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Comments 126051 to 126100:

126051. Macha at 23:12 PM on 16 December 2009
        It's the sun
        These words spring to mind. “No amount of experimentation can ever prove me right; a single experiment can prove me wrong.” and "If we knew what it was we were doing, it would not be called research, would it?". -- Albert Einstein (1879-1955) [German physicist] Just because its warming does not PROVE its CO2. Cause and effect issues. The commentary on radiative "forcing' is also a bit hard for me to understand. Is it another word for Convection? After all, hot gases rise (when not trapped in a glass greenhouse) and when surrounded by cooler gases, they lose that latent heat, clods are created, humidity changes. Where are the records and observations of the changes in humidity and cloud cover?.
        Response: "Just because its warming does not PROVE its CO2. Cause and effect issues."
        
        That is true. The reason we know the warming is caused by CO2 is because satellites and surface measurements are observing more infrared radiation being trapped at the specific wavelengths that CO2 absorbs energy. That is what is meant by 'radiative forcing' which is just another term for an imposed energy imbalance. More CO2 is causing less radiation to escape back out to space which causes an energy imbalance. The result is the planet is accumulating heat.
126052. RSVP at 22:55 PM on 16 December 2009
        Hockey sticks, 'unprecedented warming' and past climate change
        On the graph of Vostok Ice Core data above, the temperature peaks around +3, +2, and +4 degrees. How could any ice have survived these peaks?
126053. chris at 22:33 PM on 16 December 2009
        Hockey sticks, 'unprecedented warming' and past climate change
        re #15 No one is that concerned about "regurgitating hockey stick arguments" HR. It's unfortunate that this isn't always done honestly and with a bit of scientific rigour (although one shouldn't have great expectations about the more dismal corners of the blogosphere!). After all the large amount of aditional paleoproxy data since the original "hockey stick" has pretty consistently supported the initial conclusions of that study concerning the anomalous nature of late 20th century warming. Alley's analysis of GISP 2 temperature proxy data for the Greenland ice sheet is also consistent with the "hockey stick" as originally presented. It's unfortunate that some blogger has made a false representation of the warming at the Greenland ice sheet surface during the last 100 years (see my post #7 above), but again, there does seem to be a concerted effort to misrepresent the science on climate-related matters. Your comments about "criticism of the science...moved....into peer reviewed literature" isn't really correct (of course all science has an essential critical element); a Nature blog simply isn't "peer reviewed science" HR! You're also incorrect in your assertion that "Mann has refined his arguement this year to suggest that MWP was a regional phenomenon". Mann has presented evidence for a regionality of the MWP for many years (as have many other scientists). That's simply what the evidence indicates, and there are many studies in the peer reviewed literature that indictaes that the MWP was represented predominantly in the high Northern latitudes and was spatially and temporally non-homogeneous elsewhere. See, for example, the following papers [*] that discuss evidence for the regionality of the MWP in comparison with the global scale nature of late-20th century and contemporary warming. This is a conclusion that has been around for quite a while....it's certainly not a "new version". You're right that "this particular bit of science has been seriously affected by its collision with politics". How true. But why not focus on the science and treat the political nonsense on the blogosphere with the disdain it deserves? [*] PD Jones and ME Mann (2004) Climate over past millennia Reviews of geophysics 42, RG2002 T. J. Crowley and T.S. Lowery (2000) How Warm Was the Medieval Warm Period? AMBIO: A Journal of the Human Environment 29(1):51-54 Bradley, R.S., Hughes, M.K., Diaz, H.F. (2003) Climate in medieval time Science 302, 404–405 Osborn TJ, Briffa KR (2006) The spatial extent of 20th-century warmth in the context of the past 1200 years Science 311, 841-844 H. Wanner et al. (2007) Mid- to Late Holocene climate change: an overview Quaternary Science Reviews 27 (2008) 1791–1828 etc. etc.
126054. Riccardo at 20:12 PM on 16 December 2009
        Hockey sticks, 'unprecedented warming' and past climate change
        SNRatio, the 3 degrees per doubling concentration holds as long as the simple logarithmic approximation holds. For exaple, the IPCC TAR quote three different aproximations for the forcing. You get 3.71 W/m2, 3.98 W/m2 and 3.97 W/m2 respectively for doubling from 280 to 560 ppm. If you double from 140 to 280 you get the same 3.71 W/m2 (obviously), 3.8 W/m2 and 3.45 W/m2 respectively.
126055. HumanityRules at 13:36 PM on 16 December 2009
        Hockey sticks, 'unprecedented warming' and past climate change
        You can point at skeptics regurgitating the MWP/Hockey stick arguement over and over again but it shouldn't be forgotten that it was warmers who really shot this to fame. Al Gore and the IPCC 2001 made sure this would be at the centre of the climate change debate. Critisism of this science has moved from marginal skeptic websites into peer reviewed literature. You could look at the Nature blog as a jumpimg off point. For this reason I think it's wrong for John to dismiss all this as "the inevitable consquence when forced to respond to rehashed skeptic arguments." As John mentioned, in a previous post, Mann has refined his arguement this year to suggest that MWP was a regional phenomenon. It will be interesting to see if this new version can stand up to inspection. You could view all this as the normal process of a developing science but we shouldn't forget this particular bit of science has been seriously affected by it's collision with politics.
        Response: The regurgitation was refering to the use of the Climate's Changed Before argument. The YouTube movie doesn't look to dispel the hockey stick - but demonstrate that over longer periods, there have been even greater changes in climate. I've yet to encounter any peer reviewed science claiming that past climate change means that climate is not sensitive to the radiative forcing currently being imposed by rising carbon dioxide.
126056. SNRatio at 10:30 AM on 16 December 2009
        Hockey sticks, 'unprecedented warming' and past climate change
        It would be nice to have a collection of properly calibrated temperature series from cores in one easily accessible post. As chris points out, the 'instrumental record' part of fig 1 is probably misleading. Maybe not the most rewarding task, but I fear WUWT and likes will bring up this again. And again and again and again. I think it would also be worthwhile to go more into the orbit/precession/nutation material, to give better understanding of the forces at work - AND - the sensitivity.. Apropos sensitivity: Who is quite sure that a 3 deg sensitivity at the doubling from 140 to 280 ppm necessarily implies a 3 deg sensitivity at the next doubling, to 560 ppm? I'm not :-)
126057. chris at 09:59 AM on 16 December 2009
        Hockey sticks, 'unprecedented warming' and past climate change
        re #12 (i) No one claims that 15-18 ppm rise will produce a 1oC rise in temperature, livas. Taking the central value of the likely range of climate sensitivities of 3 oC (the temperature rise from doubling atmospheric CO2) the equilibrium temperature rise is expected to be: Temp rise = ln([CO2]2/[CO2]1)*3/ln2 where [CO2]1 is the starting [CO2] level, [CO2]2 is the end [CO2] level, 3 is the climate sensitivity and ln2 refers to the doubling. (ii) Note that water vapour doesn't remain at the same level. The water vapour concentration in the atmosphere rises as the atmospheric temperature rises. So water vapor provides a positive feedback to whatever forcing increases the atmospheric temperature.
126058. Riccardo at 07:01 AM on 16 December 2009
        CO2 is not the only driver of climate
        cleanwater, you forgot to mention Ångström! It's a pitty. Apart from your random quotes and some standard shouting, you're welcome to discuss science, if you'll ever will. P.S. much too easy to copy and paste to leave garbage around ;)
126059. livas16 at 06:35 AM on 16 December 2009
        Hockey sticks, 'unprecedented warming' and past climate change
        Chris, you have put it very well. For every 1oC rise in temperature we observe as a result an additional 15-18ppm of CO2 levels. Of course, this does not mean the opposite direction. 15-18ppm rise of CO2 levels do not necessary means that it will produce a 1oC rise in temperature, which is about what the anthropogenic global warming supporters claim. Not, if you ignore the fact that the other 95% of global warming factor which is water vapor will likely remain at the same levels. Not, if scientists, as I hear, have not concluded to the basic physics behind the relation of water vapor, cloud formation from water vapor and the effect of clouds in global warming.
        Response: "15-18ppm rise of CO2 levels do not necessary means that it will produce a 1oC rise in temperature, which is about what the anthropogenic global warming supporters claim"
        
        What the peer reviewed science finds is that a doubling of CO2 leads to 3°C warming. Eg - if we move from the pre-industrial levels of around 280 parts per million (ppm) of atmospheric CO2 to 560 ppm, the CO2 forcing would cause 3°C warming. We're currently at around 385ppm.
        
        For more on water vapor and how it enhances CO2 warming, see water vapor is the most powerful greenhouse gas.
126060. chris at 04:46 AM on 16 December 2009
        Hockey sticks, 'unprecedented warming' and past climate change
        Livas, analysis of the Milankovitch cycles that underlie the transitions from glacial to interglacial periods and back again, indicates that the present interglacial will likely be very long lived in the context of the last several cycles (e.g. around another 50,000 years of interglacial to go before the next descent into a glacial maximum) e.g. A. Berger and M. F. Loutre (2002) An Exceptionally Long Interglacial Ahead? Science 297, 1287-1288 http://www.sciencemag.org/cgi/content/short/297/5585/1287 On the lead/lag phenomenon of CO2/temperature. There's no question that temperature changes during ice age cycles lead CO2 changes by a few hundred years (at least in the Antarctic cores; the CO2 changes lead temperature changes in Greenland ice cores). The CO2 rises (during insolation-driven glacial to interglacial transitions) amplify the primary warming resulting from insolation-driven ice melt/albedo contributions and water vapour feedbacks. One can get a handle on the amount of atmospheric CO2 that results from glacial-interglacial transitions. The atmospheric CO2 levels rise pretty faithfully during the slow, 5000-year, glacial-interglacial transitions from around 190ish ppm to 280ish ppm (and back to 190ish ppm in the following descent to glacial conditions: http://en.wikipedia.org/wiki/Ice_age This is in response to a global temperature change near 5-6 oC. So each oC of warming produces around 15-18 ppm of raised CO2 levels (90 ppm rise resulting from 5-6 oC rise). Obviously the massive rise in CO2 from preindustrial levels (280ish ppm) to now (386 ppm and rising) can't have resulted from a temperature rise, since we've only had around 1 oC of this since pre-industrial times.
126061. oku at 04:37 AM on 16 December 2009
        Hockey sticks, 'unprecedented warming' and past climate change
        What should also be mentioned is that the graphs compare the global temperature record with a local record. I think that region in Greenland is more sensitive to changes and has warmed more than the global average, so the comparison is not valid.
126062. chris at 04:09 AM on 16 December 2009
        Understanding Trenberth's travesty
        Philippe, I agree...in my opinion the CERN experiment will never be conclusive about any putative effect of CRF variation on clouds, let alone climate. It's simply not an experiment that can yield information on this subject. The experiment will no doubt yield useful physicochemical information on aerosol particle nucleation by gamma rays under controlled conditions in a particle chamber, and its response to variation in the composition of atmospheric mimetics. Also, in my opinion, the main proponent of the CERN experiment has misrepresented the science on contributions to historical temperature variation, as a way of "beefing up" the justification for the experiment [*]. ([*] see posts #99, #127 here: http://www.skepticalscience.com/Climate-time-lag.html )
126063. chris at 03:59 AM on 16 December 2009
        Understanding Trenberth's travesty
        oops. In my post just above, I meant to say in paragraph "3.": The temperature variation leads the CRF variation reconstructed from cosmogenic isotope (14C) formation, through the MWP period. (In other words the CRF variation can't be causally related to the temperature variation of the MWP).
126064. livas16 at 03:54 AM on 16 December 2009
        Hockey sticks, 'unprecedented warming' and past climate change
        Looking at Figure 2 makes me wonder if any scientist has been able to make a computer model to reproduce this “near” periodical cycling between -8 and current temperatures in the past thousand years scale. Those supporting anthropogenic global warming say that solar activity is stable over the years, so these major temperature changes can depend mostly on earth’s axial tilt than any other factor. If a computer model is able to reproduce and verify all these past temperatures, then it would have chances to predict future climate as well. On the other hand, the skeptical argument says that coming out of the ice age into interglacial there is a delay of hundreds of years after which CO2 rises. They argue that CO2 is a product of temperature rise (maybe with some feedback effect) and not the primary cause of the temperature rise. Is it only me feeling I should enjoy the last years of interglacial before going into the next ice age?
        Response: We address the CO2 lags temperature argument here. Basically, warming causes CO2 outgassing from oceans. However, this doesn't mean CO2 doesn't cause warming - this is proven by a laboratory measurements plus empirical observations of an enhanced greenhouse effect. When you combine the two effects - warming causes CO2 rise and CO2 rise causes warming - you get a positive feedback system which enabled our planet to come out of a global ice age.
126065. Philippe Chantreau at 03:32 AM on 16 December 2009
        Understanding Trenberth's travesty
        The CERN experiment on cosmic rays is anything but conclusive so far. They are struggling to prevent interactions with the chamber wall from completely ruining the experiment. In my opinion, it does not bode well for the hypothesis in the real world, where CCN are found in the millions per liter of air, whether over land or water. And over the ocean these CCN include lots of ions.
126066. chris at 03:10 AM on 16 December 2009
        Understanding Trenberth's travesty
        re #14/17/19 HumanityRules, I think one needs to be a little more careful with “knowns” and “unknowns” and not to fall into the trap of mistaking uncertainties in sub-levels of phenomena with uncertainties in the phenomena, themselves. There’s quite a lot we know pretty well about the cosmic ray flux (CRF) and its effects on surface temperature: 1. We know, for example, that any secular trend in the CRF during the period in which it has been monitored in detail (since late 1950’s) can have made no contribution to the very marked warming in the last 30-odd years. If anything, any putative CRF effect should have caused a slight cooling. 2. We know that the CRF doesn’t seem significantly to affect low level clouds in the way proposed by the practitioners of this notion. An apparent correlation was reported for solar cycle 22. This relationship broke down through solar cycle 23. Analysis of the relationships between the solar cycle and the apparent cloud effect that was observed through solar cycle 22 indicates that is the solar irradiance component of the solar cycle that might have influenced low level clouds through cycle 22. 3. We know that there is no evidence for a CRF effect on climate during the past 1000 years. The CRF variation reconstructed from cosmogenic isotope (14C) formation leads the temperature variation through the MWP period. In other words it can’t have made a significant contribution. Likewise, the surface temperature variation through the LIA is fully understandable in terms of solar irradiance variation and other rather well characterised forcings (volcanic and greenhouse gas variations). No doubt there is uncertainty about CRF effects on atmospheric aerosol formation. However this sub-level of uncertainty doesn’t negate the broader likelihood that CRF variation hasn’t made any contribution to the marked warming of the last 30-odd years. In a similar vein, the uncertainties of how exactly how the sea level rise of the last 5 years is partitioned into its thermal and mass components doesn’t negate the broader certainty that the sea levels have continued to rise during this period. Similar analysis applies to clouds. While the earth’s surface has warmed considerably during the past century, there’s no evidence for a significant contribution from cloud cover variation. If clouds produced a negative feedback one wonders where this is! Much of our understanding of climate sensitivity (the earth surface temperature response to enhanced radiative forcing) is based on empirical relationships between historical temperatures and greenhouse gas levels. These implicitly incorporate any cloud feedbacks (and other feedbacks like fast water vapour and albedo effects). Of course if we want to understand everything in a great amount of detail, we want to have a handle on all the sub-components of the phenomenon whose contributions sum to the phenomenon itself. This is what Trenberth is attempting to establish. Unfortunately the measurements are not sufficient to do this in detail for very short time periods. For example the CERES data that yielded radiative flux at the top of the atmosphere at high precision is only available through Feb 2005. There is still some uncertainty in the ocean heat measures, particulalry at depth. As Trenberth states in the article in which he discusses the uncertainties in ascribing precise contributions to surface temperature variation and heat flow/distribution in the last few years, and suggests a number of possible contributions: ”…Perhaps all these things are going on. But surely we have an adequate system to track whether this is the case or not, do we not? Well it seems that the answer is no, we do not. But we should!” That’s what Trenberth is on about. We certainly don’t cast doubt on our understanding of the physics of a system until we have sufficient confidence in the measurements that would indicate that there is something to concern ourselves with.
126067. Noodle at 03:06 AM on 16 December 2009
        Global warming stopped in 1998, 1995, 2002, 2007, 2010, ????
        I would like to draw attention to the non-averaged version of the TSI graph used in this article, avaliable here: http://lasp.colorado.edu/sorce/images/instruments/tim/tsi_database.jpg Note that the TIM data is 4-5Wm(-2) below other instruments, and the averaged version of the graph has lowered previous records to match the TIM data. TSI is not a settled matter. The graph used on this page would be better used to demonstrate the solar cycle argument, where the image is slightly out of date (2000)
126068. ianw01 at 02:58 AM on 16 December 2009
        It's cooling
        I'm a first time visitor to this site and I'm impressed. (Understanding any of the science of global warming from the general press is futile!) I'll offer an answer and a question here: Australis: Just because the ocean has absorbed so much heat does not not mean that its temperature has increased a lot. That is because water has a high specific heat capacity. A few degrees of warming does imply that water could hold (at maximum) less CO2; however its CO2 content is largely a function of the equilibrium with the atmosphere. As atmospheric CO2 concentrations rise, the oceans will continue to absorb more CO2 despite their increasing temperatures. (Once they get close to carbonated water as we find in soft drinks, then a few degrees of temperature change could make a big difference! :-P ) And now my question: Figure 1 could also be used to advance the idea that the oceans have a tremendous ability to buffer us (on land) from global warming, and that while things may change, the consequences may be overstated. I know there are potential holes in that reasoning, but I'd appreciate links to science addressing the extension of this topic to the potential impacts. Thanks!!
126069. Ned at 01:27 AM on 16 December 2009
        Hockey sticks, 'unprecedented warming' and past climate change
        Thanks for posting that, Chris. I see that Watts or whoever was responsible for that graph penciled in a small red line labeled "instrumental record" showing about an 0.5C warming from 1900 to the late 20th C. But you rightly note that adding the actual data would show current temperatures off the top of the chart. I won't hold my breath waiting for Watts to make that correction, however.
126070. Ned at 00:55 AM on 16 December 2009
        What happened to the evidence for man-made global warming?
        Robert Ellison at #67 above quotes an article about the UAH analysis of MSU temperatures: "That works out to a global warming trend of about 0.7 degrees centigrade over (the next) 100 years," said Dr. John Christy, who compiled the comparison data. "That's a definite warming trend, which is probably due in part to human influences. But it's substantially less than the warming forecast by most climate models, and it isn't entirely out of the range of climate change we might expect from natural causes." Robert, that quote is from a 2003 story. In 2005, Mears et al. published a paper in Science showing that the UAH algorithm for processing MSU data had a sign error in the handling of the diurnal cycle. When this error was corrected, the UAH temperature trend increased 40%, putting it in much closer agreement with the other satellite and surface temperature records. Mears et al. 2005.
126071. chris at 00:29 AM on 16 December 2009
        Hockey sticks, 'unprecedented warming' and past climate change
        Figure 1 is pretty misleading - Inspection of Alley's data in the NCDC archive [*] shows that the most recent temperature data point for the GISP 2 core is for around 100 years before 2000. According to the temperature reconstruction from the ice sheet this temperature was -31.6 oC. In the intervening period, the Greenland ice sheet temperature (2 metre surface height) has risen by around 1.5 oC, averaged over the whole ice sheet [**]. It’s likely that the ice sheet summit area where GISP 2 is, has warmed more than this (NASA GISS analysis puts the warming at the Grenland summit where the GISP 2 core was drilled to more than 2 oC [***] So if we are comparing like with like [i.e. the temperature at the Greenland ice sheet summit at GISP 2 at the “height” of the MWP (-30.5 oC), and the temperature at the Greenland ice sheet summit at GISP 2 at the turn of the 20th century (-31.6 oC), we should really consider the temperature change since then at the same location. This is at least 1.5 oC warmer and likely at least 2 oC warmer. So current temperatures at the Greenland summit at the GISP 2 site are warmer than for the height of the MWP (by 0.5 to 1.0 oC or more) according to the Alley’s data, and taking account of the temperature record of the last 100 years. [*] ftp://ftp.ncdc.noaa.gov/pub/data/...gisp2_temp_accum_alley2000.txt [**] Box JE et al. (2009) Greenland Ice Sheet Surface Air Temperature Variability: 1840-2007 J. Climate 22, 4029-4049 [***] http://data.giss.nasa.gov/gistemp/maps/ (make your own map – e.g. compare the current (5 year temperature average to the 5 year temperature average around the start of the 20th century)
126072. Andreas at 23:06 PM on 15 December 2009
        Hockey sticks, 'unprecedented warming' and past climate change
        A small note: the text under figure 2 says Greenland, but the figure is from Antarctica. Not that it matters for the argument presented in the article, but anyway. Moreover, I have a general argument regarding the MWP, on which I would be happy for feedback. The thing is, I do not see how the size and coverage of the MWP affects the significance of the AGW-theory of today. Even if the MWP was shown to be a global phenomenon and much warmer than today, its causal origin need not be the same as the causal origins of today's temperature trend. What we see between 1970 and 2000 is a temperature trend that cannot yet be explained without including anthropogenic CO2 in the model. Before a suitable alternative explanation is found and supported by evidence, we are in no position to rule out the CO2-hypothesis, no matter how temperature varied in the past. If the MWP was indeed warmer it is possible that what caused it causes warming today. But unless we show what caused it, we cannot just assume that the same forcings are at play today. "Natural variability" is not an argument either, temperature does not change spontaneously - the laws of thermodynamics ensures that. My opinion is that a theory of climate using the MWP as a part of the argument needs both to address the causal origins of the MWP and to show the relevance of the same causal mechanism in today's climate. In such an argument, the peak amplitude of the MWP temperature is not as important as to what extent the suggested forcings can be shown to explain the general temperature curve.
        Response: Have corrected the caption of Figure 2, thanks for the tip.
126073. RSVP at 22:19 PM on 15 December 2009
        Hockey sticks, 'unprecedented warming' and past climate change
        Since you are bringing CO2 up again, I now actually have a question. There is a concept called free space path loss that is key to radio transmission. A simple formula describes this as loss = 20log(4*Pi*distance/lamda). As some have accused me of paper napkin numerology, you can apply this formula using a spreadsheet and easily see that the power drops off very fast, (which is why people have to pay good money for broadcasting radio and television signals). IR is electromagnetic radiation too and I assume is subject to this same phenomenon (i.e. signal dispersion which you notice by just backing your hand away from the ground on a hot day.). Anyway, I was wondering if someone knows whether this effect has been taken into account when modeling the impact of global warming on the Earth from gases at 10, 100, 1000 meters, the idea being that less and less energy would be reaching these parts and conversely, the higher the gas, the less its going to warm the Earths surface, etc.... PS. As I edit this comment, I am having a dejavu, so please excuse me if I actually already wrote this.
126074. lord_sidcup at 21:58 PM on 15 December 2009
        Hockey sticks, 'unprecedented warming' and past climate change
        “Apologies to regular readers as this post revisits existing material - the inevitable consquence when forced to respond to rehashed skeptic arguments.” Indeed. There was a nice piece from Ben Goldacre in The Guardian this weekend about the prevalence of ‘zombie arguments’ amongst AGW denialists, a ‘zombie arguments’ being “arguments which survive to be raised again, for eternity, no matter how many times they are shot down.” http://www.guardian.co.uk/commentisfree/2009/dec/12/bad-science-goldacre-climate-change Congratulations on your excellent blog by the way.
126075. batsvensson at 19:47 PM on 15 December 2009
        Hockey sticks, 'unprecedented warming' and past climate change
        Looking at the graph in figure 2 it looks like we are imminent to enter a new ice age.
126076. NewYorkJ at 19:16 PM on 15 December 2009
        Hockey sticks, 'unprecedented warming' and past climate change
        "On the contrary, the past provides evidence for our climate's sensitivity to carbon dioxide. " That's kind of an irony around the arguments from "the climate has changed in the past" and "I want the MWP to be warmer than today so I can claim CO2 doesn't cause warming and warming isn't bad" folks. If climate was almost entirely static but greenhouse gas concentrations changed significantly, it would be evidence against their impacts. The larger temperature swings between glaciation periods helps to confirm the impact of greenhouse gases, and a more variable climate and stronger temperature swings over the last couple of millenium tends to imply greater climate sensitivity to any forcing mechanism, thus confirming positive feedbacks.
126077. HumanityRules at 18:11 PM on 15 December 2009
        Understanding Trenberth's travesty
        SNRatio, you appear to be entering Rumsfeld territory here. Known unknowns and unknown unknowns. I can accept a known unknown can be constrained within the system but with some of the forcing they are approaching unknown unknowns. Take cloud as an example again. These impact on energy transport in multiple ways having both + and - affects. It seems that just what the overall nett affect of changes in cloud cover, or the processes that my drive that are completely unknown. As you say I don't necessarily make the distinction between basic and applied but if I had to I'd put this in the basic camp.
126078. ExLoony at 17:48 PM on 15 December 2009
        Human CO2 is a tiny % of CO2 emissions
        Hernandeath, the graphic states a balance which can be deduced from the atmospheric record. If the flows were not in balance, the atmosphere would not have kept roughly the same amount of CO2 for millenia. Now there may have been some give and take between land and sea but that does not change the conclusions. The systems have evolved towards a balance. The CO2 in the atmosphere is relatively tiny. Visualized as water, our atmosphere is about the same mass as 10m of water spread evenly. Out of that (by weight) the CO2 is currently about 6mm thick. Visualize a layer of glass (the greenhouse!) spread evenly. Now, it is easy to see this is tiny compared to the amount of carbon locked up in fertile soils, forests, or seas with carbonate rich muds. If those ecosystems were not finely balanced the atmosphere would have major fluctuations. But, before human large scale agriculture and industry, the records are of long constancy. And, really not so surprising that a mass of human activity reshaping our environment has produced a rapid change in the atmosphere - from bubbles in the Vostok ice cores, it seems we have produced a spill larger than any in a million years. So the New Scientist graphic may simplify, but it is basically the inescapable conclusion. The world has operated in rough CO2 balance, and we are the biggest change in the equilibrium for a very long time.
126079. Andy at 16:57 PM on 15 December 2009
        Hockey sticks, 'unprecedented warming' and past climate change
        Watching the global warming debate back and forth is like watching a boxing match between two very good fighters. Punch, counterpunch. Back and forth. Fascinating.
126080. neilperth at 14:15 PM on 15 December 2009
        What do the hacked CRU emails tell us?
        John, Re my post 48 above, you stated there is "a greater than 90% chance that humans are causing global warming (I believe this actually understates the certainty)." This 90% chance or probabilty that you mention, is this at the 90% confidence level, 95% confidence level or some other confidence level? Can you please point me in the direction of the relevamt data so that I can check your claim statistically ?
126081. yocta at 12:28 PM on 15 December 2009
        Models are unreliable
        Hi John, Great site, the best one I've seen yet, especially as you have links to actual journal articles. One thing that I've noticed is that some "skeptics" have a you feed junk in you get junk out mentality when it comes to computer models. I recall when I used to debate creationists at my university and a very similar argument was used of carbon dating of being exactly like that. Although I don't want to stretch the comparison any more than that it is just an interesting point. There is an article that discusses this a little more I've linked to below. "Are climate change deniers like creationists?" http://www.csmonitor.com/Environment/Bright-Green/2009/0828/are-climate-change-deniers-like-creationists It is the comments that are really interesting as people compare global warming alarmists to creationists, but again I feel the science is on vacation in their arguments.
126082. SNRatio at 12:24 PM on 15 December 2009
        Understanding Trenberth's travesty
        HumanityRules #17 I don't think we really disagree that much - to me it seems more a question of wording. I agree with you about the lack of knowledge you mention, to me it just seems more on an applied rather than basic level. My impression is that the basic governing equations for the situation can be set up, but we are not able to find satisfactory solutions to them. And, for instance, knowing the details of how a system is chaotic and therefore in some respects not completely predictable, is a piece of physical knowledge for me, not a lack of it.
126083. yocta at 12:09 PM on 15 December 2009
        There's no empirical evidence
        Re: #16 thereisaidit This isn't really skeptical statements i'm saying here but: I have two scenarios in my mind: 1) If renewable energy is to succeed there needs to be a massive price reduction in the price per kilowatt hour. My boss held up a $0.10AU coin and said that is the necessary goal for renewables to compete/ensure the economy can adjust. This site i've listed below has some figures though it might have company bias but as you can see in order for non CO2 producing forms of energy to flourish there needs to be something (ie.a heavy amount of research/investment etc) to get it there. http://www.coldenergy.com/difference.htm 2) This second scenario isn't so pretty. This addresses the population issue you raised. I heard an interview with Paul Ehrlich who is a Professor in population studies. He is the author of The Population Bomb back in 1967 has some very dire predictions about world population levels. http://www.abc.net.au/rn/latenightlive/stories/2009/2747139.htm On your point on the ice caps: This is something I don't know but even if we could magically turn off the "CO2 emissions switch" I would think that the Artic ice loss will continue ie no matter what we do now global warming is happening and it is only a case of damage control reducing the extent in the rise of average temperatures in the future.
126084. HumanityRules at 11:22 AM on 15 December 2009
        Understanding Trenberth's travesty
        SNRatio #16 It's my understanding that it's not just cosmic rays vs clouds that we don't understand but many more aspects of clouds such as changes in precipitation rates and cloud life that we don't understand. Look at the error bars in fig4 on trenberths paper.
126085. Phil at 10:33 AM on 15 December 2009
        What happened to the evidence for man-made global warming?
        RSVP @88 CO2 acts as a notch filter. The band does not widen with more CO2. The bands will widen with more CO2, in principle at least. This is due to increasing numbers of molecules (a) with higher rotation states, (b) transitioning between higher vibrational states (assuming the usual deviation from harmonic oscillator behavior) and (c) forming complexes. As to whether these have any significant effect or not on the greenhouse effect, I'm afraid you need a climate scientist not an ex-spectroscopist
126086. Riccardo at 09:51 AM on 15 December 2009
        The hockey stick divergence problem
        LorenzoG, right, the annual thickness of ice definitely depends on precipitation while keeping the same isotopic ratio. This is the very basic of temperature reconstructions from ice cores. You ask what may cause the divergence problem; there's the whole dendroclimatology community asking itself the very same question. Unfortunally, no one came up with a solution yet; indeed, when temperature stops being the limiting growth factors, many other may come into play, including local environment. It's not rare that only some trees in a region show divergence while others do not. I'd suggest reading the review (D'Arrgigo 2008) linked by John in this post. P.S. There's no way to use tree rings as temperature proxy without intesive data analisys, re-normalizations, "adjustments" and the like.
126087. Philippe Chantreau at 05:51 AM on 15 December 2009
        What happened to the evidence for man-made global warming?
        RSVP, the point is that, because radiative properties of CO2 are well known, the radiative forcing can be calculated precisely and has been. If you want to dispute the forcing's value, tell us why and give some alternative or references.
126088. LorenzoG at 05:22 AM on 15 December 2009
        The hockey stick divergence problem
        Riccardo, Yes, ice cores measure isotopic ratios, but the deposition of ice and the entrapment of those isotopes depends on a certain minimum level of humidity in the area. Too little humidity and there won't be any deposition, and in extremely arid conditions, ice can even sublime, along with its entrapped isotopes. Sedimentary deposits also depend on a certain level of water movement to cause erosion and transport of silt and other materials. All I'm saying is that there is some difference between the experience of low latitude trees and high latitude trees to cause the divergence problem in the proxy record. If the difference is not temperature, what is it? Could it be humidity/precipitation? Could it be cloud cover? Something else? I haven't seen any papers trying to find a real physical explanation, only re-normalizations and adjustments to old data to bring them into line with the instrumental record.
126089. pdt at 23:23 PM on 14 December 2009
        What happened to the evidence for man-made global warming?
        RSVP wrote, "And then there is the real problem that waste heat will continue to be produced regardless of the technology and no one is willing to address this problem." and later, "I was referring mainly to nuclear, however since you asked, if you had a very efficient solar panel, it would mean you are retaining sunlight (solar heat) that would otherwise be reflected into outer space (i.e. changing the Earths albedo). Supposedly CO2 is doing this and it is considered a bad thing." Not sure how "regardless of technology" could be interpreted as "mainly nuclear". With respect to solar, you mean when plants cover the earth and carry out photo-synthesis it makes the earth hotter? Forests make the earth hotter? Have you quantified the effect? So, if we went with wind, hydro, tidal, wave, and geothermal, we'd be okay then? We wouldn't cook ourselves?
126090. SNRatio at 20:15 PM on 14 December 2009
        Understanding Trenberth's travesty
        @15 I don't think we should start looking for small holes in the basic physics before we have checked out all our applications of it. To me, one of the basic problems with the budgeting is the assumptions about the radiative imbalance. As Trenberth implies in one of the emails (but not in the paper?), this is by no means constant, even though we may have rather precise estimates of the average (expectation) value (0.9 W/m2, 90% CI 0.4-1.4). Maybe it should be modeled as a stochastic variable, something like a multi-dimensional pseudo-random walk. There may also be too simplistic assumptions about the interplay between GHG forcing and water vapor. We may have small holes in the basic physics too, right now perhaps most likely in the areas of magnetism/cosmic rays vs cloud formation. But several studies indicate that this is unlikely to have any major influence on the big picture we are discussing. Where we do not attempt to model cloud formation with any great precision, but rather work out from the observed radiation balance.
126091. Riccardo at 19:33 PM on 14 December 2009
        What happened to the evidence for man-made global warming?
        no RSVP, a notch filter is an interference filter, absorption works differently. In any case, quantify this "minute" difference; it's a few tenth of a percent of the totale IR emitted. Looks pretty tiny, does it? But that's enough, few W/m2 can change the temperature significantly.
126092. RSVP at 18:35 PM on 14 December 2009
        What happened to the evidence for man-made global warming?
        Riccardo "It does not matter how large is the CO2 absorption band or the percent of its concentration" CO2 acts as a notch filter. The band does not widen with more CO2. The baseline for comparison is the change in the effect of that notch (preindustrial) with respect to the entire spectrum. Seen as a percentage of the total energy associated with the entire IR spectrum, the change is minute.
126093. RSVP at 18:24 PM on 14 December 2009
        What happened to the evidence for man-made global warming?
        PDT asks Could you explain how waste heat from solar, wind, hydro, geothermal, wave, tidal or any other renewable energy source adds energy to the Earth's climate system? I was referring mainly to nuclear, however since you asked, if you had a very efficient solar panel, it would mean you are retaining sunlight (solar heat) that would otherwise be reflected into outer space (i.e. changing the Earths albedo). Supposedly CO2 is doing this and it is considered a bad thing.
126094. RSVP at 17:48 PM on 14 December 2009
        Understanding Trenberth's travesty
        The specific heat of water (melted ice) is double that of ice. All that extra ocean should require more energy to heat.
126095. zenmark at 14:45 PM on 14 December 2009
        Some Skeptical Science housekeeping
        John, thanks for your excellent web site. You are doing everyone a service with your clear and thoughtful articles.
126096. JianqiWang at 12:39 PM on 14 December 2009
        What happened to the evidence for man-made global warming?
        All these evidences are bit misleading. The question is NOT whether the globe is warming up. The question we should ask is whether it is HUMAN who made the warming. If you look the evidence from this perspective. You will see the evidence that support AGW is really thin. I listed here: • Our planet is suffering an energy imbalance and is steadily accumulating heat (Hansen 2005, Murphy 2009, Schuckmann 2009, Trenberth 2009) • Satellites measure less infrared radiation escaping out to space at the wavelengths that CO2 absorb energy (Harries 2001, Griggs 2004, Chen 2007) • Surface measurements find more infrared radiation returning back to the Earth's surface (Philipona 2004), specifically at the wavelengths that CO2 absorb energy (Evans 2006) • Cooling and contraction of the upper atmosphere consistent with predicted effects of increasing greenhouse gases (Lastovicka 2008) Are these evidences sufficient to claim that AGW is for real? I would say those evidences are far from conclusive. Also note that if a paper was published in 2008, it is very likely that the work was done prior to 2007 and the data the work studied would be even earlier than that. Everyone know that it was relatively cold for last couple of years, as Trenberth indicated in his email.
        Response: The question of whether it's humans causing the warming is indeed the more important question. However, there are many who even question that global warming is happening (as you do later in your comment) so all bases need to be covered.
        
        That reminds me, a new paper came out this October with a more comprehensive look at surface measurements of downward infrared radiation (Wang 2009) - I'm in the process of reading through that paper and will add it to the evidence for an enhanced greenhouse effect shortly.
126097. HumanityRules at 10:51 AM on 14 December 2009
        Understanding Trenberth's travesty
        My understanding of trenberths paper is that he identifies error in the calculation of the energy balance of the planet. As he says 'Where has the energy gone?" He begins the discussion about were this error may occur identifying weakness in our measurement of many of the variables in the system as well as our lack of understanding on some of the systems (such as clouds). One thing he does is to constrain some of the possible answers to this conundrum using sea level rise. He points out that if the energy has gone into sea ice, land ice, deep oceans or land this would have had different affects on sea level. By this method he is able to rule out most of the possible options as to where the energy has gone. My understanding is there are only two possible options. Changes is cloud cover, although no mechanism is known and measurements are poor. This only exists as an option because of the poor understanding. The other mechanism is, as John pointed out, into the deep sea but this is speculative, has no known mechanism and requires re-jigging of other factors in the energy budget system in order to also satisfy the observed sea level rises. I think what Trenberth is identifying here is not weakness in models, not just weakness in our observations but also a small hole in the basic physics of the system.
126098. Tom Dayton at 08:01 AM on 14 December 2009
        Understanding Trenberth's travesty
        MACaTAC wrote " Trenberth claims in his email that the earth based systems are inadequate to account for the imbalance based upon this "Given". Being a skeptic, that makes me question the adequacy of the satellite system of measuring radiation in and out of the atmosphere." That is not what Trenberth claimed. Instead he claimed that the scientists' understanding of the Earth's energy systems is insufficient to fully account for the short term and detailed fluctuations in the energy budget. The observations of energy in and out of the Earth are solid.
126099. MACaTAC at 06:52 AM on 14 December 2009
        Understanding Trenberth's travesty
        Here is the problem for me with your article. Your explanation of the email relies upon what is set up in " An imperative for climate change planning: tracking Earth's global energy (Trenberth 2009)". In this report Trenberth clearly states what is "Given"... "Given that there is continual heating of the planet, referred to as radiative forcing, by accelerating increases of carbon dioxide (Figure 1) and other greenhouses due to human activities, why is the temperature not continuing to go up?" ..and you apparently accept this "Given" in your analysis. "Trenberth states unequivocally that our planet is continually heating due to increasing carbon dioxide." Trenberth claims in his email that the earth based systems are inadequate to account for the imbalance based upon this "Given". Being a skeptic, that makes me question the adequacy of the satellite system of measuring radiation in and out of the atmosphere. Trenberth obviously believes that this satellite data is without any substantial systematic error and the probable error of the data can be trusted with no substantial shift in actual data values due to said lack of systematic error. If not, then there is no way he could claim that the earth based systems used are inadequate. This logic reminds me of religious fanatics who can only cite the Bible as the way to prove the Bible is without error. I will now direct my attention to understanding the satellite measurements. Thank you for your article.
        Response: The point of this article is to clarify Trenberth's views which have been misrepresented. Just because Trenberth says the planet is still heating due to CO2 doesn't make it so. But it does establish that Trenberth believes it so - and thus the characterisation that Trenberth is saying global warming has stopped is erroneous.
        
        The evidence for the enhanced greenhouse effect caused by CO2 is found in satellite and surface measurements finding less heat escaping to space at CO2 absorption wavelengths and more heat returning to earth at the same wavelengths. It's not religious faith but empirical evidence.
        
        Note for future reference - comments about religious fanatics usually are deleted.
126100. pdt at 05:05 AM on 14 December 2009
        What happened to the evidence for man-made global warming?
        RSVP, "And then there is the real problem that waste heat will continue to be produced regardless of the technology and no one is willing to address this problem." Could you explain how waste heat from solar, wind, hydro, geothermal, wave, tidal or any other renewable energy source adds energy to the Earth's climate system?

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