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Comments 131001 to 131050:

131001. Quietman at 19:03 PM on 7 October 2008
        Volcanoes emit more CO2 than humans
        Patrick You still assume AGW is a big player and I do not. See the sensitivity thread.
131002. chris at 10:59 AM on 7 October 2008
        Temp record is unreliable
        Re #30-32 These questions have been addressed fairly conclusively by the science. (i) You are correct (Tree) that the earth took many millions of years to sequester atmospheric CO2 in the form of fossil fuels (oil, gas, coal, shale and so on). Around 4000 billion tons of carbon is "stored" in this manner, and it's taken around 600 million years to do this. In the last 100 years we've released around 500 billion tons of this carbon back into the atmosphere, of which around 200 billion tons has remained there (around 300 billion tons has been absorbed by the oceans and terrestrial environment). see for example: http://www.physicalgeography.net/fundamentals/9r.html (ii) It's very clear that volcanic activity is on a miniscule scale with respect to our massive release of carbon dioxide. It's easy to demosstrate this. If one examines the high resolution atmospheric CO2 record over the last 1000 years, for example, one can see that the atmospheric CO2 levels remain rather constant over the period up to around the mid to late 19th century and rise massively in response to our emissions. The absence of significant activity from volcanoes can be observed by the absense of jumps in the atmospheric CO2 record as a result of the truly hummungous volcanoes of the last 1000 years (e.g. Santorini, Krakatoa and Tambora). Volcanic activity results in the release of something a ggod bit less than 1% of our current industrial emissions. see, for example, the high resolution atmospheric CO2 record compiled on page 3 of the IPCC summary for policymakers: http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-spm.pdf (see page 3) (iii) Heat from tectonic activity is trivial with respec to greenhouse gas warming. This is one of those fallacious "arguments" that is doing the rounds! The practicioners avoid the three pertinent points. These are: (i) is there any evidence for enhanced tectonic activity during the period of very large warming (especially last 30-odd years)? After all tectonic activity has been occurring for millions of years. Has it suddenly intensified? Evidence please! (ii) how can it be that the areas of which major tectonic activity show little match to areas of temperature increase? For example Iceland is one of the most tectonically active regions on earth. However it is one of the few places on earth that has undergone a tiny bit of COOLING during the period of global warming: e.g. data on the scale and location of Arctic warming over the last 50 years from the Colorado University Arctic research center: http://arctic.atmos.uiuc.edu/CLIMATESUMMARY/2003/IMAGES/annual.1954-2003.tchange.png (iii) the heat released by undersea tectonic activity is around that of the geothermal background. This is around 0.1% of the heat energy from solar/greenhouse activity. e.g. according to Jeff Severinghaus of the Scripps Institution of Oceanography "... the average heat added from volcanoes to the ocean is of order 0.1 Watt per square meter. But the heat added (or removed) to the ocean from the sun and atmosphere is of order 100 Watt per square meter. So it is very hard for volcanoes to compete." So it's not just a question of showing that tectonic activity on the ocean bottom is significant with respect to warming (the evidence indicates it isn't), but of showing that this activity has increased in the last several decades to an extent that can have contributed to warming (the evidence indicates that it hasn't)...
131003. chris at 09:48 AM on 7 October 2008
        It's the sun
        Re #160 Wondering Aloud You state rather cryptically that "The satellite data that was supposed to prove a positive feedback from CO2 causing increased water vapor in fact show the opposite." but that doesn't seem to accord with the facts. The expectation is that as the atmosphere warms, the air will support somewhat higher levels of water vapour (since warm air has a higher saturation point for water vapour than colder air). This results in a feedback warming due to the greenhouse properties of atmospheric water vapour. So has the water vapour concentration increased during the period of massive increase in atmospheric CO2, in response to CO2-driven warming? According to the science the answer seems to be yes (as opposed to your unattributed "no"): Soden BJ et al. (2005) "The radiative signature of upper tropospheric moistening" Science 310, 841-844. Abstract: "Climate models predict that the concentration of water vapor in the upper troposphere could double by the end of the century as a result of increases in greenhouse gases. Such moistening plays a key role in amplifying the rate at which the climate warms in response to anthropogenic activities, but has been difficult to detect because of deficiencies in conventional observing systems. We use satellite measurements to highlight a distinct radiative signature of upper tropospheric moistening over the period 1982 to 2004. The observed moistening is accurately captured by climate model simulations and lends further credence to model projections of future global warming." Santer BD et al (2007) "Identification of human-induced changes in atmospheric moisture content" Proc. Natl. Acad. Sci. USA 104 15248-15253. Abstract: "Data from the satellite-based Special Sensor Microwave Imager (SSM/I) show that the total atmospheric moisture content over oceans has increased by 0.41 kg/m(2) per decade since 1988. Results from current climate models indicate that water vapor increases of this magnitude cannot be explained by climate noise alone. In a formal detection and attribution analysis using the pooled results from 22 different climate models, the simulated "fingerprint" pattern of anthropogenically caused changes in water vapor is identifiable with high statistical confidence in the SSM/I data. Experiments in which forcing factors are varied individually suggest that this fingerprint "match" is primarily due to human caused increases in greenhouse gases and not to solar forcing or recovery from the eruption of Mount Pinatubo. Our findings provide preliminary evidence of an emerging anthropogenic signal in the moisture content of earth's atmosphere." Rind D et al (1991) "Positive Water-Vapor Feedback In Climate Models Confirmed By Satellite Data" Nature 349, 500-503. Abstract: "Chief among the mechanisms thought to amplify the global climate response to increased concentrations of trace gases is the atmospheric water vapour feedback. As the oceans and atmosphere warm, there is increased evaporation, and it has been generally thought that the additional moisture then adds to the greenhouse effect by trapping more infrared radiation. Recently, it has been suggested that general circulation models used for evaluating climate change overestimate this response, and that increased convection in a warmer climate would actually dry the middle and upper troposphere by means of associated compensatory subsidence1. We use some new satellite-generated water vapour data to investigate this question. From a comparison of summer and winter moisture values in regions of the middle and upper troposphere that have previously been difficult to observe with confidence, we find that, as the hemispheres warm, increased convection leads to increased water vapour above 500 mbar in approximate quantitative agreement with the results from current climate models. The same conclusion is reached by comparing the tropical western and eastern Pacific regions. Thus, we conclude that the water vapour feedback is not overestimated in models and should amplify the climate response to increased trace-gas concentrations." Allan RP and Soden BJ (2008) "Atmospheric warming and the amplification of precipitation extremes" Science 321, 1481-1484. Abstract: "Climate models suggest that extreme precipitation events will become more common in an anthropogenically warmed climate. However, observational limitations have hindered a direct evaluation of model- projected changes in extreme precipitation. We used satellite observations and model simulations to examine the response of tropical precipitation events to naturally driven changes in surface temperature and atmospheric moisture content. These observations reveal a distinct link between rainfall extremes and temperature, with heavy rain events increasing during warm periods and decreasing during cold periods. Furthermore, the observed amplification of rainfall extremes is found to be larger than that predicted by models, implying that projections of future changes in rainfall extremes in response to anthropogenic global warming may be underestimated." Note that this effect (atmospheric temperature-induced feedback in atmospheric water vapour concentrations) can also be observed as a result of atmospheric cooling, for example due to rapid volcanic eruption-induced cooling: Soden BJ et al. (2002) "Global cooling after the eruption of Mount Pinatubo: A test of climate feedback by water vapor" Science 296,727-730 Abstract: "The sensitivity of Earth's climate to an external radiative forcing depends critically on the response of water vapor. We use the global cooling and drying of the atmosphere that was observed after the eruption of Mount Pinatubo to test model predictions of the climate feedback from water vapor. Here, we first highlight the success of the model in reproducing the observed drying after the volcanic eruption. Then, by comparing model simulations with and without water vapor feedback, we demonstrate the importance of the atmospheric drying in amplifying the temperature change and show that, without the strong positive feedback from water vapor, the model is unable to reproduce the observed cooling. These results provide quantitative evidence of the reliability of water vapor feedback in current climate models, which is crucial to their use for global warming projections." and so on....
131004. chris at 09:28 AM on 7 October 2008
        It's the sun
        Re #160 Wondering Aloud (and many others) This thread shows a breathtaking absence of skepticism! It's rather awesome the nonsense that some people are willing to swallow in pursuit of a conspiracy theory. Let's look at the "paleorecord" ("water vapour feedback" in following post) THE PALEORECORD for CO2: The scientific analysis of paleoCO2 measurements and paleotemperature measurements are highlighted in numerous reviews and articles that are appended at the bottom of the post. These show a rather strong coupling of paleoCO2 and paleotemperature. Some posters are exercised over historical records described by a German schoolteacher (Beck). They apparently show CO2 measurements that go up and down in an extraordinary manner. Mr Beck assures us of the precision of historical measures of CO2 during the last 180 years. Why might we be skeptical of this weird data with its absolutely massive rapid jumps and falls in CO2? Here's some pretty obvious reasons for skepticism: (i) Beck assures us that the measures were precise (1-3%). But we're really more interested in their ACCURACY with respect to global atmospheric CO2 concentrations. We know that a large proportion of the measurements were made in individual scientists laboratories in cities (Paris, Kew gardens London, Belfast, Clermont Ferrand, Copenhagen, Vienna, Frankfurt, Giessen, Bern, Poona India, Rostock in Denmark, Ames Iowa...etc. etc. etc.). We know that if one goes to a city today and makes CO2 measurements in the air in our city laboratories, large variations in CO2 levels will be recorded, with high values relative to the true atmospheric concentrations. Just as in the 19th and early 20th century, we’re surrounded in cities by CO2 sources (pretty much all transport and heat/cooling generation). See for example point (iii) below. Competent scientists understand the essential difference between PRECISION and ACCURACY. A local CO2 measure may be beautifully precise but wildly inaccurate with respect to the global atmospheric CO2 value. That's where Becks "analysis" is likely to fool the unskeptical. (ii) We can look at this problem of accuracy in more detail by focusing on the individual series of measurements highlighted by Beck. For example, Beck highlights W. Kreutz’s series of very high CO2 measures in 1939/40. These measurements were made just S of the city of Giessen not far from the railway station. Beck fails to point out that Kreutz’s values differ by an astonishing 40 ppm between morning and afternoon (in other words measured atmospheric CO2 values are 40 ppm higher in the afternoons compared to the mornings), that atmospheric CO2 is much lower on windy days compared to windless days and so on. This is all outlined in Kreutz’s paper on the subject (translation available here: http://www.biokurs.de/treibhaus/literatur/kreutz/Kreutz_english.pdf). Clearly atmospheric CO2 measurements in, or near, urban centres give massively high CO2 values however precisely they are measured, the CO2 levels will rise dramatically in the afternoons when everyone and their machines are active, and on windless days when generated CO2 isn’t dispersed, measured CO2 levels will be higher still. That’s all pretty obvious. A skeptic might be expected to notice these rather obvious facts…. It's fascinating that Kreutz identified and postulated that some of the high values and extreme variations in atmospheric CO2 levels in his measurements were due to soil sources and industrial sources...sadly, and rather typically, the data of the honest and comptetent Kreutz has been usurped to support a creepy agenda by the dishonest... (iii) It takes an effort to make truly accurate and unperturbed atmospheric CO2 measurements. Some early practitioners made this effort. Jules Reiset, for example, in the late 19th century, developed a methodology for CO2 measurements taken on the windy Atlantic coast, far from urban centres, and determined values rather similar to those measured in contemporaneous ice cores (around 190-200 ppm in the 1890’s). We can be rather more confident in the ACCURACY of Reiset’s measurements since he (unlike pretty much all other measurers of CO2 in the 19th and early 20th century) identified the clear signature of seasonal variation due to plant growth and decay dominated by the N. hemisphere flora. (iv) We have been observing atmospheric CO2 levels with extraordinary precision and accuracy since the late 1950’s from the Manua Loa observatory, as well as dozens of other locations around the world. Atmospheric CO2 levels simply do not undergo massive jumps of up to 100 ppm over a few years. It beggers belief that CO2 sources could release and reabsorb extraordinarily massive amounts of CO2 (see #4 just below) during a period when we weren’t actually monitoring CO2 levels very well, and yet just when we started to monitor levels with considerable ACCURACY and PRECISION, atmospheric levels immediately stopped jumping around wildly. A skeptic would be inclined to doubt the accuracy of early measurements from urban centres. (v) According to Beck atmospheric CO2 rose and fell with massive jumps/falls of around 100 ppm or more during the early and mid 19th century, and the 1930’s-40s’. Since the pre-industrial level of atmospheric CO2 (around 180 ppm) is rather similar to the entire repository of CO2 in terrestrial plantlife, the assumption is that these 100 ppm jumps/falls over a few years are associated with the rapid loss and regrowth of around half the entire plant biomass on earth? Did we really lose terrestrial plant matter equivalent to the entire Amazon and African rainforests and much of Asia during a few short years, and have these regrow again in a few years afterwards? No. We know this can’t have happened during the 1930’s and 40’s since we were monitoring the terrestrial biosphere already during these years. (vi) we have rather abundant ice core measures of atmospheric CO2. Since these measures of atmospheric CO2 locked within ice are in regions far from centres of CO2 sources (urban/plant growth) they are rather reliable measures of unperturbed and well-mixed atmospheric CO2. These show rather constant levels of atmospheric CO2 near 177 (+/- around 6 ppm) during the period from 1000 AD to the mid 19th century, and then slow gradual rises that merge in the late 1950’s with the directly measured Manua Loa and other modern CO2 measures. One can certainly argue that the ice core measures are averaged, since deposited snow in ice sheets doesn’t compact and trap ice for several years after deposition, such that there is exchange with the atmosphere for some time until the atmospheric sample becomes sealed within bubbles in solid ice. However one can’t really postulate massive rise of atmospheric CO2 apparently to value as high as 470 ppm during the late 1930’s and 1940’s, without some rising of ice core CO2 levels that match this time period. Even if the ice core CO2 values are averaged over several years, high CO2 values would have to appear for this period in the ice cores. They don’t. and so on…. ---------------------------------------------- Here's some of the abundant data that indicates a rather close coupling of paleoCO2 and paleotemperature measurements right through the last 500 million years. D.L. Royer (2006) "CO2-forced climate thresholds during the Phanerozoic" Geochim. Cosmochim. Acta 70, 5665-5675. (this is a review compiles much of the published data) Even more recent studies supplement the information in Royers compilation and cover additional periods with new data sets right through the past several hundreds of millions of years: R.E. Carne, J.M. Eiler, J. Veizer et al (2007) "Coupling of surface temperatures and atmospheric CO2 concentrations during the Palaeozoic era" Nature 449, 198-202 W. M. Kurschner et al (2008) “The impact of Miocene atmospheric carbon dioxide fluctuations on climate and the evolution of the terrestrial ecosystem” Proc. Natl. Acad. Sci. USA 105, 499-453. D. L. Royer (2008) “Linkages between CO2, climate, and evolution in deep time” Proc. Natl Acad. Sci. USA 105, 407-408 Zachos JC (2008) “An early Cenozoic perspective on greenhouse warming and carbon-cycle dynamics” Nature 451, 279-283. Doney SC et al (2007) “Carbon and climate system coupling on timescales from the Precambrian to the Anthropocene” Ann. Rev. Environ. Resources 32, 31-66. Horton DE et al (2007) “Orbital and CO2 forcing of late Paleozoic continental ice sheets” Geophys. Res. Lett. L19708 (Oct. 11 2007). B. J. Fletcher et al. (2008) “Atmospheric carbon dioxide linked with Mesozoic and early Cenozoic climate change” Nature Geoscience 1, 43-48.
131005. chris at 05:21 AM on 7 October 2008
        Solar cycles cause global warming
        Re #3 That's incorrect. Tung and Camp derive a value for the earth's climate sensitivity to raised CO2 that is completely independent of the so-called "IPCC's accepted sensitivity". That's the whole point of their work! They analyze the solar cycle contribution to warming and (according to their analysis) derive an INDEPENDENT measure of the climate sensitivity. Their value is (see equation 2 on line 379 of their manuscript): 2.3 oK < DeltaT(2xCO2) < 4.1 oK In other words according to Tung and Camp, the Earth warms by around 3 oC (plus/minus a bit) for each doubling of atmospheric CO2 concentration. The fact that this value is pretty much in line with all of the other scientific analyses of climate sensitivity (as compiled by the IPCC) is interesting and may be taken as further evidence of a consistent arrival at the climate sensitivity using a number of different methods. But it is an ENTIRELY INDEPENDENT measure and doesn't assume anything whatsoever about "the IPCC"! That's pretty straightforward...
131006. TruthSeeker at 04:15 AM on 7 October 2008
        It's the sun
        You all said that the begining of the year was cooler due to la nina, and that this coolness trend would end July - August. However, August was cooler than the last few years via NOAA. Check the link: http://www.ncdc.noaa.gov/img/climate/research/2008/aug/glob-aug-pg.gif What do you all have to say about this?
131007. Quietman at 01:08 AM on 7 October 2008
        Water vapor is the most powerful greenhouse gas
        Has Global Warming Research Misinterpreted Cloud Behavior? ScienceDaily (June 12, 2008) ["Unfortunately, so far we have been unable to figure out a way to separate cause and effect when observing natural climate variability. That's why most climate experts don't like to think in terms of causality, and instead just examine how clouds and temperature vary together.] - Spencer
131008. chris at 20:45 PM on 6 October 2008
        Climate's changed before
        That's a very odd notion. Odd in two respects. First the enhanced atmospheric water vapour that follows enhanced greenhouse atmospheric warming has been directly measured [*] and some of the consequences with respect to surface humidity and precipitation patterns are already identified in the real world [**]. Secondly, because the "gravity" notion raised in the dodgy website you linked to is a nonsense. Water vapor that partitions in the atmosphere does so according to atmospheric pressure and temperature. As the temperature of the atmosphere rises so does the water vapour concentration. Is this effect countered by gravity? Not to any significant degree. Atmospheric water exists in the atmosphere in the form of individual water molecules. The gravitational force acting on these molecules is extremely small and is opposed by the kinetic energy of the water molecules provided by the ambient thermal energy. It's only if the atmosphere cools a bit and the water vapour concentration rises above the saturation point, that gravity takes a significant macroscopic hold. Then water molecules "aggregate", the water vapour condenses, and gravity then has an effect (it rains!). So not only is the website trying to sell a ludicrous notion, but it's premise is contradicted by real world measurements (see [*] and [**] below. [*] e.g.: Soden BJ et al. (2005) "The radiative signature of upper tropospheric moistening" Science 310, 841-844. Abstract: "Climate models predict that the concentration of water vapor in the upper troposphere could double by the end of the century as a result of increases in greenhouse gases. Such moistening plays a key role in amplifying the rate at which the climate warms in response to anthropogenic activities, but has been difficult to detect because of deficiencies in conventional observing systems. We use satellite measurements to highlight a distinct radiative signature of upper tropospheric moistening over the period 1982 to 2004. The observed moistening is accurately captured by climate model simulations and lends further credence to model projections of future global warming." Santer BD et al (2007) "Identification of human-induced changes in atmospheric moisture content" Proc. Natl. Acad. Sci. USA 104 15248-15253. Abstract: "Data from the satellite-based Special Sensor Microwave Imager (SSM/I) show that the total atmospheric moisture content over oceans has increased by 0.41 kg/m(2) per decade since 1988. Results from current climate models indicate that water vapor increases of this magnitude cannot be explained by climate noise alone. In a formal detection and attribution analysis using the pooled results from 22 different climate models, the simulated "fingerprint" pattern of anthropogenically caused changes in water vapor is identifiable with high statistical confidence in the SSM/I data. Experiments in which forcing factors are varied individually suggest that this fingerprint "match" is primarily due to human caused increases in greenhouse gases and not to solar forcing or recovery from the eruption of Mount Pinatubo. Our findings provide preliminary evidence of an emerging anthropogenic signal in the moisture content of earth's atmosphere." Rind D et al (1991) "Positive Water-Vapor Feedback In Climate Models Confirmed By Satellite Data" Nature 349, 500-503. Abstract: "Chief among the mechanisms thought to amplify the global climate response to increased concentrations of trace gases is the atmospheric water vapour feedback. As the oceans and atmosphere warm, there is increased evaporation, and it has been generally thought that the additional moisture then adds to the greenhouse effect by trapping more infrared radiation. Recently, it has been suggested that general circulation models used for evaluating climate change overestimate this response, and that increased convection in a warmer climate would actually dry the middle and upper troposphere by means of associated compensatory subsidence1. We use some new satellite-generated water vapour data to investigate this question. From a comparison of summer and winter moisture values in regions of the middle and upper troposphere that have previously been difficult to observe with confidence, we find that, as the hemispheres warm, increased convection leads to increased water vapour above 500 mbar in approximate quantitative agreement with the results from current climate models. The same conclusion is reached by comparing the tropical western and eastern Pacific regions. Thus, we conclude that the water vapour feedback is not overestimated in models and should amplify the climate response to increased trace-gas concentrations." [**] e.g.: Zhang XB (2007) "Detection of human influence on twentieth-century precipitation trends" Nature 448, 461-465. Abstract: "Human influence on climate has been detected in surface air temperature(1-5), sea level pressure(6), free atmospheric temperature(7), tropopause height(8) and ocean heat content(9). Human-induced changes have not, however, previously been detected in precipitation at the global scale(10-12), partly because changes in precipitation in different regions cancel each other out and thereby reduce the strength of the global average signal(13-19). Models suggest that anthropogenic forcing should have caused a small increase in global mean precipitation and a latitudinal redistribution of precipitation, increasing precipitation at high latitudes, decreasing precipitation at sub-tropical latitudes(15,18,19), and possibly changing the distribution of precipitation within the tropics by shifting the position of the Intertropical Convergence Zone(20). Here we compare observed changes in land precipitation during the twentieth century averaged over latitudinal bands with changes simulated by fourteen climate models. We show that anthropogenic forcing has had a detectable influence on observed changes in average precipitation within latitudinal bands, and that these changes cannot be explained by internal climate variability or natural forcing. We estimate that anthropogenic forcing contributed significantly to observed increases in precipitation in the Northern Hemisphere mid-latitudes, drying in the Northern Hemisphere subtropics and tropics, and moistening in the Southern Hemisphere subtropics and deep tropics. The observed changes, which are larger than estimated from model simulations, may have already had significant effects on ecosystems, agriculture and human health in regions that are sensitive to changes in precipitation, such as the Sahel." Allan, R P & Soden, B J (2008) Atmospheric warming and the amplification of precipitation extremes" Science 321, 1481-1484. Abstract: "Climate models suggest that extreme precipitation events will become more common in an anthropogenically warmed climate. However, observational limitations have hindered a direct evaluation of model- projected changes in extreme precipitation. We used satellite observations and model simulations to examine the response of tropical precipitation events to naturally driven changes in surface temperature and atmospheric moisture content. These observations reveal a distinct link between rainfall extremes and temperature, with heavy rain events increasing during warm periods and decreasing during cold periods. Furthermore, the observed amplification of rainfall extremes is found to be larger than that predicted by models, implying that projections of future changes in rainfall extremes in response to anthropogenic global warming may be underestimated."
131009. Patrick 027 at 15:36 PM on 6 October 2008
        Volcanoes emit more CO2 than humans
        Quietman, "Re: 3 The pole remains in the Arctic yes but the amount of direct sunlight changes with the angle of attack." Yes - this much is a widely understood aspect of Milankovitch cycles. "Re: 2 I disagree here. But as with any hypothesis there is room for doubt. This is under study so I am content to wait on the outcome." If you could find articles which specify changes in time (of geologic activity, aside from major eruptions above water, of course) correlated with any climate changes on the scale of years to millenia, I'd very much like to see it. Clarification - as I recall now, there was some speculation about possible temporal changes in geothermal heating of ice at two locations - somewhere in northern Greenland, and somewhere in West Antarctica. In each case it appeared to be only speculation, though. And I don't think those could have enough regional or global significance to account for much of recent climate changes. (With all the volcanos in the world, certainly a few could just happen to change just as anthropogenic emissions are becoming a big player, but it would seem quite a coincidence if enough volcanos in the right areas happened to change activity to have regional and global climatic significance at this time and yet not for some longer period of time prior to now (as inferred by paleoclimatic records and ice sheet conditions, etc.))
131010. Quietman at 13:00 PM on 6 October 2008
        Does Urban Heat Island effect add to the global warming trend?
        any s/b and
131011. Quietman at 12:57 PM on 6 October 2008
        Does Urban Heat Island effect add to the global warming trend?
        Philippe You are missing the point that I was trying to make. By calling this "Global Warming" instead of "Climate Change" the natural reaction for people unaffected is "what warming?" any there are obviously a lot of people in this category. I have heard it called "Climate Shift" also. Shift or Change describes what is happening much better than Global Warming and is accurate. Global means all, the entire planet. But it is not all, not the entire planet and this causes a psycological rejection of the concept.
131012. Philippe Chantreau at 11:13 AM on 6 October 2008
        Does Urban Heat Island effect add to the global warming trend?
        Quietman, I have lived in the Alps and I have seen significant difference in the ski season: duration, accumulation, altitude making a ski area viable etc... Wine growers in England do not need news to tell the difference. There are many more examples opposite to your experience. I'm not sure that having more faith in individual anecdotal reports than in observers and their equipment is necessarily wise.
131013. Adamski at 08:45 AM on 6 October 2008
        Climate's changed before
        Very interesting read here...haven't heard anything about water vapour feedback yet. Enlighten me if what i say is wrong but are the IPCC models flawed in that their water vapour feedback element is missing out on a rather unavoidable factor in gravity. Douglas Hoyt discusses here http://www.warwickhughes.com/hoyt/wvfeedback.htm about how overestimated the water vapour feedback is in the IPCC models. I take the side of the devil's advocate and say that it seems the IPCC has jumped on a bandwagon and is trying to make it work their way...but it isn't.
131014. Quietman at 04:50 AM on 6 October 2008
        Is Antarctic ice melting or growing?
        DB2 Re: "(a warmer world is also a more humid world)" This is something that I have seen (and measured when I was still working). And warm+humid+CO2=better and faster plant growth (which is something I have taken personal notice of even though it has not been any warmer than normal).
131015. Quietman at 04:41 AM on 6 October 2008
        Volcanoes emit more CO2 than humans
        Patrick Much better, thank you. Re: 1 Magnetic orientation for birds etc. may simply be lines of force rather than a true polarity orientation. A reversal likely has little effect but shift does to some extent, I would not expect extinctions however. Re: 2 I disagree here. But as with any hypothesis there is room for doubt. This is under study so I am content to wait on the outcome. Re: 3 The pole remains in the Arctic yes but the amount of direct sunlight changes with the angle of attack. Re: 4 I am uncertain of this, which is why I am here.
131016. Quietman at 04:26 AM on 6 October 2008
        Does Urban Heat Island effect add to the global warming trend?
        PPS But photographs of the Arctic and Antarctic do tell a story.
131017. Quietman at 04:25 AM on 6 October 2008
        Does Urban Heat Island effect add to the global warming trend?
        PS Measurements differ by point and instrumentation. It is a large planet and I have little faith in the observers or the designer's of their equipment.
131018. Quietman at 04:22 AM on 6 October 2008
        Does Urban Heat Island effect add to the global warming trend?
        chris That at least makes sense. But personal anecdotes based on the known freezing point of water are indeed relavent. The reason so many people do not believe in GW is infact that it isn't global. They see zero warming. I have yet to live in an area that has warmed other than NJ where it was noticable close to NYC. Here in PA there has not been any warming trend. The only way I know it's actually warming is from reading the news on the web. It is a perception issue for most people.
131019. Patrick 027 at 10:12 AM on 5 October 2008
        Volcanoes emit more CO2 than humans
        ... aside from that: 1. Unclear that recent changes in Earth's magnetic field are anything unusual over the same time period in which recent climate changes are unusual. (**PS I'd be curious to see if the previous changes in magnetic field, either in strength of dipole or actual reversals, correspond in any significant way with the paleoclimatic record, or anything else. One would think it could affect some species (birds, turtles?), though there is no evidence of enhanced extinction rates during reversals, as far as I know). 2. While new discoveries are made about submarine volcanic activity, there hasn't been a discovery of temporal changes in this, either significantly correlated to ENSO or other climate variability, or to global warming, and the same for volcanic activity in general - (except perhaps for the going into and out of a ~quiet period with respect to explosive volcanism above water, which wouldn't explain global warming of the last 100 years but apparently has influence (But not control) over ENSO). 3. As far as I know, the torques on Earth that contribute to two of the Milankovitch cycles do not result in true polar wander - the rotational axis changes orientation but the whole body of the Earth shifts with it, so the North pole remains in the Arctic over such cycles. 4. anthropogenic greenhouse forcing may be a little less than 2 % of the total greenhouse 'forcing' (including water vapor and clouds), but the small size of that proportion may not mean what some may think; a total forcing (greenhouse + albedo) that in terms of globally averaged radiative forcing would be somewhere between 3 % and 5 % of the same total greenhouse 'forcing' accounts for the global warming between the last ice age and preindustrial climate.
131020. DB2 at 09:38 AM on 5 October 2008
        Is Antarctic ice melting or growing?
        A net loss of 25 Gt per year is a lot better than the 150 of Velicogna. It is true that the models predict over the course of this century that the deposition in Antarctica will be larger than the melting (a warmer world is also a more humid world).
131021. chris at 08:15 AM on 5 October 2008
        Is Antarctic ice melting or growing?
        It's worth pointing out that Wingham et all's analysis referred to in post #3 covers only 72% of Antarctica. In fact in a more recent review Wingham and Shepherd conclude that there is a net mass loss from Antarctica, and that these are dominated by ice dynamics at the continental margins: A. Shepherd and D. Wingham (2007) "Recent Sea-Level Contributions of the Antarctic and Greenland Ice Sheets" Science 315, 1529-1532. http://www.sciencemag.org/cgi/content/abstract/315/5818/1529 e.g. they state: "It is reasonable to conclude that, today, the EAIS (East Antarctic Ice Sheet) is gaining some 25 Gt year–1, the WAIS (West AIS) is losing about 50 Gt year–1, and the GIS (Greenland) is losing about 100 Gt year–1. These trends provide a sea-level contribution of about 0.35 mm year–1, a modest component of the present rate of sea-level rise of 3.0 mm year–1. Because 50 Gt year–1 is a very recent contribution, the ice sheets made little contribution to 20th-century sea-level rise. However, what has also emerged is that the losses are dominated by ice dynamics. Whereas past assessments (47) considered the balance between accumulation and ablation, the satellite observations reveal that glacier accelerations of 20 to 100% have occurred over the past decade. The key question today is whether these accelerations may be sustained, or even increase, in the future." The latter really is the key question. No one is particulary concerned about the possibility of massive Antarctic melt, and so far (as Shepherd and Wingham indicate) the losses are marginal....in my understanding it's generally been assumed that snow deposition at the high altitude central regions will more or less balance surface melt/glacier discharge at the margins. However the more vulnerable West Antarctic Ice Sheet has the potential to raise sea levels considerably if a significant melt occurred there.
131022. DB2 at 07:21 AM on 5 October 2008
        Is Antarctic ice melting or growing?
        Here is another approach to Antarctic ice measurements by Wingham et al. www.cpom.org/research/djw-ptrsa364.pdf They use satellite radar altimetry to determine the ice thickness for the 11 years from 1992 to 2003, which show the ice sheet growing at 5mm per year. They then use density estimates and arrive at a net increase in mass of 27 Gt per year.
131023. chris at 06:56 AM on 5 October 2008
        Can animals and plants adapt to global warming?
        Re #39 Mizimi, Since pretty much all of science and most economists and corporate and government leaders and so on consider that if will be increasingly more damaging to our economies to ignore the problem of massive man-made enhancement of the Earth's greenhouse effect than it will be to mitigate the effects through greenhouse gas emission reduction programmes, it's not really a choice of unknowns. We know things are going to become increasingly problematic in a warming world (enhanced drought, increased adverse weather effects, rising sea levels threatening massive coastal populations and industrial infrastructure, species extinctions, water restrictions and resulting conflicts and so on). The point is that global warming is already having adverse effects on many millions of people. So far they're largely the "readily ignorable" in Africa and other low latitude regions where global warming is already enhancing water shortages and agricultural disruption. Addressing this problem by taking mature and rational measures to limit greenhouse gas production, especially by developing and implementing alternative energy sources will benefit everyone. So your notion of choice based on an ill-informed presumption of uncertainty just doesn't accord with the informed view. And the idea of "deciding which species should be preserved" is also a fallacious one. We recognise that we are impoverished both economically and as human beings as the natural world degrades around us. The aim is to preserve the biosphere to a maximum extent (which is very widely recognised). Witness the efforts to enhance no-fishing zones to preserve ocean biodiversity (and it's obvious economic benefits) and to increase the numer and extent of wildlife preserves. These efforts will only be successful on a large scale if efforts are also made (as they are) in developing the sustainable energy sources that constitute the only possible future for mankind. So self-preservation also informs us to act rationally to limit our greenhouse gas emissions.
131024. chris at 06:36 AM on 5 October 2008
        Can animals and plants adapt to global warming?
        Re #40 HealthySkeptic Yes, as you indicate, the Earth's global temperature is intimately linked with the atmospheric greenhouse gas concentration. As you intimate, that's an inescapable conclusion of an abundant and growing body of science. However your finishing pondering is rather misplaced. The present massive outpouring of greenhouse gases from our emissions is a concern for the coming decades and few centuries. I think we can leave our descendants of 50,000 years down the road to look after themselves! After all Homo sapiens has only roamed the earth for around 200,000 years, mankind was only just dabbling in the earliest forms of agriculture, animal husbandry and early "permanent" settlements around 20,000 years ago (during the last glacial period, in fact) and recorded civilisation only goes back a few thousand years. If we look after ourselves and the rest of the biosphere over the next decades and few hundreds of years, there's a pretty good chance that our 50,000-year hence descendants may be in good shape to deal with the next major Milankovitch cycle.... ...or maybe not...who can say what might accrue in the vast period of "meantime" between now and then!
131025. chris at 06:23 AM on 5 October 2008
        Can animals and plants adapt to global warming?
        Quietman, you've made three errors in your short sequential posts. Re #41: You've mixed up "evolution" with "extinction". Evolution does favour species with appropriate adaptations. However extinction events are rather less discriminate in their effects on species survival. Many (perhaps all) of the cataclysmic extinctions in the past are well-associated with marked global-scale warming at a rate that overpowers the adaptability of species. This is what the biosphere faces now, just as in the past. Re #42: Of course the greenhouse isn't a hypothesis. It's been known since the mid 19th century (since the time of Tyndall and others) that the black body temperature of the Earth is around 30 oC colder than our extant temperature. Without our greenhouse effect there would be no liquid water on the surface of the Earth. That's not a hypothesis. That's a fact. Let's not pretend that we don't know what we do know. Atmospheric CO2 is a greenhouse gas and contributes to the Earth's warmth. If the atmospheric concentration of CO2 rises, so does the Earth's equilibrium temperature, all else being equal. Re #43: You're mistaken. Perhaps you haven't read the papaers or are unfamiliar with the science. All of the papers I've cited report independent measures of paleotemperature and paleoCO2. They make no assumptions whatsoever about "the sensitivity" and have nothing to do with "the IPCC". There's no point in saying stuff that is simply not true Quietman.
131026. chris at 05:39 AM on 5 October 2008
        Does Urban Heat Island effect add to the global warming trend?
        Re #5 Quietman, I expect that it doesn't "show up" because the NASA data is obtained from measurements rather than from personal anecdotes! In any case Southern California hasn't warmed that much in living memory. Less than 1 oC overall and if one focuses on the winter (when your pipes would have frozen) there hasn't been significant warming in Southern CA at all since the 1930's, for example. All of this does show up in the data from NASA. You can accss this yourself very interactively. Try: http://data.giss.nasa.gov/gistemp/maps/ where you can create your own spatially-resolved maps defining the measured temperature change over any specified period. You can analyze this by month, by season or annually. You'll see that Southern CA has been an oasis of cool during the winter months....
131027. Patrick 027 at 05:31 AM on 5 October 2008
        Volcanoes emit more CO2 than humans
        "I have read your argument a dozen times" Wow! Thanks for the effort! I suppose it would have been helpful if I had written a summary. TIDES ON EARTH: Outside of oceanic effects (and maybe a few glaciers at sea level), too weak to expect a significant effect on: 1. mantle convection and the overall rate of plate motions (which can't change fast anyway). 2. earthquakes and volcanic activity - at least in the longer term trends (as opposed to variations over cycles of 1/2 day, day, 1/2 month, month, etc.), if not even in those shorter term cycles. 3. the Geodynamo and outer core motion 4. the atmosphere, ionosphere (including E-region dynamo, in the base of the thermosphere), and magnetosphere (except in the magnetotail at those times of the month when the moon actually would get near or intersect it, although even then, on further reading it seems the magnetic forces on charged particles with the kinds of energies involved would overwhelm gravitational effects - and also, outside of the monthly and ~18-year cycles, what effect could that have, and even then, what would the significance of that be to Earth?) And where the tides have a significant effect, how would that effect relate to climate changes over a ~100 year period (as opposed to a ~ 20 year period or especially a 1/2-month (spring to neap to spring again)period)? TIDES CENTERED ON SUN (due to planets): far too weak to expect significant effect on: 1. solar convection or solar dynamo, and hence, 11-year sunspot cycle, other related phenomena including TSI variations 2. solar wind and interplanetary magnetic field (except, for effects on Earth, perhaps when Earth get's near the wake of Venus or Mercury, - **although most of that effect wouldn't actually be from the gravity of Mercury or Venus - and what effect could it be?) - this is especially considering the case considering the much much larger variations that do occur in solar wind density and velocity... TIDES ON SUN VS 'SOLAR JERK', FAIRBRIDGE CYCLE: I had thought that if the there was a correlation of solar TSI or solar wind and magnetic field to the solar jerk, it would be because they would both be correlated to the tides on the sun, which might have an effect on solar TSI, wind, and magnetic field (though an insigificant effect for our purposes, from my reasoning). The solar jerk is just the changing free-fall of the sun so it is hard to see how that would affect solar activity (as I explained elsewhere). However, it is interesting that while both such tides and 'jerk' depend greatly on Jupiter, the jerk depends also on the other gas giants due to their mass and distance, and the contribution of the 4 inner planets is tiny in comparison, whereas the three most important planets after Jupiter for the tides on the Sun are Venus, Earth, and Mercury. ---- ... Further reading on magnetosphere, solar wind...: (PS I have only browsed many of the following, with one noted exception): http://en.wikipedia.org/wiki/Magnetosphere http://en.wikipedia.org/wiki/Magnetosphere_particle_motion http://en.wikipedia.org/wiki/Guiding_center but of course one must be careful with wikipedia (their article on tides suggests the human menstrual period could be an evolutionary artifact of distant sea-dwelling ancestors' adaptations to tidal cycles, when in fact this doesn't seem likely at all, particularly considering the menstrual cycle periods of our closer relatives - it is just a coincidence) - on the other hand, it is possible to figure out whether or not the math and physics work out as such. But also: http://www-ssc.igpp.ucla.edu/ssc/tutorial/magnetosphere.html (which I have read completely) http://farside.ph.utexas.edu/teaching/plasma/lectures/lectures.html http://www-istp.gsfc.nasa.gov/Education/Intro.html ----- On a possible connection of oceanic tides to climate: http://www.pnas.org/content/94/16/8321.full I think there was a related article to the above, which focussed on a correlation of shorter term variability to oceanic tidal forcing. I haven't read through these closely enough to see just how much variability in tidal forcing there is relative to the tidal forcing itself - the largest I do expect is the spring-neap variation, but there are other variations... but I expect they are smaller especially in the long term variations - so I am arguing that oceanic tidal variations are significant in climate variations on the multidecadal to century to millenial or beyond timescale, but it is interesting to consider. I don't think the authors would or could argue that this could account for the warming of the last few decades...
131028. Quietman at 04:55 AM on 5 October 2008
        Is Antarctic ice melting or growing?
        There are conflicting data coming from Antarctica. DB2 makes a very valid point. One of the articles I read stated that Antarctica rebound is uneven because increased ice on one side forcing that plate down while the melting side rebounds. I forget which one but I do remember putting a link to the article in the volcano thread.
131029. Quietman at 04:49 AM on 5 October 2008
        Can animals and plants adapt to global warming?
        PPS The cited papers assumes that the sensitivity is as the IPCC hypothesizes. When reading ANY paper dealing with GHGs, keep in mind that sensitivity is still hypothetical, not proven fact.
131030. Quietman at 04:47 AM on 5 October 2008
        Can animals and plants adapt to global warming?
        PS The greenhouse is a good hypothesis but unproven as theory, ie. it is properly referred to as the "greehouse hypothesis".
131031. Quietman at 04:44 AM on 5 October 2008
        Can animals and plants adapt to global warming?
        Chris Short answer is that animals that have overspecialized are at risk but those that have retained generic traits will adapt. This is the rule in evolution.
131032. Quietman at 04:41 AM on 5 October 2008
        Volcanoes emit more CO2 than humans
        Patrick Sorry, I have read your argument a dozen times trying to see your logic but I simply can't. I am afraid it's too abstract for me.
131033. Quietman at 04:36 AM on 5 October 2008
        Does Urban Heat Island effect add to the global warming trend?
        OK, hold on. I lived outside of and worked in LA in the late 90's. At the turn of the century my pipes froze on the roof. I asked why they installed a system without taking freezing into consideration and the answer was it never froze before (within their lifetime). LA was hot (for me at least since I grew up in NY) but the rural areas I found comfortable but my neighbors (native californians) complained it had been getting colder over the years. Why does this not show up in the data from NASA?
131034. chris at 03:48 AM on 5 October 2008
        Models are unreliable
        Re #53 Dan Pangburn You are pursuing a very vague point about warming feedbacks, which you assert, in contradiction to the scientific data, don't exist. You haven't explained your argument for this other than to state the likes of (paraphrasing) "look at this ice core data - clearly feedbacks don't exist - it seems obvious, even trivial, to me." But what seems obvious, even trivial, to you, may simply be another example of misunderstanding of the science. It's simply not possible to maintain the deceit that CO2-induced atmospheric warming (or atmospheric warming from any source) doesn't result in a positive feedback from enhanced water vapour concentrations. That's really beyond dispute. So you need to try to explain rather more explicitly why you don't believe in feedbacks. I have a feeling that your particular Engineering background may have confused you over the meaning of "feedback" as applied in Engineering compared to that used in Ocean and Atmospheric Physics. But we won't know that unless you are rather more specific about your problem. Notice, by the way, that GCM's are certainly not "the only indicator that...human produced carbon dioxide is causing global warming". That's a very odd thing to say. The reason that CO2-induced warming is included in GCM's is because the physics of the greenhouse effect is rather well understood. You've rather put the cart before the horse!
131035. chris at 03:35 AM on 5 October 2008
        Models are unreliable
        re #54 Dan Pangurn is wrong again, and compounds his errors with another piece of gross misrepresentation of the science. Since Dan is pursuing these misrepresentations of the science in support of fallacious interpretations, it isn’t really “off-topic” to address them! Dan Pangburn’s nebulous point about “feedbacks” isn’t well-defined (he hasn’t really explained his problem)…we can look at that in a seperate post. Dan makes a weasel defence in his post #53 that my “disagreement is with the data” and not with him. That’s nonsense, of course. The data is fine. Dan has just cherry-picked and misrepresented it horribly. Let’s have a look again: (i) There is a vast wealth of data on millennial scale paleotemperature proxy data (see links/citations at bottom of post). To assess globally averaged paleotemperatures, competent and honest scientists use as many validated paleotemperature records as possible, using as many data points as possible, using a range of different paleotemperature proxies, from as many places on Earth as possible. Dan selected ONE data point from ONE record, from ONE location on Earth, and attempted to pursue the deceit that this indicates that the global temperature was warmer than now 400 years ago. There’s nothing wrong with the dataset. Dan has just grossly misused it by an extraordinary piece of cherry-picking. (ii) There is a wealth of data on the relationship between paleoCO2 and palaeotemperature in the deep past (see citations in my posts #46 and #48 above). These cover vast periods of the entire Phanerozoic and indicate a strong temperature/CO2 coupling throughout the last 500 million years. Dan selected ONE time period in which there is evidence of a cold Earth, and attempted to sell the notion that there is a disconnect between paleotemperature and paleoCO2. Unfortunately, there isn’t a paleotemperature proxy for this period (late Ordovician), and so Dan Pangburn’s interpretation is fallacious. (iii) Dan Pangburn has added to his set of fallacious interpretations with another piece of cherrypicking. There are many studies on paleotemperature variation throughout the last 1000-2000 years (see citations/links at bottom of the post), and these uniformly indicate that current temperatures are well above those of the past 1000 (and up to 2000) years. Dan has selected one study published in a non-science magazine whose editor openly admits to publishing non-science in pursuit of dubious agendas. Let’s look at Loehle’s paper that Dan Pangburn linked to in his post #53: According to Dan “It shows that the Medieval Warm Period, which was before the industrial revolution, probably reached higher average global temperatures than now and the steepest recent (around 1990) rate-of-change trend is about the same as it was at 4 other times in the last 800 years”. Neither of these is true; let’s see why: (a) If anyone has bothered to follow Dan’s link to the Loehle paper in “Energy and Environment”, you can see that the paper comes with a CORRECTION. There are several things that Loehle has had to correct, one of the more blatant ones being a shift in the entire data series back by around 50 years. Loehle’s original data set extended to around 2000; in the correction the data sets extend to around 1950. What’s going on there?? The answer is a bit of incompetence. Since scientists are compiling paleodata all the time, it makes sense to reference these to a common year. So when a paleodata point is dated as 1000 BP, with BP meaning “Before Present”, “Present” does not mean 2008 (or 2009 or 2010 or 2015 and so on), unless specifically indicated. In fact the convention is to use 1950 as the “Present”, so that all data sets are referenced to a common year and can thus be compared by simple juxtaposition. Loehle apparently didn’t realize this! What does this mean for Dan Pangburn’s assertion that Loehle’s “data” shows that the Medieval Warm Period (MWP) was probably globally warmer than now? It means that it’s another fallacious misinterpretation. Since Loehle suggests that the MWP might have been 0.3 oC warmer than 1950, and the globally averaged temperatures are now 0.5-0.6 oC above 1950 temperatures (e.g. NASA GISS temperature data), it’s clearly warmer now than during the MWP, even using Loehle’s decidedly dodgy analysis [see (b) and (c)]. How could Loehle publish such a nonsense? The answer is that Energy and Environment isn’t a science journal. It only pretends to be one. It’s a repository for stuff that supports the weird agenda of its Editor. The papers aren’t peer-reviewed, and so ludicrous errors aren’t picked up. In their defense they have issued a correction to Loehle’s paper. Unfortunately, as in many instances where agenda-led nonsense is subsequently corrected or debunked, the corrections may go un-noticed, and unscrupulous individuals seem happy to ignore them anyway….. Two other quick points: (b) Dan Pangburn talks about rates of temperature change, and suggests that Loehle’s data indicates that current/recent rates of temperature change are not anomalous. He says: “…. and the steepest recent (around 1990) rate-of-change trend is about the same as it was at 4 other times in the last 800 years”. Sadly, Dan has messed up yet again. Remember that Loehle made a silly boo-boo with his timescale. His data only goes up to the year 1950. The “steepest recent (around 1990) rate of change trend..” that Dan refers to is now “around 1940” in Loehle’s corrected data. In fact even using Loehle’s dubious data it’s clear that the rate of temperature increase we’ve seen during the last 30-odd years is very much faster than any time in the last 800 years (see Wikipedia link just below, for example). If one examines the science as opposed to nonsense, the paleotemperature data demonstrate that the late 20th century temperature rise is much faster than anything in the past 1000 years: http://en.wikipedia.org/wiki/Image:1000_Year_Temperature_Comparison.png (or look at the papers cited below). Since Loehle completely omits the last around 60 years of temperature rise from his analysis/presentations, the scale of the large post-1950’s temperature rise that rather dominates the record is completely lost! (c) It’s worth pointing out that apart from Loehle’s rather ludicrous error highlighted above, his data analysis is extremely dodgy. Two things are worth highlighting. For example, much of Loehle’s very limited data sets are extremely sparse in both time and location. A large chunk of the data involves data points averaged over huge time periods (e.g. a time point every 100 years). Clearly while one can “join up the points”, it’s impossible to say anything about rates of temperature change with grossly averaged data. Where spatially widespread data are used (e.g. Viau et al’s N. America composite from pollen analysis) the data actually show rather small temperature variation before the 20th century, not just for the past 1000 years, but during the 7-8000 years before the 20th century (e.g. Viau et al state “Our results show millennial-scale climate variability on the order of +/- 0.2 oC during the entire Holocene at the North American scale”; we’ve had approaching 1 oC of warming over the same region just in the last 30-odd years). One could highlight more of the dreary errors in Loehle’s analysis and Dan’s interpretations. But what’s the point? Surely if we are interested in what the science shows, we address the science published in the scientific literature. We don’t ignore the science and hunt around for dodgy nonsense from dubious sources. --------------------------------------------------Here’s some of the abundant paleotemperature data covering the last 1-2000 years: The published data from multiple sources of published scientific research is compiled by the NOAA and can be found here: http://www.ncdc.noaa.gov/paleo/recons.html Wikipedia has a reasonably good account of this data, and an overlay of many of the paleotemperature proxy data can be found here: http://en.wikipedia.org/wiki/Image:1000_Year_Temperature_Comparison.png recent papers with datasets/analyses that may not be in the Wikipedia compilation are: M. E. Mann et al (2008) “Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia” Proceedings of the Natl. Acad. Sci. USA 105:13252-13257; D'Arrigo RD, Wilson R, Jacoby G (2006) “On the long-term context for 20th century warming.” J Geophys Res 111:D03103. Hegerl GC et al (2007) “Detection of human influence on a new, validated 1500 year temperature reconstruction.” J Clim 20:650–666. Lee TCK, Zwiers FW, Tsao M (2008) “Evaluation of proxy-based millennial reconstruction methods.” Clim Dyn 31:263–281. Viau, AE et al (2006) “Millennial-scale temperature variations in North America during the Holocene” J. Geophys. Res. 111, D09102.
131036. DB2 at 01:51 AM on 5 October 2008
        Is Antarctic ice melting or growing?
        Do take the results of the Velicogna paper with some caution. (2006, by the way, not 2007). The results depend entirely on their modeling of post-glacial rebound (PGR). They write that the PGR contribution is much larger than the uncorrected GRACE trend. In fact, a "significant ice mass trend does not appear until the PGR contribution is removed." Other inputs depend upon a lot of modeling rather than direct measurements, such as continental hydrology outside Antarctica and and ocean mass variability and atmospheric mass estimates. In addition the period modeled was little more than three years. Ramillien et al. also used GRACE data from 2002-05 (and whose estimates at 40 cubic km/yr are quite a bit lower than Velicogna) conclude that "Due to the very short sampling time span for which the GRACE data are available, it is not yet possible to distinguish between interannual oscillations and long-term trend associated with climate change." DB
131037. chris at 10:08 AM on 3 October 2008
        What does CO2 lagging temperature mean?
        Re #27 Mizimi When presented with a ludicrous and blatantly incorrect paleotemperature "graph" of unknown provenance you consider it a "beautiful example to show there IS a limit to which CO2 can effect temperature changes.....(your post #16). However when presented with copious scientific data on the straightforward relationship between atmospheric paleo CO2 levels and paleotemperature (see my post #25) you suddenly lose your enthusiasm. Apparently you prefer nonsense that supports some sort of agenda position in preference to the science...try re-reading my post #26 on the nature of skepticism. Your "sub" point about paleo-warmth is unfortunately misplaced. In fact the evidence indicates that the warm periods in the past have been associated with lower biodiversity [***] and that it is the rapid increases in global warmth, largely associated in the past with tectonic events, that have been the drivers of major extinctions throughout Earth's history[*****]: [***]PJ Mayhew et al. (2007) A long-term association between global temperature and biodiversity, origination and extinction in the fossil record Proceedings of The Royal Society B 275, 47–53. Abstract: "The past relationship between global temperature and levels of biological diversity is of increasing concern due to anthropogenic climate warming. However, no consistent link between these variables has yet been demonstrated. We analysed the fossil record for the last 520Myr against estimates of low latitude sea surface temperature for the same period. We found that global biodiversity (the richness of families and genera) is related to temperature and has been relatively low during warm 'greenhouse' phases, while during the same phases extinction and origination rates of taxonomic lineages have been relatively high. These findings are consistent for terrestrial and marine environments and are robust to a number of alternative assumptions and potential biases. Our results provide the first clear evidence that global climate may explain substantial variation in the fossil record in a simple and consistent manner. Our findings may have implications for extinction and biodiversity change under future climate warming." [*****]Major extinctions are associated with long lived perturbation of the climate system and the atmosphere. For example the early Jurassic extinction is associated with events (greenhouse gas induced warming) lasting 200,000 years: Svensen H et al (2007) Hydrothermal venting of greenhouse gases triggering Early Jurassic global warming Earth Planetary Sci Lett 256 554-566 Abstract: "The climate change in the Toarcian (Early Jurassic) was characterized by a major perturbation of the global carbon cycle. The event lasted for approximately 200,000 years and was manifested by a global warming of similar to 6 degrees C, anoxic conditions in the oceans, and extinction of marine species. The triggering mechanisms for the perturbation and environmental change are however strongly debated. Here, we present evidence for a rapid formation and transport of greenhouse gases from the deep sedimentary reservoirs in the Karoo Basin, South Africa......." likewise comprehensive analyses of the coincidence of major tectonic events, and resulting elevation of greenhouse gas levels, are associated with several of the major extinctions of the last 300 million years. Note that CO2 isn't the only player. Methane is implicated in several of these events (see especially the PETM below) and sulphurous oxides and their effects on ocean acidity and oxygen content are also implicated: Wignall P (2005) The link between large igneous province eruptions and mass extinctions Elements 1, 293-297 Abstract: "In the past 300 million years, there has been a near-perfect association between extinction events and the eruption of large igneous provinces, but proving the nature of the causal links is far from resolved. The associated environmental changes often include global warming and the development of widespread oxygen-poor conditions in the oceans. This implicates a role for volcanic CO2 emissions, but other perturbations of the global carbon cycle, such as release of methane from gas hydrate reservoirs or shut-down of photosynthesis in the oceans, are probably required to achieve severe green-house warming. The best links between extinction and eruption are seen in the interval from 300 to 150 Ma. With the exception of the Deccan Trap eruptions (65 Ma), the emplacement of younger volcanic provinces has been generally associated with significant environmental changes but little or no increase in extinction rates above background levels." R. J. Twitchett (2006) The palaeoclimatology, palaeoecology and palaeoenvironmental analysis of mass extinction events Palaeogeog., Palaeoclimatol., Palaeoecol. 232, 190-213 concluding paragraph: "Mass extinction studies have enjoyed a surge in scientific interest of the past 30 years that shows no sign of abating. Recent areas of particular interest include the palaeoecological study of biotic crises, and analyses of patterns of post-extinction recovery. There is good evidence of rapid climate change affecting all of the major extinction events, while the ability of extraterrestrial impact to cause extinction remains debatable. There is growing evidence that food shortage and suppression of primary productivity, lasting several hundred thousand years, may be a proximate cause of many past extinction events. Selective extinction of suspension feeders and the prevalence of dwarfed organisms in the aftermath are palaeoecological consequences of these changes. The association with rapid global warming shows that study of mass extinction events is not just an esoteric intellectual exercise, but may have implications for the present day." Notice that greenhouse environments are associated with the very delayed (millions of years) recovery of biota following these extinctions; Fraiser ML et al. (2007) Elevated atmospheric CO2 and the delayed biotic recovery from the end-Permian mass extinction Palaeogeog. Palaeoclim. Paleoecol. 252, 164-175 Abstract: Excessive CO2 in the Earth ocean-atmosphere system may have been a significant factor in causing the end-Permian mass extinction. CO2 injected into the atmosphere by the Siberian Traps has been postulated as a major factor leading to the end-Permian mass extinction by facilitating global warming, widespread ocean stratification, and development of anoxic, euxinic and CO2-rich deep waters. A broad incursion of this toxic deep water into the surface ocean may have caused this mass extinction. Although previous studies of the role of excessive CO2 have focused on these "bottom-up" effects emanating from the deep ocean, "top-down" effects of increasing atmosphere CO2 concentrations on ocean-surface waters and biota have not previously been explored. Passive diffusion of atmospheric CO2 into ocean-surface waters decreases the pH and CaCO3 saturation state of seawater, causing a physiological and biocalcification crisis for many marine invertebrates. While both "bottom-up" and "top-down" mechanisms may have contributed to the relatively short-term biotic devastation of the end-Permian mass extinction, such a "top-down" physiological and biocalcification crisis would have had long-term effects and might have contributed to the protracted 5- to 6-million-year-long delay in biotic recovery following this mass extinction. Earth's Modern marine biota may experience similar "top-down" CO2 stresses if anthropogenic input of atmosphere/ocean CO2 continues to rise. The lesser extinction associated with the Paleo-Eocene-Thermal Maximum (PETM)55 MYA is probably the best characterised (not surprisingly since it's the most recent!) example of massive tectonic processes (the opening up of the N. Atlantic as the plates seperated) associated with enhanced atmospheric greenhouse gases, ocean acidification etc.: M. Storey et al. (2007)Paleocene-Eocene Thermal Maximum and the Opening of the Northeast Atlantic Science 316, 587 - 589 abstract: "The Paleocene-Eocene thermal maximum (PETM) has been attributed to a sudden release of carbon dioxide and/or methane. 40Ar/39Ar age determinations show that the Danish Ash-17 deposit, which overlies the PETM by about 450,000 years in the Atlantic, and the Skraenterne Formation Tuff, representing the end of 1 ± 0.5 million years of massive volcanism in East Greenland, are coeval. The relative age of Danish Ash-17 thus places the PETM onset after the beginning of massive flood basalt volcanism at 56.1 ± 0.4 million years ago but within error of the estimated continental breakup time of 55.5 ± 0.3 million years ago, marked by the eruption of mid-ocean ridge basalt–like flows. These correlations support the view that the PETM was triggered by greenhouse gas release during magma interaction with basin-filling carbon-rich sedimentary rocks proximal to the embryonic plate boundary between Greenland and Europe." And even the end-Cretaceous extinction (that did for the dinosaurs) seems to have had at least a significant component from massive flood basalt events (that resulted in the Deccan Traps in what is now India). In fact there is increasing evidence that the impact that resulted in the Chicxulub crater in the Yucatan post-dates the onset of the extinction by several 100,000's of years, and the extinction is associated with global warming (including a sudden contribution from the impact into limestone-rich deposits that vapourized massive amounts of carbonate (limestone) back into CO2): Keller G (2005) Impacts, volcanism and mass extinction: random coincidence or cause and effect? Austral. J. Earth Sci 52 725-757. Abstract: "Large impacts are credited with the most devastating mass extinctions in Earth's history and the Cretaceous - Tertiary (K/T) boundary impact is the strongest and sole direct support for this view. A review of the five largest Phanerozoic mass extinctions provides no support that impacts with craters up to 180 km in diameter caused significant species extinctions. This includes the 170 km-diameter Chicxulub impact crater regarded as 0.3 million years older than the K/T mass extinction. A second, larger impact event may have been the ultimate cause of this mass extinction, as suggested by a global iridium anomaly at the K/T boundary, but no crater has been found to date. The current crater database suggests that multiple impacts, for example comet showers, were the norm, rather than the exception, during the Late Eocene, K/T transition, latest Triassic and the Devonian-Carboniferous transition, but did not cause significant species extinctions. Whether multiple impacts substantially contributed to greenhouse worming and associated environmental stresses is yet to be demonstrated. From the current database, it must be concluded that no known Phanerozoic impacts, including the Chicxulub impact (but excluding the K/T impact) caused mass extinctions or even significant. species extinctions. The K/T mass extinction may have been caused by the coincidence of a very large impact ( > 250 km) upon a highly stressed biotic environment as a result of volcanism. The consistent association of large magmatic provinces (large igneous provinces and continental flood-basalt provinces) with all but one (end-Ordovician) of the five major Phanerozoic mass extinctions suggests that volcanism played a major role. Faunal and geochemical evidence from the end-Permian, end-Devonian, end-Cretaceous and Triassic/Jurassic transition suggests that the biotic stress was due to a lethal combination of tectonically induced hydrothermal and volcanic processes, leading to eutrophication in the oceans, global warming, sea-level transgression and ocean anoxia. It must be concluded that major magmatic events and their long-term environmental consequences are major contributors, though not the sole causes of mass extinctions. Sudden mass extinctions, such as at the K/T boundary, may require the coincidence of major volcanism and a very large Impact." Beerling DJ et al. (2002) An atmospheric pCO(2) reconstruction across the Cretaceous-Tertiary boundary from leaf megafossils Proc. Natl. Acad. Sci. USA 99 (12): 7836-7840 Abstract: "The end-Cretaceous mass extinctions, 65 million years ago, profoundly influenced the course of biotic evolution. These extinctions coincided with a major extraterrestrial impact event and massive volcanism in India. Determining the relative importance of each event as a driver of environmental and biotic change across the Cretaceous-Tertiary boundary (KTB) crucially depends on constraining the mass of CO2 injected into the atmospheric carbon reservoir. Using the inverse relationship between atmospheric CO2 and the stomatal index of land plant leaves, we reconstruct Late Cretaceous-Early Tertiary atmospheric CO2 concentration (pCO(2)) levels with special emphasis on providing a pCO(2) estimate directly above the KTB. Our record shows stable Late Cretaceous/ Early Tertiary background pCO(2) levels of 350-500 ppm by volume, but with a marked increase to at least 2,300 ppm by volume within 10,000 years of the KTB. Numerical simulations with a global biogeochemical carbon cycle model indicate that CO2 outgassing during the eruption of the Deccan Trap basalts fails to fully account for the inferred pCO(2) increase. Instead, we calculate that the postboundary pCO(2) rise is most consistent with the instantaneous transfer of approximate to 4,600 Gt C from the lithic to the atmospheric reservoir by a large extraterrestrial bolide impact. A resultant climatic forcing of +12 W(.)m(-2) would have been sufficient to warm the Earth's surface by approximate to7.5degreesC, in the absence of counter forcing by sulfate aerosols. This finding reinforces previous evidence for major climatic warming after the KTB impact and implies that severe and abrupt global warming during the earliest Paleocene was an important factor in biotic extinction at the KTB."
131038. Philippe Chantreau at 19:52 PM on 2 October 2008
        The link between hurricanes and global warming
        If you have other pointers, HS, by all means post the links, I've already invited you to do so earlier on this thread.
131039. HealthySkeptic at 12:38 PM on 2 October 2008
        Can animals and plants adapt to global warming?
        Chris, It's interesting that you mention the review by Royer (D. L. Royer (2006) "CO2-forced climate thresholds during the Phanerozoic" Geochim. Cosmochim. Acta 70, 5665-5675") Based on historical evidence, there is a real danger of a future return to a new ice age. So it makes sense to ask what concentration of carbon dioxide would be adequate to stabilize climate so as to extend the current inter-glacial indefinitely. Royer's work gives some idea of the range of concentrations needed. In the paper you cited above, he found that over the Phanerozoic, consistent levels of carbon dioxide below 500 ppmv are associated with the two glaciations of greatest duration... those that occurred during the Permo-Carboniferous some 300 Myr ago and the Cenozoic, within which we are now living. Cool climates were found to be associated with carbon dioxide concentrations below 1000 ppmv, while no cool periods were associated with concentrations above 1000 ppmv. Some support for the idea that moderately increased carbon dioxide concentrations could extend the current interglacial period also comes from the work of Berger and Lautre [A. Berger and M. F. Loutre, “An Exceptionally Long Interglacial Ahead?”, Science 297, 1287-1288 (2002). Working with projections of June insolation at 65 deg. N as affected by Milankovitch variations over the coming 130,000 yrs, they used a 2-dimensional climate model to show that moderately increased carbon dioxide concentrations, coupled with the small amplitude of future variations in insolation, could extend the current interglacial by some 50,000 years. The insolation variations expected over the next 50,000 yrs are exceptionally small and occur only infrequently, the last time being some 400,000 years ago. They also found that a carbon dioxide concentration of 750 ppmv would not extend the interglacial beyond the next 50,000 years. In addition, concentrations of less than 220 ppmv would terminate the current interglacial. Perhaps one day we will wish we never attempted to limit CO2 levels.
131040. HealthySkeptic at 11:50 AM on 2 October 2008
        The link between hurricanes and global warming
        Yes indeed, nothing like someone with "more awareness" to give us "pointers"... as long as those pointers are pointed in the right direction, right? :)
131041. chris at 08:46 AM on 2 October 2008
        Does Urban Heat Island effect add to the global warming trend?
        Re #1 Greg's post is incorrect, and highlights the problems associated with careless interpretations of pretty straightforward studies. The url that Greg cites relates to a study of temperatures in Los Angeles. This shows a rise of 2.8 Celcius over the past century. That's a massive rise in temperature. And of course much of it is due to an urban effect in the city. However the analysis of temperature rise associated with global warming (by NASA or the NOAA or the Hadley Centre in the UK, and so on) takes the urban heat effect into account, by either (i) ignoring all urban temperature data sets, or (ii) correcting urban data sets by comparison with surrounding rural data. The SPECIFIC error that Greg makes is in stating that "NASA which ascribes most of the warming this century in California to urbanisation". In fact NASA do nothing of the sort. If one looks at the surface temperature data compiled by NASA for California as a whole, the temperature increase is around 1 - 1.5 oC: http://data.giss.nasa.gov/gistemp In the NASA GISS data, the surface temperature has been corrected for urban effects, either by eliminating the latter or correcting this by referencing with respect to the rural data. The mistake that Greg has made is in taking the massive temperature rise of 2.8 oC for LA reported in the study that he links to, and then assuming/pretending that because NASA ascribe most of this temperature rise IN LOS ANGELES to urbanisation, that this applies to CA across the board. That's simply incorrect, as perusal of the NASA GISS temperature anomaly data indicates (see my link - you can create your own temperature anomaly data there). That's the SPECIFIC error in Greg's post. The more GENERAL error relates to the attribution of global warming to urban heat effects. It's rather obvious that massive attenuation of mountain glaciers and polar ice caps and sea ice, particularly in the Arctic, has ZERO relation to urban heat effects, since these regions are far from urban centres. Likewise the large warming of the ocean surface cannot have any relation to any urban heat effects. We could go back to California and look at this more closely. For example, in Northwestern USA, global warming has seen an extension of the wildfire season since the 1970's, resulting from an earlier onset of Spring (and Spring snowmelt), higher summer temperatures and an extension of the wildfire season into late summer. The greatest increase in wildfires is in the regions with elevations around 2000 metres, where progressively earlier Springs, and earlier Spring snowmelt reduces snow and meltwater protection of timber with respect to wildfire hazard. Once the snowmelt is completed, the forsts are rather quickly prone to combustion. Westerling, et al. (see abstract below) have shown that since the 1970's, global warming has extended the wildfire season by well over two months, with rather large increases in costs and damages. Obvoulsy the earlier Spring, greater summer temperatures, and greatly extended wildfire season in NW CA has nothing whatsoever to do with urban heat effects in LA! Westerling AL et al (2006) "Warming and earlier spring increase western US forest wildfire activity" SCIENCE 313, 940-943. Abstract: "Western United States forest wildfire activity is widely thought to have increased in recent decades, yet neither the extent of recent changes nor the degree to which climate may be driving regional changes in wildfire has been systematically documented. Much of the public and scientific discussion of changes in western United States wildfire has focused instead on the effects of 19th- and 20th-century land-use history. We compiled a comprehensive database of large wildfires in western United States forests since 1970 and compared it with hydroclimatic and land-surface data. Here, we show that large wildfire activity increased suddenly and markedly in the mid-1980s, with higher large-wildfire frequency, longer wildfire durations, and longer wildfire seasons. The greatest increases occurred in mid-elevation, Northern Rockies forests, where land-use histories have relatively little effect on fire risks and are strongly associated with increased spring and summer temperatures and an earlier spring snowmelt."
131042. Patrick 027 at 04:11 AM on 30 September 2008
        Volcanoes emit more CO2 than humans
        Because I mentioned the motion of charged particles in the Earth's magnetosphere ealier: (PS all the following (except stated formula) is just from visualization; so some uncertainty in some places) About motion (velocity v) of charged particles in magnetic field B, without other forces considered (if I'm not mistaken), where component of v parallel to B is vB, the component perpendicular to B is vp, all acceleration is is in direction of vector cross-product q(v x B) = q(vp x B), which is perpendicular to v, so that |v| is constant (q is electric charge (more generally, force F = q(E + v x B), where E is electric field (as a vector), and so acceleration is proportional to q/m, m being the mass); with E set to zero, let r be the radis of curvature of the trajectory projected onto the plane normal to B; so that |vp|^2/r = centrifugal acceleration = q/m * |vp x B| = q/m * |vp||B| r = (m/q) * |vp|^2 / (|vp||B|) r = (m/q) * |vp|/|B| 1. Constant field B: helix on a cylindrical surface (field lines parallel to surface), would would appear as a straight line on the surface if unrolled. |vB| and |vp| are constant. Radius of cylinder proportional to |vp|. 2. Change in magnitude of B in direction perpendicular to B (aside from 1., the easiest to visualize): The trajectory, or it's projection onto a plane normal to B, has tighter curvature in regions of higher B. This leads to a net displacement over the course of one revolution (to where v has the same direction). Their is thus a net drift in the direction that v has in the weaker B side of the field. Looking with B vectors directed toward you, positive charges revolve clockwise (turn to the right), and the net drift is directed with the stronger B field to the right. Negative charges: opposite. Smaller q/m ratio (as with proton compared to electron): larger radius of curvature, which itself means greater net displacement over each revolution, but also means greater variation in |B| over the range of each revolution, which means even greater net displacement over each revolution. 3. Variation in field strength along B - convergence or divergence of field lines (also means, over distance perpendicular to B, change in direction of B in the same dimension): helix on a conical surface (or something like that) - vB shrinks to zero and then reverses as larger B is approached, so the trajectory is 'repelled' by larger B values. This means |vp| must rise approaching larger B. In the other direction, as B shrinks, vp also approaches shrinks as v becomes more parallel to B. 4. Over distance perpendicular to B, change in direction of B, but in direction perpendicular to both B and to the direction along which the variation is detected: Suppose there is one field line, aligned with the z-axis, where x and y = 0, about which the particle is revolving in the same dimension. Case A: variation only in the x direction, all field lines parallel to y-z planes, where in the positive x axis, field lines have increasing slope dy/dz. In this case, when v is in the positive x direction, B is changing so that ... well, to make a long story short, I think the result is a helix on a cylinder, but the cylinder (whose axis is the z axis) is flattened in the x direction (?). Case B: braided (twisted) field lines. In this case, if one starts with vB in the positive z direction, then if the field lines curve around each other going in the postive z direction in the same direction as vp, then vp is less than otherwise, vB is more than otherwise, and the result is a helix on a cylinder (??) with a larger radius than otherwise for the same velocity in the x-y plane. If B is twisted in the opposite direction, the cylinder would have a smaller radius for the same velocity in the x-y plane. 5. Change in direction of B along B (curved field lines) This one is trickier to visualize... Locally one may consider approximately constant field strength and field line curvature; but when the radius of curvature is small enough or the range of positions large enough, constant curvature of field lines requires change in field strength along field lines, while constant field strenght requires increasing field line curvature toward a center of curvature, unless field direction is also changing as in case 4. above. --- There are someone conically shaped regions above each polar region; With B directed from the south pole to the north pole, if one visualizes the Earth with north pole pointing up, then within the ~ conic regions, B is downward, while outside the ~ conic regions, B is upward; B should increase in field strength toward the Earth. Thus, protons should have a net westward and electrons a net eastward drift especially outside of polar regions due to effect 2., many are 'repelled' from the poles due to effect 3. Effect 5 will also come into play (not sure of effect); 4, or at least 4B, is not a feature of a basic dipole field but I suppose it might occur due to disturbances or to the motions of charged particles themselves (and also within the core?).
131043. Patrick 027 at 02:47 AM on 30 September 2008
        Volcanoes emit more CO2 than humans
        ... I was thinking of the heat content of the material at a given temperature, and the the difference in heat capacity of two phases must be related to the latent heat of phase transformation - and it's dependence on temperature, by the requirement that whatever path is taken, taking one phase at T1,p1 and ending up at another phase at T2,p2, the same net change in heat content of the material must have occured. But that's an assigned temperature change. A cycle of out-of-equlibrium (time-delayed) phase transitions might concievably require a net mechanical energy input and so would produce heat... But see the last part of comment 53 (PS I had meant to identify that it was comment 46 which contained the paragraph I was correcting in comment 53).
131044. Patrick 027 at 02:41 AM on 30 September 2008
        Volcanoes emit more CO2 than humans
        "However, the specific heat of the material will also vary, and I suspect the end result of all this is no net temperature change over time." Well, now I'm not sure about that...
131045. Patrick 027 at 02:35 AM on 30 September 2008
        Volcanoes emit more CO2 than humans
        CORRECTION: PARAGRAPH IN "Patrick 027 at 14:27 PM on 24 September, 2008": "Dissipation: heat - atoms have to move around in a phase transition; conceivably, even in a short period, some portion of the atoms near phase transitions in the mantle might be cycled through different arrangements (statistically - I wouldn't imagine the phase transition is knife-edge, or that on that timescale it could get near equilibrium (?), and there are the gradual phase transitions from or to garnet, so I wouldn't expect it's the same atoms each time around) - that might be a location where there is some relative concentration of tidal dissipation into heat energy. Not that it would be a significant source of heat. I would try comparing it to the radioactive heat generation in the mantle per unit volume if I had the time. " Some of the logic I used above should be correct, BUT not the part about phase transitions dissipating the forcing that drives them into heat - that was totally wrong. Atoms move around due to thermal energy - those that have enough energy (statistically some fraction will, depending on temperature) can reach some threshold and leave the energy well of their former position in the crystal lattice (or in other situations: overcome the kinetic barrier to chemical reaction or nuclear fusion, etc.) and then fall into another position - in this case, kinetic energy is converted into potential energy, and then back into kinetic energy. Lack of thermal energy simply reduces the number of atoms that are able to move around like that, and so reduces the speed at which a phase transition can occur. Of course, if the final energy well is shallower or deeper than the initial, then there will have been a net exchange between kinetic and potential energy, which tranlates to taking up or giving off latent heat. Since material properties are temperature and pressure dependent (which is of course why the thermodynamic stability of a phase is dependent on these things), there could be a net latent heating or cooling over a cycle if the phase transition in one direction and in the reverse are not occuring at the same T,p - which of course will happen if there is a time lag due to the kinetic barrier. However, the specific heat of the material will also vary, and I suspect the end result of all this is no net temperature change over time. Except in the case that there is a net change in the microstructure over the course of many cycles - crystal grains have to form and reform, and if the grain sizes over time shrink, then there will be an increasing number of atoms whose energy is not as it would be within the crystal lattice... (PS this might build up to a point of dynamic equilibrium, beyond which factors that tend to increase grain size over time (annealing?) would balance those tending to reduce grain size over time. But anyway, as interesting as it is to consider tidal cycling of phase transitions in the mantle, I expect this is a very, very, very minor effect in the scheme of things.
131046. DB2 at 10:59 AM on 28 September 2008
        Does Urban Heat Island effect add to the global warming trend?
        Steve McIntyre looks at urban and rural temperature data since 1885 from Peterson www.climateaudit.org/?p=1859 and has a couple of graphs where the two subsets are separated. He has a couple of possibilities for the trend difference.
131047. Dan Pangburn at 09:18 AM on 28 September 2008
        Models are unreliable
        We seem to have drifted off point (as presented at 41 and 45). The Middlebury website is offered as a source for graphs of government and other credible data. Your disagreement with that data is with the government and the other sources, not me. The issue confronting humanity today is whether human produced carbon dioxide is causing global warming. The only indicator that it is comes from GCMs and then only when their users impose significant net positive feedback. Without significant net positive feedback, the GCMs do not predict significant Global Warming from increased atmospheric carbon dioxide. The proof that significant net positive feedback and therefore AGW does not exist DOES NOT USE anything from A/S. The proof that significant net positive feedback and therefore AGW does not exist DOES NOT USE anything from the Holocene. (For those interested, http://www.ncasi.org/publications/Detail.aspx?id=3025 , which uses data from many different proxies but excludes tree ring proxy data, is an assessment of the average global temperature for the last 2000 years.) This may be the source that Chris alludes to. It shows that the Medieval Warm Period, which was before the industrial revolution, probably reached higher average global temperatures than now and the steepest recent (around 1990) rate-of-change trend is about the same as it was at 4 other times in the last 800 years. A temperature trend direction change proves that there is no significant net positive feedback. Temperature data have been extracted from ice cores and are reported by NOAA and ORNL. All that is needed to determine if there is net positive feedback is a temperature trace for a long enough time to average out cyclic variation from random noise and other factors. The temperature trace does not even need to be correct in absolute terms just reasonably accurate in relative terms time-wise. This is obvious, even trivial, to me. Apparently the importance of the change in direction of temperature trend is not recognized by those who do not understand how feedback works. The trends used in the example in 51 are each about 5000 yr long and other trends have various lengths. The shortest Milankovich cycle is about 23000 yr. Milankovich can have no significant influence on the direction changes of the trends. Besides, the direction changes go both ways. You state “primary effects (raised CO2 levels) supplemented with feedbacks can be overpowered by other effects (reduced insolation during waning Milankovitch cycles)”. If feedbacks can be overpowered by other effects then ‘other effects’ determine which direction future temperature trends will go and predictions of GCMs are meaningless. Either way, the GCMs are invalidated as temperature predictors. That is pretty much the point.
131048. Mizimi at 22:50 PM on 27 September 2008
        What does CO2 lagging temperature mean?
        Quite so. Paleoproxy data are at best an indication of what conditions MAY have been like at some distant time in the past; equally they are mostly not relevant to current climate conditions because 'modern' land mass distribution is radically different from those times. What (little) can be deduced is that CO2 levels were considerably higher than todays and both plant and animal life flourished during the warmer periods (however high the actual temperature might have been).
131049. chris at 06:42 AM on 27 September 2008
        Models are unreliable
        Don't be silly Dan, It's you that is "worrying about a specific data point" or actually two specific data points. NUMBER ONE: I am basing my understanding of the strong relationship between paleoCO2 measures and paleotemperature measures right back through the last 500 million years, BASED ON HUNDREDS OF CONTEMPORANEOUS CO2 and TEMP MEASURES (see data in my references cited in the posts above) You are taking one specific part of the paleodat where there is evidence for glaciation (i.e a coolish/cold Earth) and assuming that there is no relationship with atmospheric CO2. However THERE IS NO CONTEMPORANEOUS PALEO-CO2 MEASURE THAT OVERLAPS THIS PERIOD...and therefore your focus on a specific data point is spurious. NUMBER 2: I am basing my understanding of the paleotemperature data of the last 2000 years which indicates that late 20th century and contemporary warming is well above anything experienced during this time period. THIS DATA IS BAED ON NUMEROUS DATA SETS USING NUMEROUS METHODS OBTAINED FROM MANY DIFERENT PLACES ON EARTH. You are making a blatant misrepresentation of the data by basing your interpretation on ONE data point, from, ONE location, using ONE method. For some reason you're trying to construct a whole edifice of misrepresentation based on single data points. And for some reason, despite your assertions of scientific credentials you can't seem to grasp that primary effects (raised CO2 levels) supplemented with feedbacks can be overpowered by other effects (reduced insolation during waning Milankovitch cycles)... ..your blatant fallacious misinterpretations of paleodata don't actually give us very much confidence in your misassertions aboutfeedbacks...
131050. Mizimi at 04:47 AM on 27 September 2008
        Arctic sea ice melt - natural or man-made?
        Phillipe: #253 I echo QM's comment; thanks also. I wonder what limitations there are to this effect..if any? On Krill: An article suggesting GW is the cause thro' loss of sea ice is countered by another pointing to the decline in blue whale numbers ( the whales provide iron through their excrement which is essential for the plankton) and another that challenges the data supporting the hypothesis. Another study shows krill at ocean depths well below that expected which suggests krill numbers may be higher than supposed. http://www.worldclimatereport.com/index.php/2004/11/11/krill-the-messenger/ http://www.asoc.org/Portals/0/decline%20of%20whales%20decline%20krill.pdf http://www.physorg.com/news123165274.html http://www.ccamlr.org/pu/e/sc/fish-monit/hs-krill.htm krill limits http://uplink.space.com/showflat.php?Cat=&Board=sciastro&Number=45459&page=1&view=collapsed&sb=3&o=0&fpart=

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