. Mann. To borrow a line from you, "your comments might be convincing to the guy down the street but they aren't going to work with me".
  34. How do we know CO2 is causing warming?
    I also found: http://www.isprs.org/publications/related/ISRSE/html/papers/332.pdf Which also shows an upward trend in overall OLR.
  35. How do we know CO2 is causing warming?
    Riccardo, I wholeheartedly agree - My concern is that the decreases detected due to trace gases (CO2, CH4...) by Harries and others may or may not result in an overall decrease in OLR. A cursory look at the change in spectrum would imply an overall increase. Do you have a good reference for the overall OLR trend? I found: http://www.atmos-chem-phys-discuss.net/4/2727/2004/acpd-4-2727-2004-print.pdf Which indicates an upward trend for OLR.
  36. What do the hacked CRU emails tell us?
    Scientists are not naturally more honest than the rest of us. They don't have some natural immunity from falling in love with their own ideas, getting defensive in the face of criticism, or believing the idea that corresponds best to their own material well-being. No. What keeps scientist honest is skeptics looking over their shoulder, demanding their data, reproducing their results and critiquing their methods. What is damning about the CRU emails is that they show evidence of collusion designed to prevent anyone from checking their results by refusing to release data, and working to keep dissenting voices out of the journals so they could be dismissed as unpublished. People have noticed that Jones et. al. did not answer FOIA requests. It is a scandal that one scientist should have to submit a FOIA request to get data from another scientist, esp. a publicly funded scientist. And now CRU tells us they threw away the raw temperature data, so nobody can reproduce their results? People who behave like they have something to hide, usually do have something to hide. If Phil Jones et. al. were expert witnesses in a trial, the judge would have thrown their testimony out of court based on what the emails reveal.
  37. Was there a Medieval Warm Period?
    Dhogaza, you said in regards to accessing and replicating the data. "Oh, gosh, such an insurmountable obstacle, you might have to partition a disk and recreate Mann's directory structure on it, the horror! The unscientificness of it! As a software engineer with nearly 40 years experience in my field, this complaint makes me laugh. It might take a day or so to replicate the environment or to change the directory and file structure embedded in the code." You might want to read the programmers comments embedded in the code(not sure what data he refers to), seems like some pretty precise work that they do to determine the earths temperature from thousands of data points, etc etc etc. all very very precise. I Saw Mommy Kissing Santa Claus.... http://www.torontosun.com/comment/columnists/lorrie_goldstein/2009/11/29/11967916-sun.html As you read the programmer's comments below, remember, this is only a fraction of what he says. DHogaza, your comments might be convincing to the guy down the street but they aren't going to work with me! - "This whole project is SUCH A MESS ..." (266) - "But what are all those monthly files? DON'T KNOW, UNDOCUMENTED. Wherever I look, there are data files, no info about what they are other than their names. And that's useless ..." (Page 17) - "It's botch after botch after botch." (18) - "The biggest immediate problem was the loss of an hour's edits to the program, when the network died ... no explanation from anyone, I hope it's not a return to last year's troubles ... This surely is the worst project I've ever attempted. Eeeek." (31) - "Oh, GOD, if I could start this project again and actually argue the case for junking the inherited program suite." (37) - "... this should all have been rewritten from scratch a year ago!" (45) - "Am I the first person to attempt to get the CRU databases in working order?!!" (47) - "As far as I can see, this renders the (weather) station counts totally meaningless." (57) - "COBAR AIRPORT AWS (data from an Australian weather station) cannot start in 1962, it didn't open until 1993!" (71) - "What the hell is supposed to happen here? Oh yeah -- there is no 'supposed,' I can make it up. So I have : - )" (98) - "You can't imagine what this has cost me -- to actually allow the operator to assign false WMO (World Meteorological Organization) codes!! But what else is there in such situations? Especially when dealing with a 'Master' database of dubious provenance ..." (98) - "So with a somewhat cynical shrug, I added the nuclear option -- to match every WMO possible, and turn the rest into new stations ... In other words what CRU usually do. It will allow bad databases to pass unnoticed, and good databases to become bad ..." (98-9) - "OH F--- THIS. It's Sunday evening, I've worked all weekend, and just when I thought it was done, I'm hitting yet another problem that's based on the hopeless state of our databases." (241).
  38. Was there a Medieval Warm Period?
    Seriously, I respect this blog and the blog owner trying to enforce a "code of conduct", but what term could I use but calling Mann a LIAR? in his response to the commenter who asking him about grafting? Please tell me where I am talking nonsense? I have a funny feeling that Mann would come up with a very confident retort as he did in that 2004 RC post. We have to look at credibility, it is vital to science, in fact it is science.
  39. Was there a Medieval Warm Period?
    This is extremely interesting. http://icecap.us/index.php/go/political-climate Let's look at the "credibility" of the Mann of who is at the heart of this data... _______________________________ In fact, one skeptic raised this very issue about tree-ring data in a comment posted in 2004 on RealClimate, the blog operated by climate scientists. The comment, which questioned the propriety of “grafting the thermometer record onto a proxy temperature record,” immediately drew a sharp retort on the blog from Michael Mann, an expert at Penn State University: Mann: “No researchers in this field have ever, to our knowledge, ‘grafted the thermometer record onto’ any reconstruction. It is somewhat disappointing to find this specious claim (which we usually find originating from industry-funded climate disinformation Web sites) appearing in this forum.” Dr. Mann now tells me that he was unaware, when he wrote the response, THAT SUCH GRAFTING HAD BEEN DONE IN THE EARLIER PRIOR COVER CHART, and I take him at his word. But I don’t see why the question was dismissed so readily, with the implication that only a tool of the fossil-fuel industry would raise it. Here it is here on RealClimate: http://www.realclimate.org/index.php/archives/2004/12/myths-vs-fact-regarding-the-hockey-stick/#comment-380 Is Mann referring to the 2001 IPCC? Or whatever cover, you mean he didn't know about it????? This was the fault of the fossil-fuel industry, their influence? Sadly, people who don't know how to type to keep a bookmark folder seem to know very little about any of this!
  40. The physical realities of global warming
    Okay, HR, don't pretend -- but they're only numbers. Pick some other numbers if you like. The point is that the numbers are multiplicative. As to the misanthropy and pessimism of the green movement -- note that I'm the greenie in the above conversation and RSVP is the skeptic. The greenie is the one who's optimistic about our chances of meeting the challenges of the future, and the greenie is the one who doesn't support focusing on population reduction. In fact, the whole point of my comment was to correct the skeptic assertion that striving for sustainability involves reducing quality (and quantity) of human life. Who is the fear monger here?
  41. What do the hacked CRU emails tell us?
    Riccardo, "It would be really poor science if they throw away thousands of data sets just because a few got weird. Indeed, they are studying the divergence problem, which is related more to tree physiology than to climate." I am still not convienced, because it appears to me that the only "cross" checking that resulted in throughing out "wierd" data was only inexistance in the most recent times. Who's to say that if you had temperature readings in the past that you wouldn't find other divergances?
    Response: I was reading through the peer reviewed literature last night, investigating that very question. What they found was the divergence problem has only occured in the last few decades and there is no evidence of similar divergences in the past. They determined this firstly by comparing tree ring records with the instrumental record going back to the early 1800s.

    To look at earlier periods, they found that the divergence problem was mostly found in high latitude northern sites - sites in more southern locations showed much less or no divergence. So comparing divergent northern tree-ring series with southern tree-ring series found that the only period where the two series diverged was in the last few decades.

    Anyhoo, I was reading through this because I'm currently doing a thorough write-up on the divergence problem. Hopefully I'll find the time to complete it later today.
  42. The physical realities of global warming
    I'm not sure I even want to pretend you could reduce population by 35%. No doubt if we ever got a green government it would be a possible 'policy option'. The basic misanthropy of the green movement shouldn't be ignored. I'd fear a government that had an ingrained belief that humanity was a disease on this planet. The Malthusian ideas that we will reach limits have had a long and varied history and you would have lost money if you bet on any of them. The fact that they are appealing today says more about the pessimism in political and social life than it does about any real natural limits. India in the 21st century will not follow the same development path that the US followed in the 20th. We need policies of boundless development to encourage the best future for all. Not fear that these countries we drag us all down in their pursuit of what we have.
  43. What do the hacked CRU emails tell us?
    "In a statement on its website, the CRU said: “We do not hold the original raw data but only the value-added (quality controlled and homogenised) data.” " The fact that they no longer have the "original" data is a big problem. How can anyone independently validate their findings (either in prof or disporf) without the data. Why would any of you believe something/claims that can't be independently verified?
  44. Was there a Medieval Warm Period?
    Mann 2009 is an interesting paper since it shows characteristic MCA patterns particularly warm north atlantic and cold equatorial pacific,another earlier paper, Trouet 2009 linked the persistent NAO+ pattern to cold pacific ocean. I've plotted a map from NOAA dataset with a similar colormap except that i've added two color at the extreme due to some pixel above 1.4°C anomaly in the last decade: http://ultraxs.com/image-8871_4B140B80.jpg
    Response: Thanks for the very relevant link to Trouet 2009 and the NOAA colourmap which is particularly useful because it uses the same colour scale as Mann 2009. I've added the graphic below:

  45. CO2 lags temperature
    toadhall, would you say that a lighter is useless to make a gas tank explode? More seriously, at equilibrium CO2 alone accounts for about a third of the whole effect, the other 2/3 are feedback. The feedbacks are intrinsic in the climate system, not just related to CO2. And indeed the orbital forcing due to the Milankovitch cycles alone cannot explain the ice ages cycles. You are also confusing CO2 as a feedback and as a forcing. What we are seeing now is the increase of CO2 concentration due to an external factor, human emissions. So, CO2 was a feedback in the past but now is acting as a forcing.
  46. How do we know CO2 is causing warming?
    guinganbresil, you can not draw conclusions on the overall energy budget looking just at a small wavelegth range. Ice crystals and aerosol in general, for example, influece the energy budget also in the visible. On the contrary, absorption by CO2 and CH4 is at discrete frequencies and can be assessed by looking at a single frequency band.
  47. CO2 lags temperature
    Correct me if I'm wrong, but CO2 is a pretty useless greenhouse gas. Feedback mechanisms and climate disaster modelling is predicated on a small bit of CO2 induced heating leads to increased atmos water vapour+ methane (a bad greenhouse gases) which leads to a large heating. i.e. CO2 starts it off, but watervapour/methane are the true baddies and contributors to the warming. If there is a 800 year lag between temp rising and CO2, then it suggests that a water vapour/methane feedback loop has already occurred anyway and, when CO2 turns up, it may add to the problem but it is effectively a side issue, driven by temperature and not the other way round. It seems to me that this is the mother of all correlation versus causation mistakes. Would like to hear a layman alternative?
    Response: Allow me to correct you. We have directly observed the enhanced greenhouse effect from rising CO2, both by satellites measuring infrared radiation escaping out to space and by surface observations of the infrared radiation returning back to Earth. They find that more heat is being trapped at the wavelengths that CO2 absorbs energy. This is empirical confirmation of the human signature in the greenhouse effect.
  48. How do we know CO2 is causing warming?
    Riccardo - Thanks for the prompt response! As I understood Harries, the issue of incomplete removal of the ice crystal effects was due to the large difference in FOV of the IMG (8x8Km) and IRIS (95x95Km) detectors. However, I see in Griggs (figure 2 B & C, watch out for incorrect axis labels) that the AIRS detector has a field of view much closer to IMG and it still shows this effect. The increase of the ice crystals (or whatever it is) appears to track with time (1970, 1997, 2002) vice FOV (IRIS-95, IMG-8, AIRS-13.5). I know this is a subtle point, but if this ice crystal effect is not just a messy data issue it seems it would have a significant impact on the overall OLR trend and radiative balance due to the higher brightness temperature over the 800-1000 cm^-1 range.
  49. Was there a Medieval Warm Period?
    To Steve L Thank you for educating me on the term. Googling it took me to this: http://climateprogress.org/2009/03/12/what-exactly-is-polar-amplification-and-why-does-it-matter/
  50. Was there a Medieval Warm Period?
    Standard cherry-picking broght to the extreme consequences. Just a single (and not understood) line of code demonstrates the frode. The magic of out of context claims. It's useless keep crying about "the code's not clear enough". Why the hell should it be? The only thing that matter is the output of the code. I read claims by software engineers that the code is not well written. Probably; i also write the code myself and the only thing a care of is if it's correct, if it run smooth and efficiently, not if it's nice or easily readable. Forget the code, take the data or collect your own if possible, analyze and compare. This is the standard practice. Everything else is just chattering.

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