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Comments 125401 to 125450:

  1. Skeptical Science now an iPhone app
    Riccardo, FYI the last shift to a cooling PDO regime took place circa 1945, the shift in 1977 was to a warming regime. Cheers, :)
  2. It's cooling
    Doug Cannon, the fact that we still cannot identify the details of how heat goes around in the climate system in the short term (four years is not that much) should not rise any alarm. Altough some phenomena show a (sort of) cyclic behaviour they all average out in the long run. For example, look here for the PDO. In the end, they could at best justify some "noise" in the trend; no overall energy balance has been altered and these "oscillation" can just move around the heat through the climate system. Indeed, this is what Trenberth refers to in the stolen email, look at the other things he said.
  3. It's cooling
    Riccardo Perhaps my reference to Latif implied I was focusing on a relationship between short term and long term variability. There may be one but that wasn't my intention. But trying to say too much in too few words may have caused confusion. I referred to the "past few years". Being more specific, the GRL data at issue is from 2005 up to 2009. When Trenberth said "...we can't account for the lack of warming at the moment and it is a travesty that we can't" he was referring to a similar period. He wasn't talking about a seasonal or yearly basis. He has subsequently made it clear that, his intent was to say that with todays technology we should be able to find the effect of the increased trapped heat, but we haven't yet been able to. (My reading of his meaning is that we will be able to, given all the effort being put on it.) I've not concluded that "we don't understand enough about the natural forcing elements" as you suggest. The point I was making is that Latif has made that conclusion; specifically about "internal decadal variability". He was talking about the North Atlantic in that particular case. In fact he is "lobbying" for a research program to be able to predict that variability. He wasn't referring to El Nino and neither was I. (I don't think you mean to say that we know enough about all the natural forcing elements except for short term phenomena like El Nino. But your comment seems to imply that.) So, to belabor the "arbitary mixing" a bit further: (a)the lack of warming that Latif suspects is due to natural forcing that we need to understand better and.. (b)Trenberth's frustration with our inability to find the warming that has to be there based on the absorbed/reflected radiation imbalance... are connected in a way. They relate to the same earth during the same period of time. It doesn't seem to arbitrary to wonder if the long term cycle in (a) is in a phase of it's cycle that affects the warming in (b). I shouldn't be so presumptious to think that I know the answer. I don't. But I reserve the right to wonder if understanding the decadal oscillations of the oceans and an improved ability to measure the heat content of the oceans would lead us to an answer.
  4. Skeptical Science now an iPhone app
    Might have snow in the Aussie Alps this Sunday (my snowboard is itching). I'm waiting for an Andrew Bolt (check him out SS, he's a nutbag, writes for the Herald Sun) article claiming that coz it's snowing in Jan, GW/AGW is a sham!
  5. Skeptical Science now an iPhone app
    shawnhet, 0.4 °C between the last two PDO shifts (1977 and 1998) means roghly 0.2 °C/decade of anthropogeic warming. I bet many others will agree.
  6. Skeptical Science now an iPhone app
    Chris, as a non-scientist, can I pass on my appreciation of your clear, informed posts on this site. Thanks to John Cook also for providing such a valuable resource among the slosh of irrational and ignorant nonsense around the net.
  7. Skeptical Science now an iPhone app
    Here is the Mann paper in question: Observed and simulated multidecadal variability in the Northern Hemisphere T. L. Delworth1 and M. E. Mann2 Abstract  Analyses of proxy based reconstructions of surface temperatures during the past 330 years show the existence of a distinct oscillatory mode of variability with an approximate time scale of 70 years. This variability is also seen in instrumental records, although the oscillatory nature of the variability is difficult to assess due to the short length of the instrumental record. The spatial pattern of this variability is hemispheric or perhaps even global in scale, but with particular emphasis on the Atlantic region. Independent analyses of multicentury integrations of two versions of the GFDL coupled atmosphere-ocean model also show the existence of distinct multidecadal variability in the North Atlantic region which resembles the observed pattern. The model variability involves fluctuations in the intensity of the thermohaline circulation in the North Atlantic. It is our intent here to provide a direct comparison of the observed variability to that simulated in a coupled ocean-atmosphere model, making use of both existing instrumental analyses and newly available proxy based multi-century surface temperature estimates. The analyses demonstrate a substantial agreement between the simulated and observed patterns of multidecadal variability in sea surface temperature (SST) over the North Atlantic. There is much less agreement between the model and observations for sea level pressure. Seasonal analyses of the variability demonstrate that for both the model and observations SST appears to be the primary carrier of the multidecadal signal. http://www.springerlink.com/content/ght24jjem312qnh0/ Ned:"When I asked you for a physical justification of PDO as a "substantial forcing" of global climate, you said that Michael Mann's proxy studies show a "60 [] year cycle" that's "consistent with" the PDO." Well, frankly, the broad components of a physical mechanism isn't that hard to come by. PDO can affect ocean temps, precipitation, air pressure and (probably) cloudiness, and causes wide shifts in some biological markers as well. some combination of these factors could easily have climate effects. "Second, you're blurring the distinction between correlation and causation. Suggesting that the PDO is a "substantial forcing" wrt global climate is not the same as suggesting that it's "correlated with" (or "consistent with" as you wrote) global climate." I'm not sure what point you are trying to make here, but you asked for evidence that it was a substantial forcing and I pointed you in what was IMO the right direction. "Thirdly, PDO ain't ENSO. How many "sixty year cycles" have we been through since the start of the global mean temp record?" See Mann above. "With all due respect, as far as I can tell, your "skepticism" is purely unidirectional. When it comes to claims for the existence of anthropogenic climate change, you're exceptionally skeptical. When it comes to claims that might question the existence of anthropogenic climate change, the skepticism all disappears. A true skeptic wouldn't promote the idea that a mysterious and poorly understood "PDO" is a substantial forcing of climate without strong evidence e.g. a clear physical basis or very strong empirical analysis." It seems to me that someone who was a skeptic would look at the good correlation btw PDO and climate and say that there is a pretty good chance that whatever causes changes in the PDO index can also cause changes climate. He would not hand wave about it being mysterious or poorly understood, he would go about seeing what he can predict about climate using that idea. For the record, I have no disagreement with anthro warming effects, my disagreement is with the proposed magnitude of the anthro effect. On John Cook's PDO correlation page, he states that when the PDO last shifted towards cold as it seems to now, temps were 0.4C cooler. I don't have an issue with ascribing that entire 0.4C to anthro causes. Cheers, :)
  8. Skeptical Science now an iPhone app
    I think you're misunderstanding or misinterpreting Mann’s work shawnhet. Let’s look at the question of the role of natural (ocean) “oscillations” to long term surface temperature trends from the point of view of Mann’s studies (focussing on relevant work from the last few years, since this is more likely to represent current scientific knowledge and Mann’s current views). I’d say the following points are supported by the scientific evidence; they’re all from Mann’s recent analyses. 1. There’s no doubt that historical measures/proxies of ocean indices (Nino/ENSO; PDO, NAO etc), shows that these indices undergo fluctuations that are associated at the first level with local changes in sea surface temperature (SST) (and at secondary levels with various local effects experienced on inhabited land surfaces, like temperature variations, rainfall and drought levels etc.). 2. Mann has published many examples of these. The general conclusions might be summarized as: a. These indices show variability but are neither periodic in the manner that might be meant by the term “oscillation” [see (b.)], nor do they contribute to long term temperature trends. Thus in Mann and Emanuel (2006) and Sabatelli and Mann (2007), measured and proxy values of El Nino and NAO indices expending back into the 19th century are presented and discussed. These don’t show any regular variation or trend; they’re fluctuations around a mean value. Might they contribute to long term temperature trends in the manner that you and Pielke suggest? Mann doesn’t think so [Mann and Emanuel (2006)]:
    “In short, there is no evidence that a natural climate oscillation contributes to long-term tropical North Atlantic SST variations.”
    b. What is the origin of ocean fluctuations? Might they be internal elements of the climate system that can periodically “pump up” (and cool down) the surface temperature in the manner you suggest? Or might they be responses to variations in external forcings? Mann’s analyses supports the latter interpretation. In his recent review of climate over the last 2000 years (Mann, 2007), he ascribes long term fluctuations in various ocean indices as the response to external forcings:
    “ The substantial cooling in large parts of Europe at the height of the conventionally defined European LIA during the late seventeenth and early eighteenth century appear to be related in large part to long-term variations in the NAO, discussed above, which in turn appear to have been associated (Figure 8) with a large-scale dynamical response of the climate system to natural radiative forcing by explosive volcanic activity (Shindell et al. 2003, 2004) and solar output (Shindell et al. 2001, 2003).”
    Likewise Mann ascribes variations in ENSO as a response to variations in external (volcanic/solar) forcing. In other words (according to Mann), changes in ocean fluctuations (that some seem to want to ascribe as internal “oscillations” of the climate system), likely aren’t internal oscillations at all, but responses to external forcing. c. Are changes in local SST as measured by various ocean “indices”, indications of global scale temperature variations? Mann doesn’t think so. In his recent review (Mann, 2007), he presents evidence, for example, that during the MWP and LIA, the warming (MWP) and cooling (LIA) in the high N latitudes, were associated with cooling (MWP) and warming (LIA) in the tropical Pacific:
    “The conclusion that the tropical Pacific appears to have been in a cold La Niña–like state during the MWP and a warm El Niño–like state during the LIA implies that surface temperature changes in the tropical Pacific may have offset extratropical temperature changes (where these periods were relatively warm and cold respectively), reducing the amplitude of global or hemispheric-mean temperature changes from what would be deduced based on extratropical proxy data alone.”
    In summary, Mann’s published analyses support the conclusions that: (i) Ocean SST fluctuations as indicated by various ocean “indices” don’t contribute to long term temperature trends in the manner you and Pielke suggest. (ii) Rather than being internal “oscillations” of the climate system that have significant “oscillatory” contributions to global surface temperature trends, local short and long term ocean fluctuations are likely largely a response to external forcing (solar, volcanic, and no doubt to anthropogenic greenhouse and aerosol forcing). (iii) When considered on a global scale local ocean fluctuations tend to cancel (as one might expect from the redistribution of ocean heat either due to internal or forced effects), and so these indices don’t indicate much of a contribution to global scale temperature trends. This is all pretty much consistent with the work by Tsonis, Swanson, Latif and Keenleyside cited in papers in my post above (see post #16), that ocean variations (in heat distribution) might modulate the surface temperature, but on the long (multidecadal scale) relevant to predicting the effects of massive enhancement of greenhouse gas concentrations on global surface temperature, these average to something close to zero, and thus (as Mann states explicitly) don’t have much of an effect on the temperature trend arising from an external forcing (like massive enhancement of greenhouse gas concentrations). M. E. Mann and K. A. Emanuel (2006) Atlantic Hurricane Trends Linked to Climate Change EOS 87, doi:10.1029/2006EO240001 M. E. Mann (2007) Climate Over the Past Two Millennia Annual Review of Earth and Planetary Sciences 35: 111-136 Sabbatelli TA and Mann ME (2007) The influence of climate state variables on Atlantic Tropical Cyclone occurrence rates J. Geophys. Res. 112, art #D17114
  9. Skeptical Science now an iPhone app
    "Well, you could look up the papers of that rabid anti-warmer Michael Mann whose tree-ring proxy studies have found a 60 or year cycle in temps consistent with the PDO ;)" You might want to run by your hypothesis by Dr. Mann, rather than assuming your interpretation of his work is correct. "IAC, as I have said, pretty good evidence is plotting the correlation of temps vs. PDO." Science is not based on finding correlations. There's a correlation between the Dow Jones and global mean temperature as well. Global warming causation solved! "You may want to pay particular attention to the inflection points where a period with a rising temperature trend shifts to a falling one and vice versa." PDO positive phases are associated with somewhat more and stronger el Ninos, and negative phases with somewhat more and stronger la Ninas and less el Ninos. So affect on the short-term trend (few years of transition between each phase) might be observed. RealClimate has a nice post on the topic that takes apart Roy Spencer's attempt to assign a more significant portion of warming to natural cycles. http://www.realclimate.org/index.php/archives/2008/05/how-to-cook-a-graph-in-three-easy-lessons/
  10. Skeptical Science now an iPhone app
    Shawnhet, you wrote "I think that you'd find that giving the PDO index a substantial forcing value will improve the fit quite a bit btw forcing and temp." When I asked you for a physical justification of PDO as a "substantial forcing" of global climate, you said that Michael Mann's proxy studies show a "60 [] year cycle" that's "consistent with" the PDO. That's not very helpful, IMHO. First, I strongly doubt that Mann would agree with your characterization that PDO is a "substantial forcing". Second, you're blurring the distinction between correlation and causation. Suggesting that the PDO is a "substantial forcing" wrt global climate is not the same as suggesting that it's "correlated with" (or "consistent with" as you wrote) global climate. Thirdly, PDO ain't ENSO. How many "sixty year cycles" have we been through since the start of the global mean temp record? With all due respect, as far as I can tell, your "skepticism" is purely unidirectional. When it comes to claims for the existence of anthropogenic climate change, you're exceptionally skeptical. When it comes to claims that might question the existence of anthropogenic climate change, the skepticism all disappears. A true skeptic wouldn't promote the idea that a mysterious and poorly understood "PDO" is a substantial forcing of climate without strong evidence e.g. a clear physical basis or very strong empirical analysis.
  11. It's cooling
    Doug Cannon, in your comment i found two different concepts mixed arbitrarly, short versus long term variability. If, with Tremberth, we can't say where the heat has gone on a sesonal or yearly basis, the same does not apply to longer periods. You are not allowed to do this extrapolation. Even worst, you cannot conclude that "we don't understand enough about the natural forcing elements." unless by "enough" you mean, for example, the timing of next El Nino and its strength or the like. Skepticism is definitely healthy and is at the very core of the progresses of science; misinterprenting or disregarding what is known is not.
  12. Skeptical Science now an iPhone app
    Ned:Is there any physical basis for this? Do you have citations to any papers discussing why "PDO" should represent a large forcing on global climate Well, you could look up the papers of that rabid anti-warmer Michael Mann whose tree-ring proxy studies have found a 60 or year cycle in temps consistent with the PDO ;) "PDO isn't really an "oscillation", it's just a numerical index that flips back and forth at irregular intervals and that doesn't seem to have a strong physical manifestation (compared to, say, ENSO). If we're going to posit that it plays an important role in modulating global climate, I for one would like to see some convincing evidence." ??? It flips back and forth, but isn't an oscillation? IAC, as I have said, pretty good evidence is plotting the correlation of temps vs. PDO. You may want to pay particular attention to the inflection points where a period with a rising temperature trend shifts to a falling one and vice versa. Ray Ladbury, meet the physics of turbulent systems, you two haven't met at all. Cheers, :)
  13. It's cooling
    "How do we find out what's happened from 2003 until now? Unfortunately, there is no time series (that I know of) of the planet's total heat content up to present time." Information from Sydney Levitus, Geophysical Research Letters, 2009 shows that for past few years the heat content of the oceans has not been rising (rising sea level in that period can be accounted for by runoff; not temperature.) This is what Trenberth and Latif have been referring to. Basically the books don't balance. I appreciate that not everyone places a high faith in satellite measurements, but they all say that the earth has been absorbing more energy during that time. If so, it has to show up somewhere and the mystery is that it hasn't. Latif seems to think it's in the oceans. Probably more sensible than any other alternative. But he acknowledges that we don't understand enough about the natural forcing elements. To me this also raises serious doubts that we really can get a true average measurement of ocean heat content. To those of us who believe that scientific skepticism is healthy, it would seem to be a mistake to conclude that we know the earths total heat content is still rising without looking for alternative answers to the mystery.
    Response: Levitus' data covers only the upper ocean heat which shows more variability than the total ocean heat. Measurements of ocean heat down to 2000 metres deep show that the oceans are still accumulating heat.
  14. Skeptical Science now an iPhone app
    shawnhet writes: "I think that you'd find that giving the PDO index a substantial forcing value will improve the fit quite a bit btw forcing and temp." Is there any physical basis for this? Do you have citations to any papers discussing why "PDO" should represent a large forcing on global climate? IMHO it's not uncommon for people who don't want to accept the idea of anthropogenic climate change to fall back on rather vague and unscientific suggestions about "oscillations" (be they PDO, AMO, or AO). PDO isn't really an "oscillation", it's just a numerical index that flips back and forth at irregular intervals and that doesn't seem to have a strong physical manifestation (compared to, say, ENSO). If we're going to posit that it plays an important role in modulating global climate, I for one would like to see some convincing evidence.
  15. Why does CO2 lag temperature?
    I could not find anywhere in the post the claim that CO2 in the *only* feedback ... probably thingadonta missed the title of this post.
  16. Why does CO2 lag temperature?
    RE$ thingadonta Care to back it up with the actual papers that support your hypothesis?
  17. Why does CO2 lag temperature?
    "the usual 'insertion' of greenhouse gas forcings favoured by some academics", and, um, favoured by physics.
  18. Why does CO2 lag temperature?
    "•Deglaciation is not initiated by CO2 but by orbital cycles •CO2 amplifies the warming which cannot be explained by orbital cycles alone •CO2 spreads warming throughout the planet". Inconvenient fact No. 1, not mentioned. On any normal day which warms after a cool night/period, cloud cover decreases, which amplifies the warming substantially. None of the papers you refer to mention this simple fact. If the earth warms, cloud cover, especially in temperate zones, decreases. There are numerous papers on this subject. It's therefore not all c02 amplifying and spreading the warming after ice ages. Inconvenient fact No.2, not mentioned. When ice cover decreases after an ice age, the amount of reflected sunlight substantially decreases; this happens in a relatively short time once the ice cover thins from widespread but thin cover over Eurasia and North America early in the warming trend, to vast areas which rapidly thin to next to nothing, causing a tipping point reduction in reflected sunlight over large areas, further reduced cloud cover and amplifying the warming trend. Inconvenient Fact No.3, not mentioned. Oceans take many centuries/thousands of years to warm after an ice age. Once ocean current patterns begin to change, also associated with ice break ups, the redistribution of heat leads to relatively rapid earth warming. Such factors as above can account for amplifying warming at the end of the ice age without the usual 'insertion' of greenhouse gas forcings favoured by some academics. C02 and other greenhouse gases are not the only driver of warming after an ice age as you fail to mention; apart from orbital changes, other natural earth factors than a small rise in greenhouse gases substanitally amplify the warming.
  19. Models are unreliable
    By the way, have you read this RC post?: http://www.realclimate.org/index.php/archives/2009/12/updates-to-model-data-comparisons/ It seems that Hansen's 1988 model is indeed (slightly) overestimating the observed warming trend: "the old GISS model had a climate sensitivity that was a little higher (4.2ºC for a doubling of CO2) than the current best estimate (~3ºC) [...] it seems that the Hansen et al ‘B’ projection is likely running a little warm compared to the real world". Hansen's model shows 0.26 +/-0.05 ºC/dec, whereas the real world shows 0.19 +/-0.05 ºC/dec. However, for this comparison, as well as the climate sensitivity, it must be taken into account that "Scenario B in that paper is running a little high compared with the actual forcings growth (by about 10%)". AR4 models give 0.21 +/-0.16 ºC/dec. Anyway, this was already highlighted by Hansen et al 2006: "Close agreement of observed temperature change with simulations for the most realistic climate forcing (scenario B) is accidental, given the large unforced variability in both model and real world. Indeed, moderate overestimate of global warming is likely because the sensitivity of the model used (12), 4.2°C for doubled CO2, is larger than our current estimate for actual climate sensitivity, which is 3+/-1°C for doubledCO2, based mainly on paleoclimate data"
  20. Models are unreliable
    A bit nitpicking on my side, John, but in the "Further reading" section you say "Tamino compares IPCC AR4 model results[...] versus observations", wherheas the picture is his Fig. 3: "compare the GISS data to the models listed in IPCC AR4 chapter 8 except for the CCCMA models". The one that reflects all the IPCC models is his Fig. 1. Both graphs are very similar, indeed. Cheers!
    Response: Thanks for the feedback, I've updated the wording to reflect this.
  21. Skeptical Science now an iPhone app
    John:"Response: Some of the later comments address this issue thoroughly but for the record, we look at the correlation between the PDO and global temperature here..." This is an interesting page that I hadn't seen before. However, it would've been much better if you'd posted the PDO index on the same graph as the forcing vs. temp. I think that you'd find that giving the PDO index a substantial forcing value will improve the fit quite a bit btw forcing and temp. Cheers, :)
  22. Skeptical Science now an iPhone app
    Macha writes: I don't see the scientific evidence that shows how one molecule (CO2) per ~3,000 molecules of air can cause a catastrophy, less so when its 1 in ~80,000 (only the manmade CO2). [...] CO2 is a minor bit-player NOT a driver. We've increased the concentration of CO2 in the atmosphere by over 100 ppm, so that's 1 part in 10,000 not "1 part in ~80,000" and of course it's increasing every year. More to the point, small quantities of stuff can have large effects. One mg arsenic per 30,000 mg body mass will have a 50% probability of killing the organism that ingests it. Finally, there's plenty of evidence that CO2 in the atmosphere warms the planet and that adding CO2 will increase the global mean temperature. See other recent posts here: How do we know CO2 is causing warming? Are humans too insignificant to affect global climate? CO2 is not the only driver of climate If you browse the archives of this site, you'll find lots of good summaries of the peer-reviewed literature on this and other topics. Regards, Ned
  23. Skeptical Science now an iPhone app
    Macha, CO2 is a driver, this is well understood. Also, you need to consider what we did to the stratospheric ozone above Antarctica by producing CFCs which are measured in parts per trillion, versus parts per million for CO2. Not a perfect analogy, but it at least addresses the myth that CO2 concentrations are "so low that they can have no impact". I do agree with you that that climate models need to deal with convection better. That is touch, b/c one need a horizontal grid spacing <4 km, ideally <2 km to have explicit convection in a model. Very recently this has become possible for for some operational weather forecasting models run over sub-domains, but we are not even close for AOGCMs. The AOGCM runs do allow for variable insolation. Leo G, I used to think that Pielke Snr was not a denialist, but his very peculiar behaviour of late has my alarm bells going off-- just peruse the posts on Pielke Jnr's blog, some of them are outright bizarre. So his son is clearly a lost cause. I still hold out some hope for his dad (I have one of his textbooks on my shelf here), it would be sad to lose Pielke Snr to the dark side. Yes, land use change can have important impacts on the mesoscale surface energy budget, but those changes (from deforestation for example, or other land use changes) do not explain what is going on globally in the mid trop and stratosphere, or the polar regions. It seems to be that the Pielkes are trying to find a silver bullet to absolve us from doing any thing and to rationalise maintaining the status quo; that or they are trying to muddy the waters for the same purpose.
  24. Hockey sticks, 'unprecedented warming' and past climate change
    It's not. You may want the empirical evidence or a more detailed explanation. Or both.
  25. Svensmark and Friis-Christensen rebut Lockwood's solar paper
    I'm new to all this - so still undecided, weighing up the arguments, trying to wrap my head around the science. So help me out here... As i undersatnd it, Svensmark was saying that the Heliosphere has a cycle - it expands and contracts just outside the solar system acting as a filter for cosmic radiation - when it is strong not much CR makes it to the lower atmosphere and when it is weak a lot does make it. this CR acts a cloud seeding catalyst for low level high albedo cloud - which reflects incoming light from the sun back out. so would there be a correlation between cooling and the phases of the heliosphere - and would that be a forcing or is it a feedback? sorry - some of this stuff is confusing for the layman.
  26. Hockey sticks, 'unprecedented warming' and past climate change
    is the following statement true - "The essence of the error (fraud) is in claiming some radiation goes around the center of absorption peaks for CO2 but gets picked up on the shoulders of the peaks. Even the shoulders absorb in such a short distance that increasing the CO2 only shortens a short distance. Cooling of the planet is caused by long wave infrared radiation which goes around the shoulders as well as the peaks." from - http://www.nov55.com/gbwm.html
  27. Skeptical Science now an iPhone app
    JMA have a weekly anomaly map for Jan 5th to Jan 12th, slightly more relevant than the last week of December yet it paints a similar picture. Cold and hot areas haven't moved much http://ds.data.jma.go.jp/tcc/tcc/products/climate/synop.html
  28. Skeptical Science now an iPhone app
    To anyone who knows... Parking the question of global warming for one second, and considering that local climates tend to have different behaviors, when comparing anomalous temperatures around the entire Artic Circle, does this refer to a change in the statistical variance of a region, or simply deviation from the statistical mean? Thanks in advance.
  29. A visual deconstruction of a skeptic argument
    Many people think that the amount of CO2 that mankind is putting into the atmosphere is minuscule compared with the amount of CO2 that is absorbed by natural processes each year. They are, of course, right. But it's not enough to stop there: we need to think it through. So, here’s an analogy. Imagine a publican has a regular order each day for 100 bottles of beer. Each morning the delivery man arrives at the pub with a lorry loaded to maximum, takes the full bottles out of ten crates (ten bottles to the crate) and fills the ten crates with the 100 empties from the night before. After signing the delivery note, the publican takes the full bottles inside to put in his cellar. Then during the evening the bartender brings the empties out and stacks them outside the back door of the pub. Now next door to this pub lives a chap who likes the same brand of bottled beer. Each day he brings home his evening meal and a bottle of his favourite beer. Being a lazy chap he can’t be bothered to take the empties back – and the refuse collection won’t take glass because it should be recycled – so, before he goes to bed, seeing the pile of empty bottles outside the back door of the pub, and knowing the brewery come to collect them, he takes his empty bottle over and leaves it with the others. Of course, when the delivery driver comes next day there’s an empty bottle too many but, because all the crates on his lorry are full, he has to leave the single empty behind. The pub and the brewery have evolved an ideal system established over years: the brewery delivers 100 full bottles and receives 100 empties back. It’s in perfect balance. The man next door thinks he’s doing fine – I mean that insignificant single bottle is just lost amongst that big pile of empties outside the back door of the pub. It takes him quite a while to notice that the pile of bottles seems to be increasing week on week – but they can’t be his, can they, given the amount the pub has delivered every day compared with his single one? So it isn’t until there's a pile of 365 bottles outside that pub before the publican wonders where they were all came from. Do I need to say, “for bottles substitute CO2”?
  30. Scientists can't even predict weather
    One of the issues that many non-scientists have trouble in understanding is the concept of a small but significant change being masked by larger, more immediate, fluctuations: just like weather and climate Here’s my analogy (I think it's original but someone might know better). Imagine walking down to a pristine beach -- say on your first day of a holiday -- when you don't know the tide times. You stand and watch the waves crashing in on the gently sloping sandy shore. Is the tide coming in or going out? You can't tell. Carry on watching the waves come in for a while. Some are larger, some are smaller. Every so often there's a much bigger one and, between, some quite small ones. After two minutes, and let's say thirty waves, you're still not sure but you're starting to think that it looks like the tide might be going out. You have started to see a trend. You might be prepared to put a fiver on it but you still wouldn't bet your life-savings on it. But I ask you: how long before you would? Eight minutes? Ten minutes? By averaging the distance those waves travel up the beach, a pattern has emerged and the direction of the tide has been established. Interestingly, the analogy holds up if we extend it. Now go back to the top of the paragraph and walk along the beach as you watch the waves. Is the tide coming in or out? After half an hour we still can't tell: the waves just come in with varying strength and as you walk -- and thus your reference points change -- it's impossible to estimate the trend. The opposite also holds true. Start back at the top of the paragraph and come down with a bunch of friends and spread out along the beach at, say, twenty metre intervals. Now each person shouts 'A RECORD!' each time a wave appears that's bigger than any preceding wave. By sampling at intervals along the beach within a minute we can establish the pattern. Either the shouts of 'A RECORD!' diminish to zero (tide going out), or they become consistent and regular (tide coming in). Now think of the waves as weather and the tide as climate and you've got it. One large wave (1998) is irrelevant, there are too many other factors that dictate the height of individual waves (let's face it, it might have been the residual wave of a passing ferry). What matters is the pattern of waves as they hit the shore, which tells us that the tiny gravitational force of that distant moon underlies all earth-generated influences like the wind, the bloke on the jet ski 100 metres away, or that distant passing ferry.
  31. Skeptical Science now an iPhone app
    WOW! I find it hard to believe that R.P. Sr. is getting booted about on this site. He has both of his feet squarely in the pro side. The only thing that I have seen that he is different about is the cause of the warming. From what I have read on his site, he doesn't argue against CO2, he just thinks that there are other causes, that regionally have as much of an effect as CO2. All of them man made! Overall CO2 may be the driver, but you dont think that when we rip up hundreds/thousands of acres of grasslands/forests et al to put in urban sites that it doesn't add to the positive trend in temps? He may be an outlier, but for God sakes, he is not a denialist!
  32. Skeptical Science now an iPhone app
    Albatross, I understand what you're saying-as I've often said it myself-a single heat-wave or cold-snap proves *nothing*, either way. I was simply highlighting how the denialists will disparage heat waves, whilst being quick to cite cold-snaps-which makes them hypocrites in my books. I'm much more interested in the global average, over several decades, to tell me whether the planet is warming or not. I'm also more interested in the correlation between CO2 changes & temperature anomaly changes (which is a *very strong* 78% for the 1950-2009 period).
  33. Skeptical Science now an iPhone app
    John, I agree with Pielke Sr. I don't think that he is saying that globally things are not getting warmer. Actually, he says that they are. But where I think he is going with the regional look is that we can better identify the other forcings that are pushing that region. Like in my home province, we actually had a cooler then normal spring and summer. But the wierd thing was we had a heck of lot less rain. More sunshine, cooler temps. Yet right now, we are having about 2-4*C warmer winter then normal (but overall we were warmer in 09). Why are we at a lower end while Alaska is at a much higher divergence? In my opinion it has to do with our Pine Beetle killed forests. But maybe as the new growth of this vast amount of land regenerates in the next 15-30 years, we may experience a colder divergence. This then would be a regional anomoly. That would be good to know. You know?
  34. Skeptical Science now an iPhone app
    RSVP, sorry you post @6 does not mean much. 1), it is a wunderground forecast for one point (it is bad enough that people misunderstand regional variability), 2) The AO has been increasing steadily for a few days now, and as expected colder air is making its way back into the Greenland region. See here for observations and ensemble forecasts of AO and other teleconnection indices: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.shtml Medium-range ensembles suggest a return to neutral AO around 23 January, with hints of a drop again thereafter, but nothing like we just had. NAO looks to return to be neutral or slightly negative, so western Europe should see milder air moving in again soon (it has already started to some degree). Global NAEFS forecasts still show large areas with above average temps. in the coming two weeks-- there is a big world out there that many of us are completely ignorant of that fact, even though we have the internet: http://www.weatheroffice.gc.ca/ensemble/naefs/semaine2_combinee_e.html Let us not make the mistake of saying "Oh, I am in Adelaide and it is +37C, so AGW is real" or "I am in Poland and it is abnormally cold, so AGW is a hoax". One has to look at the global mean temperature anomalies for extended periods of time to identify any statistically significant trends. These internal climate modes may modulate global temps to some degree, but they do not explain all the variance, not even close, and they certainly do not explain the increase in global temperatures. Some internal climate modes (such as ENSO) do teleconnect globally. However, impacts from the PDO, AO and NAO are almost exclusively regional in nature. Those in denial insist on looking for a silver bullet to absolve them of any responsibility and for them to defend maintaining the status quo. Internal climate modes may give some regions a break from the warming for short periods of time, while at other time sand regions they may enhance the background warming from higher GHGs. But that is about it IMHO. Marcus @20, Chris and dhogaza good points! PS: Here on the Canadian prairies we were 5 C above average in November, 6C below average in December and January will probably be 3-4C above average. These are huge swings in anomalies. If that example does not caution one of the follies of making deductions about global temperature trends using even monthly data from a tiny percentage of the planet's area, then nothing will.
  35. Skeptical Science now an iPhone app
    Chris, what is the average PDO index for the period btw 1910 and 1945? Btw 1946 and 1976? Btw 1977 and 2007? As to how a value that fluctuates around a mean can add to the long term trend, that is easy - if the mean value is consistent with a long term natural warming from (let's say) the LIA, then the warmer PDO phase will cause an even greater warmer amount of natural warming. IOW, if a biproduct of the warming trend from the LIA(to pick one point) is a mean PDO value of 0, then there will still be an underlying natural trend. IAC, in those terms, I am not talking about the long-term trend, I am talking about the approximately 30-year trends, which have observably changed dramatically over the ~100 years. Cheers, :)
  36. Skeptical Science now an iPhone app
    Yes, it is possible that there are other explanations for this besides the fact that the PDO has a strong influence on climate, but they have not yet been established.
    No, you don't get a good correlation, because the PDO plot shows no trend. It's just shifting energy around. While global temps do - an upward trend. Thus Chris's comment stating that such phenomena *modulate* the warming trend, rather than cause it.
  37. Skeptical Science now an iPhone app
    re #19.....Inspection of the temporal evolution of the PDO yields exactly the interpretation that Tsonis and Swanson and Keenleyside and Latif etc. are making, namely that ocean oscillations might have small modulating effects on the temporal evolution of surface temperature under enhanced greenhouse forcing, but have close to zero contribution to the long term trend which is dominated by the enhanced forcing (long term being the multi-decadal timescale of relevance to the consequences of enhanced greenhouse forcing). If you inspect the PDO for example (Wikipedia has a decent short account): http://en.wikipedia.org/wiki/Pacific_decadal_oscillation it's obvious that the value of the PDO index now is essentially the same as it was in 1900 (or 1800 or 1700 for that matter). How can a phenomenon that has a low amplitude oscillation around an essentially constant value make a significant contribution to a long term trend? And that's exactly what Tsonis and Swanson, who have examined this contribution to the surface temperature evolution over the 20th century, have found (see citation/and link to abstract in my post #16 above). The ocean oscillations and other natural contributions slightly enhance the externally forced warming trend during some periods and slightly oppose it during others. But overall the contribution to the long term warming trend is close to zero. As Swanson et al state:
    "Removal of that hidden variability from the actual observed global mean surface temperature record delineates the externally forced climate signal, which is monotonic, accelerating warming during the 20th century."
    ...("hidden variability" being the natural variation including ocean oscillations), and they conclude that the nett contribution of these effects to 20th century warming is as close to zero as makes no difference (perhaps 0.03 oC). That's the scientific basis on which Pielke's comment that you posted is specious. We know that there is internal variability in the climate system. That obviously makes short term (mulityearly, decadal) prediction difficult. But these oscillations sum to something close to zero, and so our predictions of enhanced greenhouse-forcing-induced warming in the long term aren't very much affected by these small amplitude oscillations.
  38. Skeptical Science now an iPhone app
    Well said Doug-that's exactly why they average the temperatures over a 30-31 day basis, then over a 20-year basis, because that helps to smooth out the irregularities from the odd extremely hot or extremely cold day. Its worth pointing out that-according to the Met Office-average UK temperatures for Winter 08/09, Spring 09, Summer 09 & Autumn 09 were all between 0.6 & 1.5 degrees warmer than the 1971-2000 mean http://www.metoffice.gov.uk/climate/uk/2008/winter.html http://www.metoffice.gov.uk/climate/uk/2009/spring.html http://www.metoffice.gov.uk/climate/uk/2009/summer.html http://www.metoffice.gov.uk/climate/uk/2009/autumn.html which is why I find it odd that people are so focussed on the extreme cold of the last 30-odd days, whilst happily ignoring the fact that the UK spent the bulk of the remaining 13 months with temperatures that were well above average!
  39. Skeptical Science now an iPhone app
    "That (Pielke's) is a specious "argument" shawnhet. If one inspects the science in which these issues are described, it's pretty obvious that the effects of El Nino's/La Nina's (especially) and ocean circulation changes like the Arctic oscillation result in modulation of the warming, which has little effect on the long term warming trends [*]. It is the latter that are likely rather well predictable, and important for consideration of impacts from largescale augmenting of the earth's greenhouse effect." It may be pretty obvious to you, Chris, but that doesn't mean it is accurate. If one plots the PDO index against the temperature one gets a very good correlation for as long as we have had decent records. Yes, it is possible that there are other explanations for this besides the fact that the PDO has a strong influence on climate, but they have not yet been established. IAC, my point here was not to defend this position in detail, but rather to correct the impression that Pielke was arguing that warming had stopped. Cheers, :)
    Response: Some of the later comments address this issue thoroughly but for the record, we look at the correlation between the PDO and global temperature here...
  40. Skeptical Science now an iPhone app
    How many times must it be said, in how many different way? With 6.5 billion persons on the planet, probably a few million different ways. Weather is more difficult to predict than climate. How so? For commuters: We accept that our daily commute might involve different delays at different places on different days but we know that we'll generally arrive at our destination more or less within a certain window of time. Climate change is a variation on the same boring routine. Arrival at a commute destination is governed by -average- speed, arrival at a certain future climate regime is governed by -average- energy input versus loss. It's just not that complicated to reason out, unless somebody is constantly trying to confuse readers, that is. Shame on Pielke; he should hand in his sheepskin.
  41. Skeptical Science now an iPhone app
    "The obvious response to these claims is that if we cannot predict weather features such as the Arctic oscillation or an El Niño under current climate, how can anyone credibly claim we have predictive skill six months into the future from both natural and human caused climate forcings? The short answer is that they cannot." His point was not that the Earth has stopped warming, but that we cannot reliably predict what warming will happen in the future.
    I've changed Pielke's statement in a way that should make the falseness of it obvious. The fact that we can't predict near-term weather with great accuracy says nothing about our ability to make sound predictions on other time scales. Average July temps will be warmer than average January temps in Portland, Oregon. Our understanding of the fact that natural forcings on this timescale far exceeds any change due to anthropomorphic causes, and that we know how those natural forcings change, allows me to make this claim. If you believe Pielke's claim is correct, I am willing to make a wager on it.
  42. Skeptical Science now an iPhone app
    That (Pielke's) is a specious "argument" shawnhet. If one inspects the science in which these issues are described, it's pretty obvious that the effects of El Nino's/La Nina's (especially) and ocean circulation changes like the Arctic oscillation result in modulation of the warming, which has little effect on the long term warming trends [*]. It is the latter that are likely rather well predictable, and important for consideration of impacts from largescale augmenting of the earth's greenhouse effect. Pielke's is the same tired argument that "one can't possibly predict the consequences of greenhouse release on future climate if we can't even predict the weather a few weeks in advance". To invoke El Nino's as a flaw in our predictive ability of climate consequences of greenhouse enhncement is pretty pathetic....and to similalry invoke short term modulation of surface temperature by ocean circulation effects, which seem to average out to near zero on meaningful timescales (much as we should expect), isn't much better. [*] For example Swanson and Tsonis (much cited by those who wish to use similar specious "arguments" to downplay likely consequences of mssive greenhouse gas release), have analyzed the contribution of ocean circulation changes to 20th century warming and concluded that their nett contribution is near zero [**] Likewise Keenleyside and Latif (also widely misrepresented to support specious "arguments" about supposed cessation of warming) predict an extremely marked warming over the next 10-15 years [**]. [**] K. L. Swanson, G. Sugihara and A. A. Tsonis Long-term natural variability and 20th century climate change http://www.pnas.org/content/106/38/16120.abstract N. S. Keenlyside, M. Latif et al. (2008) Advancing decadal-scale climate prediction in the North Atlantic sector Nature 453, 84-88 http://www.nature.com/nature/journal/v453/n7191/abs/nature06921.html
  43. Skeptical Science now an iPhone app
    We've been having a rather warm winter here in Southern California. So far.
  44. Skeptical Science now an iPhone app
    Since Pielke's position is at issue here, I think it would be fair to mention his main point which he lays out here(from the above linked post): "The obvious response to these claims is that if we cannot predict weather features such as the Arctic oscillation or an El Niño under current climate, how can anyone credibly claim we have predictive skill decades into the future from both natural and human caused climate forcings? The short answer is that they cannot." His point was not that the Earth has stopped warming, but that we cannot reliably predict what warming will happen in the future. Cheers, :)
  45. Skeptical Science now an iPhone app
    dhogaza #11 You copied and pasted my post inaccurately, misrepresenting my post, which refers to a statement in the article. No problem really. :)
  46. Skeptical Science now an iPhone app
    Marcus, I assume the data is accurate, however, I thought it might help to get an idea of what "unusualy warmth" is like in Greenland. As far as "anomalies", you might note how much the temperature fluctuates in this region just from one day to the next.
  47. Skeptical Science now an iPhone app
    RSVP posts ... ""On the other hand, Greenland, eastern Siberia and the Arctic ocean are experiencing unusual warmth." Weather forcast, Ilulissat, Greenland http://www.wunderground.com/global/stations/04221.html Tue, high -1, low -10 C Wed, high -6, low -25 C Thu, high -19, low -28 C Fri, high -17, low -18 C Sat, high -16, low -29 C" Hmmm, OK, the cold is returning to Greenland, meanwhile warmer than average temperature has temporarily returned to Denver, Colorado. Temps in Boston will rebound and be above normal by Friday. And in Madrid, temps are bumping up by several degrees C. Gee, RSVP, when the cold air gets pushed south, places like Greenland are warmer than normal. Now the huge high apparently is breaking down, cold temps are returning up there, and warmer weather is appearing in the south. Gosh geewillikers. Some ice age!
  48. Predicting future sea level rise
    This common misinterpretation was worth a climate crock of the week.
  49. What ended the Little Ice Age?
    batsvensson, since DeNihilist and I were talking about climate sensitivity and you commented, i assumed you had a knowledge of the subject. I always assume that people commenting on a topic have at the very least the basic knowledge. I was wrong, apologize; i guess there's no need to point you to wikipedia for a general introduction to climate sensitivity. Anyway, your ignorance of the subject does not allow you to presume mine, just explicitly ask for a reference. I probably made the same mistake assuming you are aware of the basic statistical analisys on the temperature time series. This would explain your (wrong) reasoning on my negative confirmation procedure, it's the opposite indeed. It's the analysis of past climate forced variability one of the strong point of AGW theory. And, for example, it's the statistical analysis of unforced variability that strongly contrast the claims of the halting of global warming. Similarly, the fact that a low climate sensitivity can not explain glacial cycles is *not* negative confirmation but analysis on data already statistically assessed. You know, physics works this way, at least if we stick to physics and not to the metaphysics of all the possible worlds.
  50. Skeptical Science now an iPhone app
    I think this weather pattern is in large part due to global warming. In Northern Europe, we have had the western winds "missing" us for about one month now, they are going south of us or north of us, where temeratures are 7-10 C above normal. - And it's not the first time for this to happen in recent decades. Because of its stability this does in fact produce some cold records - very little in single measurements (the troposphere is way too hot for that), but in cold periods. And because of the reduced diurnal variation, daily mean temperatures are extremely low - some 15-20 C below recent years' Dec/Jan average many places.

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