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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 107551 to 107600:

  1. DMI and GISS Arctic Temperatures: Hide the Increase?
    Frank, The impacts of the UHI are taken into consideration, see Tamino's recent post on Tokyo's temperatures. Anyhow, I am not sure what your argument is. Is it that the warming may be less than observed b/c of the alleged impact of the UHI? If so, then that can be discussed on the appropriate thread. There are very few skeptics even who consider the various SAT records and satellite records to be compromised-- that argument is usually made by "conspiracy" theorists. Anyhow, the Arctic is warming. ERA-interim data show warming, GISS shows that, and satellite data to 82.5 N show that. There is no reason to believe that there would be some rapid change or discontinuity in the temperature anomalies north of 82.5 N-- especially give that we know the correlation length-scale of anomalies is on the order of hundreds of km. I have a huge issue with people (including you) claiming that the "Arctic" is not warming when they are not even talking about temperatures north of the Arctic circle, but rather north of 80 N. The Arctic, of course, starts at the Arctic circle, which is much further south than 80 N, and that is an important difference. Do you disagree with the excellent agreement between GISS and DMI shown in Ned's post @31? So I'm not sure what kind of glasses you are wearing when you look at that graph. I also find it odd that "skeptics" ridicule the models, except that is when they think the output supports their point of view. Well, in this case the ECWMF reanalysis data do not support the claim that the Arctic has been cooling since 1958. Increase in mean near-surface temperature (°C) from (1989-98) to (1999-2008) "The lower figure is the ECMWF analysis which uses all available observations, including satellite and weather balloon records, synthesised in a physically- and meteorologically-consistent way, and the upper figure represents the same period from our HadCRUT record. The ECMWF analysis shows that in data-sparse regions such as Russia, Africa and Canada, warming over land is more extreme than in regions sampled by HadCRUT. If we take this into account, the last decade shows a global-mean trend of 0.1 °C to 0.2 °C per decade. We therefore infer with high confidence that the HadCRUT record is at the lower end of likely warming." DMI really needs to generate a product that is representative of the Arctic circle, not just north of 80 North.
  2. DMI and GISS Arctic Temperatures: Hide the Increase?
    FLanser, Are surface temperature records reliable? (argument #6)
    The warming trend is the same in rural and urban areas, measured by thermometers and satellites.
    Does Urban Heat Island effect exaggerate global warming trends? (argument #21)
    Urban and rural regions show the same warming trend.
  3. DMI and GISS Arctic Temperatures: Hide the Increase?
    Hi Peter! Its true, GISS has mostly 2 "products", its only in one they use the projections. Non the less, these projections are seen not rarely when argumenting for global warming, for instance in this NASA graphic used to show that the Arctic is going crazy: http://hidethedecline.eu/media/arctic%20temperatures/nasa2005.jpg But to make the Arctic look Sooooo dark red as on the NASA site here, they used start year 1955. But as you see in comment 46 above, start year 1937 would have shown something else. And using DMI/ERA-40 data would have shown a more nuanced picture. If you say that both GISS and DMI is only so-so useful, then i think they should make the area grey. K.R. Frank
  4. DMI and GISS Arctic Temperatures: Hide the Increase?
    Hi Albatross, The resemblance or lack of same between different sources of temperature data i have written a lot about: http://hidethedecline.eu/pages/posts/the-perplexing-temperature-data-published-1974-84-and-recent-temperature-data-180.php Here i would focus on PART 4, where for example this graphic appears: http://hidethedecline.eu/media/PERPLEX/fig78.jpg Here, notice how UAH OCEAN temperatures rather nicely follow the SST (called CSST, an average of different hadley and NOAA sources to SST). But the UAH LAND temperatures does not match the different sources of land temperatures, being GISS, GRUTEM3, Vinnikov and NCDC. The overall difference between UAH and the land based readings are not so easy to see when land and ocean are combined, but difference for land is clear. This indicates that something makes land temperatures (mostly taken from cities) are too hot, and this could be explained by UHI. But this general idea you have that all the different sources just shows the same is very wrong. Even the individual balloon sources dissagre (!) RATPAC has one story, ERA-40 another for example. But to get back to the Arctic area near the North pole 80-90N: We have only the choice between data measured in the area (DMI) or data projected from land far away. I think you need biiiig globalwarming glasses not to see what data source is most reliable. K.R. Frank Lansner
  5. DMI and GISS Arctic Temperatures: Hide the Increase?
    FLansner at 08:28 AM on 21 October, 2010 As I understand it, GISS has access to relatively high spatial resolution land and ocean measurements over most of the globe, and they have no need to extrapolate unless station data is actually not available (as over much of the very high Arctic) or SST data and local air temperature are very different (as near the "boundaries" of the high Arctic sea ice).
  6. DMI and GISS Arctic Temperatures: Hide the Increase?
    Berényi Péter at 01:53 AM on 21 October, 2010 The first data you cite is ocean flux buoy data (ocean temperature data) which is not quite relevant to surface temperature, but the second linked data set is recent and pertinent. The snippet of data in the link very nicely shows the Summer 0 degrees C clipping effect. I will try to get the complete high resolution time series updated (given time) as I have the earlier buoy data. If we look at slightly less up to date buoy data as in Polyakov 2002, where: “The datasets of monthly surface air temperature and sea level pressure used in this study contain data from land stations, Russian NP stations, and drifting buoys operated by the International Arctic Buoy Programme (IABP)”. We see again GISS correlates well over the buoy data period. Below I have plotted the Polyakov Arctic annual values with publicly available GISS annual Arctic zonal values. The buoy data is used from around 1950 onwards in Polyakov.
  7. Throwing Stones at the Greenhouse Effect
    RSVP, Any object with a temperature above 0K never stops radiating - ever. Finding an object that does not radiate, or a process to make any object not radiate, would unsettle our most basic understandings of the physical universe. DSL, RSVP is trying. He's trying to force the accumulated scientific knowledge to conform to his preconceived notions.
  8. DMI and GISS Arctic Temperatures: Hide the Increase?
    Hi Frank (re #44), Could you please explain to us why then there is such excellent agreement between the surface temperature data and those from the satellite MSU data, not to mention the balloon data and OHC data? And note that the MSU satellite data are not calibrated against the surface temperatures. Your concerns have been addressed on this very site and elsewhere. The surface SAT records (GISTEMP, HadCRUT, JAMA, NOAA-NCDC), despite their known limitations, are robust. The Arctic is warming at twice the rate of the rest of the globe-- that has been determined from multiple, independent data sets, and is explained by a phenomenon called "polar amplification". It is no artifact.
  9. DMI and GISS Arctic Temperatures: Hide the Increase?
    Hi Peter Hogarth! Im very positively surpriced by your kind tone and welcome indeed. One could hope the climate debate was like this in general. I am answering questions on 3 blogs now on this issue, so i hope you can forgive im a little late, here. As I understand you, there are trouble for GISS projections in regions near pacific equator. Well... :-) Why do GISS then do this? But very important: What I showed in my original article was, that GISS projections for SST has problems all over the world. May i remind you this important graphic from the article: http://hidethedecline.eu/media/ArcticGISS/fig6big.jpg I have made many areas black so that only GISS projected SST are shown in the UPPER graphic. And then the corresponding HADLEY SST is shown in the lower graphis. The match in the whole world [SNIIIIP] aerm... is not good. Its not just the Arctis, its not just somewhere we see a terrible mismatch. Its everywhere. If such a match is good enough for a method to be used by NASA, its really incredible. K.R. Frank Lansner
  10. Do critics of the hockey stick realise what they're arguing for?
    Chriscanaris #61 "What false premise?" The one where one creates policy based on assuming that the true value of an estimate is at the extreme negative value of a very wide error bar. "However, your suggestion that I should be more careful in how I express myself lest I be seen as trotting out sceptical talking points does test my patience." Sorry, I should be more clear here. Scientific language is generally very cautious and conservative. Much of the 8 year or longer training process for practicing scientist involves getting practitioners used to this aspect. It's not a personal attack, or a search for heresy, it's an observation about the conventions that allow us to use scientific data to draw conclusions.
  11. Throwing Stones at the Greenhouse Effect
    RSVP, wth? You aren't even trying anymore. So it's not true that any object above 0K will radiate? You should win the Nobel for this one. Tell me something, though: how does the nugget know when it's surrounded by ground? Is there a God particle involved? Does the nugget somehow magically 'sense' that it's surrounded by ground and stop radiating?
  12. Increasing southern sea ice: a basic rebuttal
    See the intermediate version of this article. The Zhang paper looks at SST 1979 to 2004 showing significant warming all around antarctica.
  13. DMI and GISS Arctic Temperatures: Hide the Increase?
    Berényi Péter at 01:53 AM on 21 October, 2010 If you go to the "advanced" post linked at the beginning of this article, you'll see some actual buoy data. You can assume most published work on Arctic surface temperatures in the ten years since 2000 (such as Polyakov 2002) will reference this. GISS are of course well aware of the satellite and buoy data, and DMI incorporate buoy data. I cover this briefly. michael sweet at 06:34 AM on 21 October, 2010 The "analysis" link is not connecting? Although the DMI data is from a model, the model is loaded with actual measurements, and quite a lot of them from satellites to get the high spatial resolution necessary for "weather forecasting".
  14. Throwing Stones at the Greenhouse Effect
    doug #92 Simpifying... the answer to your question... A hot nugget will radiate, but not when buried in a hole in the ground. As for the rest, take a break. See you tomorrow.
  15. DMI and GISS Arctic Temperatures: Hide the Increase?
    Why is BP posting data that does not show the last 13 years of warming? Those years are when the Arctic warmed the most.
  16. Do critics of the hockey stick realise what they're arguing for?
    Oh that precious Steve Goddard. After ranting about how John's graph shows more recent warming than the Hadley land+ocean data, he adds an update. "Reader “robert” tells me that Cook is using land-only northern hemisphere data in his “northern hemisphere” graph." No freaking duh. Past temperature reconstructions are based on land proxies (mainly in the Northern Hemisphere), and thus represent land-only NH temps. So that is the appropriate instrumental data to use. As usual, Goddard spends an entire blog post criticizing somebody who's correct. What a joke. Goddard also claims that John "goes on and does climate sensitivity calculations based on bogus data from a cherry-picked hemisphere." Aside from the data neither being bogus nor from a cherrypicked hemisphere (anyone even slightly familiar with temperature reconstructions should know they're usually done for the NH, from which more proxy data is available), John doesn't do any climate sensitivity calculations at all in this post. It amazes me that somebody so completely ignorant about climate science could be so utterly oblivious as to write a climate science blog.
  17. Do critics of the hockey stick realise what they're arguing for?
    I see you have rattled a cage over with Steve Goddard who is claiming your Moberg graph is 'a new level of BS'; http://stevengoddard.wordpress.com/2010/10/20/cooks-hokey-stick/
  18. DMI and GISS Arctic Temperatures: Hide the Increase?
    BP, Adrian, Flansner, Where is the data from 30 years ago to compare the current bouys to? GISS has published an analysis of this data and have shown that their estimates are closer to reality than using the global average. HADCRU has published a paper stating that they underestimate the arctic temperature rise due to their use of the global average. Can you produce peer reviewed papers that support your claim that the GISS estimates are inferior to your proposals? Without data you are just suggesting you are smarter than GISS. The DMI data comes from a model, not actual measurements. Can you suggest why it is better than the GISS model? Provide data please, not just opinions. The data Peter shows here shows that the two analysis are similar. Perhaps the bias introduced by DMI changing models is the only problem.
  19. Throwing Stones at the Greenhouse Effect
    RSVP honestly your perceptions are so muddled or at least dysfunctional in the mechanical sense that it's very hard to understand what you're intending to convey. What your words rather clearly implied is that certain tangible things on Earth can emit IR while others may not. If you were referring to surface area as opposed to volume or more precisely specific heat times mass being a measure of ability to store energy, find a way of saying so that is articulate. Elsewhere on Skeptical Science you've demonstrated a clear inability to discern between orders of magnitude, or at least you're unable to admit how you do understand such a thing as 10 X 1 = 10. This is consistent with such confused remarks as "We experience delays in communication systems daily. These may last two seconds at the most. Are you trying to say that two more seconds of lingering heat after the Sun sets is causing global warming?" Our (or my) understanding of what you know is based on what you say; with your track record of misunderstanding I'm simply going to read what you say and not attempt to use x-ray vision to tease out whatever cogs are seized up and stripping on their axles in your brainbox. All this would ordinarily be fine and dandy; it's a fact that people here are usually amazingly kind and patient. Some of us (me, again) become irritated with you when you express your inner fog with assertions implying your perspective is more useful, such as the embarrassingly tangled "AGW folks are the real unprepared optimists, because they think this problem will go away when CO2 emissions are reduced, when in fact the level of stored energy has no reason to drop without a significant radiative forcing also dropping off."
  20. It's the sun
    @KL: I don't dispute your capacity to make mathematical operations. I simply think you're not very apt at clearly presenting your arguments, hence the impression that you obfuscate issues by throwing around of math. Your inability earlier to understand such as simple matter as relative deltas instead of absolute values seems to confirm this hypothesis. If you truly understand an issue, you should be able to explain it to non-technical people like me. The fact you cannot seem to make a clear argument with all those equations is telling, and that's all I'll say on the matter before getting even more off-topic.
  21. It's not bad
    hapivibe, There is a lot of discussion of AGW because the science is being actively debated (I would say more like attacked) by a large and influential group of skeptics. Breast cancer for example does not require this discussion, as nobody seriously doubts that it is real and thus there is no discussion to be had. If you find AGW so unworthy of discussion, then tell me, why are you here adding to it? If you would rather discuss overconsumption, then visit a blog about overconsumption, or better yet, start your own. If you can generate some interesting and compelling discussion then your pet issue will attract more attention, and more power to you if it does.
  22. Throwing Stones at the Greenhouse Effect
    An image illustrating the GHG notches from Has the greenhouse effect been falsified: Integrating under the curve of the top image gives you the total energy radiated to space. Without GHG's the spectra would be a smooth curve (lacking notches), and a lower temperature would give an equal amount of energy radiated to space.
  23. Throwing Stones at the Greenhouse Effect
    And, very importantly, a planet and an atmosphere with GHG's has a very different emission spectra than one without GHG's - it has notches where ~half the IR gets re-emitted back to the surface. In order for the integrated thermal spectra leaving the atmosphere to equal the energy coming in as sunlight (where the atmosphere is essentially transparent), a planet with GHG's (notched spectra) must have a higher temperature than one without (close to blackbody spectra), when both are at equilibrium.
  24. Throwing Stones at the Greenhouse Effect
    RSVP, The travel time of emitted photons is not the only thing determining delay. There is also a delay between absorption and subsequent emission of said energy. The rate of this emission is bound by the Stefan-Boltzmann Law. Also consider that we aren't talking a single round trip transmission like in your communications example. The energy could be "bouncing around" many times.
  25. DMI and GISS Arctic Temperatures: Hide the Increase?
    My apologies, I was incorrect in my last post. The figure as represented on the summary web site shows white from -1.0 to +0.5, but the originals from the paper show a light blue from -1.0 to -0.5, and white from -0.5 to +0.5. Looks like some color fidelity got lost when putting together the summary website.
  26. DMI and GISS Arctic Temperatures: Hide the Increase?
    Huh, that's weird. In any case, a better copy of the image from the original source;
  27. DMI and GISS Arctic Temperatures: Hide the Increase?
    Examining the image (having copied it into an image processing program from the original site), the -1.0 to +0.5 region is entirely white. There's an apparent contrast over the -0.5, but that's an optical illusion. Poor choice of image colors, in my opinion.
  28. DMI and GISS Arctic Temperatures: Hide the Increase?
    If you go to the original site by clicking on the image it is possible to see that the -1.0 to -0.5 range is actually a very light grey rather than white.
  29. Throwing Stones at the Greenhouse Effect
    TOP, >The ocean's albedo is extremely low which means whatever gets in very little gets out You've got that backwards. Kirchoff's law states that low albedo implies high emissivity. If something absorbs more energy then it also has to emit more. This is a consequence of the 2nd law of thermodynamics.
  30. Throwing Stones at the Greenhouse Effect
    "all you need do is wish different physics into being and you'll be entirely impossible to ignite" doug_bostrom wins the Internet.
  31. DMI and GISS Arctic Temperatures: Hide the Increase?
    Adrian @35....no, it seems not. Weird. It is a poor quality image, so maybe the colours are not represented correctly.
  32. DMI and GISS Arctic Temperatures: Hide the Increase?
    I see -1.0 on the left side of the white -0.5 in the middle and +0.5 on the right side of the white part of fig. 9 are my eyes playing tricks on me?
  33. Do critics of the hockey stick realise what they're arguing for?
    I encourage people to actually read the discussion section of the paper by van Hoof et al. that BP is citing @64. There are many caveats in there. BP also left out this part regarding what is meant by "A significant CO2 change during the 13th century AD" as inferred from their research: "The effect of the synthetic smoothing of CO2 [SI] leads to a 25% reduction of the amplitude from 34 ppmv in the raw data to a maximum of 25 ppmv according to the model output." Others found an increase of 12-15 ppmv in the 14th Century. So the changes are at most < 10% of pre-industrial levels of CO2; to place that in context we have already increased CO2 by 40% over pre-industrial levels and will go on to double the concentration of CO2. And we know form isotope analyses that the increase in CO2 levels are primarily from anthropogenic activities, not hypothetical random walks or hypothetical "century scale unforced changes" (more on that below). It should also be noted that that particular study found the increase in CO2 in the Antarctic ice core to occur around 1300 AD, whereas multiple paleo temperature reconstructions for the N. Hemisphere show the peak MWP to be around 1000 AD (e.g.,Ljungqvist, Mann, Moberg), with notable cooling starting shortly thereafter. So the MWP occurred some 300 years earlier than the small increase found by van Hoof et al. This is not surprising given that in the past CO2 changed primarily in response to feedbacks, and probably indicates that the small (<10%) increase observed in CO2 circa 1300 AD was in response to the warming in the N. Hemisphere (most likely arising from regional warming b/c of changes in internal climate modes) during the MWP some 300 years prior. So, to me, these papers that BP is citing demonstrate that in ambient CO2 levels can increase/decrease in part because of (lagged) positive feedbacks, and that these feedbacks can occur on account of internal climate variability or internal climate modes (such as the AMO and NAO, see Mann et al. 2009). Looking forward, the contribution of the feedbacks to global CO2 levels will probably be dwarfed by present and future anthro emissions. I am a little suspicious of the CO2 levels shown in Kouwenberg et al. Note the huge decadal variability/noise-- with shifts in CO2 levels of 50-100 ppm between subsequent data points (separated by as little as 50 years). We have over 50 years of high temporal resolution and reliable CO2 measurements from Mauna Loa, and there is no sign whatsoever of natural variability or random walks causing huge departures (on the dacadal time scale) from the long-term trend. So again, Kouwenberg seems to be way too noisy and it is quite conceivable that the century-scale variability in CO2 that BP is alluding to is an artifact of that noise. Regardless, the climate sensitivity has been derived from multiple, independent lines of evidence, including estimates of climate sensitivity following volcanic eruptions (e.g., Pinatubo). And they all point to a climate sensitivity of near +3 C for doubling CO2. At the end of the global SATS are currently warmer were observed during MWP (e.g., Mann et al. 2009), and Hansen et al. (2010) has showed that the long-term rate of warming has continued more or less unabated. What we are going to experience ion terms of warming will dwarf the MWP, so "skeptics" harping on the MWP is, IMHO, a simple diversionary tactic from this:
  34. DMI and GISS Arctic Temperatures: Hide the Increase?
    Should have also mentioned; those maps BP put up are 13 years out of date.
  35. Do critics of the hockey stick realise what they're arguing for?
    chriscanaris: At the same time, I certainly want to know more whether it's in my professional life or in an area of interest. What may be confusing people is the apparent implication that this somehow makes you different from anyone else, or that this view is some sort of alternative or corrective to what the what of us think. Everyone here wants to know more. Climate scientists also want to know more, obviously, and are working hard to do so, even though it's a thankless task at the best of times. That said, we also know that we need to act, for the simple reason that the uncertainties here are unlikely to work in our favor. Things could be much worse than we expect, a little worse, about the same, a little better, or a lot better. The only one of these possibilities that doesn't require timely action is the last one, and it's also the least likely.
  36. Throwing Stones at the Greenhouse Effect
    @Very Tall Guy "Looking at an old post by Eli... it appears that the atmosphere sans GHGs is almost transparent to IR: ... This implies to me that the atmosphere is far too thin to act as a blackbody and merely transmits surface emitted radiation." If you remove GHG (See Doug's Graph on page 1) not only will you emit IR to space but you will get far more energy at the surface because GHG also block a lot of the UV coming in. Anyway, Doug's graph shows how the black body temperature could shift to the right without any CO2. But looking at the bigger picture, if you could somehow remove water vapor and still keep the oceans you still would absorb a huge amount of solar radiation and not emit it back to space. The ocean's albedo is extremely low which means whatever gets in very little gets out. This includes IR. Water is a GHL (Green House Liquid).
  37. Philippe Chantreau at 03:39 AM on 21 October 2010
    Increasing southern sea ice: a basic rebuttal
    chriscanaris, this image says it is for 10/18/2010. Do you have SST temperature anomaly data for a longer period of time (like 30 years or so)? That would be necessary in order to assert that Antarctic waters are cooling.
  38. It's not bad
    hapivibe > You have not provided evidence that proves that global warming is the biggest threat. The goal of this site is not to rank every threat faced by mankind. I'm not sure what the point of such a ranking would be anyways. Are you implying that humanity is only capable of dealing with a single issue at a time? Should we halt all cancer research until we solve overconsumption or whatever issue you feel tops the "worst threat" ranking? There are over 6 billion people on this earth, I think we can deal with more than one issue at a time.
  39. DMI and GISS Arctic Temperatures: Hide the Increase?
    Adrian #32: "What am I missing when I look at those maps?" The 'white' range is actually -0.5 to 0.5, rather than just -0.5 as you stated. A white area on the map could thus represent anything from mild cooling to mild warming. Also, while there is alot of white, the Winter and Fall maps show areas of warming greater than 0.5 in the 80 degree area (innermost circle) and Spring shows alot. Only Summer is completely white and thus 'flat'. The other three seasons show warming. Thus the warming trend shown in the annual DMI data for that region and only the Summer data being flat... because of the ice cover. Looking at satellite images of the Arctic ocean it looks like the 80 N area has been almost completely ice covered even at the September minimum point every single year recorded. There simply haven't been any large / prolonged areas of open water in that zone to allow temperatures to start increasing. Yet. If ice volume continues to decline at the rate it has been that previously permanent ice cover in the 80 N circle is going to change in the next few years... and then we'll see increasing temperatures for that region just like most of the rest of the planet (i.e. pretty much everything except a similar small area around the opposite pole).
  40. Roger A. Wehage at 03:35 AM on 21 October 2010
    Record snowfall disproves global warming
    Re: Daniel Bailey @3: I didn't claim that lake effect was the only contributing factor to the large snowfalls in the Upper Peninsula. But it is likely the most significant factor. If it were not, then one might expect similar snowfalls over northern Minnesota, northern Wisconsin, the Upper Peninsula, and parts of Canada to the west and northwest of Houghton. For example, the most snow to fall in a season anywhere in Minnesota was 170 inches, far short of Houghton and Calumet. One could look at current and historical weather radar data to see the origin and extent of rain and snowfall in particular areas. Typically one often sees precipitation originating and falling over the water and moving inland. Another factor is that warm, moist air over lake waters likely moderates temperatures downwind and increases the amount of snow associated with Alberta Clippers. And I agree with your comment about heavy snows from the southwest, which shouldn't be affected by lake moisture. Minneapolis has experienced a number of heavier snowfalls over the past 40-50 years, and it is likely that more of the moisture comes up from the southwest.
  41. It's not bad
    hapivibe - I have to agree with Ned. This site is dedicated to discussing/dissecting the "skeptic" response to global warming, which involves a great deal of bad logic, cherry-picking, and some very odd approaches to science. Overfishing is a big problem. So is population growth, resource overutilization, and any number of other topics. But those topics are not what this website is devoted to, unless those are related to global warming. They are simply off-topic and inappropriate here; and it feels like you're nagging participants for putting energy into this discussion.
  42. It's not bad
    Sorry I know I am curious and I couldn't find a section on the site. Let's say I'm sceptical about being sceptical about being sceptical but an answer would be good as I am interested in any psychological aspect. If you are in the gw 'bubble', it is indeed an open forum where I can enter and challenge this and I appreciate it. Sorry for any offence and I do honour web etiquette.
  43. It's not bad
    We talk about climate change because this is a website about climate change. This is one of those basic rules of web etiquette. The web is a big place. If you want to talk about overfishing or poodle-grooming or sports or whatever, there are plenty of other sites elsewhere. But going to a discussion forum dedicated to Topic X and telling people that they really ought to be discussing Topic Y instead is generally not appreciated.
  44. It's not bad
    No, i'm sorry. You have not provided evidence that proves that global warming is the biggest threat. And I still don't know why there is so much attention paid to it compared to the other issues. You have not shown me a link to a discussion site where people are this involved for any other topic. Why does this topic generate a disproportionate amount of interest? Can you just give straight answers if possible and not links this time as I don't need links? Thank you.
  45. Do critics of the hockey stick realise what they're arguing for?
    chriscanaris writes: I certainly don't believe we should quietly continue business as usual in the expectation of a series of volcanic eruptions conveniently saving our bacon. [...] Ultimately, I'm asking because I'm curious rather than contrary. Yes, I understand that and appreciate your reasonableness. However, I do think you're still stuck on the (mistaken) idea that cloud cover is somehow independent of climate sensitivity. The uncertainty in cloud albedo feedback is directly responsible for much of the uncertainty in climate sensitivity. So, if someone looks at the MWP/LIA (or at Pinatubo for that matter) and concludes that those events had a significant impact on climate, you're right that that implies a "high" (or at least non-"low") climate sensitivity. But the further implication is that there isn't a huge negative feedback from clouds. Remember that with no feedbacks at all, climate sensitivity is around 1C. The sensitivity range given in IPCC (2-4.5C, with a best estimate of 3C) specifically includes the effects of feedbacks. If feedbacks turn out to be more negative than the best estimate, then sensitivity must also be lower than the best estimate, and that would argue against the existence of a high-amplitude, globally consistent MWP or LIA. assuming we're on the same continent, we both seem to live by a most uncivilised timetable Actually, I am writing this from New England, USA, where it is just about noon on a gorgeous autumn day.
  46. DMI and GISS Arctic Temperatures: Hide the Increase?
    Has anyone really looked at Berenyi Peter's seasonal sat.trends figure 9? If you look at the scale white would seem to indicate some cooling above 80 degrees for summer fall and winter.I don't get it.What am I missing when I look at those maps? The middle of the white scale is -0.5. So I'm correct in assuming the arctic has been cooling for three seasons and not just the summer.....anyone?
  47. Do critics of the hockey stick realise what they're arguing for?
    skywatcher @ 62: I suspect that clouds (like the poor) will always be with us. AR4 pretty well declares that they comprise a substantial negative feedback albeit with what certainly looks like a 'scary to terrifying' margin of error. Some cloud cover changes under a warming scenario may comprise a positive feedback - hence presumably the size of the error margin though agreement between these data and model projections remains problematic. I've just noticed Ned's post @ 65 - assuming we're on the same continent, we both seem to live by a most uncivilised timetable :-). Thank you for putting in the time and effort to explain your argument. Climate sensitivity on a purely intuitive basis seems clearly 'high' - I think Mt Pinatubo serves as prima facie evidence. Mt Pinatubo significantly exerted its transient effect in the face of what was already a substantial CO2 forcing. So what forcing comes most strongly into play will depend very much on whether increased CO2 will be accompanied by concomitant rises in aerosols and the nature of changing cloud cover all of which as best as I can ascertain from my forays on the Internet remain very uncertain (though for the sake of coherence, I have highlighted work pointing towards a more pessimistic scenario). I certainly don't believe we should quietly continue business as usual in the expectation of a series of volcanic eruptions conveniently saving our bacon. I guess the question remains whether a low range (as opposed to a very low range) climate sensitivity renders a LIA or MWP impossible or highly implausible as opposed to merely unlikely. I don't feel remotely qualified to attempt an answer to that one but can't help but wonder in the light of the error margins involved. Moreover, while any atmospheric aerosol or cloud at a particular point in time represents a transient phenomenon (in contrast to anthropogenic CO2 which is very long lived), cloud cover and aerosols comprise a self-renewing and hence non-transient process. Ultimately, I'm asking because I'm curious rather than contrary.
  48. DMI and GISS Arctic Temperatures: Hide the Increase?
    adrian smits writes: No Ned they are guessing because they use temperature measurements from 1000 km away on land that is not covered with ice.That's why the GISS temperature anomaly is so far out of whack with the DMI measurements. Except they aren't "out of whack" at all. Did you even bother reading the article by Peter Hogarth at the top of this thread? The 50-year trend for DMI is +0.37C/decade and for GISS it's +0.35C/decade. Here's Figure 3 from Peter's post, in case you're having trouble finding it: Figure 3: Annual DMI and GISS Arctic temperature anomalies and trends So, if you like the DMI data, you ought to conclude that GISS does a good job of estimating Arctic surface temperature trends.
  49. DMI and GISS Arctic Temperatures: Hide the Increase?
    BP, that's basically non-responsive. If anything, the figure you paste in confirms my point nicely -- trends at or near the pole tend to be more similar to trends elsewhere in the high Arctic than to trends further south. Presumably, if your figures extended to the equator, there'd be no visible correlation at all there. Lansner specifically asked why GISS doesn't just leave the Arctic blank. I answered that question -- leaving any region "blank" when calculating a global mean temperature anomaly implicitly assumes that that region's anomaly is identical to the average of the rest of the globe.
  50. Do critics of the hockey stick realise what they're arguing for?
    HumanityRules - there are certainly gaps in our knowledge. However, a significantly higher climate sensitivity to solar effects than greenhouse gases is not consistent with what we know. Consider for example the early 20th century, during which there was a significant increase in solar activity to the "Modern Maximum". Yet during that period, when there were other positive radiative forcings at play, the planet only warmed about 0.4°C. The data just doesn't jibe with a higher climate sensitivity to other forcings.

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