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Comments 130851 to 130900:

130851. Patrick 027 at 05:42 AM on 20 October 2008
        Arctic sea ice melt - natural or man-made?
        0.1 (PS after a while you might figure out what these numbers meand): Attribution: To clarify: "Just once? To repeat from above, stratospheric cooling"... "increased warming of nights" ... I also noted that stratospheric ozone depletion could also qualitatively explain stratospheric cooling (and some amount of tropospheric+surface (TPSF for future reference) warming ), and that albedo cooling such as from aerosols (of the right mix) could also qualitatively explain a decrease in diurnal temperature ranges. One key there is 'qualitatively' - for attribution, one would want the numbers. If one expects x degrees change from forcing A and y degrees change from forcing B, then one might start by looking at z/(x+y), where z is the observed change, and attribute z proportionately. One then may need to adjust that if there is some reason to suspect that the relative error in modeling/calculating is different for x and for y. If x can be modelled with more confidence than y (***ie if for x relative to y, the physics are better understood, model resolution and sub-grid scale issues are less of a concern (such as if y depends more on a smaller part of the atmosphere in particular?), or if forcing A is better known than forcing B), then it may make more sense to asign a greater likely share of the theory-observation mismatch to y. However, it would be erroneous, without some reason to do so, to just assume that y was correct and x is off or vice versa. (PS this would also apply when unforced variability is thrown into the mix). The other key is that there may additional aspects that are different for the climatic response to each forcing (as similar solar and GHG forcing of TPSF temperatures have different effects on the stratosphere). For example, increased albedo of course has a cooling effect and can't by itself explain an average TPSF warming (and there could be more subtle differences among different albedo forcings - volcanic vs tropospheric vs land cover). Absorbing atmospheric brown clouds would tend to increase the diurnal temperature range of the air volume they occupy (but that's not much to begin with, away from the surface)but could decrease the surface range, so that would be a candidate. Of course, the horizontal variations of these various aerosols and land-cover matters are quite different and that opens up another avenue for distinguishing their effects. ... One could imagine some combination of solar forcing and aerosol forcing could result in warming with reduced daytime warming, but again, 1. How would the numbers work out exactly?, 2. Other effects - So far as I know no significant albedo enhancement exists that would cool the stratosphere (reflection from below and perhaps scattering from within (? and/or the nonzero absorptivity of even relatively reflective stratospheric aerosols) may tend to warm the stratosphere slightly - **** THEN again, some climate feedbacks themselves might cause some stratospheric cooling - decreased albedo at the surface, and water vapor and the LW (greenhouse) effect of clouds with sufficiently high tops - although an increase in albedo from increased cloud cover, except over or replacing snow and ice (PS clouds over snow and ice could in some cases reduce albedo, I think) would tend to warm the stratosphere for reasons described above... But there may be some horizontal variation fingerprints to these various processes... Well, there is yet another way to distinguish - seasonal variations - ozone has seasonal variations and anthropogenic changes to ozone has seasonal variations. The seasonal variations of solar and GHG forcings, etc, may also be different. The overall seasonal variations (and spatial variations) in climate response in TPSF may be too similar but perhaps some stratospheric responses might contain clues. Then of course, there's the thermosphere, which doesn't have much ozone (chemical equilibria favor atomic oxygen over ozone and at sufficient height over diatomic oxygen, actually) but has the opposite sign of response to solar and GHG forcing. There is also of course the longer term temporal variations - volcanic aerosols have distinct pulses, anthropogenic GHGs have steadily risen, anthropogenic aerosols have their own trend, solar, etc... this can get tricky because of the internal variability on those timescales, of course. To sum up, if you have n unknowns and m equations, you can solve for the unknowns if m = n. If m > n, then any random combination of equations may yield conficting results - mathematically they can't all be true; but - these equations aren't random - they're rooted in physics and must agree with each other. Uncertainty allows for some disagreement (the ranges of allowable values won't be identical, but using many equations would tend to reduce the resulting uncertainty in the unknowns (and perhaps would then feedback as knowlegdge about how to improve some of those equations). Science is putting together a puzzle; sometimes the puzzle pieces have fuzzy edges and they don't fit precisely but additional pieces can help decide which arrangement is most likely, etc... On internal variability - that will always make attribution a little difficult but refer back to above. If we understood the forced responses better than internal variability then it wouldn't make sense to assume any little wobble outside the expected range of variability would render our models incorrect with respect to a forced response - and certainly variations within the expected range of variability don't render models in error. 0. Quietman 259: "Re: Hansen's prediction - Off by 50%, He predicted exactly twice the warming that actually occurred." That's a common misunderstanding (which had been spread by Pat Michaels). A. http://www.columbia.edu/~jeh1/2005/Crichton_20050927.pdf B. http://sciencepolicy.colorado.edu/prometheus/archives/climate_change/000836evaluating_jim_hanse.html From the later: "Perhaps the errors cancel out, but an accurate prediction based on inaccurate assumptions should give some pause to using those same assumptions into the future." These errors are errors in emissions scenarios for different greenhouse gases. However, what matters to climate science, assuming similar efficacies of those GHGs, is the history of the sum of those forcings. From the earlier, in footnotes: " Climate sensitivity is usually expressed as the equilibrium global warming expected to result from doubling the amount of CO2 in the air. Empirical evidence from the Earth’s history indicates that climate sensitivity is about 3°C, with an uncertainty of about 1°C. A climate model yields its own sensitivity, based on the best physics that the users can incorporate at any given time. The 1988 GISS model sensitivity was 4.2°C, while it is 2.7°C for the 2005 model. It is suspected that the sensitivity of the 2005 model may be slightly too small because of the sea ice formulation being too stable. " I would guess then that running the same model from 1988 with the realized forcing history would produce a bit too much warming, but not so much more (assuming 2005 model is more accurate, (4.2-2.7)/2.7 = 1.5/2.7 = 5/9. Okay, that is just over 50 % error, BUT that is not twice the warming, that is just over 1.5 times the warming. And the last part of that footnote suggests the error may be a bit less than that.
130852. chris at 04:15 AM on 20 October 2008
        Arctic sea ice melt - natural or man-made?
        Re #259 I'm skeptical about your comments re Hansen's forecast of global temperature change under the influence of enhanced greenhouse-induced warming. You suggest that "he predicted exactly twice the warming that actually occurred." Can you indicate how you come to that conclusion? I'm interested in the evidence that informs your opinion..
130853. Quietman at 03:21 AM on 20 October 2008
        Volcanoes emit more CO2 than humans
        Patrick Your explanations and willingness to look at both sides is exactly why I asked you to come to this site. In most cases I can see your logic and find it convincing. Keep in mind that this type of science is new to me. I have a beckground in engineering research (product developement) and bench testing emissions but I have never done well with theoretical math only logic and applied math, so keep it simple. Trust me, it is just as frustrating for me when someone points to a paper and claims it as fact without a logical explanation as it is when I get quoted from a bible passage. The fact that you don't resort to that is quite refreshing.
130854. Quietman at 03:07 AM on 20 October 2008
        Arctic sea ice melt - natural or man-made?
        I will try to reply to the rest when you finish your analysis. Sounds good so far.
130855. Quietman at 03:03 AM on 20 October 2008
        Arctic sea ice melt - natural or man-made?
        Patrick Re: Fire and Ice - Sorry, I should have. Re: Hansen's prediction - Off by 50%, He predicted exactly twice the warming that actually occurred.
130856. chris at 02:08 AM on 20 October 2008
        Does model uncertainty exagerate global warming projections?
        Wondering Aloud, HealthSkeptic, Mizimi I thought you guys (gals?) are supposed to be skeptics!So what do you make of the "graph" reproduced in post #8? Let's have some considered thought and opinion. (hint: The data presented is nonsense - can you see why?)
130857. Patrick 027 at 15:05 PM on 19 October 2008
        Arctic sea ice melt - natural or man-made?
        (continued from comments 96 - 104, and perhaps 95, at "It's volcanoes (or lack thereof)") 1. 'solar dimming/brightenning' - I'm not sure what terms are used for what exactly here, but this is confusing, because it sounds like one is discussing solar TSI changes, when it was intended to discuss global dimming - the reduction in solar radiation reaching the surface. Global brightenning might not even be the opposite of that - I could imagine global brightenning might be used to refer to an incress in albedo as seen from TOA (top of atmosphere) - PS hypothetically if this occurs it could be seen on the dark portion of the moon - Earthshine reflecting off the moon's night side. I don't know if there are any observations indicating a trend in that or not. 2. Quietman 87: "Fire under the ice International expedition discovers gigantic volcanic eruption in the Arctic Ocean" http://www.eurekalert.org/pub_releases/2008-06/haog-fut062508.php You should post that website under "It's volcanoes"... - it's the first I've seen with actual evidence of a change in volcanism. However, the changes are still just on the scale of individual eruptions - Whether the the lack of knowlegde of prior such eruptions is an actual knowledge of a lack of prior such eruptions depends on whether it could have been expected to be noticed or missed - in this case I am very skeptical that there is any evidence at all of a trend here. And even if there were, I am very skeptical it could account for any significant portion of climate change, even regionally (consider the numbers - the actual geothermal heat output of an eruption compared to the actual heat going into the ocean - and by the way, remember that the global average geothermal heat flux at the surface is a little under 0.1 W/m2, and most of that is just thermal conduction through a temperature gradient in solid rock (and groundwater, but in most areas I don't think it's sufficient to drive groundwater convection?? or that groundwater flow is fast enough to cause rapid changes), with radioactive heat contributions - nothing that could change fast, except maybe where there's fast-flowing groundwater or hydrothermal vents, and how fast could those change on what timescales...?). 3. Notice in Quietman 107: "Surface warming by the solar cycle as revealed by the composite mean difference projection" "Charles D. Camp and Ka Kit Tung Received 29 March 2007; revised 15 May 2007; accepted 14 June 2007; published 18 July 2007. Geophys. Res. Lett., 34, L14703, doi:10.1029/2007GL030207." " [12] We will argue in a separate paper that the observed warming is caused mostly by the radiative heating (TSI minus the 15% absorbed by ozone in the stratosphere), when taking into account the positive climate feedbacks (a factor of 2?3) also expected for the greenhouse warming problem. " I haven't seen it myself but it sounds like they've found some reason to think that it is indeed solar TSI forcing at the tropopause (or nearly that) and not some aspect of solar forcing that wouldn't apply to GHGs - perhaps a difference in timing between TSI and solar wind variations, etc.? 0. Quietman 151: "The lies come from both deniers and alarmists, those of us who are skeptical do not need to lie, we simply ask for proof of your hypothesis. Make a prediction that pans out for a change, just once, and you will convince us skeptics. So far it's a no hitter. " Just once? To repeat from above, stratospheric cooling (with some qualifications because ozone depletion contributes, but there may be some spatial-temporal distinction there, and attributed proportions should be calculable - ie that ozone could only account for x, GHG's for y, etc..); increased warming of nights (the trend has not been constant but it's in there)... These two things would not be explained by solar forcing. The increased night warming could be explained by volcanic and anthropogenic aerosols if the forcing is sufficient - ie they do have the quality of cooling days more than nights... Add to that: Svante Arrhenius (spelling?) over 100 years ago (maybe 200?) predicted warming from CO2 increases. James Hansen 1988 - his graph for the forcing scenario most closely matched has thus far stayed close to the temperatures. And: Increased storm activity in the Arctic. Some other circulation changes - there may be evidence of expansion of the Hadley cell, for example. I think evidence of changes in rainfall patterns (space and time, etc.). And: greater warming in the Northern Hemisphere, with especially lower warming in the ocean around Antarctica and in the North Atlantic near Greenland (granted I'm not sure when these predictions were first made but at least for the first part (ocean around Antarctica), it's in a book from 1994. And: simple one-dimensional radiative-convective models from a few decades ago. And: extending the record back even farther with new data, the correlation between CO2 (and CH4) and climate continues. And: glaciers melting around the world - not just Greenland, not just Arctic sea ice, not just Kilomanjaro - and among other tropical glaciers, evidence that it is unusual in the last several thousand years (- that the ice is that old, in other words - yes, ice can flow, but there are some details - that for example, in the ice core, no evidence of melt going back x years, and then the team returns to the site and they find the ice is melting... something like that). And: sea level rising. ocean heat content increasing (that and a number of other things above argue against this all being urban heat islands - that and maybe also the lack of warming in SE U.S. - after all, there are cities there, aren't there - or have they not been growing as fast as other urban areas?). And: both the observations and the theory are a bit unclear on this one, but it does seem like tropical cyclones have been getting more intense - if not more numerous (outside the Atlantic multidecadal cycle)... to be continued...
130858. Patrick 027 at 14:17 PM on 19 October 2008
        Volcanoes emit more CO2 than humans
        Since much of what I am about to say applies to the "Arctic sea ice"... , I'm going to post a few comments there now. If after that I haven't covered some of what was brought up here in comments 87-95, I'll come back here.
130859. Patrick 027 at 14:13 PM on 19 October 2008
        Volcanoes emit more CO2 than humans
        ... of course, I've never been quite clear on 'global dimming - H2O evaporation' - of course if water is being heated to higher temperature, the tendency is for faster evaporation under the same wind and relative humidity. But there has been global warming along with 'global dimming' (? - according to some comments at "Arctic sea ice..."), so how does decreased solar radiation reaching the surface affect evaporation independently of temperature? Is it analogous to the photoelectric effect - in this case, individual higher energy photons are able to kick off H2O molecules into the air even if the temperature is low (but not too low)? Sounds conceivable, but then again, the absorption of solar radiation is distributed within a depth of water from the surface downward; less so for the shortest wavelengths, red light and solar IR, but I suspect it's a tiny tiny fraction that would be absorbed within a 'molecular layer' or two from the surface.
130860. Patrick 027 at 14:04 PM on 19 October 2008
        Volcanoes emit more CO2 than humans
        "so perhaps this is partly why I hear of atmospheric brown clouds (dark absorbing aerosols) in particular reducing vertical motion by increasing stability." Actually, the full effect may be an increase in stability to moist convection by reduction in evaporation; in so far as dry convection is concerned, while the heating has been moved upward from the surface, it won't generally be all the way up to the tropopause; while there will tend to be increased stability beneath such a brown cloud, there will tend to be reduced stability above it. The heating of the brown cloud itself will tend to cause a low pressure beneath it and a high pressure above it, and the brown cloud itself will tend to rise.
130861. Patrick 027 at 13:13 PM on 19 October 2008
        Volcanoes emit more CO2 than humans
        ... or 5. internal variability greater than thought __________ About efficacy of forcings: I haven't actually read much about that but here's what I would expect: Consider a forcing by Solar TSI LW (greenhouse) forcing volcanic stratospheric aerosols tropospheric aerosols surface albedo For any given forcing - let's start with radiative forcing - there is: 1. a global average TOA (top of atmosphere) value, R-TOA. 2. a global average tropopause value, R-tp 3. a global average surface value, R-sfc. 4. Some spatial-temporal (seasonal, perhaps interannual) variation in either of R-TOA, R-tp, R-sfc, which I will simply refer to here as R-var. 5. Some climatic response which results from the effect of R and feedbacks. - To start with, we might assume an approximation that the climatic response in so far as global average is concerned, is similar to any R-tp or R-TOA for any forcing. Then we might look for deviations from that. Differences: R-TOA is the forced net change in downward minus outgoing radiation 'at' the top of the atmosphere. R-tp is different then R-TOA; both are different from R-sfc - First: 1. An increase in solar TSI - if the same % increase at all wavelengths - the forcing is a heating distributed (unevenly) through the atmosphere and surface. R-TOA is the sum of all of this heating; R-tp is only the heating below the tropopause and is therefore somewhat less than R-TOA; R-sfc is only surface heating and is therefore less than R-tp. Typically changes in solar TSI are greater in UV in particular, so a larger fraction than otherwise of solar forcing goes into heating the upper atmosphere, thus decreasing R-tp even further. 2. Greenhouse forcing is a reduced cooling to space, which is a heating of the surface and/or lower atmosphere. The cooling to space of the stratosphere and above, however, increases, while the heating of higher atmospheric layers by the surface and/or lower troposphere decreases. Thus for greenhouse forcing, R-TOA will be a little less then R-tp. Starting at minimal LW opacity, R-sfc might be greater than R-tp (?), but at least for CO2, my impression is increases from the current amount result in greater R-tp than R-sfc. Water vapor is a feedback, but applying the same concepts to water vapor, I think, at least under some conditions, R-sfc is greater than R-tp for water vapor. This is at least in part due to water vapor's increasing concentration toward the surface. Ozone concentration is also variable so greenhouse effects of ozone changes may be a bit different than the 'typical' well-mixed greenhouse gas. The exact relationship between R-tp, R-sfc, and R-TOA for even well-mixed greenhouse gases (like CO2, CH4, N2O, CFCs) (they have some spatial and seasonal variations but not to the degree of ozone or water vapor) could vary because they have different spectrums, and temperature (and water vapor, ozone, cloud content) varies with height (and other dimensions), they may overlap with each other and other things in different ways due to the above differences, and they have different initial amounts before changes occur. 3. a decrease (to keep the same sign of forcings for more straightforward comparison) in volcanic stratospheric aerosols - this would reduce albedo. The aerosols reflect SW (solar) radiation back up from the stratosphere, thus cooling the troposphere and surface but possibly heating the air above; and perhaps heating the stratosphere a little bit (? I think the stratosphere or some part of it actually warms up after relevant eruptions - this might be due to the nonzero absorption of solar radiation by the aerosols themselves) (some of the solar radiation is scattered downward or sideways - for a near-overhead sun (middle of day, summer midlatitude, or at low latitude), this can increase the path length before reaching the surface, thus increasing the portion absorbed in the air...) ... SO scattering of radiation is complicated (but not so much that it isn't understood), but reducing volcanic aerosols results in an R-sfc and R-tp greater than R-TOA, and I suspect R-sfc would be greater than R-tp. 4. tropospheric aerosols 4a. A decrease in the albedo from reduced scattering by aerosols: R-sfc will be greater than R-tp and R-TOA as some of the reflected and scattered radiation had been absorbed by air and clouds. 4b. An increase in the atmospheric heating by increased absorption of aerosols: R-TOA and R-tp will be positive while R-sfc is negative. 4c. scattered radiation can be subsequently absorbed in the air; the total effect of aerosols is not simple, but again, it isn't an impossible riddle either. 5. Decrease in albedo due to surface conditions: The change in albedo actually at the surface may have to be greater than that which results at TOA, due to clouds, but also time of day and year issues, and latitude. Anyway, reflected solar radiation has a second chance to be absorbed by the air, so the decrease in albedo because of surface conditions may result in R-sfc greater than R-tp and R-tp greater than R-TOA (but perhaps only slightly). HOWEVER: R-tp may be (as it is in IPCC work) defined as that which occurs after the stratosphere and above have reached thermal equilibrium with the forced heating or cooling (R-TOA - R-tp) which occurs there (PS notice this is not the same as that equilibrium which would result after the climate response including the tropsophere and surface). If R-TOA is greater than R-tp, then the stratosphere, etc, will have warmed, so R-tp will be a little higher as a result due to increased downward LW radiation (or a decrease in net upward LW radiation). If R-TOA is less than R-tp, the opposite will be true. In other words, R-tp will get closer to the original R-TOA (But I don't think it would be equal to the original R-TOA - I expect it to still be less or greater than R-TOA, whichever was the case to begin with). R-sfc might also shift in the same direction but not as much so long as there are any greenhouse agents within the troposphere. Of course, in the full climatic response, however tropospheric heating (R-tp - R-sfc) is distributed within the troposphere, or however much it is, as an upper layer warms up, it reduces convective heat transport from below, thus the tendency is for the full effect of R-tp to propogate by convection to the surface, whatever R-sfc was. However, a larger R-tp - R-sfc and/or smaller or negative R-sfc value will tend to reduce convection from the surface - HOWEVER, after all feedbacks have occured, the radiative heating/cooling distribution may be different again. ***I think this would be less true for regionally-concentrated forcings (pockets of high aerosol concentrations, for example), because advection into and out of the area would prevent a radiative convective equilibrium on the regional scale, so perhaps this is partly why I hear of atmospheric brown clouds (dark absorbing aerosols) in particular reducing vertical motion by increasing stability. So a global average R-tp will tend to result in some global average tropospheric and surface temperature increase. Some other effects due to the vertical distribution may change the feedbacks that occur and thus the resulting temperature changes in the surface and troposphere - but to my knowledge that is not a big effect (?). The horizontal (and seasonal, if and when it matters (ozone)) variations could also affect the actual global average results. For example - the R-tp and R-TOA of albedo reduction from BC landing on snow/ice will likely be a little smaller than the R-sfc value (some radiation reflected from the surface can be reflected back to the surface by clouds, aerosols, and air molecules); furthermore and perhaps much more importantly, the effect is concentrated where a positive feedback is also concentrated (snow-ice albedo feedback). Thus the climate sensitivity could be expected to be larger to BC on snow/ice forcing than to some other forcings, to the extent that the forced heating is not entirely advected away from similar locations. As far as anthropogenic well mixed greenhouse gases (WMGHG - to adopt the acronymn I saw in a paper - this includes CO2, CH4, N2O, CFCs - well, at least a couple CFCs) compare to solar radiative forcing - the geographic distribution of R-tp is going to be at least a little similar on a broad scale - the LW forcing is highest in the subtropics because of the relatively dry cloud-free air and higher lapse rates; high cloud tops in the tropics prevent greenhouse gases below them from having any direct effect on R-tp; lower tropospheric and surface temperatures in general and smaller lapse rates at higher latitudes reduce the difference in outgoing LW radiation (at least at tropopause level - and the tropopause is lower there, too) that would result from changing greenhouse gas concentrations (and the lower surface temperatures. Solar forcing will generally be greatest at low latitudes, during the day, and/or in summer, where there are fewer clouds, reflective aerosols, darker surfaces (ocean, forests), etc. For example, the dry subtropics (but unlike WMGHGs, solar forcing would not be as large over dry light-colored landscapes as it would be over dark oceans). Etc. R-tp will be higher than otherwise when there is less stratospheric ozone. There is a latitudinal and seasonal ozone variation - there tends to be more ozone at higher latitudes in winter/spring, I think - because while stratospheric ozone is produced more at low latitudes, winter stratospheric circulation brings it into high latitudes, and actually 'piles it up' there, in part (if not in whole) because the stratosphere is thicker at higher latitudes (lower tropopause)... ---- Of course anthropogentic GHG forcing is expected to result in a cooler stratosphere (observed - although stratospheric ozone depletion also has a similar effect - but each can be calculated so it should be possible to attribute portions of cooling), and greater warming at nights during days near and at the surface over land (not much diurnal cycle to begin with over oceans because of heat capacity) - (also observed, at least somewhat). Positive solar forcing that would warm the surface and troposphere would also warm the stratosphere (not observed). However, because of this, there could be effects on atmospheric circulation that are different than for GHGs, which might affect climate sensitivity (but how much and in what direction?).*** (Quietman - if you want to show a reduced climate sensitivity by way of greater total forcing, you might try looking into how solar forcing, including non-TSI or non-UV effects, affect not only the stratosphere, but also the ionosphere, and for example the E-region dynamo, and how geomagnetic effects also affec the E-region dynamo and solar-magnetospheric-ionospheric interactions, and what any resulting circulation pattern changes would be, and if and how that propogates downward. I am not saying that I expect you to be successful, but it's a thought - while I have my doubts, I think it's got a lot more potential than submarine volcanism, solar jerk, tides on sun, Spencer's PDO+ENSO work, Spencer's cloud forcing work, urban heat island dominance, or the idea that there hasn't been a recent spurt of global warming above and beyond internal variability.)
130862. chris at 07:14 AM on 19 October 2008
        Models are unreliable
        Re #56 Quietman, the posting of your link to a paper purporting to identify an incompatibility between tropospheric temperatures in the tropics and modelled tropospheric temperature is fascinating. Here’s a very recent paper by a large group of 17 climate scientists. It (abstract at bottom of post) completely contradicts the paper that you linked towards: B. D. Santer et al. (2008) Consistency of modelled and observed temperature trends in the tropical troposphere. International Journal of Climatology 28, 1703 – 1722. You can download and read it from here: https://publicaffairs.llnl.gov/news/news_releases/2008/NR-08-10-05-article.pdf What can be going on? The answer is the guys whose paper you linked towards (Drs Douglass, Christy, Pearson and Singer; DCPS) messed up somewhat (incidentally you should always be a little suspicious of papers containing the rather dubious S. Fred Singer). Here’s the story: 1. Simple atmospheric physics indicates that as the atmosphere warms under the influence of raised [CO2], a water feedback (raised water vapour in a warming atmosphere) should kick in resulting in additionally raised atmospheric temperature. This is observed in models (both the raised water vapour and atmospheric temperature), and is generally consistent with real world measurements. 2. But not fully. There has been an apparent mismatch between predicted tropospherical warming and measured warming in the tropics. Radiosonde data (crude temperature measures in weather balloons) especially, don’t seem to show the predicted temperature increase. Something is wrong. 3. But what? In this case it looks like it might be the measurements that are wrong. In fact the paper you linked towards (DCPS) was not so much about demonstrating that there is a mismatch between the models and tropical tropospheric temperature measures (there quite likely isn’t), but in asserting that the tropospherical tropical temperature measurements are sufficiently free from error that such a comparison can be reliably made. In fact it seems that they aren’t. 4. What does the evidence indicate? It’s been known for some time that there is a very significant problem with the radiosonde tropospheric data, and this is particularly severe in the tropics. If these errors are taken into account, then the model and tropical tropospheric temperature can be be reconciled. However this requires a recognition of the substantial errors in the measured raiosonde data and a proper evaluation of these errors when assessing any real or potential disparity with the models. S. C. Sherwood et al. (2005) Radiosonde Daytime Biases and Late-20th Century Warming Science 309, 1556 – 1559. Abstract: “The temperature difference between adjacent 0000 and 1200 UTC weather balloon (radiosonde) reports shows a pervasive tendency toward cooler daytime compared to nighttime observations since the 1970s, especially at tropical stations. Several characteristics of this trend indicate that it is an artifact of systematic reductions over time in the uncorrected error due to daytime solar heating of the instrument and should be absent from accurate climate records. Although other problems may exist, this effect alone is of sufficient magnitude to reconcile radiosonde tropospheric temperature trends and surface trends during the late 20th century.” L. Haimberger et al (2008) Toward Elimination of the Warm Bias in Historic Radiosonde Temperature Records—Some New Results from a Comprehensive Intercomparison of Upper-Air Data. J. Climate 21, 4587-4606. M. P. McCarthy et al. (2008) “Assessing Bias and Uncertainty in the HadAT-Adjusted Radiosonde Climate Record”. J. Climate 21, 817-832. P. W. Thorne et al. (2007) Tropical vertical temperature trends: A real discrepancy? Geophys. Res. Lett. 34, L16702. And so on… 5. And in fact, if tropical tropospheric temperatures are assessed using other measured correlates of temperature, there is increasing evidence that in fact the tropical troposphere is warming as predicted: Allen RJ and Sherwood SC (2008) Warming maximum in the tropical upper troposphere deduced from thermal winds. Nature Geoscience 1, 399-403. Abstract: "Climate models and theoretical expectations have predicted that the upper troposphere should be warming faster than the surface. Surprisingly, direct temperature observations from radiosonde and satellite data have often not shown this expected trend. However, non-climatic biases have been found in such measurements. Here we apply the thermal-wind equation to wind measurements from radiosonde data, which seem to be more stable than the temperature data. We derive estimates of temperature trends for the upper troposphere to the lower stratosphere since 1970. Over the period of observations, we find a maximum warming trend of 0.65 +/- 0.47 K per decade near the 200 hPa pressure level, below the tropical tropopause. Warming patterns are consistent with model predictions except for small discrepancies close to the tropopause. Our findings are inconsistent with the trends derived from radiosonde temperature datasets and from NCEP reanalyses of temperature and wind fields. The agreement with models increases confidence in current model-based predictions of future climate change." 6. What are the conclusions? The first is that one should be carefully not to be fooled by dubious papers that are circulated around the blogosphere to fool the unwary. There are usually a number of papers that are relevant to assess particular issues, and one should try to address all of the evidence. Secondly, one can only assess the relationship between predicted/modeled analyses and real world data if the real world data is sufficiently accurately defined to make a valid comparison. Although this is often the case, in the particular instance of measured tropical tropospheric temperatures, the evidence indicates that the real world measurement errors are still too large. However as Santer et al indicate, they are improving, and there is now no substantial disagreement between modelled and measured data. ----------------------------------------------------- B. D. Santer et al. (2008) Consistency of modelled and observed temperature trends in the tropical troposphere. International Journal of Climatology 28, 1703 – 1722. Abstract "A recent report of the U.S. Climate Change Science Program (CCSP) identified a potentially serious inconsistency between modelled and observed trends in tropical lapse rates (Karl et al., 2006). Early versions of satellite and radiosonde datasets suggested that the tropical surface had warmed more than the troposphere, while climate models consistently showed tropospheric amplification of surface warming in response to human-caused increases in well-mixed greenhouse gases (GHGs). We revisit such comparisons here using new observational estimates of surface and tropospheric temperature changes. We find that there is no longer a serious discrepancy between modelled and observed trends in tropical lapse rates. This emerging reconciliation of models and observations has two primary explanations. First, because of changes in the treatment of buoy and satellite information, new surface temperature datasets yield slightly reduced tropical warming relative to earlier versions. Second, recently developed satellite and radiosonde datasets show larger warming of the tropical lower troposphere. In the case of a new satellite dataset from Remote Sensing Systems (RSS), enhanced warming is due to an improved procedure of adjusting for inter-satellite biases. When the RSS-derived tropospheric temperature trend is compared with four different observed estimates of surface temperature change, the surface warming is invariably amplified in the tropical troposphere, consistent with model results. Even if we use data from a second satellite dataset with smaller tropospheric warming than in RSS, observed tropical lapse rate trends are not significantly different from those in all other model simulations. Our results contradict a recent claim that all simulated temperature trends in the tropical troposphere and in tropical lapse rates are inconsistent with observations. This claim was based on use of older radiosonde and satellite datasets, and on two methodological errors: the neglect of observational trend uncertainties introduced by interannual climate variability, and application of an inappropriate statistical consistency test."
130863. chris at 05:28 AM on 19 October 2008
        Models are unreliable
        Re #57, on CO2 and feedbacks. There is a large amount of paleodata on the relationship between Earth’s paleotemperature data and paleoCO2 measures, and these indicate that the Earth in the deep past was warm when atmospheric CO2 levels were high, and cool/cold when atmospheric CO2 levels were low. Some of these data are listed at the bottom of the post (data set #2).. Dan makes an odd statement about the record of “30 year long up and down temperature trends during the steady progressive rise in atmospheric carbon dioxide level of the 20th century”. But one only needs to look at the temperature record (e.g. http://data.giss.nasa.gov/gistemp/), to see that the trend is a positive one. The earth’s surface temperature is undergoing a rapid increase in temperature that is following the extraordinarily rapid rise in atmospheric CO2. But one needs to be careful of course. The temperature rise that results from enhanced atmospheric CO2 levels relates to the temperature AT EQUILIBRIUM. There are two problems with Dan’s simple misrepresentation. Internal variations in the climate system (ocean currents, El Nino’s, La Nino’s) that temporarily redistribute heat, the effects of volcanic eruptions that transiently cool the atmosphere (or man made aerosols), the solar cycle, and so on, result in fluctuations around the equilibrium temperature that is effectively “set” by the solar output and the greenhouse effect. So we obviously don’t expect to see a perfectly steady increase in temperature as CO2 levels rise. The earth’s temperature has been rising by around 0.2 oC per decade during the last 30-odd years. However internal variation can be as large as 0.1-0.2 oC per year. So the temperature rise is overlaid with “noise” from these fluctuations. That’s pretty obvious. Likewise right now we’re smack at the bottom of the solar cycle. So for the last couple of years and for perhaps another couple the Earth’s temperature rise is being opposed by a slightly cooler sun. In a couple of years the rise in solar output will add to the greenhouse warming.. ..and so on. The fact is that when we assess the trends over longish periods, the Earth is on a warming trend…we’re around 0.5 oC warmer globally than 30 years ago. The temperature may have gone “up and down” a bit during this period...but overall it’s gone up! A large number of analyses indicate that the Earth’s EQUILIBRIUM temperature rises by around 3 oC (+/- a bit) per doubling of atmospheric CO2. A significant part of this temperature rise results from feedbacks, the most important one being the water vapour feedback. As the atmosphere warms under the influence of raised CO2 levels, so the atmospheric concentration of water vapour rises. Does this feedback actually exist? Yes. We can measure the enhanced atmospheric water vapour directly in the real world [see Soden et al (2005); Brogniez H and Pierrehumbert RT (2007); Santer BD et al. (2007); Buehler et al. (2008); Gettelman and Fu (2008)…and so on (citations below]. So the major feedback to enhanced CO2 level exists. As atmospheric CO2 levels rise so atmospheric water vapour levels rise, pretty much in expectations with predictions based on straightforward atmospheric physics (not to mention models which also predict the observed tropospheric moistening). It’s difficult to know exactly where Dan is confused with respect to “feedbacks” since he is very vague. Notice that Dan is being a tad dishonest in his comments in post #57, since I don’t refer to feedbacks as “vague” and “nebulous” at all, but to Dan’s “discussion” of these as vague (this dishonesty is similar to Dan’s pretence that my criticism of Dan’s appalling cherrypicking of paleotemperature data equates to a disagreement on my part with the data). The problem is that Dan makes very vague comments about feedbacks. He talks about “feedbacks, known or not”. He alludes to negative feedbacks without really addressing what these might be, other than alluding to a negative feedback “identified” by Dr. Richard Lindzen and “his iris effect”. But of course Lindzen didn’t “identify” an “iris effect”. Lindzen hypothesised such a possibility…however real world analysis hasn’t really provided any evidence for such a thing (see below). Lindzen earlier postulated that increased CO2-induced warming would cause a drying of the troposphere, but in the face of real world data world [see Soden et al (2005); Brogniez H and Pierrehumbert RT (2007); Santer BD et al. (2007); Buehler et al. (2008); Gettelman and Fu (2008)…and so on (citations below], Lindzen had to dump that notion too. Unverified or disproven hypothesis don't constitute evidence of anything. The problem with vague assertions about hypothetical negative feedbacks is not just that these are ill-defined, and that the evidence indicates that these hypothetical feedbacks don’t exist or are small. Real world observations support the conclusions that (i) that the climate sensitivity to raised CO2 is rather significant (around 3 oC per doubling of atmospheric CO2), and (ii) that putative, hypothetical negative feedbacks are not very significant. Thus many of the determinations of climate sensitivity are empirical analyses that relate warming to variations in forcings and accommodate all feedbacks whether negative or positive. Thus determination of a climate sensitivity to CO2 by analysis of glacial-interglacial transitions, by analysis of paleotemp/paleoCO2 data [Royer et al (2007)]; by analysis of the Earth’s temperature response to the solar cycle [Tung and Camp (2008)], and so on, implicitly incorporate all of the forcings whether negative or positive. These give values near 3 oC of warming per doubling of atmospheric CO2. Likewise we’ve had a very marked warming during the last 30 years (around 0.5-0.6 oC) in response to an increase in atmospheric CO2 from 330 ppm to 385 ppm. If we’ve had 0.5-0.6 oC of temperature rise from a “small” (!) CO2 rise of 55 ppm on the course of a potential doubling of 330-660 ppm, then that seems highly inconsistent with a low climate sensitivity; the same conclusion arises from the extent of warming we’ve had in response to a relatively small proportion of doubling of atmospheric CO2 during the 20th century. In fact the temperature increase of the 20th century, modelled using the full set of known contributions, is entirely compatible with the effects of feedbacks (Hansen et al, 2005) and predictive simulations set up in the 1980’s have done a rather good job of predicting the subsequent global temperature increase (Hansen et al, 2006) and so on. Thus it’s perverse to suggest that what exists (since we can measure it in the real world) doesn’t exist…or to assert that what doesn’t seem to exist (since there seems precious little evidence for it!), does. Dan also needs to be far less vague about his comments concerning temporal relationships between temperature and greenhouse gas levels during glacial cycles. He’s confused over something and thinks that everyone else might be wrong…but unless he is explict about his problem we’re unlikely to be able to help him… Buehler SA (2008) An upper tropospheric humidity data set from operational satellite microwave data. J. Geophys. Res. 113, art #D14110 Brogniez H and Pierrehumbert RT (2007) Intercomparison of tropical tropospheric humidity in GCMs with AMSU-B water vapor data. Geophys. Res. Lett. 34, art #L17912 Gettelman A and Fu, Q. (2008) Observed and simulated upper-tropospheric water vapor feedback . J. Climate 21, 3282-3289 Hansen, J. et al (2005) Earth's energy imbalance: Confirmation and implications. Science, 308, 1431-1435. http://pubs.giss.nasa.gov/docs/2005/2005_Hansen_etal_1.pdf Hansen, J. et al. (2006) Global temperature change. Proc. Natl. Acad. Sci., 103, 14288-14293. http://pubs.giss.nasa.gov/docs/2006/2006_Hansen_etal_1.pdf Royer DL et al. (2007) Climate sensitivity constrained by CO2 concentrations over the past 420 million years Nature 446, 530-532 Santer BD et al. (2007) Identification of human-induced changes in atmospheric moisture content. Proc. Natl. Acad. Sci. USA 104, 15248-15253 Soden BJ, et al (2005) The radiative signature of upper tropospheric moistening Science 310, 841-844. Tung and Camp (2008) Solar Cycle warming at the Earth’s surface and an observational determination of climate sensitivity http://www.amath.washington.edu/research/articles/Tung/journals/solar-jgr.pdf ------------------------------------------------- Data set #2: A wealth of paleoproxy data support the conclusion of a strong relationship between atmospheric CO2 and earth’s surface temperature during the deep past. These data support a high climate sensitivity to CO2 and indeed analysis of the relationships between paleotemperature and paleoCO2 indicate that the earth’s temperature sensitivity to enhanced CO2 has been high for 500 million years. Explicitly a value for the climate sensitivity of 2.8 oC per doubling of atmospheric CO2 has been determined (see Royer et al (2007) in the citayions listed above. 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.
130864. chris at 05:06 AM on 19 October 2008
        Models are unreliable
        Re #57 There are some extraordinary misconceptions and lovely examples of deliberate misinterpretation in Dan’s post. Let’s have a look (a response to Dan’s “feedback” stuff in a separate post): We can examine the wealth of paleoproxy data published in the scientific literature (these can be found in the NOAA site urled in the list below, and some of these are compiled in a graph on the Wikipedia page...…more recent data sets that aren’t in the Wikipedia composite are cited below too). All of this data from a very large number of analyses indicate that we are a good bit warmer now (by 0.4-0.6 oC or more) in the Northern hemisphere now than during the so-called “Medieval Warm Period” (MWP). Dan has chosen to ignore all of the published data, and to refer us to an article in a non-science magazine who’s editor is quite open about her inclusion of (non-peer reviewed) stuff that supports her rather odd political considerations. Dan's article is scuppered by a ludicrous howler in which the author (Loehle) misunderstood the dating of paleodata and thought that his data sets progressed to the present, when in fact they extend at the very most to 1949. In other words Loehle misses out completely the very marked global scale warming of the last nearly 60 years. Loehle corrected his analysis.....now taking Loehle’s own CORRECTED data at face value his analysis demonstrates that it is a good bit warmer now that during the MWP. So Dan got it wrong. Note that although Loehle was honest enough to print a correction of his paper, Dan chose to base his original “analysis” (post #53) on the incorrect presentation even ‘though the correction is joined into the same document as the original incorrect article...that’s a dull piece of contrived misrepresentation and cherrypicking……sadly, that seems to Dan’s modus operandi (see posts #46, 48, 50, 52, 54). It’s worth noting Dan’s attempt to “rescue” the “situation”. Dan points out that Loehle still considers that the MWP might have been (in the Northern hemisphere) as warm as now. However Loehle makes another fundamental error here. Note that Loehle’s paleodata set is extremely sparse (18 records) and some of these records themselves are extremely sparse (e.g. a paleotemperature point every 100 years). This might be contrasted with the recent paleoanalysis of Mann et al (2008), for example, which also addressed the paleodata without using tree ring proxies, and who's analysis uses around 170 paleotemperature data sets with the stipulation that the data has at least decadal temporal resolution. Examination of Loehle’s original sparse records shows considerable variability, and (as is quite normal) in order to make the paleotemperature variations accessible and to incoproprate disparate sets into a common record, the data are smoothed by averaging in the time domain. Loehle used a 30 year running mean (changed to a 29 year running mean in his correction). The problem is that Loehle then chose to compare his most recent paleoproxy temperature point (the year 1935), with the instrumental temperature record (from NASA GISS: http://data.giss.nasa.gov/gistemp/) smoothed as a 29 year running average. Of course that doesn’t make any sense. We know what the earth’s land/sea surface temperature has done since 1935. It’s risen by around 0.6 oC. If one arbitrarily averages the real measured temperature with a 29 year running average, one arithmetically “magic’s” away a good bit of the warming. O.K. so Loehle’s analysis is pants on a number of levels. But for all its ludicrous faults, taken at face value it still indicates that we are a good bit warmer now (in the N. hemisphere) than during the MWP. I would suggest that if anyone is interested in looking at what the science indicates on this subject, they look at the paleodata on the NOAA NCDC database or download the very recent extensive analysis of Mann et al (2008) published as an Open Access article in the Proceeds of the National Academy of Sciences (http://www.pnas.org/content/105/36/13252.full) 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 ------------------------------------------------------- The extensive published paleoproxy temperature data is compiled 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. (http://www.pnas.org/content/105/36/13252.full) 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.
130865. Patrick 027 at 04:48 AM on 19 October 2008
        Volcanoes emit more CO2 than humans
        Echoing Philippe 190: Your complaints about abuse of peer review - this really doesn't prove anything regarding AGW but it may be worthwhile to note that one line of attack by creationists/ID proponents is to complaign about how their side is 'shut out' by the scientific establishment. ---- I can see why you would have gotten upset by the tone of your opponents; however, I can see why your opponents overall could have gotten very frustrated with you and why they would have labelled you a contrarian/denier. Also, your references to bibles and fundamentalists and evolution, and suggesting that a person should think for him/herself, were offensive because they imply things about your opponents which I don't think were generally true (certainly not anymore than they would apply to yourself - no offense.). More on that later... -- I can see why you (Quietman) and chris were having a hard time discussing the conclusions/interpretations of the paper(s) which used observed responses to solar forcing to figure out a climate sensitivity, which would then apply to CO2 forcing. What would have been helpful would have been for you to explicitly state one or more of the following (whichever applies to your thoughts): 1. the efficacy of the forcings could be different (** more on that later) 2. the solar forcing may extend beyond TSI (**although I would point out the authors apparently went on to find evidence for TSI being most/all of the solar (or solar-cycle-correlated??) forcing - I am only infering this from a quoted portion in the comments). 3. solar forcing may be correlated with some other forcing. 4. CO2 forcing is significantly overestimated (which is highly unlikely, I think - refer back to our earlier discussions). Any of these might have yielded some interesting conversation?
130866. Patrick 027 at 04:29 AM on 19 October 2008
        Volcanoes emit more CO2 than humans
        Re Quietman 186 (Arctic sea ice melt...): Many different people at different times may use any given word. People change. It's not even the same people around today as back then. In today's world, the worst treatment of returning soldiers and their families of which I am aware is by a far-right-wing reverend from - Kansas? - who goes around protesting at funerals, and by the government itself, but of course none of this is pertinent to the subject at hand. I was once told in high school by an aquaintance not to say 'pasta' because it's a 'yuppie word'. I was a bit puzzled by her concern on the matter - sure it's from a foreign language and may sound 'fancy' (if you're not used to it), but ... (doesn't my using it make it not so much of a yuppie word anymore?)
130867. Patrick 027 at 04:21 AM on 19 October 2008
        Volcanoes emit more CO2 than humans
        - now up to 170... will comment more later but a brief note... Do the math. Do the math. Do the math. Do the math. Do the math. Do the math.
130868. Patrick 027 at 15:46 PM on 18 October 2008
        Volcanoes emit more CO2 than humans
        - now up to 158. Interesting. Not necessarily in a good way... :)? (PS there has not been an overall warming trend in the last five million years - if anything an overall cooling trend (PS NOT claiming it is a constant linear trend) - superimposed on which are glacial-interglacial fluctuations.)
130869. Dan Pangburn at 15:03 PM on 18 October 2008
        Models are unreliable
        A list of all legitimate indicators that human produced carbon dioxide is a substantial contributor to global warming is welcome. The record of approximately 30-year long up and down temperature trends during the steady progressive rise in atmospheric carbon dioxide level of the 20th century certainly is not one since it corroborates that there is no significant correlation between rising atmospheric carbon dioxide and global average temperature. All of my sources are cited so that they can be checked. None are misrepresented. Quoting a maximum or minimum in a data set hardly qualifies as ‘cherry picked’. The Middlebury link (post 41) includes links to all of the source data that is graphed there. The corrections to Dr. Loehle’s paper are included with the original in the link at http://www.ncasi.org/publications/Detail.aspx?id=3025 . Select ‘Download File’ to get both the original and the corrections. Contrary to assertions by Chris, review of this paper reveals that the ‘corrections’ made little change to the results. Loehle used a 29 year smoothing which allowed comparison only through 1992 at the time of the paper. The smoothed average global temperature in 1992 reached about the same as was reached during the Medieval Warm Period. Loehle describes all of the data sources and methods that were used and solicits feedback by also giving his email address. Regarding the Medieval Warm Period, this is what Dr. Loehle actually said (in the correction): “The peak value of the MWP is 0.526 Deg C above the mean over the period (again as a 29 year mean, not annual, value). This is 0.412 Deg C above the last reported value at 1935 (which includes data through 1949) of 0.114 Deg C. The standard error of the difference is 0.224 Deg C, so that the difference is significantly non-zero at the 10% level (t = 1.84). While instrumental data are not strictly comparable, the rise in 29 year-smoothed global data from NASA GISS (http://data.giss.nasa.gov/gistemp) from 1935 to 1992 (with data from 1978 to 2006) is 0.34 Deg C. Even adding this rise to the 1935 reconstructed value, the MWP peak remains 0.07 Deg C above the end of the 20th Century values, though the difference is not significant.” Utilizing information from several publications as well as the web helps to compensate for the bias, agenda, group-think and de facto censoring that can exist with a particular publication. There are undoubtedly many publications that supposedly show that added atmospheric carbon dioxide is a significant cause of Global Warming. That can happen when you start out with a conclusion and then set out to justify it. I started out with the relation of carbon dioxide and Global Warming as a question. Although I try to listen very carefully to what others say, I withhold judgment as to validity until vastly corroborated and even then remain alert to contradiction. The above and, except for mentioning feedback, the lengthy comments by Chris are not particularly relevant to the issue of reliability of GCMs. Although reliability as used here is ambiguous, I assume, as probably most do, that it means that it pertains to whether GCMs can reliably predict future climate. Maybe some day some of them will be able to but not yet. Three major issues are apparent: 1) Vertical convection is subjectively parameterized. 2) Clouds are also subjectively parameterized, and rather poorly (see post 17). 3) The users arbitrarily impose substantial positive feedback which, climate history proves is a mistake. There are other issues as listed at post 32 (Average temperature anomaly from NOAA for Jan thru Sept 2008 is 0.445). There is one exact computer of earth’s climate as I described at post 45 above. Of course any credible temperature proxy can be used as an archive of results. It appears that Chris either did not read or did not understand my earlier post (43) on feedback. Referring to feedback as “vague” and “nebulous” further verifies a lack of understanding of feedback. Failure to see the difference between the paraphrase of my words “clearly feedbacks don't exist” and my actual assertion that NET positive feedback does not exist also indicates a lack of understanding of feedback. Failing to understand feedback explains why temperature TREND reversals during the previous glaciation are not recognized as proving that significant NET positive feedback does not exist in climate. Actual temperature response is influenced by NET feedback. NET feedback is the combined effect of positive feedbacks such as water vapor, negative feedbacks such as Lindzen’s iris effect, and all other feedbacks whether recognized or not. Although the numerical values and formulation are different between engineering feedback and Ocean and Atmospheric Physics feedback, positive feedback means the same thing in both. The response is greater with positive feedback than it would be if there were no feedback. NET means the combined effects of all active feedbacks whether known or not. A temperature TREND direction change proves that there is no significant NET positive feedback. Any credible source of temperature can be used. All that is needed to determine that there is no net positive feedback is a temperature trace for a long enough time to average out cyclic variation from random noise and other factors such as ENSO. Of course it must also be substantially longer than any smoothing period that was employed. The temperature trace does not even need to be correct in absolute terms just reasonably accurate in relative terms time-wise. Apparently the importance of the change in direction of temperature trend is not recognized by those who do not understand how feedback works. Without significant net positive feedback, the GCMs do not predict significant Global Warming.
130870. Patrick 027 at 12:23 PM on 18 October 2008
        Volcanoes emit more CO2 than humans
        - started reading comments in "Arctic sea ice melt - natural or man-made?" - up to 119 so far... will return later...
130871. Quietman at 07:29 AM on 16 October 2008
        Volcanoes emit more CO2 than humans
        The link in 94 did not work. I think I put a slash after stm so heres a copy and paste version: http://news.bbc.co.uk/2/hi/science/nature/7081331.stm
130872. Quietman at 07:20 AM on 16 October 2008
        Volcanoes emit more CO2 than humans
        PS I suggest that you read this BBC November 2007 article as it does explain the skeptic attitude on this issue.
130873. Quietman at 07:09 AM on 16 October 2008
        It warmed before 1940 when CO2 was low
        The fact of the matter is that there is no actual evidence for the 30 years of warming attributed to CO2 to be anything other than natural. Our contribution, of various sources, not just CO2 is negligable. Most of the arguments presented against CO2 have some merit and the answer is most likely in the combination of all.
130874. Quietman at 04:49 AM on 16 October 2008
        Climate sensitivity is low
        Patrick You did start explaining your logic but diverted to an unrelated subject. While I did find your argument very interesting, I was not convinced that you actually proved Spencer incorrect. Actually, I have not read any papers or articles that show him incorrect, only alternatives. I view the IPCC alternative as incorrect because it has not produced the promised evidence in degree ie. Spencer has shown that his numbers equal observation while the IPCC numbers are way off from the observations. This is why their models don't work.
130875. Quietman at 04:45 AM on 15 October 2008
        Volcanoes emit more CO2 than humans
        Excuse the spelling, my attention is somewhat divided today with a sick grandson.
130876. Quietman at 04:44 AM on 15 October 2008
        Volcanoes emit more CO2 than humans
        Re: Your comments on plausibility. Yes the senate has even looked into the matter. If the scientist has a position like Spencer he can speak out, it's only reputation at stake. If the scientist is junior he can be fired or asked to resign. It has in fact happened. Polotical correctness is a disease of society that has been with us since the commie hunt back in the 1950s. That is why I said to read carefully. When a scientist skirts the issue it means that he/she does not agree but will not say so.
130877. Quietman at 04:16 AM on 15 October 2008
        Volcanoes emit more CO2 than humans
        Re: "Potentially so but only in a few locations, whereas the ice mass loss and general warming are far far far more widespread and general." Of those known or recognized at this point in time. All of these articles are findings after the IPCC had decided the cause was AGW. Re: "I think at least some of the articles you referenced did say that, not about some of the specific locations but about much of the other warming." Yes some cite AGW but without making it an argument (ie. it is assumed from the start). They did not look at the issue without the background assumption that it could only be AGW. Look at the facts, not the assumptions.
130878. Quietman at 04:09 AM on 15 October 2008
        Volcanoes emit more CO2 than humans
        Re: "Meltwater could come from the surface, flowing down into the glacier through moulins - this source would explain the seasonality of any meltwater-induced lubrication of the glacier. (Of course, however the ice is melted or induced to flow, the resulting thinning would lower the ice surface and cause warming of the ice surface that way.)" Agreed.
130879. Quietman at 04:08 AM on 15 October 2008
        Volcanoes emit more CO2 than humans
        Re: "Dark aerosols are/have contributed to arctic warming and melting in that way; that is true. tropospheric ozone has also contributed to Arctic warming and melting. So has CO2, CH4, etc. However, the highest albedo is from fresh snow. Old snow and ice tends to have a lower albedo." Agreed.
130880. Quietman at 04:05 AM on 15 October 2008
        Volcanoes emit more CO2 than humans
        Patrick Re: My response to chris. It is exactly what he/she? has accused me of on several occasions because I often do not accept an authors conclusions, especially Hansens.
130881. Quietman at 04:00 AM on 15 October 2008
        Volcanoes emit more CO2 than humans
        Patrick (and chris) The papers (all papers, peer reviewed or otherwise) present an argument. That state their observations, methods used (so you can duplicate the test) and references to avoid restating prior arguments. The argument is presented largely in the "conclusions". The papers are all worth reading but it must be remembered that the paper IS AN ARGUMENT, attempting to persuade others to see the authors viewpoint. Accepting the authors conslusions is not mandatory. Peer review indicates that at least one other person in the same field of research agrees, it does not make it fact. If you read the papers carefully, in particular the methods and results you can often come to a totally different conclusion using a wider bas of information. All of the articles cited are related but the authors have not connected the dots. Ignore their conclusions, connect the dots and draw your own conclusions. THAT is what science is all about.
130882. Patrick 027 at 14:38 PM on 14 October 2008
        Volcanoes emit more CO2 than humans
        "To save time and server space, I ask you to read the comments in "Arctic sea ice melt - natural or man-made?"" ... will do, eventually... -------- a few loose ends: quasistationary planetary waves - they don't tilt much with height - at least not relative to their wavelengh. Systems can/could also grow through barotropic instability, which is an instability caused by larger horizontal wind shear (such as on the sides of a jet stream). I don't know as much about that.
130883. Patrick 027 at 12:42 PM on 14 October 2008
        Volcanoes emit more CO2 than humans
        "But in fact the thinned crust is the northern end of Greenland (in the articles linked in this thread) and surrounding Arctic ocean and that is exactly where the largest glacial melt is AND IT IS FROM THE BOTTOM. " I only read the abstract. It sounds like chris may have read more. Is he incorrect about the article? "But top down melting would not produce the same results" It depends on what exactly the results are. Meltwater could come from the surface, flowing down into the glacier through moulins - this source would explain the seasonality of any meltwater-induced lubrication of the glacier. (Of course, however the ice is melted or induced to flow, the resulting thinning would lower the ice surface and cause warming of the ice surface that way.) -- "Ice albedo will remain until all the ice is gone. Soot in the top layers lower the albedo so fresh ice will have a higher albedo if we control the output of soot." Dark aerosols are/have contributed to arctic warming and melting in that way; that is true. tropospheric ozone has also contributed to Arctic warming and melting. So has CO2, CH4, etc. However, the highest albedo is from fresh snow. Old snow and ice tends to have a lower albedo. When snow melts and refrezes or otherwise changes to form larger particles, the reflectivity is reduced - light may penetrate deeper before being reflected, giving it greater chance to be absorbed. Aerosols (and rocks), natural or anthropogenic, will be concentrated as the ice volume is reduced. Sea ice will become more transparent and thus darker when it gets thin enough to see the water beneath. The loss of sea ice will likely have a warming effect (in the winter, at least) on the region, not just where the ice was lost. -- "suggest that vulcanism is a "contributer" in an earlier article" Potentially so but only in a few locations, whereas the ice mass loss and general warming are far far far more widespread and general. "They do not say if it is AGW either." I think at least some of the articles you referenced did say that, not about some of the specific locations but about much of the other warming. ____________________________________ Entering danger zone? "Keep in mind that while you and I can speak openly for or against the AGW concept. there are others who need to be politically correct or they will lose their jobs or grant money and therefore skirt the issue." Scientists and politicians and everyone else are only human. However, if a scientist does work that has errors, and especially if it is a matter of interest to people, I expect some other scientist would want to capitalize on the opportunity to point out those errors. Can scientists be friends with each other? Yes, but that doesn't prevent them from pointing out each other's errors - especially if they don't take it personally. There may be actual examples to back up that point but I'll leave that to others. What about money and prestige? If there were no 'climate crisis', then there would be less money available to study AGW and climate in general, right? Well, I hardly think there's a Higg's particle crisis (that we know of :) ), and yet we've got a Large Hadron Collider now. Still, though, the argument is plausable. Then again, if there were more controversy than there would need to be more work done to resolve it, so... Still, though, whereever the bulk of the money and attention are going, there could be some scientists out there who would like to make a big name for themselves by successfully overturning the conventional wisdom of the day. If they are not able to do so, then there might be a reason why. And unless scientists are actually making up the data, the data is what it is, the potential error in that data and all, the theory (logic) is what it is, and any scientist, or student, with sufficient education can ask, does this make sense? There are people with an interest in overturning the current accepted science of global warming. Some of them have lots and lots and lots of money. Yet, rather than having funded real science on the matter (at least any that would successfully accomplish their goals), they instead lobby the government while launching silly propaganda campaigns about how CO2 'is life' (or that any effort to reduce CO2 emissions will harm the poor (often arguments ironically made by people who would rather not have the government do the poor any special favors, I think), or that free market capitalism will solve everything and any government involvement works against innovation - when in fact a carbon tax or some equivalent, etc, could help spur innovation and may be justified by (market) economic principles) ... Meanwhile, my impression is that, if anything, the IPCC summary for policymakers is watered down in favor of anti-alarmism, rather than hyped in the other direction. "Then there are those, like one poster at this site, that are environmental fanatics who look upon AGW as a bible thumper looks to the word of God." I can't help but wonder if this is the result of misunderstanding (not that I would pretend to know how your conversations with others have gone - I don't know). Not that it can't happen - many people don't understand science, regardless of what they have come to believe or accept as true (although the people who do understand science are more likely to accept or lean towards the accepted science or at least one or more promising contenders). But sometimes people who do know stuff just get tired and impatient from explaining and explaining and explaining and explaining and explaining and explaining and explaining and explaining and explaining again, especially when so many turn a deaf ear towards it or come back with accusations of communism, or just keep making the same arguments over and over and over and over and over and over and over and over and over and over and over and over and over and over and over and over and over, no matter how well it's been refuted to them (and maybe in some cases, being caught telling other people something totally false about what you told them - this has happened to me). Then what may happen is that people misread each other, assuming that the other guy is a member of the group of ignorant jerks s/he's become accustomed to dealing with. It may happen in particular when a new face advances an argument that the other person has seen before, perhaps from an actual 'denier/contrarian'. Or to save time, a person might refer to the 'scientific consensus', from which the other person may unfairly conclude that the other is just arguing 'from authority', rather than understanding the significance of such a consensus (ie sure, we can't be 100% sure about much, but there comes a time when we've got to make a decision - what do we put in our science textbooks? What do base public policy on? While there are loose ends still being worked out, relativity and quantum mechanics are scientific consensus. Many details have not been found, but the general picture of biological evolution by natural selection and some other things is scientific consensus. That the Earth is ~ 4.5 billion years old ... etc. PS Relativity didn't overturn Newtonian mechanics entirely (we still use the later for many things), and aside from that, if the argument is made that Einstein successfully overturned a consensus, 1. does that mean we could expect that Einstein will also be shown to be wrong someday, and 2. for every Einstein, how many had an idea that didn't pan out?) Although it is unfair, it is sometimes understandable why a person may make an assumption about someone's attitude to reality. There is also the time constraint - if a person smells 'silly' in an argument, they may decide (rationally) to not bother with it, hence, dismissing it. Certainly if I didn't have the time I couldn't have been discussing/arguing with you about the merits of various possibilities. I myself am quite satisfied that 'it' (you know what I mean) is mainly AGW. There are many arguments I won't look into further, because I judge them ahead of time to be wild-goose chases that will lead nowhere - I can do that with some confidence because of the arguments I have looked into that turned out to be just that, empty fluff. Occasionally I will look into such an argument though, just to debunk it - but of course, if I can't debunk it, that will tell me something, won't it? (Either that it may be possible, or that it is beyond my knowledge). Another aspect to this - perhaps an application of Occam's razor - there are so many things that are known, that lead to an expectation of significant CO2 causing significant warming - that Arrhenius (sp?) predicted as much long before CO2 emissions ever rose to such a level - the understanding of how radiation transfer actually opperates has been refined since then, as have the radiative properties of gases, etc, - but not in a way to discredit the basic idea, rather just to refine the theory. Then there is paleoclimatology, the computer models, the observations so far, etc. - they all inform each other, of course, but even taken independently they point in the same general direction. Given all that, some of these alternative explanations - it seems like throwing in extra Rube Goldberg devices and lasers to explain how the toaster works, after you've already seen the nichrome wires glowing red... Now, I may still want to learn about some things for other reasons - I don't think the tidal-driven ocean mixing will account for much of recent changes but I find it interesting as a phenomenon all by itself, for example. "Hopefully we will get to the truth behind all this regardless of their attempts to "enlighten" us "deniers" (that is their demonization of skeptics vocabulary, not mine)." This is messy. Take out the 'offensive words', and what is left behind essentially describes, in my mind, what I hoped to accomplish - enlighten you. Why wouldn't I call you a denier or contrarian? Well, because you've been polite and seem willing to listen, you haven't accused me of being a communist, a dumb parrot, or having malice or indifference towards innocent people, and you aren't trying to cast yourself as a climatologist or a scientist in some related field. I was actually afraid I've 'led you on' when you implied someone else might consider me a denier, so now - in jest - I will say that some of those I have argued with would call you a communist. As for those words - denier, contrarian - there are people out there to whom I think they would justifiably apply. For example, dare I say Fred Singer and Richard Lindzen. I don't say this just because they say things I disagree with - I say it because they say things that can't be backed up, they make arguments that are shot full of holes, and especially in Fred Singer's case, I am tempted to doubt whether he himself could possibly buy into his own arguments - or else, I think he must be horribly confused and sloppy - yet, perhaps some of his sleight-of-hand reasoning is too clever for that explanation? Other people - whether they knowlingly lie or just want to believe in those things that help them politically - Rush Limbaugh, Michael Crichton, Ann Coulter, James Inhoffe, James Dobson, CEI, etc... and even Jon Stossel and Glenn Beck, - well, ... they don't identify themselves as scientists, but in some cases they are quite biased in their work, and in some cases there furosity ... Some would say 'denier' is offensive because it may have been inspired by the use of the word next to 'Holocaust'. I can see that, however, I can also see that it is a word, like red, and certainly no one thinks cherries are communist. Does a person 'deny' in an irrational or dishonest way? Your response to chris: "Yes but first you have to examine it instead of dismissing anything you don't like off hand or because you don't like the author or what he/she says. You can't skip through and ignore key words and phrases the way you like to and you can't assume that a paper is fact, peer reviewed or not. It is an argument, ie. a hypothesis." Actually, I think chris may have been saying somewhat the same thing to you. Aside from that, of course one shouldn't assume a paper, even having passed peer review, reaches the correct conclusions. But there are so many many papers ... the balance of evidence tilts clearly toward significant AGW. That there are uncertainties in feedbacks - this applies to any climate forcing, so AGW still 'has a leg up on' various alternatives (in the sense of contenders to being the major forcing of relevant changes), and the 'burden of proof' doesn't fall all the way back to showing CO2, et. al., as big players, just because of feedback uncertainties. In particular with 'dismissing offhand' - see somewhere above...
130884. Patrick 027 at 10:16 AM on 14 October 2008
        Climate sensitivity is low
        "Actually you dismissed the idea rather abruptly" But I did explain why I was dismissing it (or perhaps more accurately, debunking it, or at least trying to debunk it). So what would really be helpful is if you could find errors in my reasoning - the gist of which was that Spencer was considering temperature response to cloud variability on short timescales, short enough that thermal inertia would limit the temperature response. And now I don't remember off hand, but I do wonder how it could be determined with such an apparently simple method to what extent the cloud variability caused the temperature and vice-versa. And the other problem - it seems to me cloud feedback is a part of climate sensitivity to other things, but there is little (on these short timescales) CO2 feedback to cloud 'forcing', and even less so feedback by changes in solar activity, etc.
130885. chris at 09:56 AM on 14 October 2008
        Volcanoes emit more CO2 than humans
        Re #80/#81 That makes no sense at all. The reason I questioned your choice of links is that I downloaded and read each paper thoroughly (rather than just the press releases). So I certainly "examined it"! In fact I thought the papers were excellent (papers have to be pretty good to be accepted in Proc Natl Acad Sci or Science and so on...). I thought the authors were fine and I was perfectly happy with what they said (male and female alike!). So your odd accusations don't apply and one wonders why you don't address the critique of your interpretations, rather than reply with inappropriate insults. There's clearly valid questions of whether (a) undersea volcanic/tectonic activity has increased in a manner that could have a causal relationship with the rather large global-scale warming of the last 100 years, especially the last 30; (b) whether tectonic activity has made a significant contribution to widescale polar ice melt. A skeptic should like to see some real world evidence. The point is that the papers that you cited don't support your notion. In other words you can't use as evidence of undersea tectonic contributions to Greenland melt, a paper that describes high level ice sheet surface melt at the ablation zone 1500-2000 metres in altitude in Western Greenland. That's not the result of undersea tectonic activity. It's a consequence of enhanced atmospheric warmth. Likewise one cannot use as evidence of enhanced tectonic contributions to global warming a paper whose essential analysis is to describe the continual steady decrease in thermal heat from plate boundaries due to their consolidation from previously smaller fragments over millions of years. And it's obvious that every paper about tectonics does not willy-nilly constitute an "argument" about tectonic contributions to global warming! We all know that plate tectonics is a fundamental element of the earth system. The question with respect to largescale global warming is whether this activity has increased recently. So there's nothing wrong with the papers - you've just chosen to cite papers that provide data and evidence that contradicts the notion that you are pursuing. And one should be careful in relying on press releases for scientific information.
130886. Quietman at 09:13 AM on 14 October 2008
        Volcanoes emit more CO2 than humans
        Patrick "Sandwiched between Earth's crust and molten outer core, the vast mantle accounts for 83 percent of the planet's volume. It is filled with solid rock but, heated by the core and by its own radioactive decay, it circulates like a pot of impenetrable soup. That circulation is the driving force behind the surface motion of tectonic plates, which builds mountains and causes earthquakes." Ref: Geophysicists Propose A New Model Of Earth's Mantle ScienceDaily (Mar. 19, 1999) - Earth's mantle, a region as scientifically remote as outer space and the object of the most heated debate in geophysics, gets a remodeling this Friday by researchers at UC Davis and MIT PS I would remind you that the capacity for "sudden" changes was covered in my post 36. But I found a good link for the article at ScienceDaily (June 20, 2008) — Surprisingly Rapid Changes In Earth’s Core Discovered " The movements in the liquid part of the Earth’s core are changing surprisingly quickly, and this affects the Earth’s magnetic field, according to new research from DTU Space." ... “What is so surprising is that rapid, almost sudden, changes take place in the Earth’s magnetic field. This suggests that similar sudden changes take place in the movement of the liquid metal deep inside the Earth which is the reason for the Earth’s magnetic field,” Nils Olsen explains. Ref: The Abstract in Nature. Viewed with the article of Tectonics acting as the Earths thermostat it can be seen how the thermostat can become suddenly reset for periods of time.
130887. Quietman at 08:46 AM on 14 October 2008
        CO2 lags temperature
        Re: "On the other hand it's not obvious why you consider a truism to be an assumption! It's been known since the middle of the 19th century that the earth's temperature is defined by the insolation from the sun (which gives the Earth a black body temperature near -15 oC) and the greenhouse effect arising largely from water vapour and CO2 that supplements the black body temperature by around 30 oC." Because it has been determined slightly more recently that your truism isn't. It is incomplete. Because it is incomplete the concepts that assumed it to be correct are also incorrect albeit not entirely. Just enough to skew the results and point in the wrong direction.
130888. Quietman at 08:40 AM on 14 October 2008
        Volcanoes emit more CO2 than humans
        PS Re: "SO how/why would global warming alter storm tracks?" I thought that you made a good explanation or at least a good argument for that in the Bertha thread.
130889. Quietman at 08:36 AM on 14 October 2008
        Volcanoes emit more CO2 than humans
        Patrick That was directed at chris. You put forward a good argument regardless of what points I disagree with and do so using logic rather than a peer review bible. Keep it up, you do a good analysis.
130890. Quietman at 08:32 AM on 14 October 2008
        Volcanoes emit more CO2 than humans
        In science it's all about the evidence Quietman. Yes but first you have to examine it instead of dismissing anything you don't like off hand or because you don't like the author or what he/she says. You can't skip through and ignore key words and phrases the way you like to and you can't assume that a paper is fact, peer reviewed or not. It is an argument, ie. a hypothesis.
130891. Quietman at 08:28 AM on 14 October 2008
        Climate sensitivity is low
        Patrick Re: "I covered that very argument in some of our last comments in "Science and Society"." Actually you dismissed the idea rather abruptly, but that's OK. But it doesn't mean that I did. On the solar wind I will have to find the links again. I know I posted them on this site somewhere.
130892. chris at 22:33 PM on 13 October 2008
        Volcanoes emit more CO2 than humans
        Re #74: The suggestion that scientists "skirt the issue" because of worries about funding/grant money or political correctness is ludicrous and isn't a scientific argument. It's a conspiracy theory. The essential element of science and one that allows us to address difficult and complex issues relating to real world phenomena is that it is evidence-based. All discoveries/interpretations that are supported by the evidence have a place in science and are likely to appear in the peer-reviewed scientific literature. If interpretations are not supported by real world evidence they are very unlikely to appear in the literature or to be taken very seriously, especially be scientists who are pretty skeptical people. And of course we should all be skeptical of assertions/arguments without an evidence-base. Of course we're free to discuss unsupported hypotheses to our hearts content, but unless evidence accrues to support these, one should remain skeptical. Castigating individuals as "environmental fanatics who look upon AGW as a bible thumper looks to the word of God", seems more like an insult that a scientific argument! I haven't posted here that long and haven't come across any people that seem to have unreasonable concern for the environment. However surely one should address their argument/evidence rather than insult them. In science it's all about the evidence Quietman.
130893. chris at 20:36 PM on 13 October 2008
        Volcanoes emit more CO2 than humans
        Re #66, 67, 71, 73 etc. The notion of significant volcanic/tectonic contribution to polar ice melting simply isn't supported by the evidence, Quietman, and most of the articles that you link to don't support that notion either. Much of the analysis of enhanced melt/glacial runoff that is contributing to nett mass loss in Greenland is from regions far from the Gakkel ridge in the far NE region N of Greenland where some tectonic activity has been found. It's already been pointed out by Patrick that the surface melt highlighted by Tedesco et al in their EOS article is incompatible with the effects of undersea tectonic activity. This is highlighted by Tedesco himself who indicates that the snow melt is associated with surface/air maximum temperatures 3 oC above average. Clearly that cannot be the result of undersea volcanos. The situation is similar to the article you linked to on the Greenland thread (your link in post #66 above). It's easy to see that this article (citation below) discusses surface melt on the Western region of the Greenland ice sheet, and specifically concerns surface melt in the ablation zone 1500-2000 metres high up in the ice sheet. This enhanced surface melt cannot be the result of undersea volcanic activity 1000 miles away. and so on. The papers you link to are inconsistent with the effects of undersea tectonic activity. An additional problem relates to the question whether this activity (undersea tectonics) has increased in a manner that is consistent with the timescale of enhanced warming. You linked to a paper in your post #13 above which you consider to be some sort of support for a contribution from tectonic activity to the very marked enhanced warming of the last century and especially the last 30-0dd years. However this paper (Loyd et al, 2007; citation below) simply doesn't support that notion. The specific point of the Loyd paper that you link to is that the release of thermal heat from the earth's tectonic activity has steadily decreased over the last many million years. Now it may be that there is some evidence for enhanced tectonic activity, but the paper you linked to certainly doesn't provie any. If anything it provides completely contrary evidence to your hypothesis. R. S. W. van de Wal (2008) “Large and Rapid Melt-Induced Velocity Changes in the Ablation Zone of the Greenland Ice Sheet” Science 321, 111 – 113. S. J. Loyd et al (2007) "Time variability in Cenozoic reconstructions of mantle heat flow: Plate tectonic cycles and implications for Earth's thermal evolution" Proc. Natl. Acad. Sci. USA 104, 14266-14271.
130894. Patrick 027 at 16:12 PM on 13 October 2008
        Climate sensitivity is low
        "You apparently confuse ocean tides with tectonic tides" No, but I do recognize that solid earth tides must respond to oceanic tides and vice versa, but except maybe for around the Bay of Fundy and that one place in France - well... "The concept that the solar wind does not have an effect on climate is wrong." Could you explain how it works or describe the observations supporting it? For example, from the article on Forbush and Heliospheric current sheet crossings etc. (PS you'd have to quantify the radiative forcing of that and then figure out a multidecadal trend...) Or does it affect circulation patterns directly via the E-region dynamo (within the base of the thermosphere) - ps mass of E-region dynamo is something like a millionth of the whole atmopshere, give or take a factor of ten (just because I can't look it up right now), but if you could find some mechanism to propogate a pressure perturbation or pattern downward while amplifying it... "I have a link posted here to Spencer's argument in comment 9. " I covered that very argument in some of our last comments in "Science and Society".
130895. Patrick 027 at 16:00 PM on 13 October 2008
        Volcanoes emit more CO2 than humans
        *A3*. If anticyclones are larger horizontally they will then tend to propogate westward relative to the wind faster than cyclones (beta effect), so cyclones will tend to move eastward with the overall wind faster than anticyclones, or in order to move at the same speed, anticyclones would have to be closer to a westerly jet ... etc... AND as anticyclones sort out equatorward of stormtracks, they would experience higher beta and so their eastward movement would be slower for that reason as well - unless there is another effect that counteracts this. PS to be clear, My understanding is that: In baroclinic instability, eddies grow by taking available potential energy (APE) from the average state (averaged along a storm track across a full eddy wavelength, for example, or a full zonal average across all longitudes for the overall midlatitude storm track activity) and thus creating eddy APE, essentially by moving the cold air and warm air into each other (creating a wave pattern in the isotherms or isentropes along a horizontal or near horizontal surface) - at the same time, this disrupts geostrophy so that a thermally direct circulation occurs, with winds moving from high to low pressure horizontally, with warmer air rising and colder air sinking. This converts some of that eddy APE to eddy kinetic energy (KE), which enables the eddy to distort the isotherms even more, and thus continue to grow - for small disturbances, growth can initially be exponential. Two things: when warm air is pushed as a protrusion into colder air, the resulting pressure perturbation is initially unbalanced by the coriolis effect and so the warmer air rises - warmer air that was initially surrounded (horizontally) by air of a more similar temperature is now surrounded by colder air, and so rises, just as actually adding heat to a region of air tends to make it rise. However, depending on the geometry, some of the surrounding colder air may also sink as it is now next to warmer air. The effect may not be as strong as in the warmer air since the colder air is not surrounded by the warmer air, however (mathematically, it depends on the laplacian of the temperature advection). But if new warm air continues to flow from the main warm air mass into the cold air, the cold air will eventually adjust and stop sinking while the warmer air is still coming into a new situation and will still rise. IF the temperature gradient is initially constant from warmer to colder, than, for the sake of clarity, assuming an initially north-south temperature gradient (east-west isotherms), a wave pattern of flow that is limited from north to south will pull isotherms apart in the warmer side while pushing them together in the colder side, or vice versa, and where isotherms are pulled apart, a thermally indirect circulation will develop, converting KE to APE. However, where isotherms are pushed together, the thermal gradient can get higher and higher (until some ageostrophic effects associated with frontal zones get strong), whereas the pulling apart of isotherms can at most reduce the gradient to zero (PS I haven't actually calculated this but I would assume this means the thermally direct circulation eventually dominates while the themally indirect circulation dies out). Also, if the initial thermal gradient is concentrated near or along the storm track, there might not be so much pulling apart of isotherms even initially to cause a balancing thermally indirect circulation. Anyway, an east west cross section of an idealized series of such growing eddies may show alternating high and low pressure centers tilting westward with height, regions of rising and sinking motion, strongest in midlevels (air won't rise into space or go down into the surface) which also tilt westward with height but not as much, and regions of warmer and colder air that tilt eastward with height. The air flows through these features from west to east higher up and from east to west closer to the surface. Because the temperature and vertical motion patterns don't tilt the same way with height, there can be some pockets of thermally indirect circulation, but overall it is mostly thermally direct. What is really interesting about these kinds of systems - you might well wonder, how can they grow - how can the pressure systems get stronger - when the thermally-direct motions that create the kinetic energy associated with the wind requires that air is on average flowing into low pressures and out of high pressures? The answer: by temperature advection (transport of air)(not actually by heating, although that will occur but is not part of this explanation), the air in between the highs and lows is warmed or cooled because of the north-south flows. But the east-west flows through the system act on this pattern, so that the resulting temperature field doesn't tilt as much as the pressure field and actually tilts the other way. The vertical motion reduces the growth of the temperature pattern by adiabatic cooling and warming of the warmer and colder air, respectively, and this effect is greatest at midlevels (or tends to be, but will also be greater at levels with higher static stability). Near the surface, warmer air is closer to lower pressure; at higher levels it is closer to the higher pressure (opposite for colder air). Pressure drops faster with height through colder denser air than through warmer air, so the low pressure tilts with height over the colder air to its west, and the high pressure tilts with height over the warmer air to its west. The temperature field explains the way pressure changes with height, but what explains the actual pressure field at any one level, such as the surface? There has to be some total divergence through the whole column of air above the surface low pressure to result in lowering the pressure (assuming flat topography - pressure systems can also be produced by motion over slopes). There has to be convergence into the low pressure on average in order to increase kinetic energy. But with height, the high pressure tilts part of the way over to above the surface low, so divergence from that high pressure can lower the pressure at the surface, while convergence at the surface increases the high pressure aloft. What about angular momentum? Air is vertically stretched beneath warm rising air at midlevels, while also being transported by relative westward motion (relative to this whole pattern) into the low pressure at low levels levels; so cyclonic relative vorticity is created that can nearly balance the pressure - but not quite, or else their could not be net convergence into the low (actually, there could also be some effect of centrifugal force, which affects high and low pressures asymmetrically - although centrifugal force depends on the trajectories, whereas vorticity is determined from streamlines**), and at upper levels, air is vertically stretched above sinking motion while being transported westward into the low pressure at that level. And so on for the growth of anticyclonic vorticity in the high pressure areas. The whole pattern can grow exponentially, up to a point. When the flow pattern of the disturbances is stronger, the warmer air is not just moved east west toward low and high pressure centers, but continues to move north and south more significantly due to the wind of the disturbances. Thus warm air flows northward from south of the low (did I mention I'm describing a Northern Hemisphere version) east of the low and westward relative to the low, into the low as the low moves east, but also continues northward and goes north of the low. Rising motion and the surface low itself will follow. Another way of looking at it is that the flow of air above the low is not just westward but northwestward, between a trough and a ridge at mid-to-upper levels... and generally, features at one level in the atmosphere tend to propogate with the wind at another level because the wind at that level must adjust to the feature, and the feature must adjust to that adjustment... So in the 'sorting out' process where the highs and lows at the surface tend to end up on different sides of the jet stream and temperature contrast associated with the storm track, when the motions are averaged along the length of the storm track, it may appear that colder air is rising and warmer air is sinking, but this may largely be (?) the result of warmer air rising while surrounded by colder air, and colder air sinking that is surrounded by warmer air. Mathematically this can be worked out as a thermally direct eddy circulation which is producing more kinetic energy than is being taken back by the weaker thermally indirect averge motion. At some point, though, I could imagine that even while the warmer air and colder air are still warmer and colder than their immediate surroundings, they may have cooled and warmed enough, respectively, that they are no longer warmer and colder than each other, respectively; at that point the average thermally indirect motion would be stronger than the eddy thermally direct motion, I think, so that in total kinetic energy is being converted to APE. Of course, the eddy motion itself might start converting some KE to APE at some point during the decay stage (?)- perhaps frictional dissipation may force cold air up in the lower levels of the low pressure system, for example - which would strengthen the low pressure aloft but reduce it at the surface (although the convergence at the surface would reduce it at all levels, but at higher levels the disruption of geostrophy would induce flow to counteract whatever pressure tendency there is - not entirely unlike the way electric currents respond to a changing magnetic field). I did see your most recent comments and I'll get back to you about that.
130896. Patrick 027 at 12:59 PM on 13 October 2008
        Volcanoes emit more CO2 than humans
        SO how/why would global warming alter storm tracks? I know a good amount about circulation patterns in the atmosphere and yet there is A LOT I don't know, but what I know, have been able to deduce, or otherwise have gotten the impression of, is: Remember hot air tends to rise and cold air tends to sink; this happens because of the pressure variations caused by the variations in air density. For a column of warmer air, the pressure is either lower than otherwise below it, higher than otherwise above it, or some combination of the two (at least for the hydrostatic approximation). The coriolis effect, on the large scale more than on smaller scales, tends to impede the simple 'thermally direct' circulation just described by causing wind to blow nearly parallel to isobars (or lines of constant geopotential on isobaric surfaces). The atmosphere is generally at least somewhat stable to dry vertical motion; this means that dry adiabatic cooling and warming are such that, the rising/sinking induced by a warm/cold anomaly tends to reduce the anomaly. Midlatitude storms do get some energy from latent heating (as with tropical storms), but unlike tropical cyclones, midlatitude storms get much of their energy from the available potential energy of a background horizontal thermal gradient. This thermal gradient supports a vertical wind shear (hence the jet streams). In the hydrostatic approximation (which is a good approximation in the asence of significant vertical acceleration, which is generally the case of larger scale motions), horizontal divergence/convergence must occur along with vertical compression/stretching (in pressure coordinates), respectively, which implies variations in vertical velocity with height (in pressure coordinates). In order to conserve angular momentum, which is the case in the absence of friction (and friction is generally weaker than the pressure gradient and coriolis forces in the midlatitudes), horizontal convergence/divergence must occur with an increase/decrease in the magnitude of vorticity - vorticity is a measure of the air's 'spin'. It's important to realize that this pertains to absolute vorticity, which is the sum of planetary vorticity (which is proportional the coriolis effect itself) and relative vorticity. Relative vorticity can be cyclonic or anticyclonic, such as in cyclones or anticyclones, respectively (although horizontal shear also contributes to vorticity). But the absolute vorticity is never anticyclonic except near the equator. Thus, vertical stretching, such as below rising motion or above sinking motion, tends to cause cyclonic motion, which requires a low pressure area to be balanced; and the opposite tends to cause anticyclonic motion, etc. *A1*.(Notice that if continued to extremes, relative anticyclonic vorticity can be at most equal and opposite to planetary vorticity, whereas there isn't such an upper bound to cyclonic vorticity, aside from the limits of the vertical stretching itself). Related to that, centrifugal forces allow for, for a given wind speed, greater pressure gradient around a low center than around a high center. (?? Another potential reason for assymetry is that divergence is ultimately limited by space but convergence is not ??, and also, a divergent air mass is growing larger in area whereas a converging air mass is shrinking ??, although air diverging from one point must ultimately also be converging toward another. ??) PS the measure of absolute angular momentum that is conserved during any inviscid (frictionless) adiabatic motion is isentropic potential vorticity. With constant static stability, potential vorticity (PV) is higher where absolute vorticity is higher; with constant absolute vorticity, PV is higher where static stability is greater. AND THEN: Disturbances in a region of vertical shear that are tilted into the shear - that is, if the vertical shear is westerly (eastward) with increasing height, the tilt of the pressure perturbations is westward with height - and moving at an intermediate speed between the extremes that occur higher and lower in the troposphere - can grow because the configuration allows for ...(Baroclinic instability) ... okay, well that's too complicated to go into right now, but to summarize: I think these disturbances can grow faster when the vertical static stability is lower - that is, when the laspe rate is higher. At the same time, higher lapse rates favor shorter-wavelength systems for maximum growth rates. Development is enhanced by greater horizontal temperature gradients and associated vertical wind shear. Although these disturbances could start out sufficiently small that linearized equations may describe them initially, they may eventually grow to the point that nonlinearities become important, and nonlinearities may be important to start with depending... so surface low pressure systems develop east of developing upper level troughs (assuming overall westerly average winds) and west of developing upper level ridges, and high pressure systems at the surface would develop east of upper level ridges and west of upper level troughs. There are also fronts. warm air heads poleward east of the low and rises, cold air west of the low heads equatorward and sinks. The configuration is such that (generally**) the low pressure system itself will tend to build poleward, eventually with the center attached to the warm air mass at the surface by an occluded front that underlies warmer air aloft. The high pressure will build equatorward. The pressure systems eventually lose some of their tilt, and thus their ability to strengthen vanishes. At this point, due to the sorting out of surface highs and lows, there is an overall westerly flow at lower levels in between them. If the north-south transport of heat by these systems was fast enough relative to the gradients in radiative and latent heating, vertical shear will have been reduced within the heart of the storm track, though it and the temperature gradient may actually have increased on the edges of the storm track as the warm fronts push into the cold air and the cold fronts push into the warm air. The overall effect of the disturbances may generally be to concentrate westerly momentum at upper levels into the storm track but also to transfer westerly momentum from upper levels to lower levels. Eddy potential energy and kinetic energy have both been produced from some of the available potential energy of the original horizontal thermal gradient, but also some has been produced from eddy-correlated latent heating and perhaps radiative heating (??) patterns, although radiative heating in the absence of cloud or humidity variations will tend to reduce eddy energy; some eddy kinetic energy is transferred back into the kinetic energy of an average across disturbances, and some of this kinetic energy is actually converted back into available potential energy by a thermally indirect circulation. I think this is because as the lows and highs 'sort out' and the warm air and cold air masses move past each other, the rising motion is shifted to the cold side of the storm track and the sinking motion is shifted to the warm side of the storm track. One way of quantifying this is with something called the EP flux, which is related to a potential vorticity flux. Factors, such as the horizontal shear of the average state, may affect the 'sorting' out process and the life cycles of the disturbances... Energy generated in the troposphere in these disturbances is spent in the lower stratosphere by lifting colder air and 'pulling' warmer air down. I'm not sure whether this energy is lost (radiatively ?) or is transferred back into the troposphere (to the extent the stratosphere acts like a trampoline). The thermal pattern produced in the lower stratosphere acts to reduce the strength of the disturbances at yet higher levels, thus they do not penetrate much above the lower stratosphere (though larger scale features do). Larger scale features (longer wavelength troughs and ridges) exist which do not grow in strength from baroclinic instability (although different waves can interact through nonlinearities), but rather propogate westward throw the air at all levels in the troposphere. These larger scale features may be excited by the wind's flow over topography and by some variations in temperature, and also by propogation around the globe of barotropic Rossby waves that are produced by convection over tropical sea-surface temperture anomalies, etc. These features affect the distribution/patterns of storm track activity. ------- So with global warming (in general, not generally specific to cause): The expected pattern in the Northern hemisphere (which would, I think, be expected in both hemispheres in the longest-term equilibrium states) is enhanced warming in the mid-to-upper troposphere in low-latitudes and, especially in the colder seasons, in the lower troposphere and surface at higher latitudes. This is because: At high latitudes, there is a strong albedo feedback, associated with reduced seasonal snow where there is some sunlight in winter, and summer sea-ice loss nearer the pole, which has a warming effect in winter by absorbing summer sun and taking longer to freeze while giving off more heat in the process during winter. The atmosphere is generally more stable at higher latitudes, especially in colder months, so the additional heat at lower levels may not be transfered to the rest of the troposphere by convection so much as it otherwise would. At low latitudes, there is a negative feedback over the ocean and moist surfaces (so long as they remain moist) as evaporation is faster at higher temperatures; the upper level heating is from the corresponding condensation of moisture. Some of that heat can be transported out of cloudy areas by circulation, of course. The changing lapse rate can be related to the temperature dependence of the moist adiabat. Thus the equator-to-pole temperature gradient, and thus the vertical wind shear at some point in between, is reduced at lower levels (except perhaps in summer or around that time of year) and increased at upper levels. These trends won't be distributed at both levels in the same way and won't be distributed evenly at all latitudes and longitudes, but starting with an even distribution assumption: 1. Due to the temperature gradient changes in the lower troposphere, one would expect reduced midlatitude storm track activity overall (except perhaps in or around summer, when it is not as great to start with, although mesoscale circulation (thunderstorms, squall lines, MCCs, etc.) do produce severe weather and intense precipitation events at that time, and severe thunderstorms are aided by vertical wind shear as well as moisture and moisture contrasts **). It might also perhaps allow for greater poleward-penetration of conditions that allow tropical cyclone development. HOWEVER: 2. Due to the temperature gradient trend at upper levels, one might expect greater midlatitude storm track activity (although this may be more sensitive to lower level thermal gradients and wind shear than upper level thermal gradients and wind shear), and also perhaps limit the regions that allow tropical cyclone development. 3. Interesting feedbacks: greater thermal gradients tend to enhance storm track activity which itself mixes the air on large scales which ultimately reduces the thermal gradient, so changes in storm track activity can be a negative feedback to changes in thermal gradients. If the reduced thermal gradient at lower levels reduces storm track activity, heat transport may be reduced at all levels, allowing the thermal gradient to increase at upper levels. If the increased thermal gradient at upper levels increases storm track activity, heat transport may be increased at all levels, reducing the thermal gradient at lower levels. Although of course the heat transport for a given circulation pattern will be greatest where the thermal gradient is greatest. (note that general circulation models, although not perfectly, will incorporate these effects, so the expected pattern of temperature change described before wouldn't necessarily be different because of storm track activity feedbacks). 4. Greater overall moisture in the atmosphere will also enhance storm track activity by adding to eddy available potential energy (and through that, to kinetic energy) by greater latent heating. *A2*. Since this affects essentially only precipitating systems, it's effect is asymmetrical between cyclones and anticyclones (as might also be the case with eddy-correlated cloud feedbacks). However, the more intense latent heating tends to be concentrated on smaller scales, so I'm not to what degrees it would enhance the synoptic-scale system, enhance mesoscale features, or change the character of the low pressure system, perhaps by making it more intense but more compact with more intense precipitation over a smaller area (?). Would there be more subtropical storms? PS more moisture overall in the air may also imply greater moisture transport across a given moisture gradient, and if temperature were rising equally everwhere, the moisture concentration gradients would increase - except of course, the temperature is not rising evenly everywhere. But temperature increases could increase the effect on regional and global circulation patterns of any given SST (Sea Surface Temperature) anomaly, such as that associated with ENSO (which itself may increase due to the delayed warming of upwelling cold water). Mesoscale humidity contrasts (drylines) are important in many severe thunderstorms, including tornadic storms. 5. IF the lapse rate were to remain constant, the greater latent heating would reduce the static stability effect on cyclones, which might then develop more rapidly, especially those with smaller horizontal sizes, but not on anticyclones. The greater latent heating itself may reduce the lapse rate, perhaps reducing but not eliminating the changes in cyclone development, while also slowing the development of anticyclones, especially smaller anticyclones. (If larger anticyclones are preferred ??, would that lead to larger airmasses, with reduced thermal gradients across some regions but enhanced thermal gradients around the edges of anticyclones, perhaps if wind is delivering air from longer distances without getting side-tracked, and hence over shorter times ??). 6. Note also that the overall expected temperature change pattern is such that vertical static stability is increasing at lower latitudes, but is decreasing at higher latitudes. This could concievably account in part for a tendency to shift the storm track activity poleward Notice this may mean a poleward expansion of subtropical dry regions into the midlatitudes as well as an increase in precipitation at higher latitudes on top of what might be expected from higher humidity alone. 7. Interesting feedbacks. When the overall thermal gradient is increased from a low value, the circulation due to synoptic scale eddies (includes storm track extratropical cyclones) increases. This includes vertical motion. Hence, there is greater vertical heat transport, which tends to increase vertical static stability, which slows the development of these baroclinic disturbances (baroclinic eddies; a.k.a. midlatitude storms and anticyclones), especially those of shorter wavelengths. In actual 'dishpan' experiments (a spinning pan filled with fluid and differentially heated and cooled), when the thermal gradient is very low, there is a Hadley cell; when it is increased, baroclinic disturbances form, when it is increased further, the wavelengths of the disturbances increase (as I recall), up to a point, until the wavelength of unstable disturbances is too large to fit into the pan, and so the Hadley cell resumes. However, there isn't an actual short wave cutoff in the atmosphere, although some simplified mathematical descriptions produce one - but it is true that the most unstable wavelength increases with increasing vertical stability. In the actual atmosphere one can also have small scale overturning as in cumulus clouds and thunderstorms. If the large scale overturning of either the Hadley cells or the extratropical circulations or both were reduced, one might expect that the vertical stability would decrease until and causing the smaller scale overturning to pick up the slack. 8. The coriolis effect is of course also very important. The coriolis effect varies with latitude, increasing away from zero at the equator. The variation of the coriolis effect over a north-south distance is called beta, and beta effects tend to cause disturbances, especially larger horizontal wavelength disturbances, to propogate westward relatively to the air flow; this produces a long-wave cutoff where some wavelengths are too large to develope by baroclinic instability. If the wavelengh, beta, and windspeed are right, a wave may remain nearly stationary - such quasistationary planetary waves can be excited by topography and variations in temperature, as mentioned before. I think beta also reduces the mechanism by which baroclinic disturbances grow through baroclinic instability, by contributing to convergence where there is divergence and vice-versa - at upper levels, anyway (maybe the opposite at lower levels, however - do the effects cancel?). Perhaps not as much if the overall flow is somewhat northward or southward over a whole wavelength of ridges and troughs...? - actually, this might turn out to be mathematically equivalent to some fraction of the other beta effect in the prior paragraph. Beta decreases away from the equator, to zero at the poles. So if the storm tracks move, the coriolis and beta effects will vary as applied to the storm track activity. Also, the tropopause is expected to rise. But the tropopause slopes downward toward higher latitudes. So it is unclear what happens to tropopause height at a moving storm track. A higher tropopause could affect storm track activity - for example, for a given wind shear, the total variation in wind would be greater across the troposphere. Perhaps the effect of topography would be slightly reduced at the upper levels ???? - And a given level of divergence in the air through the troposphere could increase the surface pressure fall if occuring through a greater thickness of air ????. And the relationship to the stratospheric circulations... the energy generated in the troposphere relative to that expendended in the stratosphere, that relationship would change.... More generally, deeper convection = more intense precipitation, and higher cloud tops increase the cloud's contribution to the greenhouse effect. 9. So the storm track activity changes. This changes the average wind patterns. That affects the way quasistationary planetary waves develope from topography and temperature variations, which again affects the wind and thus the storm tracks. Changes in SST affects how the SST anomalies (which themselves could change in frequency/intensity/location/etc.)affect all of the above (including but not limited to ENSO, PNA?). Etc. One way storm track activity can change is by changing the motion of storms - if storms move more slowly or are farther apart, for example, one could have greater risks of floods or droughts, and the opposite for the reverse; a greater portion of precipitation coming in intense events may lead to greater runoff; the frequency and locations of blocking events could change; blocking anticyclones are associated with dry spells and heat waves; I suppose they might lead to the opposite somewhere else since cyclones may be rerouted around such anticyclones...Etc. Changing winds, wind shear, and static stability, affect the distribution of gravity waves and whether and how they propogate vertically, which would affect transfer of momentum from the troposphere to the mesosphere; the vertical propogation of planetary waves into the stratosphere could also be affected and that is associated within 'Sudden Stratospheric Warmings', and stratospheric circulation can then affect the troposphere. Related: would NAM, SAM, NAO, and QBO be affectd? Etc. I might be wrong about some things - especially towards the end, some of that was speculation (where I was unsure I tried to indicate as much). But at least I hope to have given you a sense of how global warming can alter weather patterns.
130897. Quietman at 11:31 AM on 13 October 2008
        Volcanoes emit more CO2 than humans
        Patrick To save time and server space, I ask you to read the comments in "Arctic sea ice melt - natural or man-made?" as that is where I presented my hypothesis en todo. It technically should have been placed here, but I got angry and a little carried away when I got double teamed. But there were some good points made by all in my opinion.
130898. Quietman at 11:24 AM on 13 October 2008
        Volcanoes emit more CO2 than humans
        Patrick Keep in mind that while you and I can speak openly for or against the AGW concept. there are others who need to be politically correct or they will lose their jobs or grant money and therefore skirt the issue. Then there are those, like one poster at this site, that are environmental fanatics who look upon AGW as a bible thumper looks to the word of God. Hopefully we will get to the truth behind all this regardless of their attempts to "enlighten" us "deniers" (that is their demonization of skeptics vocabulary, not mine).
130899. Quietman at 11:18 AM on 13 October 2008
        Volcanoes emit more CO2 than humans
        They do not say if it is AGW either. In fact they do not say why at all (in that article). But top down melting would not produce the same results, nor would it be restricted to only northern Greenland where the crust is thin (they DO describe it as a "hot spot" in the other article and suggest that vulcanism is a "contributer" in an earlier article. I do think they are at last on track.
130900. Quietman at 11:12 AM on 13 October 2008
        Volcanoes emit more CO2 than humans
        Ice albedo will remain until all the ice is gone. Soot in the top layers lower the albedo so fresh ice will have a higher albedo if we control the output of soot.

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