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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 106601 to 106650:

  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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?
  6. 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:
  7. DMI and GISS Arctic Temperatures: Hide the Increase?
    Should have also mentioned; those maps BP put up are 13 years out of date.
  8. 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.
  9. 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).
  10. 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.
  11. 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.
  12. 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).
  13. 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.
  14. 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.
  15. 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.
  16. 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.
  17. 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.
  18. 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.
  19. 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?
  20. 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.
  21. 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.
  22. 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.
  23. 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.
  24. Do critics of the hockey stick realise what they're arguing for?
    Reading the posts by "skeptics" (or critics of the HS (reconstructions) on this thread seems to perfectly illustrate that they indeed do not realise/know what they're arguing for....what I see are non-coherent and sometimes even contradictory arguments.
  25. It's not bad
    hapivibe wrote : "This web site is unbelievably passionate and detailed to the tune that it comes across as believing that global warming is the biggest threat facing humanity. Where is the evidence for this? I know it's a threat but is it definitely, beyond doubt the biggest threat? I would hate all this effort to go to waste if we realised too late that overconsumption, for example is the biggest threat and the focus on global warming means we are taking our eye off the ball. Is the biggest threat not over consumption? Should we all be debating about how to consume less and do more to change things for the better?" Global warming is a threat alongside and above all the other causes you seem to be trying to emphasise as greater threats (without any evidence so far). I have already given you examples of how AGW is connected with the rainforest and fishing, and it is also linked to availability of drinking water, coastal habitation, agriculture, etc., etc. Each on its own is a serious problem but AGW has detrimental effects on all of them. Surely that warrants special attention, since it's mitigation will have consequent benefits for all the concerns you have ? As for over-consumption, that will continue for as long as there are goods to consume and there are goods that can be made to be consumed. Again, AGW will have an effect on that because our carbon-based economies make over-consumption easier and cheaper to carry out - while polluting the atmosphere. Anyway, many people have many different opinions as to which threats are most important, and there's even a WIKIPIDIA page which lists them all. There is also a UN organisation (UN DESA) which tries to join-up reaction and help to all of them, including AGW. In other words, don't worry about us here (on a site pertaining to AGW) not spending too much time on all those other matters - there are many others out there who are. Perhaps that is where you should be addressing your questions ?
  26. Berényi Péter at 01:53 AM on 21 October 2010
    DMI and GISS Arctic Temperatures: Hide the Increase?
    #26 Ned at 00:31 AM on 21 October, 2010 Which seems like a more reasonable estimate for the temperature anomaly at the North Pole: a weighted average of temperature anomalies at other Arctic sites, or the average temperature anomaly for the whole rest of the world, the vast majority of which is outside the Arctic? Neither one, of course. The proper thing to do is to measure it directly. As you can see arctic temperature trends are quite different above land, sea ice and open sea. As there are all kinds of buoys drifting in the ice, air temperature above the Arctic ocean is actually measured. Why is it so hard to incorporate these data into the surface datasets? Or at least to use them as controls to validate eerie interpolation algorithms? Informatics anyone? There is even a buoy with a webcam deployed each year right at the pole, with its own temperature record.
  27. DMI and GISS Arctic Temperatures: Hide the Increase?
    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.Besides CBDunkerson claims the temperature hardly changes at all in the summertime in the high arctic so why should they be extrapolating from so far away where the land does get clear of snow and warm up.CBDunkerson has explained the mechanics of of how things work up there reasonably well.but those mechanics where the same 50 years ago and with more and more open water in that region supposedly getting warmer and warmer why does DMI show average cooling that is fairly pronounced in the summertime over the last 50 years....still waiting. thank you.
  28. Throwing Stones at the Greenhouse Effect
    The thought experiment on how an atmosphere without GHGs would affect (or otherwise) the Earth's temperature is interesting. Looking at an old post by Eli http://rabett.blogspot.com/2009/12/answer-to-puzzler-couple-of-days-ago.html it appears that the atmosphere sans GHGs is almost transparent to IR: "If there is no absorption at a particular frequency you are looking at emission from the surface." This implies to me that the atmosphere is far too thin to act as a blackbody and merely transmits surface emitted radiation. Ergo the surface temperature would average -15 or whatever the albedo corrected blackbody temperature would be. I'd guess that convection would smooth day/night differences to somehat less than would be the case for no atmosphere whatsoever. I look forward to those with more expertise than me critiquing this ! On a somewhat related point - the lapse rate is something I've never really understood properly. What would be the atmospheric temperature profile in this scenario?
  29. DMI and GISS Arctic Temperatures: Hide the Increase?
    FLansner at 23:58 PM on 20 October, 2010 Thank you for responding here. My sincere apologies for the typo on your name at the start of the article, I have corrected this. The "advanced" version does cover the question of the 1000km interpolation used by GISS in the high Arctic. This has been shown to be reasonable based on studies of the station data and NP and IABP drifting buoy data, temporary Ice Station/aircraft comparative studies, as well as the satellite data from AVHRR. The temperature anomalies are fairly homogenous over quite large distances in the ice covered Arctic. This is clearly not the case in the tropical regions where El Nino upwelling occurs, which is the example of land/ocean transition you use in your article to cast doubt on the use of interpolation. Obviously the tropical land/ocean and polar land ice/sea ice coastal regions are very different. DMI also suggest that transitions (bias) for example from ERA-40 to later higher resolution models could account for some of the Summer differences you have highlighted. These differences are clearly small compared with the average overall rising trend in the same DMI data. You may be interested in the more detailed comparison of GISS 12 month rolling average data gridded above 80N compared to DMI >80N rolling 365 day average data in the chart in the advanced version? The Arctic region presents challenges, and we should treat the data carefully, but as Ned says, we are far from wild guessing.
  30. Record snowfall disproves global warming
    Re: Roger A. Wehage (1,2) While I appreciate you using an example so near to my hometown (Marquette), I would be cautious in extrapolating local conditions from an area of complex weather patterns to the globe as a whole. Given the proximity of the Great Lakes to the Northern Jet Stream and the Arctic in general, weather here is highly variable. Even in conditions optimal for snow, if the wind direction is slightly out of alignment for any length of time, the big snow cannon in the lake doesn't hit full output. When winds are more stable, it is common to receive 4-8" of snow overnight...for many consecutive nights. The big dumps, however, come from system-generated snowfalls, not lake-effect. An "Alberta Clipper" dipping down out of the Canadian plains brings with it compressed isobars due to the deep low at the core. The high winds and energy sheer drives blizzards of 1-2 day duration, along with 18-24" snowfalls. The other source, more common now than when I was a boy in the '60s &'70s, is pressure systems moving up from the Gulf of Mexico. The enormous moisture levels they import, coupled with the colder air masses at surface levels and the tight rotation of the lows, results also in 18'24" snowfalls. The difference between them being the moisture contents of the snow they bring. Gulf-originating snowfalls tend to have moisture contents nearly double that of the Alberta Clippers. And as snowfall accumulations here are a function of moisture contents, total precipitation may be a better comparator for weather patterns here pre-1980 and post 1980. But thanks for the trip down memory lane. By the way, the record snowfalls up in the Copper Country (where Houghton is located) is 355" in the winter of 1978-1979. Marquette received over 320" the winter of 2001-2002. PS: Snow melts throughout the winter (through various warm spells), but spring onset happens well before May. This year, March had no snowfall recorded here and temps were in the 40s. Apart from a brief 2-day snowfall in early April, spring came in March this year, with April hitting 80s and May, 90s. Too hot. The Yooper
  31. Throwing Stones at the Greenhouse Effect
    hapivibe #80 Yes, but for the blow by blow you would have to go to the thread that argues for the contribution of industrial waste heat. If anything changed in my mind from that discussion, it was 1) an increase in CO2 simply redistributes energy vertically, such that it might be a tad warmer in lower altitudes at the cost of a cooler stratosphere, and 2) any additional energy that is accumulating has its source in industrial waste heat (this means the total amount of exothermic energy released since the beginning of the Industrial Revolution)... which is consistent with AGW's model that assumes forcings have only favored retention of radiative energy, so this extra energy (accounting wise) has had no outlet so that any extra energy has simply been accumulating, and 3) the effect is clearly observable in retreating glaciers, etc. I will admit that it may be hard to tell the difference as to what is going on given that heat is heat is heat, however the implications for CO2 are very different. 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.
    Moderator Response: No more discussion of waste heat on this thread. In the Search field type "waste heat."
  32. Throwing Stones at the Greenhouse Effect
    Thanks, CBD. (There's something wrong with that link but I gather this is what it's supposed to be: http://www.skepticalscience.com/Climate-Change-The-40-Year-Delay-Between-Cause-and-Effect.html )
  33. It's the sun
    CBD #701 KR #703 archiesteel #704 "So no, KR probably 'does not get' that flat forcing factors do not change the climate. Because they don't" Flat forcing is not 'zero' forcing CBD & KR. The numbers I presented show a F.Solar of about 0.4W/sq.m from the IPCC Fig 613 Chart which is also available in numerical form (worked elsewhere by kdkd)from AD1950 onward, and 0.1-0.2W/sq.m before that. A 'flat' 0.4W/sq.m integrated wrt time will give you a linearly increasing number of Joules/sq.m - the unit of energy. Energy is what you need to heat mass. Note the units of specific heat of water (or other mass)are Joules/kG-degC - NOT Watts/kG-degC Linearly rising energy in Joules will linearly raise the temperature of a given mass (without phase change). Hence rising temperatures with 'flat' non-zero forcing are quite consistent with the 'Temperature vs. Solar Activity chart on the Basic version of this thread' Add to that a 'theoretical' roughly linearly rising forcing F.CO2 and you will get a squared function non-linear rising curve of energy wrt time. This is Grade 11 maths. What counts is the sum of and proportions of the energy added by the two sources. I calculated previously that on the IPCC data the energy proportions were about 55/45 CO2GHG/Solar since AD1750. The question then becomes how reliable and accurate are these forcings. We have some proxy and direct measurement for TSI and F.Solar. KR: "Now, if there's a linear offset in TSI measures (direct or using sunspots as proxies), as you have argued, there would be a difference in slope between measured TSI responses and temperature over the entire temperature/TSI record, not just the last 60 years" Wrong - see above. Non-zero constant forcing produces linearly rising temperature for a given mass. How long do we have Satellite TSI data? - since 1978? Again high precision - low accuracy. Will tell you the deltas within an individual satellite record - maybe spliced together between satellites (maybe not too) - but no good for accurately measuring absolute TSI (SORCE TIMS is a good example). Archiesteel - don't know what your technical training or background is - but kdkd will tell you that it is risky to call me on the sums.
  34. Do critics of the hockey stick realise what they're arguing for?
    chriscanaris writes: Ned @ 27: 'It's not reasonable to assume a high value for climate sensitivity in order to get a large MWP, while also assuming a low value for climate sensitivity in order to minimize the effect of AGW.' With respect, Ned, I'm not making any assumptions. I'm simply looking at the range of possibilities which flow from the AR4. On one scenario, clouds may exert a negative feedback greater than the positive feedback of CO2. Is this so? At this stage, we can only guess. I'm afraid I must not be explaining my argument well. You're free consider scenarios where negative feedbacks from clouds are larger than expected. The logical consequence of that is that those scenarios would presumably have a climate sensitivity on the low end of the range (< 3C). But the point is that under such scenarios it would be hard to get a warm MWP or a cold LIA. (If you make the negative feedbacks strong enough, it would be hard to get any glacial/interglacial cycles.) The problem arises when somebody (not necessarily you, just a hypothetical commenter) claims that the MPW/LIA variance was large and simultaneously claims that climate sensitivity is low and/or there are large negative feedbacks from clouds or whatever. This is the climate-skeptic equivalent of trying to have one's cake and eat it too.
  35. Increasing southern sea ice: a basic rebuttal
    Redirecting HR to another page when the article makes specific reference to land ice seems a touch pedantic. However, I don't dispute the GRACE data underpinning these assertions other than to note that ice loss may be proceeding at a steady pace rather than accelerating as per Velicogna (see here). However, ice loss is ice loss unless we come up with evidence of a major flaw in the GRACE methodology. At the same time, satellite data suggests that Antarctic waters are cooling, not warming. Trenberth's missing heat notwithstanding, I find this counterintuitive. Perhaps the hole in the ozone layer is still doing its work - Sigmond and Fyfe (2010) comprises a model rather than the last word on the subject.
  36. Throwing Stones at the Greenhouse Effect
    VoxRat #81: See this article. Basically, while some temperature feedbacks (e.g. ice albedo) would take centuries to fully materialize most of the warming for a given CO2 level would be evident within about 40 years.
  37. Berényi Péter at 00:41 AM on 21 October 2010
    Do critics of the hockey stick realise what they're arguing for?
    #63 skywatcher at 23:43 PM on 20 October, 2010 the large excursion that is not represented in direct measurement data is still present when smoothed You'd better check your facts. Tellus B Volume 57, Issue 4, pages 351–355, September 2005 DOI: 10.1111/j.1600-0889.2005.00154.x Atmospheric CO2 during the 13th century AD: reconciliation of data from ice core measurements and stomatal frequency analysis THOMAS B. Van HOOF, KARSTEN A. KASPERS, FRIEDERIKE WAGNER, RODERIK S. W. Van De WAL, WOLFRAM M. KÜRSCHNER & HENK VISSCHER "A significant CO2 change during the 13th century AD is evident from direct measurements of CO2 in gas enclosures in the Antarctic ice core D47 as well as from stomatal frequency analysis of fossil oak leaves. The independent detection of this CO2 shift, and the good agreement between the different records, provides persuasive evidence for the reality of this event."
  38. DMI and GISS Arctic Temperatures: Hide the Increase?
    Why dont they mark the ice sheet covered area GREY and stop wild guessing? If you're calculating a global mean temperature anomaly, and you leave the high-latitude Arctic out of your analysis, you're effectively assuming that the Arctic has the same temperature anomaly as the rest of the globe. Which seems like a more reasonable estimate for the temperature anomaly at the North Pole: a weighted average of temperature anomalies at other Arctic sites, or the average temperature anomaly for the whole rest of the world, the vast majority of which is outside the Arctic? Incidentally, interpolation is a well defined mathematical process, and the GISS algorithm for doing this has been replicated nicely by others (e.g., Clear Climate Code). Let's reserve the term "wild guessing" for cases where people are ... actually guessing.
  39. Throwing Stones at the Greenhouse Effect
    I have a question I think is reasonably relevant to this post. (If not, maybe someone can direct me to a more relevant one.) Is there any published data or theory on how long it takes for the global climate to equilibrate after an increment in [CO2]? To put it another way: can we assume that if we stabilized the the [CO2] today at the current level, that temperatures will have stabilized by, say, next year? Next decade?
  40. Increasing southern sea ice: a basic rebuttal
    HR #8: The same Duncan Wingham you MIS-cite here has been at the forefront of some of the subsequent studies (e.g. Pine Island Glacier) which have shown the coastal mass loss that Jeff talks about. As the lead scientist on the Cryosat-II mission he will also likely play an important part in figuring out what is going on with the Antarctic sea ice... as well as finally nailing down the volume losses for the Arctic sea ice, Greenland, and Antarctica.
  41. DMI and GISS Arctic Temperatures: Hide the Increase?
    - And im sooo sorry for my Danglish, but maybe you guts has the format to figure out the message anyway? K.R. Frank Lansner ...My name has been spelled wrong 2 times in this skepticalscience writing, I think I can cope :-)
  42. DMI and GISS Arctic Temperatures: Hide the Increase?
    Hi John and company :-) Simple question: When everyone (?) can see, that its rather risky business for GISS to guess what temperatures are in the ice sheet near the North pole just using land temperatures over 1000 km away - why do GISS do this? Why dont they mark the ice sheet covered area GREY and stop wild guessing? K.R. Frank Lansner
  43. It's not bad
    This web site is unbelievably passionate and detailed to the tune that it comes across as believing that global warming is the biggest threat facing humanity. Where is the evidence for this? I know it's a threat but is it definitely, beyond doubt the biggest threat? I would hate all this effort to go to waste if we realised too late that overconsumption, for example is the biggest threat and the focus on global warming means we are taking our eye off the ball. Is the biggest threat not over consumption? Should we all be debating about how to consume less and do more to change things for the better? Thanks JMurphy, I know what this web site is about and I am still trying to figure out if the activity is in or out of proportion to the threat posed by GW. As I said in earlier comments, perhaps taking more action is better than sitting at a computer typing about it. Perhaps the biggest threat facing humanity is apathy - I don't know.
  44. Do critics of the hockey stick realise what they're arguing for?
    BP - why should you trust that obscure paper, which relies entirely on a proxy (and which has been almost exclusively cited only by it's own authors and those who wish to promote a certain point of view) rather than papers that rely on the actual measurements? Did it ever cross your mind that those results could be incorrect? I'm not suggesting they i>are incorrect, just suggesting that a single paper evaluating data from a proxy necessarily has more errors than multiple papers relying on direct measurements... The key here is the large excursion that is not represented in direct measurement data is still present when smoothed, suggesting that the stomatal data may be in error here.
  45. DMI and GISS Arctic Temperatures: Hide the Increase?
    Adrian: Fill a pot with ice cubes. Add water. Put a thermometer on top of the ice and water. Put the pot on the stove. Turn the stove on. Watch the thermometer. So long as the ice remains the surface temperature reading will be right about 0 C. All the heat being generated by the stove goes into melting the ice. Exactly the same thing is happening in the Arctic. Until that ice is gone the temperature will stay right around 0 C. In the Arctic it gets a bit warmer (1 C) because wind and currents can move the ice around and cause areas of open water, but those are minor weather fluctuations with no statistically significant trend. This can be clearly seen in Figure 2 above... the red annual trend in the DMI data is clearly increasing while the green summer trend is nearly flat. The enhanced greenhouse effect is present year round, but in the summer the extra energy it causes has not yet melted away the ice in the small area covered by the DMI data. Do the ice in the pot experiment. It should help you understand that anyone claiming that lack of warming over an ice covered ocean contradicts AGW is lying to you. So long as satellites show that area covered by ice the temperature CAN'T go up... but that doesn't mean there isn't more heat - any more than the lack of temperature increase at the water surface of the pot means that the stove isn't generating heat. It should also be pointed out that the DMI results are "extrapolated" just like the GISS results... just from a smaller/more geographically concentrated set of measurements.
  46. It's not bad
    happivibe wrote : "What I am saying is the sea runing out of fish by overfishing may be a more pressing issue than AGW/CC as it may affect humans more and first. Don't you think this is equally as big an issue? Do you think overfishing receives less coverage even though it is just as important as AGW/CC. Maybe it is more important. Do you know? Does anyone know? Has this been raised before on this site - does this mean it is being overshadowed?" Last thing first : The goal of this site is stated to be "to explain what peer reviewed science has to say about global warming." If you want to know more about over-fishing, there are more detailed sites available, like OverFishing.org, the UN's FAO (SOFIA), and Greenpeace. There is also this study, which shows fish size decreasing, in relation to global warming - perhaps related to the smaller fish sizes being noticed in connection with what is normally regarded as being solely due to overfishing : Global warming benefits the small in aquatic ecosystems But, even here on Skeptical Science, there is a link given on this thread which will take you to ClimateShifts.org, who "cover a range of other threats like overfishing and pollution and other aspects of marine biology and coral reef science". So, not ignored or lessened in importance or overshadowed, really : just the nature of this site, so to speak.
  47. Do critics of the hockey stick realise what they're arguing for?
    chriscanaris - you keep suggesting clouds might have a large negative feedback, and that therefore the climate sensitivity would therefore be lower. But I don't see you reconciling that with the evidence presented in Knutti and Hegerl for both observational and modelled equilibrium sensitivity being rather similar. As angliss put very well, we know from palaeoclimatic data the value of the equilibrium sensitivity (within it's error constraints, which seem to range from scary to terrifying), and this necessarily includes clouds, therefore all that can change is just how we get there. The only impact clouds can have is some temporary alteration of the manner in which we get from our present climate to the new equilibrium climate. It seems pretty unlikely, given a total lack of evidence to the contrary, that the trajectory from our lower equilibrioum temperature to our higher equilibrium temperature would involve an initial negative or very low slope excursion from that trajectory (which would then have to accelerate to make up the difference in order to reach the new, higher, equilibrium temperature).
  48. Do critics of the hockey stick realise what they're arguing for?
    kdkd @ 57: What false premise? I didn't create the numbers - I merely quoted AR4. I was actually surprised by the data - they don't get much prominence in most AGW sites though I'm aware Roy Spencer talks a lot about this stuff. I've never delved into his site barring a very occasional glance but these data suggest I ought to take him more seriously. 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. Such language is redolent of heresy hunting. Facts are facts and numbers are numbers. As scientifically minded folk, we are not bound by articles of faith nor should we be wary of doctrinal transgressions. I come to this site for science and not for spiritual sustenance. For the latter, I go to church :-).
  49. Berényi Péter at 23:24 PM on 20 October 2010
    Do critics of the hockey stick realise what they're arguing for?
    Posted by John Cook on Tuesday, 19 October, 2010 at 18:07 PM If for some reason, temperatures over the Medieval Warm Period turn out to be warmer than previously thought, this means climate sensitivity is actually greater than 3°C. The climate response to CO2 forcing will be even greater than expected. So to argue for a warmer Medieval Warm Period is to argue for greater climate sensitivity and greater future warming due to human CO2 emissions. Houston, we've had a problem. Reconstruction of climate forcing in Crowley 2000 may be bogus. He assumes an essentially zero CO2 radiative forcing prior to 1600 AD and a very small one before the 20th century. However, in reality it may not be the case. This paper uses density of stomata on fossil leaves, tiny pores doing gas exchange to reconstruct historic CO2 levels. Geology, 01/2005, vol. 33, Issue 1, p.33 DOI: 10.1130/G20941.1 Atmospheric CO2 fluctuations during the last millennium reconstructed by stomatal frequency analysis of Tsuga heterophylla needles Kouwenberg, Lenny; Wagner, Rike; Kürschner, Wolfram & Visscher, Henk Long term average of preindustrial CO2 might have been pretty stable around 290 ppmv, however, they say there were large century scale fluctuations which are invisible in the ice core record due to late bubble enclosure time in the firn-ice transition zone (and diffusion in ice proper, I must add). The most robust feature of their millennial CO2 analysis is a decline after 1000 AD followed by a sharp increase during the 13th century. After that time CO2 forcing based on their data matches Crowley 2000 reasonably well, but for the MWP there is a huge mismatch. The excess warming goes right against changes in forcing and there is no way solar forcing could compensate for it. Strong negative forcing (~ -1 W/m2) between 1160-1180 went with higher than average temperatures while a 1 W/m2 increase of CO2 forcing during the next century is accompanied by steadily decreasing temperatures. A multidecadal transient solar burst of such magnitude and at just the right time is out of the question. Therefore most of the medieval warming must have been unforced variation. Climate can do that, for a strong random walk component with red noise statistics is always present. However, as soon as the possibility of century scale unforced changes is acknowledged, the entire conceptual framework your climate sensitivity calculations are based on collapses.
  50. Throwing Stones at the Greenhouse Effect
    #75 Have you said how you believe warming is happening then?

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