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Comments 115751 to 115800:

115751. daniel at 23:53 PM on 6 July 2010
        Sea level rise is exaggerated
        Yikes pete, sure I'll read them. But did you reconstruct the data from table 1? We can see that using high uncertainty low res data we still have roughly the same linear trend into the modern age. This is evidence of undersampling of a higher amplitude trend. A high amplitude trend directly measured in recent times using a tide gauge. You seem to think that the data points lie perfectly on a linear trend when even the centres of the boxes don't do that. Coupled with the error margins there is indeed enough slack im the data for higher amplitude trends. Therefore the link to Anthropogenic CO2 as a driver is undermined.
115752. Peter Hogarth at 23:45 PM on 6 July 2010
        Tai Chi Temperature Reconstructions
        chris at 23:22 PM on 6 July, 2010 You are absolutely correct and I don't want to mislead here. Global is really a misnomer. There are only eight SH proxies here, and only a further eleven from the Equator up to 30 degrees N. In the text I try to highlight that this is not a true gridded, weighted, interpolated, output. The averaged data is biased heavily towards the NH, and probably Northern Europe, and reflects a bias in the coverage of proxy records in general. Some of this is due to the nature of proxy records and different ratio of land mass to ocean, NH to SH.
115753. JMurphy at 23:45 PM on 6 July 2010
        Tai Chi Temperature Reconstructions
        That shape in those graphs of temperatures over the last 2000 years, they look like, er, hockey-sticks. Shall we call them 'hockey-stick graphs'...
115754. thingadonta at 23:31 PM on 6 July 2010
        Tai Chi Temperature Reconstructions
        There is at least one problem with your analysis that needs mentioning. -Generally speaking, with any type of scientific measurement, the further one goes back in time, the more smoothed, smeared, uncertain, and 'averaged out' the entire process becomes, from methodological selection, sample selection, collation, and interpretation, to the very response of the proxies themselves and the natural limits to the data that can be measured and inferred. Mathematicians usually fail to fully understand and appreciate this sort of thing; that their data contains a lot of structure, or in the words of Enrst Mayr when referring to the genotype as a whole, ‘cannot be understood by a purely reductionist approach’. I would contend that your analysis is largely reductionist, in that it ignores the basic structural features, limitations and variations that occur within any large scale proxy analysis. Most (all?) proxies you care to consider, whether response of corals to temperature shifts, or red shifts in galaxies, or radioactive dating in ancient rocks, will tend to exhibit a lagged/smoothed response to any rapid-real time fluctuation, such as temperature, and this smoothing will tend to increase the further one goes back in time, which therefore means that any comparison with actual measured (not proxy) temperatures, and proxies, particularly ywith regards to changes and variations in slope, is always misleading. Observations are always sharper than a response to a fluctuation, which is then collected and measured, and collated and compared over time; whether in proxies, or elsewhere. For this reason alone, one can't make the conclusion the recent temperature changes are faster than any former temperature changes in eg the last 2,000 years, (ie 'unprecendented') because one is a real time, direct, measurement (measured temperature in recent centuries), and one is a biological/ biochemical response to a fluctuation, which has to be selected (researchers bias), collected (sample contamination and availability), ‘inferred-measured’(significant figures and error bars change with time, and with differential response to short term fluctuations), and finally, submitted to mathematical analysis (including averaging out already-smoothed proxies, even further),and placed alongside and compared with real-time observations. It is no wonder that such reconstructions give a sharp slope in recent, measured, centuries compared to a flattened slope with older data, anyone who is familiar in the field (not in a air conditioned office) with limitations to proxy collection and analyses will tell you that you can get this sort of graphical features with virtually any averaged out collection of inferred times- series analysis, and the further back in time one goes, the stronger it gets. You don't even have to splice datasets to confront this kind of problem, any time series analysis of proxies will tend to exhibit a smearing of response/delineation of measurement, the further one goes back in time, and even more so if one then averages out the data between many types of proxies-all this does is further flatten older proxy responses compared with more recent ones. To repeat, proxy error bars increase with age, and the more error bars one ‘averages out’, over a longer and longer time period, the more smoothing occurs, compared to both more recent proxies and actual recent observations.
115755. Peter Hogarth at 23:29 PM on 6 July 2010
        Tai Chi Temperature Reconstructions
        rway024 at 23:14 PM on 6 July, 2010 In my simplistic case, I am relatively lucky in that so many of these proxies overlap over considerable periods, and it is only the tapering of record density in the last century that presents problems. Here I used a long common period (of most of the record) for simplicity. This should standardise things to a good approximation and still allow us to average the extended records. I guess a standardisation formula could be used, but I'll try to have a look at the exact methods used in the official reconstructions.
115756. chris at 23:22 PM on 6 July 2010
        Tai Chi Temperature Reconstructions
        which leads me to another question for Peter: Your Graphs 2 and 3 are depicted as "Global Average Anomaly of 50 Temperature Proxies". To what extent are these actually "Global" and opposed to N. hemispheric? i.e. what is the proportion of S. hemisphere proxies in the data? My understanding is that if one is sampling the past 2 millenia, the number of S. hemisphere proxies is very small.
115757. chris at 23:18 PM on 6 July 2010
        Tai Chi Temperature Reconstructions
        RSVP at 22:22 PM on 6 July, 2010 Your argument isn't quite right RSVP. Although global temperatures have a large (especially latitudinal) variability, the yearly (or decadally) averaged temperature at a single location on Earth doesn't vary that much. Since all proxyreconstructions (Peter's included) determine a temperature anomaly, the large intraEarth variability isn't so relevant. Where it is relevant relates to the likelihood that there are location-specific responses to forcings. These do have a significant latitudinal dependence (e.g. polar amplification, and any response that involve significat changes in thermohaline circulation that carries heat to the high Northern latitudes, etc.). We are still in the situation that the S. hemisphere is poorly represented in paleoproxyreconstructions.
115758. robert way at 23:14 PM on 6 July 2010
        Tai Chi Temperature Reconstructions
        How does one deal with proxy series which do not overlap in terms of the anomaly calculations. For example if only 15 of the 50 overlap but some extend further and so on? Would one use a standardization formula such as (X value - Mean of whole series)/ Standard Deviation of whole series?
115759. Peter Hogarth at 23:13 PM on 6 July 2010
        Arctic Ice Part 2: A Review of Factors Contributing to the Recent Decline in Arctic Ice
        Arkadiusz Semczyszak at 21:04 PM on 6 July, 2010 I cited Graverson 2010, and I have suggested that atmospheric and Ocean current contributions play a role. I don't disagree on this. The interaction of THC and NAO and Eastern boundary currents etc is something I am thinking of posting on, as part of looking at longer term variations. It will take a while. You have mentioned the possible freshwater effect on THC, I admit I referred to the measured freshening very briefly, but you also need to ponder the "T" in THC, and I try to cover oceanic warming in some detail, where does the warmth come from?, discuss.
115760. Peter Hogarth at 22:58 PM on 6 July 2010
        Tai Chi Temperature Reconstructions
        RSVP at 22:22 PM on 6 July, 2010 Yes, this is partially the point. Lots of averaging should extract any common signal from noisy data. Of course official reconstructions do a lot more than this, but I hope the general idea gets across.
115761. Peter Hogarth at 22:53 PM on 6 July 2010
        Tai Chi Temperature Reconstructions
        chris at 21:30 PM on 6 July, 2010 Difference is that the error bars are removed, which allows vertical scale to be zoomed a little, and annual and ten year averages are shown superimposed. Otherwise they are the same. HumanityRules at 21:34 PM on 6 July, 2010 The text is correct, there are 50 records given as temperature values which are easy to average in this simple approach, the other 18 are Sigma values, which are difficult just to add in (though I try to show an indication of how this may affect the average in the 1850 to present chart), the remaining 3 are not publicly available, though Ljungqvist gives visual charts of them.
115762. Peter Hogarth at 22:40 PM on 6 July 2010
        Sea level rise is exaggerated
        daniel at 08:21 AM on 6 July, 2010 If "wordy" bothers you I can draw some pictures? As a professional scientist I have concerns about your recent comments and general analytical approach to this data set. As we have sparse data and Donnelly gives error estimates, might I suggest again a statistical approach? It also worries me that you have not followed through on physics or measurement based evidence which suggest your “short term large variation” hypothesis is highly improbable. High resolution temperature reconstructions are available and do not support your proposal - Grinsted covers this well. Please read it. Back to Donnelly, we have more plenty of points here near point 1. The uncertainty in point 1 is shown. It is consistent with the other data which has higher certainty and fits the given trend, statistically speaking. If your argument had any chance of surviving critical scrutiny you would expect deviation of the error envelope from the “curve” for at least some of the other points, which we do not see. The total error envelope would have smooth upper and lower bounds, and I agree we could see variation within these bounds, but this is relatively small and does not compare with the overall rise or the recent rise in rate. This is the point of Donnellys paper. Coupled with evidence of lack of variability in the drivers for your hypothesised variations, this greatly diminishes the probability of your hypothesis being correct. Add to this data from other sources which also give points with high uncertainty but which also fit on the shallow curve (given the error envelope) increase the probability of the low amplitude variation fit being statistically robust, and diminish further the probability of your hypothesis being correct. The recent acceleration in sea level is well documented as are the physics based drivers for this. The overall picture is consistent. For you to hide behind "ad hominem" when it is suggested that Donnelly has access to a great deal more data than he is presenting in one paper on one specific site, reflects poorly on your argument, and I expect better from anyone who claims a science background. Here are some further references (in no particular order) on proxy records, physical basis of sea level rise, recent acceleration, and extended tide gauge data, I hope you will read them, and follow through on a few of their references, and come back with a bit more knowledge and a bit less uninformed opinion: Woodworth 2008, Engelhart 2009, Woodworth 2009, Yasuda 2008, Romundset 2009, Engel 2009, Gonzalez 2009, Leorri 2008, Miller 2008, Goodwin 2008, Wopplemann 2008, Merrifield 2009
115763. Arkadiusz Semczyszak at 22:34 PM on 6 July 2010
        Tai Chi Temperature Reconstructions
        The primary disadvantage of most of the reconstruction is over-smoothing (especially multi-proxy). How to avoid this, I recommend: http://www.rni.helsinki.fi/research/info/sizer/.
115764. RSVP at 22:22 PM on 6 July 2010
        Tai Chi Temperature Reconstructions
        I personally have no problem believing that world climate has warmed some (within the last 50 years), the most obvious proxy being the trend in Artic ice breakup and glaciers generally receding. On the other hand, temperatures around the world vary nominally within a range of about 50 degrees C, so in order to use proxies to detect a global anomaly of one degree, they would require linear accuracy of less than one degree for this full range.
115765. JMurphy at 22:15 PM on 6 July 2010
        Arctic Ice Part 2: A Review of Factors Contributing to the Recent Decline in Arctic Ice
        Arkadiusz Semczyszak wrote : Is the Thermohaline Circulation Changing?, Latif et al., 2006: “Analyses of ocean observations and model simulations suggest that there have been considerable changes in the thermohaline circulation (THC) during the last century. These changes are likely to be the result of NATURAL multidecadal climate variability and are driven by low-frequency variations of the North Atlantic Oscillation (NAO) through changes in Labrador Sea convection.” And to complete the abstract : Indications of a sustained THC weakening are not seen during the last few decades. Instead, a strengthening since the 1980s is observed. The combined assessment of ocean hydrography data and model results indicates that the expected anthropogenic weakening of the THC will remain within the range of natural variability during the next several decades. LINK. Arkadiusz Semczyszak wrote : Influence of the Atlantic Subpolar Gyre on the Thermohaline Circulation, Hátún et al., 2005: “ During the past decade, RECORD-HIGH SALINITIES have been observed in the Atlantic Inflow to the Nordic Seas and the ARCTIC OCEAN, which feeds the North Atlantic thermohaline circulation (THC).” And to complete the abstract : This may counteract the observed long-term increase in freshwater supply to the area and tend to stabilize the North Atlantic THC. Here we show that the salinity of the Atlantic Inflow is tightly linked to the dynamics of the North Atlantic subpolar gyre circulation. Therefore, when assessing the future of the North Atlantic THC, it is essential that the dynamics of the subpolar gyre and its influence on the salinity are taken into account. LINK As for the Graversen paper, if you actually have a link to it you will see that it has been opposed by three further papers : Cecilia M. Bitz & Qiang Fu A. N. Grant, S. Brönnimann & L. Haimberger Peter W. Thorne And just to round things off, there is a reply to these from the original paper's authors : R. G. Graversen, T. Mauritsen, M. Tjernström, E. Källén & G. Svensson So, things are not as settled as some would want us to believe, and some people prefer the original paper and would like to ignore the others. Is that what is known as 'cherry-picking' ? Now I understand why so-called skeptics don't include links.
115766. Dan Olner at 21:48 PM on 6 July 2010
        Tai Chi Temperature Reconstructions
        Reading good analyses always feels drinking drinking cool, clear water. Reading bad ones is like eating mud. This is great.
115767. HumanityRules at 21:34 PM on 6 July 2010
        Tai Chi Temperature Reconstructions
        Thanks Peter, The 2nd and 3rd figures both say 50 record but the 3rd is meant to be 50 plus an unstated number. This an error? Out of suspicious curiosity could you show just the non-NOAA average.
115768. chris at 21:30 PM on 6 July 2010
        Tai Chi Temperature Reconstructions
        very nice indeed Peter. Your recent articles here have taken analysis to a level that beautifully bridges the gap between the layman and the science, and helps to show that the gap isn't as large as one might think. Can you clarify the difference between the 2nd and 3d figures? It's not obvious to me what you've done differently to the data in these two graphs. P.S. it would be worth adding Figure no's (i.e. Figure 1; Figure 2 etc.) to the figure legends since the figures are bound to be referred t in the comments...
115769. Arkadiusz Semczyszak at 21:04 PM on 6 July 2010
        Arctic Ice Part 2: A Review of Factors Contributing to the Recent Decline in Arctic Ice
        @ Peter Hogarth What about this paper: Vertical structure of recent Arctic warming, Graversen, 2008,? “We conclude that changes in atmospheric heat transport [tropic] may be an important cause of the recent Arctic temperature amplification.” First, a warmer upper layer [...] of the Arctic troposphere. Graverson 2008 argues that originates from the tropics to 25% of the heat in the Arctic. Significant Addendum: Influence of the Atlantic Subpolar Gyre on the Thermohaline Circulation, Hátún et al., 2005: “ During the past decade, RECORD-HIGH SALINITIES have been observed in the Atlantic Inflow to the Nordic Seas and the ARCTIC OCEAN, which feeds the North Atlantic thermohaline circulation (THC).” Is the Thermohaline Circulation Changing?, Latif et al., 2006: “Analyses of ocean observations and model simulations suggest that there have been considerable changes in the thermohaline circulation (THC) during the last century. These changes are likely to be the result of NATURAL multidecadal climate variability and are driven by low-frequency variations of the North Atlantic Oscillation (NAO) through changes in Labrador Sea convection.”
115770. Arkadiusz Semczyszak at 19:04 PM on 6 July 2010
        Archibald’s take on world temperatures
        @Agnostic “As you point out, the highest global temperatures have been recorded during a low period in the solar cycle.” It has always been. The greater the change in to solar activity, the response (temperature) more remote in time. Take a look: http://upload.wikimedia.org/wikipedia/en/1/16/Sunspot-temperature-10000yr.svg, like circa 7400 BP - solar activity is very low. Temperature by EPICA Dome C - maximum. Delaying even a circa 800 years. But the last period (last millennium - less than 100 years).
115771. Arkadiusz Semczyszak at 18:26 PM on 6 July 2010
        Arctic Ice Part 2: A Review of Factors Contributing to the Recent Decline in Arctic Ice
        @ Peter Hogarth 1.“It is unlikely that you have read all of the references ...” - It's true. But ... In many discussions on the Arctic ice I proposed on this page reflect on the main alternative scenario (at least for NIPCC) - increasing the coverage of THC to NH (Recent changes of the thermohaline circulation in the subpolar North Atlantic, Bersch, 2007). Generally, the amount of energy transported by the THC may even drop (it is irrelevant to other sources), but the change of the deposition of significantly changing albedo, atmospheric and oceanic circulation. It runs a lot of positive feedback, perhaps such as the release of CO2 from the Arctic sea and ice, feedbacks, which causes faster warming in the Arctic („Quadfasel continues by pointing out the significance of the possible implications, with palaeoclimate records showing drops of air temperature up to 10°C within decades, linked to abrupt switches of ocean circulation when a certain threshold is reached.” - based on: Oceanography: The Atlantic heat conveyor slows, Quadfasel, 2005). Reasons for amendment of the scope of THC may be different. Who will read my previous posts knows that I put on the gravity of the Sun and Moon (The impacts of the Luni-Solar oscillation on the Arctic oscillation, da Silva and Avissar; 2005). The influence of long tides on ecosystem dynamics in the Barents Sea, Yndestad, 2009; and: Lunar nodal tide effects on variability of sea level, temperature, and salinity in the Faroe-Shetland Channel and the Barents Sea, Yndestad et al., 2008.: “In addition, correlations better than R=0.7 were found between dominant Atlantic water temperature cycles and the 18.6-year lunar nodal tide, and better than R=0.4 for the 18.6/2=9.3-year lunar nodal phase tide. The correlation between the lunar nodal tides and the ocean temperature variability suggests that deterministic lunar nodal tides are important regional climate indicators that should be included when future regional climate variability is considered. The present analysis suggests that Atlantic water temperature and salinity fluctuations in the Nordic Seas are influenced by forced tidal mixing modulated by harmonics of the nodal tide and influencing the water mass characteristics at some point “down stream” from the Faroe-Shetland Channel. The effects of the modulated oceanic mixing are subsequently distributed as complex coupled lunar nodal sub-harmonic spectra in the THERMOHALINE CIRCULATION.” In another study, the authors arrive at the main - the final conclusion: “In this analysis we may understand the forced gravitation oscillation between the earth, sun and the moon as a forced coupled OSCILLATION SYSTEM to the earth. The tide and the earth rotation responds as a non-linear coupled oscillation to the forced gravity periods from the moon and the sun. This is a complex oscillation in periods between hours and THOUSANDS of years. The forced gravitation introduces a tidal mixing in the Atlantic Ocean. This tidal mixing introduces temperature and salinity fluctuations that influences climate and the eco system.” “In light of the DEFICIT OF THE SCIENTIFIC understanding of the thermohaline circulation and the feedback potentials between the two deepwater sources, it is difficult to predict the influence of global climate change on the dynamics of the thermohaline.” (Coastal Wiki) I agree. When you do not check everything, you can not say we do not understand what that's for sure CO2 ... 2.Lockwood papers shows how a small change in the sun is able to significantly change the temperature of winter in the vast areas - adjacent to the Arctic - the Arctic ice. Establishment of the locality of this change, for the fact that all the oceans - the World ocean currents form a whole - a system - it is unscientific. I recommend my favorite work based on a very wide literature ("pros and cons" - not only cherry picking): Holocene weak summer East Asian monsoon intervals in subtropical Taiwan and their global synchronicity, Selvaraj et al., 2008.: “PERSISTENT LINKAGE of weak summer EAM-tropical PACIFIC and NORTH ATLANTIC COOLING-reduced GLOBAL wetland extent during these intervals is believed to be driven by coupled OCEAN-ATMOSPHERE INTERACTIONS, especially reduced heat and moisture transport and enhanced El Niño-Southern Oscillation in the tropical Pacific, as well as SOLAR ACTIVITY.”
115772. Red XIV at 17:08 PM on 6 July 2010
        Other planets are warming
        On the simplest level, if Pluto were being warmed significantly by increase in solar output despite how very far away it is, a much closer planet like Earth would be fried by that increased output.
115773. robert way at 13:20 PM on 6 July 2010
        Archibald’s take on world temperatures
        Grace satellite measurements have been affirmed by radar interferometry, laser altimetry and melt modeling. Like I said, a post will be coming and this will be set straight because there are far too many people who are commenting without knowing the basics of glaciology. Ice loss (ablation) in antarctica is 90% through calving and NOT surface melting. Calving is caused by completely different mechanisms than surface melt which dominates the greenland signal (although recent measurements indicate that calving is taking over). In antarctica, glaciers accelerate and thin which causes more ice loss. Once again, I understand the dynamical nature of the west antarctic ice sheet and of other submarine basins in antarctica, but far too many people confuse melt with ice loss... nevertheless, i should have been more clear I guess.
115774. scaddenp at 12:58 PM on 6 July 2010
        Archibald’s take on world temperatures
        rway024 can answer for himself, but I believe he means by "melt" is melting due to overly warm air temperatures and/or rain onto ice. Ice loss can be by direct melt (more important in Greenland) or by calving into a warm ocean (more important in antarctic). At least that is my take. Roy, I think you have been taken in by some skeptic site as virtually all those statement are wrong. eg "The test of math models is whether they work reliably. Observed data is below the model error bounds, so the models are wrong. " Pardon? Doesn't fit with this. Perhaps you point us to papers that support your assertions?
115775. Riduna at 12:32 PM on 6 July 2010
        Archibald’s take on world temperatures
        rway024 at 26 Am I misunderstanding your claim that ..Melting is basically irrelevant in Antarctica and important in Greenland .. If GRACE satellite measurements are to be believed, ice loss in the Antarctic, particularly from WAIS is not only significant but has the potential to be disastrous. WAIS, being a marine ice sheet is particularly vulnerable to attack from warm ocean currents causing large areas of ice resting on the seabed to float. Hardly irrelevant where rising sea-levels are concerned.
115776. robert way at 11:25 AM on 6 July 2010
        Archibald’s take on world temperatures
        previous post was to Roy Latham at 04:35 AM on 6 July, 2010
115777. robert way at 11:25 AM on 6 July 2010
        Archibald’s take on world temperatures
        There is indeed a relation between temperatures and the AMO which results in positive phases having more warming in the north pole and negative phases having more warming in the south pole. This is shown in a recent paper Chylek et al. 2010. Pertaining to your comment about the IPCC’s statements on ice caps, I first have to point out that Ice Caps and ice sheets are not the same thing. Secondly the IPCC statement on Ice Sheets was wrong, and recent studies have shown that the IPCC was far too cautious in their assessments of Ice Sheets. They completely ignored dynamical ice processes. Finally your last point, there will be a blog post on here soon pertaining to the statement but to summarize. Antarctic ice losses are caused only 10% by melting and the rest is due to bottom melting from increased sea temperatures and increased glacier flow rates. You should stop listening to Goddard over there at WUWT about this stuff. He doesn’t have a clue about glaciology. It was shown time and time again in the comments after his post on grace. Melting is basically irrelevant in Antarctica and important in Greenland. Different places, different processes. Don’t get confused by the rhetoric.
115778. Bern at 11:16 AM on 6 July 2010
        Archibald’s take on world temperatures
        Humanity Rules @ #8: You're absolutely right, there is something significant about the 1970s:

        Governments have made efforts since the 1970s to reduce the production of sulfur dioxide into the atmosphere

        (from Wikipedia) I'm sure I don't need to remind you that sulfur dioxide is an aerosol, with relatively short residence time in the atmosphere, which reduces solar input to the surface, and has a cooling effect?
115779. Riduna at 10:32 AM on 6 July 2010
        Archibald’s take on world temperatures
        Esop – 7 As you point out, the highest global temperatures have been recorded during a low period in the solar cycle. What should concern everyone is the effects that more pronounced solar activity will have on global temps. Presumably Archibald thinks that the measurements provided by satellites such as GRACE are wrong? Archibald’s claims of a cooling world really are at odds with empirical data and do little more than repeat assertions made by such luminaries as Lord Monckton and Ian Plimer. One wonders why they make claims which are so easily shown to be wrong?
115780. Riccardo at 10:15 AM on 6 July 2010
        CO2 is Good for Plants: Another Red Herring in the Climate Change Debate
        johnd, real life is different from a controlled experiment. It's already difficult enough to assess the effect in controlled experiment at CO2 concentration more than double current value to think that it should have already be noticed in managed (hyper-fertilized) farms.
115781. johnd at 10:00 AM on 6 July 2010
        CO2 is Good for Plants: Another Red Herring in the Climate Change Debate
        Riccardo at 09:17 AM, I wasn't meaning extrapolating backwards, but to what has shown up in actual observations within the natural environment. The study of plant growth is not a new science. CO2 began it's upward trend over 100 years ago and has accelerated in recent decades. If any short term effects from increased CO2 fertilisation disappear after a few years, then such effects should have been readily observable long ago in any studies of plant growth, as well as in the horticultural industry where it has been practiced for decades. It would also mean that current experiments should see an immediate decreased response to growth, but even in the experiment cited, that apparently was not the case.
115782. ProfMandia at 09:56 AM on 6 July 2010
        Archibald’s take on world temperatures
        Call me crazy, but when somebody asks me what the temperature is I do not look out my window to see if there is snow cover. I check the thermometer. Scott A. Mandia, Professor of Physical Sciences Selden, NY Global Warming: Man or Myth? My Global Warming Blog Twitter: AGW_Prof "Global Warming Fact of the Day" Facebook Group
115783. Riccardo at 09:17 AM on 6 July 2010
        CO2 is Good for Plants: Another Red Herring in the Climate Change Debate
        johnd, the paper focus on the response to elevated CO2 concentration (720 ppm) in a controlled experiment. I don't think it can be extrapolated backward and in a generic environment.
115784. kdkd at 09:14 AM on 6 July 2010
        Astronomical cycles
        Ken #130 I see you're still having trouble with the validity of your argument. However, you do seem to have some kind of estimate of the measurement uncertainty of the global energy imbalance. There might be some validity to attempt to formally reconcile this information with the sea level rise data, temperature anomaly, glacier melt data, ecosystem changes and any other indicators of global warming in order to see if your argument has any validity. i.e. If there is a coherent and consistent body of knowledge that supports your argument. However, you have been unprepared to do this to date, apart from a spot of numerology (impressionistic and opportunist eyeballing of data with no regard for statistical validity).
115785. daniel at 08:21 AM on 6 July 2010
        Sea level rise is exaggerated
        KR I think you should reconstruct the data from table 1 and include sample 1 like I asked Peter to and you will find that Donnely's data supports my conclusion. The linear fit is quite possibly an undersampling of a higher amplitude trend.
115786. johnd at 08:00 AM on 6 July 2010
        CO2 is Good for Plants: Another Red Herring in the Climate Change Debate
        Riccardo at 22:54 PM, given that CO2 levels began rising over 100 years ago, and as well the introduction of legumes that fix nitrogen into the soil has become part of modern farming practices, if the finding of the study cited are valid, to what extent has the CO2 fertilisation effect been suppressed, and to what extent have C4 plant encroachment occurred in todays environment compared to that before CO2 levels began rising and the widespread introduction of legumes began?
115787. Johngee at 07:25 AM on 6 July 2010
        A Scientific Guide to the 'Skeptics Handbook'
        Hi all. New here :0) Love the booklet. Was wondering about other evidence. Like the increase in co2 correlation with decrease in atmospheric oxygen pointing to the combustion process as source for co2. And also the carbon isotope that points to it's origins from plant take up during photosynthesis and hence released when burned. Pardon my lack of sources. I think I read about them on real climate or a few things I'll considered. I am not a scientist so could these also be explained in your booklet?
        Response: Good points. I cover these (among many) in the human fingerprint on global warming. The reason I don't cover them in the Scientific Guide is because it addresses a very narrow question - is there evidence that more CO2 causes warming? The Skeptics Handbook doesn't question whether humans are the cause of rising CO2 levels so in the interest of keeping the Guide tight and focused, I don't go borrowing trouble :-)
        
115788. Peter Hogarth at 07:02 AM on 6 July 2010
        Archibald’s take on world temperatures
        Roy Latham at 04:35 AM on 6 July, 2010 Global record UAH LT V5.3 May 1995 to May 2010 trend is +0.13 C/decade, almost identical to that of the entire record. Continental USA record RSS TLT V3 entire record (1979 to 2010) trend +0.15 C/decade These are public access direct satellite measurement records. Your statements on this are not supported by the evidence. Arctic sea ice 70 years ago was around 20% greater (mean level) than today, from our best overall publicly accessible records. For Antarctic we have very sparse records for pre 1950s, so your statement is dubious to start with, however whaling records, proxy records, and a few voyages we do have a few records from suggest that Antarctica had significantly higher sea ice levels than today, though no precise figures exist. The rise in maximum or mean Antarctic sea ice over the 1978 to present satellite period is just above borderline significant. The 1972 to 1978 interrupted satellite record shows a drop in maximum extent from a higher value than present. The earlier record has uncertainty attached, but it is the best information we have. None of this is based on modeling. Your statements on this are not supported by evidence. If you have other sources please give them. Time permitting I will provide them for all numbers and statements above.
115789. Peter Hogarth at 06:14 AM on 6 July 2010
        CO2 was higher in the late Ordovician
        Tom_the_Bomb at 04:22 AM on 6 July, 2010 Sorry "well tested" should be "well trusted"! These are the two references that stood out in my memory. Minton 2007 is a good introduction, and explores the difficulties with the standard solar model and young sun model with regard to the very early climate, and Gudel 2007 gives a comprehensive exploration of models and other stars as well as the sun. Hope they are of interest.
115790. JMurphy at 06:13 AM on 6 July 2010
        Archibald’s take on world temperatures
        Roy Latham wrote : For example, there is a global warming trend, but there has not been an observed warming trend in the United States in recent decades Do you have any further information to back up that claim ? Just quickly looking at the NOAA site, I have found a 0.31F/Decade trend since 1990, and a 0.43F/Decade trend since 1980. Try it yourself here. All based on a 1901 to 2000 base period. Do you mean since 2000 ? Here the trend is -0.73F/Decade but surely you don't find that significant ? And that is only one decade - hardly "recent decades".
115791. Neven at 05:56 AM on 6 July 2010
        Arctic Ice Part 2: A Review of Factors Contributing to the Recent Decline in Arctic Ice
        Wonderful stuff, Peter! This will save me so much time.
115792. Jim Eager at 05:45 AM on 6 July 2010
        Archibald’s take on world temperatures
        He probably gets it from the widely disseminated misquoting of Phil Jones.
115793. Peter Hogarth at 05:29 AM on 6 July 2010
        Arctic Ice Part 2: A Review of Factors Contributing to the Recent Decline in Arctic Ice
        Andrew Xnn at 04:23 AM on 6 July, 2010 On wind speed, the mean wind speed could decrease but the standard deviation increase, hence more positive peaks, more maximums. I am not suggesting the wind speed is behaving in this nice statistical way, but illustrating the possibility of both occurring concurrently. I'll try to get the satellite wind speed records to see if they match the re-analysis wind speed data. In terms of behaviour, the difference between summer minimum ice extent and winter maximum extent has also increased, though the mean level and winter levels have both decreased. The minimum ice extent in September is simply when ice growth starts to outpace ice melt. If the Spring melt is enhanced by extra downwelling IR, (ie melt rate increases) there is less to melt in Summer when the sun is up 24/7, all other things being equal. The minimum will still occur around September due to the combination of seasonal factors.
115794. KR at 05:17 AM on 6 July 2010
        Sea level rise is exaggerated
        Daniel - you're apparently missing the point from both Peter and myself. The data points from that paper (core samples) fit a linear trend. There is no evidence from those samples of any higher frequency changes (short term), since if there were short term changes those data points would be extremely unlikely to all fall on a linear fit line. Peter said that quite clearly, so did I. The evidence in that paper supports a linear fit - not a long term linear fit with lots of short term excursions. I think Peter said it better: "If there were short term variations of the magnitude which you suggest between the sparse points then the probability of all of these randomly sampled points fitting any smooth long term curve is small." If a rise such as seen in the last 200 years occurred some time in the remaining 600 years covered by the Donnally paper, those carbon dated sediments would not fall on or near the linear fit line for 1400-1800, especially given an average sampling of 60 years. There is no evidence in the data that supports your assertion of short term variations, and hence none are postulated by Donnelly. If you think that there are, you need to find some evidence for them. There's certainly no such evidence in the Donnally data points. If you don't get that, there's really nothing I can say other than to suggest you find out more about data fitting and evidentiary rules in science.
115795. McCloud at 05:17 AM on 6 July 2010
        We're heading into an ice age
        Question: In the projections shown in Figure 4, it looks like there is an upper limit of about 4 degrees C for the temperature anomaly, even at 5000 Gigatonnes CO2 emission, and only about 2 degrees for 1000 Gton. However, the graph in Figure 2 shows that the temperature anomaly is projected to reach 4 degrees C in just under 100 years, on a more or less exponential path, with no sign of slowing down. Is there or is there not an upper limit to the temperature anomaly given these assumptions about the magnitude of CO2 emissions? How sure can we be that the projections shown are correct, given the chaotic nature of the planet's climate? Question 2: Can climate change result in positive feedback as ocean warming leads to the release of more CO2?
115796. Rob Honeycutt at 05:15 AM on 6 July 2010
        Archibald’s take on world temperatures
        GISS link messed up... GISS
115797. Rob Honeycutt at 05:12 AM on 6 July 2010
        Archibald’s take on world temperatures
        Roy Latham... I'm not sure where you get "no global warming trend in the past 15 years." The data don't seem to support you in this statement. UAH GISS RSS
115798. Peter Hogarth at 05:01 AM on 6 July 2010
        CO2 was higher in the late Ordovician
        Tom_the_Bomb at 04:22 AM on 6 July, 2010 The evidence partly comes from analysis of similar stars to our sun at different stages in their life cycle and well tested physics based models. Stars of a certain mass profile appear to display similar growth and fusion burn and brightness patterns, many have star spot cycle activity similar to our sun. I'll dig out some references.
        Response: How the sun was cooler and how this affects climate is discussed in more detail at CO2 was higher in the past.
        
115799. Roy Latham at 04:35 AM on 6 July 2010
        Archibald’s take on world temperatures
        Archibald seems to be in error on two accounts: North America does not equate to the world and snow pack is a consequence of precipitation amounts as well as the temperature. For example, there is a global warming trend, but there has not been an observed warming trend in the United States in recent decades. Of course, there has not been a global warming trend for the past 15 years. The surface ice in the Arctic melts roughly every 70 years, with the last melt in the 30s, and the one before that around 1880. National Georgraphic Magazine about a year ago had an article that described the oscillation. When sea ice decreases in the Arctic it increases in Antarctic, and that has happened this time as well. Sea ice depends upon the relative warmth ocean currents. As to the ice caps, the last IPCC report claimed that the total land ice is very close to stable. If temperatures are well below zero, warming does not cause melting. In the climate debate, the burden of proof is for advocates to prove that there is a climate crisis. The crisis theory is based entirely upon math models that predict the earth will warm considerably more than the straight physics of carbon dioxide predicts. The test of math models is whether they work reliably. Observed data is below the model error bounds, so the models are wrong. The present task therefore ought to be to find models that work.
115800. Andrew Xnn at 04:23 AM on 6 July 2010
        Arctic Ice Part 2: A Review of Factors Contributing to the Recent Decline in Arctic Ice
        Peter; Thanks for the additional clarification. Apparently, I became confused with the following sentence: “Indeed year on year variations in wind speed correlate well with ice extent changes Ogi 2010b, but what about the longer term?” Understand now that this is in reference to seasonal variations. However, the overall decrease in wind speed with increasing storm activity doesn’t make a lot of sense. Understand that downwelling longwave radiation follows cloud cover. However, the shift in sea ice extent is seasonal and the change In cloud cover appears inconsistent with ice observations. That is the greatest negative ice anomaly over the last 3 years has tended to be in September, while cloud coverage in Summer/Fall is small. So, why are we seeing the largest anomalies right around sunset? My guess is that this is when thicker ice is more prominent as a fraction of the total basin. Perhaps in contrast, during the winter max, thinner ice is a misleading observation.

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