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Comments 72901 to 72950:

  1. Greenland ice loss continues to accelerate
    (Since 2007 that is. Since 2002 we're looking at roughly twice that.)
  2. Greenland ice loss continues to accelerate
    Surface area of the earth's oceans = 360x1012 m2 1000Gt = 1012 m3 Therefore sea level rise = (1/360) m ~ 3mm.
  3. Understanding climate denial
    Skywatcher and Moderator My apologies that my last post came ahead of the receipt by me from the moderator of a response. I had taken the trouble to look through much of this site long before making a comment but I will try to comment in more detail on your comments in the right area in future [snip] To stick to the topic here, I think my main point was that the situation of global warming is quite different from that of smoking or AIDS. There is proper science to back those areas whereas the science is lacking for AGW. The whole scientific process for AGW is odd. We do not appoint an equivalent of the IPCC for any other area, nor would we expect eg cancer treatments to be determined by a consensus decided by looking at peer reviewed publications. What we do is look at the competing views and treatments (quite the reverse of consensus in many ways). Underlying this article is a belief that the writer is correct and that anyone who disagrees must be suffering from some sort of delusion or at best be hopelessly ill informed. This has been the way with pseudo science for many years. It is not so long ago that Marxists claimed to have discovered scientific laws about the development of society and Freudians were able to explain anything that any patient brought to them through their "science".
    Moderator Response: [Dikran Marsupial] Moderation complain snipped. This thread is about denial. There are many that are ill-informed regarding the science of climate change, however this is not denial. To be in denial is to be reject evidence of the anthropogenic climate change withoit being able to refute the evidence that is presented, and continue to hold and promote their belief without being willing to discuss the state of the science.
  4. Pielke Sr. and SkS Warming Estimates
    critical mass - We do not need to know the historical forcings to estimate the current (2011) radiative forcing from all sources and the current radiative imbalance (using ocean heat storage changes). This is one of the first questions that should be answered in a climate change assessment. I do not see how this is confusing. :-)
  5. Greenland ice loss continues to accelerate
    It would be interesting to know the sea level rise represented by that lost ice.
  6. Pielke Sr. and SkS Warming Estimates
    I agree with MA Roger #26 that Dr Pielke's responses are somewhat confusing. In all these discussions of Radiative forcing using the AR4 chart, the 'Human Activity' forcings are referenced to year 1750, when it is assumed that these forcings were 'insignificant' ie: zero. That means that all these forcings are absolute numbers baselined to zero. This might answer Dr Pielke's confusion. As Tom Curtis points out from AR4 "The only increase in natural forcing of any significance between 1750 and 2005 occurred in solar irradiance." The problem with including solar forcing in the sum of the AR4 chart has been pointed out by others in SKS threads in that we don't know if there was a positive or negative planetary warming imbalance in 1750, and whatever it was - it could only have come from solar irradiance since all the 'human activity forcings' are zero. It is likely that as the Earth warmed out of the little ice age, the solar irradiance imbalance was positive - not zero, so the AR4 value of 0.12W/M2 should be added to whatever the 1750 value was in order to get a comparable absolute value in 2005. Further, the climate responses are not included in the AR4 chart and Dr Trenberth has calculated these at a net minus (-)0.7W/M2 which brings the net warming imbalance down to +0.9W/M2. It should be noted that Dr Trenberth uses a figure of minus (-)2.8W/M2 for radiative cooling (stefan-boltzman) and +2.1W/M2 for water vapour and ice albedo feedback to arrive at the net minus (-)0.7W/M2 climate response. Of course the +0.9W/M2 is also in dispute in recent times due to Dr Hansen's claimed increased aerosol reflectivity and effective reduction of the warming imbalance to about +0.6W/M2. The point to be made here is that since 1750, all the increasing 'human activity' forcings and climate responses have acted together producing a continuously changing net imbalance forcing, the sum total of which integrated over time will represent the net energy gained by the planet. Most of this energy must be sequestered in the oceans and represented by past temperature increase and phase changes in ice or water. Arguing the proportions of CO2 forcing to the percentage point without accurately knowing the historical forcings from solar, aerosols and the feedbacks is somewhat academic.
  7. Pielke Sr. and SkS Warming Estimates
    Professor Pielke used a value of 1.1 W/m2 not 1.4 W/m2 for the CO2 forcing. He did this to leave the total forcing from greenhouse gases unchanged. After increasing the forcing for CH4 he was obliged to decrease the forcing for CO2. "By summing the 0.8 Watts per meter squared for methane and using the total of 2.4 Watts per meter squared of the well-mixed greenhouse gases from the IPCC Report, the radiative contribution of CO2 reduces to about 46% of this component of radiative forcing (1.1 Watts per meter squared)." As was pointed out on real climate at the time this is totally unjustified since the forcing effect of CO2 is independently derived.
  8. Eric (skeptic) at 00:25 AM on 12 October 2011
    Weather vs Climate
    Tom, your point is valid, namely that a forcing must make a direct and permanent difference in the TOA radiative balance. I believe the position of the polarjet passes that test in several ways. The main one is that a meridional jet will transfer more heat to higher latitudes to be radiated away. In the general, the further south the polar jet, the higher amplitude the long waves within it. The redistribution of heat will directly raise the global net outgoing-incoming radiation. On El Nino, Tom, your points are very valid. I mentioned the regional differences of El Nino around the globe. Despite those offsetting differences, the net effect is to increase outgoing-incoming. I should have also mentioned the relative increase in warmer SST area and increased OLR from that. I am not sure how a permanent El Nino could be compensated for elsewhere, where is elsewhere? muoncounter, your definition of forcing seems to match Tom's, namely a change in albedo or a change in trapped heat. I believe that is a bit too narrow as I explained above. Specifically the uneven distribution of heat that you maintain is not a forcing can be a forcing if there is a permanent change causing it that is not an effect of a average temperature change. If, as a hypothetical example, we slow the spinning of the earth, the lengthening of the diurnal cycle will cause an average global temperature increase as night temperatures tend to have a lower limit but day temperatures would rise relatively more (ignoring other potential effects of a slowing rotation). But that would be a forcing because it causes a change in temperature even though it doesn't directly change radiation or albedo.
  9. Understanding climate denial
    Sphaerica, You asked two questions, and yes, this is not the thread to get into a lengthy discussion about such. TO answer accurately, is to know exactly to what you are referring. If you are asking has the Earth warmed, and is CO2 contributing, then the answer is yes. However, if you are asked to what extend does CO2 contributes to the observed warming, and what will be the future impacts, then I would have to say no. The blogosphere would have people believe that there are two, and only two, sides to the debate when there are in actuality, several different theories (or maybe nuances to the central theory) which explain various portions of the observations. This is where the disagreement occurs, which some seem to think indicates that there is disagreement about the whole. I am not sure how the whole argument started. I suspect it may have been an argumentum ad verecundiam (appeal to authority). Whatever the reason, whether a consensus exists or not is immaterial. The science will progress, and move in whatever direction the research leads. Most of the scientists will follow, and if a consensus is reached, fine. But it is not necessary.
  10. Pielke Sr. and SkS Warming Estimates
    paulhtremblay - I never said it was 20%. My estimate was higher than that but significantly lower than 50%. I presented a way to resolve this issue. It seems, however, that the comments on this thread has deteroriated again, as instead of answering my questions, you (and others) keep insisting that I agree with your view, even when I present information/questions that conflict with your statements. For example, why does it matter if the fraction of radiative forcing in 2005 compared with pre-industrial was 28% or 48%? My analysis suggests a smaller fraction but it is increasing with time. However, why do we care? Its biogeochmeical effect is directly connected to its atmospheric concentration and we know that much better than we know the global average radiative forcing. By focusing on such trivial questions as this fraction, the really important science questions which I have raised are being ignored on SkS.
  11. Pielke Sr. and SkS Warming Estimates
    Tom Curtis - Your extract from the IPCC AR4 adds some information on the water vapor overlap issue. However, it still does not quantify how much of the CO2 radiative forcing is not occuring due to the water vpaor overlap. The statement ""The simple formulae for RF of the LLGHG quoted in Ramaswamy et al. (2001) are still valid. These formulae are based on global RF calculations where clouds, stratospheric adjustment and solar absorption are included, and give an RF of +3.7 W m–2 for a doubling in the CO2 mixing ratio. (The formula used for the CO2 RF calculation in this chapter is the IPCC (1990) expression as revised in the TAR." is incomplete as I do not see "water vapor" listed. Here is the simple question: What would be the global annual average radiative forcing change since pre-industrial with CO2 without the water vapor overlap and with the the overlap? On whether the figure is interpreted as the 2005 radiative forcing or the difference since preindustrial, I agree it is the later. The figure caption and text I quote said otherwise. The FAQ you listed was a correction to the original SPM [which still contains the erroenous information].
  12. Pielke Sr. and SkS Warming Estimates
    MA Rodger - Regarding your question #1, both estimates are likely wrong. As I have written, there are several unresolved issues on how to calculate this fraction. On question #2, the change in surface temperatures over the last 100 years is a still poorly understood mix of added CO2, aerosols, land use/land cover change, poor siting of land data, solar influences, volcanoes and internal long term climate variability.
  13. Weather vs Climate
    Eric#126: "for the glacial period, summer is gone," That's a bit of an over generalization; summers may be shorter, but they are not absent. All that is necessary for glacial advance is an excess of snowfall/accumulation over summer melt. That does not require that 'summer is gone.' The glacial margin areas of New England the upper Midwest have many varved clay deposits, sedimentary evidence of winter/summer cycles. In addition, the Gulf of Mexico has a large column of sediments deposited during the glacial stages, carried south from glacial margin runoff by shortened versions of the rivers we see today. "if we entered a regime of El Nino all the time ... ENSO would be a forcing." We must not be using the same definition of 'forcing.' A cyclical response mechanism, driven by an uneven distribution of heat cannot (as I understand the word) be a 'forcing.' The primary forcings are those agents that either trap heat (ie, GHGs, black carbon), alter insolation (solar variation, orbital parameters, etc) or change albedo (aerosols, etc).
  14. Clouds Over Peer Review
    Micawber Nature and others attempted open peer reviews back in the 90s. There's also a critique of the process by Rothwell, P. M. (2000). These days publication is being seen as less of an endorsement (rightfully so) and more of a final barrier of entry to where the true critiquing occurs.
  15. Greenland ice loss continues to accelerate
    Yes, that's interesting. I think the highlands are still significantly subzero even in summer (sorry, don't have a source)? Top is over 4000m/13000ft, so ~25C cooler than sea level? So presumably if the interior is now losing ice, it is due to increased glacial flow. Contributary factors then presumably include both increased pressure from above from the last decade of extra ice, and reduced back pressure from below as the periphery melts out?
  16. Weather vs Climate
    Eric (skeptic) @126, a condition of permanent El Nino would increase OLR, not decrease it. If conditions could maintain the El Nino permanently, this would be compensated for by other cooling effects elsewhere in the climate to restore the OLR to the equilibrium level. More likely, the excess loss of energy to space would result in a termination of El Nino conditions. I should note that El Nino is associated with precipitation in some areas (Eastern Australia), but with a lack of precipitation in others (New Zealand, Peru), so your simple mechanism of El Nino => increased water vapour => reduced OLR does not work. On the other hand, El Nino's are associated with extended hot surface waters on the Pacific, which means the mechanism El Nino => warm water => increased upwelling radiation => increased OLR does work.
  17. Greenland ice loss continues to accelerate
    This volume loss from Greenland Ice Sheet from GRACE is corroborated by the negative mass balances from Mittivakkat Glacier, thinning and retreat from outlet glaciers and appearance of new islands on the periphery such as at Kong Oscar or Upernavik Glacier. The evidence is clear regardless of the measurement technique.
  18. Weather vs Climate
    Eric (skeptic), what was the net (down minus up) change in irradiance at the tropopause at the LGM due to the change in the position of the northern polar jet stream? I am not raising an issue of uncertainty here. Rather, I am raising a definitional issue. The radiative forcing is defined by the IPCC as follows:
    "The radiative forcing of the surface-troposphere system due to the perturbation in or the introduction of an agent (say, a change in greenhouse gas concentrations) is the change in net (down minus up) irradiance (solar plus long-wave; in Wm-2) at the tropopause AFTER allowing for stratospheric temperatures to readjust to radiative equilibrium, but with surface and tropospheric temperatures and state held fixed at the unperturbed values."
    (quoted from wikipedia.) Patently, a change in the position of a jet stream will make no direct difference to the net irradiance at the top of the troposphere. As such, if treated as a forcing, then its forcing is, always, 0 W/m^2. Hypothetically such a change could result in more snow or ice, resulting in a higher albedo, but those changes would all be feedbacks and hence not part of the forcing. So, even if it where appropriate to treat a change in jet stream position as a forcing, adding its value to the graph would not change by an iota the estimate of the climate sensitivity. This is if you persist in ignoring the logical point that changes to the position of the jet stream is a response to temperature changes, and hence part of the feedback system.
  19. Understanding climate denial
    elsa wrote: "It is not satisfactory to say eg that rising sea levels demonstrate that the world is warming" Really? Then what is your alternative hypothesis? Have millions of comets fallen into the oceans while no one was looking? Is rock spontaneously transmogrifying into water? Are the oceans filling with the tears of angels? What other than warming explains rising sea levels? Can you name a climate scientist who suggests some other cause? I don't recall seeing even one. Nearly everyone on the planet knows that ice melts into water and water expands as it gets warmer. From these facts it is then obvious that a warming world will cause sea levels to rise both by melting ice and causing water to expand in volume. Could 'something else' cause sea levels to rise? Yes... but absolutely no one (that I know of) has suggested that anything else is doing so. Because there is no evidence of anything else and overwhelming evidence of a warming world... which the rising oceans are just one more confirmation of. So why do you introduce a completely substanceless objection? Unless you really do have an alternate hypothesis for why sea levels are rising... or are just casting about for any pretext on which to deny the evidence.
  20. Eric (skeptic) at 22:35 PM on 11 October 2011
    Weather vs Climate
    KR, a permanent shift in the jet stream (southward in the NH) due to ice sheets growing in the NH is a forcing just like the change in (global average) albedo caused by the ice sheets. It must therefore be added to the diagram that was shown in the Pielke thread that claims the only forcing is from ice albedo and GHGs. If the southward migration of the jet (NH) only caused more snow and a larger ice sheet, then the chart in the diagram would be correct. If the change in jet configuration were due merely to temperature changes specifically GAT, that chart would be more or less correct. But neither of those conditions is true. Also that diagram is missing forcing from dust. In short, the estimates of the first order forcing effects of ice sheets must include the permanent changes in weather, not just ice and snow albedo changes. There are many papers on the topic of LGM climate discussing LGM weather. Among the cooling influences are increased meridional flow (more heat loss in higher latitudes) and increased water cycle (although that one less certain). Here's one such paper: http://www.cnrm.meteo.fr/recyf/IMG/pdf/Laine_et_al09.pdf noting that the results are very model-dependent. The two consequences of permanent weather change forcing is that the diagram in the Pielke thread is incomplete and the CO2 change sensitivity cannot be calculated statically. Thus it requires the same models used for modern climate sensitivity studies, except with much more uncertainty since modern studies can be verified against present-day weather and paleo-weather models cannot. Another consequence is that the paleo sensitivity evidence is not an independent line of evidence, but another use of the same models used for modern sensitivity derivations. Muoncounter, seasonal cycles show that weather is a feedback to solar-driven temperature changes. But for the glacial period, summer is gone, replaced by a short rainy season. The cause of the change is the ice sheets, specifically their orographic and local temperature effects. Note that is not global temperature or average temperature or anything that can be used to estimate sensitivity but a specific local temperature contrast between the cold ice sheet and the warm land areas, a southerly jet with a stronger storm track. I should have used clearer language. The change in paleo weather varies by season and there are seasonal cycles. But the change is secular. ENSO is is mostly a cycle that redistributes heat between parts of the ocean and atmosphere and then reverses and returns the heat to the source. But ENSO can also exhibit secular changes that amount to a forcing. As a simple hypothetical example, if we entered a regime of El Nino all the time then we would have less outgoing longwave radiation all of the time and thus global warming and in that (hypothetical) case, ENSO would be a forcing. The connection is that ENSO modulates precipitation (El Nino = more precip) and precip is negatively correlated with OLR. Regional differences are quite pronounced so it can be a bit difficult to see the global effect. La Nina is a major cause for the Texas drought. If we entered a semi-permanent La Nina, then Texas would have a semi-permanent drought all other things being equal.
  21. Greenland ice loss continues to accelerate
    It is interesting to note that even the small mass accumulation in the central highlands has disappeared. This would seem to indicate that we've reached the point where the entire island is now impacted by increased temperatures to a sufficient degree that it is more than offsetting increased precipitation. Antarctica, being much larger, still maintains temperatures well below zero in the deep interior and thus continues to show some mass accumulation there (though less than the mass loss around the edges).
  22. Greenland ice loss continues to accelerate
    Arkadiusz Semczyszak yes, there's a lot of discussion on the physical mechanism behiand glacier sliding. Also, different glaciers behave differently depending on several factors. Whatever, 200+ GTon/year get lost.
  23. Arkadiusz Semczyszak at 21:52 PM on 11 October 2011
    Greenland ice loss continues to accelerate
    Well, maybe I’ll add a little "interesting background" for the information above (ie post J.C.) - by Sundal et al. 2011: “Simulations of the Greenland ice-sheet flow under climate warming scenarios should account for the dynamic evolution of subglacial drainage; a simple model of basal lubrication alone misses key aspects of the ice sheet’s response to climate warming.” “The Greenland ice sheet is safer than we thought," said Professor Andrew Shepherd of the University of Leeds, coauthors.
    Response:

    [DB] I would suggest reading the full paper, not just the abstract.  Sundal et al 2011 is fully consistent with other work in the area (as the authors note), including Schoof et al 2010, for example.  This is essentially stating that an enhanced Zwally Effect will not be the primary driver for the expected mass loss of the 21st Century (which Sundal et al note is still expected).

    It is through an enhanced Jakobshavn Effect (calving at the marine-terminating glacial fronts) that the mass-loss is expected to occur. 

    See Greenland Ice Sheet outlet glaciers ice loss: an overview and

    Zebras? In Greenland? Really? for more background.

  24. Pielke Sr. and SkS Warming Estimates
    My old professor used to tell me that if I couldn't present what I was trying to say on a single side of A4, then I didn't really understand what I was trying to say. Given the length of Pielke Sn's replies to this post, I here attempt to summarise them. If the summary is poor it is (with due respect) because the replies are so poorly structured and verbose. This SkS post is asking Pielke Sn two questions (1) Is his comment that CO2 is but 26% or 28% of human-caused forcing wrong & actually more like 50%? Pieke Sn @ 4 replies that given the numbers, the figure should be 40% but is not sure if this includes all humidity effects. Pieke Sn then guestimates the figure would be 35% if the CO2 forcing was taken as the present-day radiative imbalance. Pielke Sn sees it as important that we understand that the contribution of CO2 to the warming is less than 50% (for unstated reasons) but also sees the proportion of CO2's contribution rising higher in future. He asks SkS what it thinks of NGoRF. He also points to the present-day radiative imbalance & associated feedback figures not yet given by SkS. Pielke Sn asks for these figures (in @7 & @11) asserting the present-day radiative imbalance is the important factor. And so CO2 induced warming in past years he sees as unimportant without a good reason being given. Pielke Sn considers the % of human-caused forcing due to CO2, be it 25% or 50%, irrelevant (@22) (2) What temperature rise over the last 100 years is down to human activity? Pielke Sn points to a reference where land use is an important factor but gives no direct answer, and (@11) that too little is known to say, although it was “significant”. Piekle Sn concludes CO2 is important to climate forcing and mentions its removal from the atmosphere. He mentions other causes of human-caused forcing, emphasising that these should have elevated concern as this matters most to society and the environment (for unstated reasons).
  25. Clouds Over Peer Review
    Problems with peer reviewed publication, in science and medicine, were pointed out as long ago as 2003. This article is well worth re-reading: Peer trouble How failsafe is our current system at ensuring the quality and integrity of research? Not very, says John Crace The Guardian Tuesday 11 February 2003 http://www.guardian.co.uk/education/2003/feb/11/highereducation.research The solution of on-line open peer review seems to answer the problem. European Geosciences Union (EGU), sister organisation to American Geophysical Union (AGU), has brought out a whole series of online publications; EGU Open Access Journals http://www.egu.eu/publications/open-access-journals.html Papers are published online along with editor-appointed-peer reviews, either anonymous or open. An online open review takes place with input from qualified scientists. Authors answer the comments and may modify papers accordingly. Finally the paper is either rejected or published in final version online and in print with copies to permanent archives. This appears to me the best possible way to conduct scientific research. It ensures qualified people conduct the review process and findings can be refined down to a widely accepted version. Criticisms can be answered before the final publication. It seems there is little scope for plagiarism or pseudo science. Moreover, the results of timely research can reach a global audience rapidly. Hopefully this can mark the end of the specially invented pseudo scientific publications intended to mislead the gullible. It appears to be the scientists' own Skeptical Science peer review publication system.
  26. Understanding climate denial
    "It is perfecly reasonable to include sea levels and ice caps in the discussion as the consequences of anthropogenic climate change are relevant to any policy decisions, so it is vital to have the science right on the likely consequences as well as the causes." I would agree with that. But you need to be sure that it is done that way round, that is to say as consequences of climate change. It is not satisfactory to say eg that rising sea levels demonstrate that the world is warming still less that they demonstrate that the world is warming as a result of mankind.
    Moderator Response:

    [DB] "It is not satisfactory to say eg that rising sea levels demonstrate that the world is warming still less that they demonstrate that the world is warming as a result of mankind."

    Without more to go by, you give us hand-waving.  Unfortunately, this is redolent with denial.  Please see my response to your previous comment.

    [Dikran Marsupial] As requested, please take the discussion of specific scientific topics to a more appropriate thread. As I pointed out, the evidece that the observed warming is substantially anthropogenic in origin is pretty well established, see the multiple lines of evidence in the article I mentioned in my previous comment.
  27. Understanding climate denial
    correction to my #192 - I meant the expansion rate of the Universe rather than the distances through redshift - oops! Distances are measured through Type 1A supernovae, known as such due to their spectral characteristics.
  28. Understanding climate denial
    elsa, you really need to look at the link in Dikran's response to you. You claim the evidence for AGW is based on models, yet it is not. There is a wealth of observation you appear not to be seeing. For just one example, you are ignoring the changes in longwave radiation escaping Earth or returning to the surface that are measured, and just so happen to be at specific absorbtion wavelengths for CO2. Different molecules absorb and re-emit radiation at very specific different frequencies - this is the foundation stone of modern astronomy (spectroscopy) among other things, without which we would not know such things as the composition of stars or the distances to galaxies (through redshifting of specific wavelengths of radiation). The relationship between CO2 and longwave IR was first experimentally observed in the 19th Century! You do know that you yourself can conduct a CO2 experiment with a couple of bottles, a couple of thermometers and a source of CO2?
  29. Greenland ice loss continues to accelerate
    Adam Gallon @3 links us to this carefully selected graph: Carefully selected, of course because he has carefully dropped of 60 years of data: Carefully selected also, because it wouldn't do for us to look at the wrong station data. And it certainly wouldn't pay to look at the Greenland ice sheet temperatures rather than one carefully selected location:
    Response:

    [DB] Fixed image.

  30. Understanding climate denial
    DSL You say "climate modeling is an attempt to forecast climate based on a sound physical model and probable conditions." I don't really understand what you mean by "a sound physical model". As far as I know we have no knowledge outside the models themselves of the relationship between eg CO2 and temperature. We are not given the information by physics that we could then test. What we have is information obtained by measurements about temperature and CO2 which we then fit together in a model. But the logic here is circular. Of course the data will fit because we have made it do so! Where the relationship between the two variables does not hold we add in something else to ensure that it continues to do so. This is quite the reverse of Sir Richard Doll's work. When he started out he had no preconceptions about what was causing the rise in lung cancer rates. His initial hunch was that the tarmacing of roads was the problem. Only after his work did he come up with the smoking/cancer relationship. In my view this is the flaw in the warmist argument. The "scientific" evidence for AGW is completely lacking because it is dependant on the models, which are not really scientific at all, although by using maths and complex jargon they give a sophisticated impression. Until the warmists are able to come up with falsifiable propositions a truly scientific consensus cannot come about.
    Response:

    [DB]  "The "scientific" evidence for AGW is completely lacking because it is dependant on the models, which are not really scientific at all, although by using maths and complex jargon they give a sophisticated impression."

    It is indeed hard to take you seriously when you make statements like this.  The "evidence" is largely empirical, consisting of things we can see and measure in our world.  Multiple, independent lines of consilient evidence exist, all fully consistent with the radiative physics of CO2:

    F1

    Your comments reveal a fundamental lack of knowledge (which is no slam, as we all start somewhere), so let's start at the beginning:  Welcome to Skeptical Science! 

    There is an immense amount of reference material discussed here and it can be a bit difficult at first to find an answer to your questions.  That's why we recommend that Newcomers, Start Here and then learn The Big Picture.

    I also recommend watching this video on why CO2 is the biggest climate control knob in Earth's history.

    Further general questions can usually be be answered by first using the Search function in the upper left of every Skeptical Science page to see if there is already a post on it (odds are, there is).  If you still have questions, use the Search function located in the upper left of every page here at Skeptical Science and post your question on the most pertinent thread.

    All pages are live at SkS; many may be currently inactive, however.  Posting a question or comment on any will not be missed as regulars here follow the Recent Comments threads, which allows them to see every new comment that gets posted here.

    Comments primarily dealing with ideologies are frowned upon here.  SkS is on online climate science Forum in which participants can freely discuss the science of climate change and the myths promulgated by those seeking to dissemble.  All science is presented in context with links to primary sources so that the active, engaging mind can review any claims made.

    Remember to frame your questions in compliance with the Comments Policy and lastly, to use the Preview function below the comment box to ensure that any html tags you're using work properly.

    As for models, perhaps start with the Models are unreliable page.

  31. Greenland ice loss continues to accelerate
    You're right Arkadiusz Semczyszak, always stick to the science, as is done in this post. I'll never give up repeating this mantra.
  32. Greenland ice loss continues to accelerate
    Adam Gallon I'd suggest to widen your view to a larger portion instead of a single location, the picture may be completely different. As an example, take a look at Tamino's take.
  33. SkS Weekly Digest #19
    The toon doesn't show in IE9 in either page. In Chrome on the toon on the home page I right-click 'inspect element' and expand the 'Computed Style'. That shows a height of 2487px, where it gets this 'computed style height' from is beyond my ken.
  34. Understanding climate denial
    I don't think I suggested that consensus advances science so my apologies if I gave that impression. The smoking consensus was not raised by me it was raised in the article. The HIV/AIDS point seems to me no comparison at all. We can test the HIV/AIDS theory. If for example we found an AIDS patient without the HIV we could demonstrate the theory to be wrong. Mr Mbeki has, so far as I know, no qualifications at all in this area. If I did not think that the HIV explanation was a very good one I would be interested to hear his alternative, but as it is I have no great inclination to seek out what is almost certainly a load of rubbish. I do not understand why you say the data that supports AGW is overwhelming "without any model data at all". I agree that there is good evidence that the world has become a bit warmer in recent years. How you manage to attribute that to specific causes is the question. The data you refer to is all indicative of warming but nothing more. It does not establish a link between CO2 and the recent rise in temperature. Nor do I really understand why if you perceive the science to be about temperature and mankind you then talk about ice, sea levels etc. These could change for other reasons. I would have thought if you were interested in the science it would be better just to stick to temperature and not confuse the issue.
    Moderator Response: [Dikran Marsupial] There are many lines of evidence that are finger prints of anthropogenic climate change that are independent of the models, for instance a cooling stratosphere. There is certainly rather more than merely "good evidence that the world has become a bit warmer in recent years." If you wish to discuss how warming can be attributed to anthropogenic causes, then I'm sure that there are many here who would be happy to join you in such a discussion, but it is heading off-topic for this thread, the one I linked to above would be more appropriate. It is perfecly reasonable to include sea levels and ice caps in the discussion as the consequences of anthropogenic climate change are relevant to any policy decisions, so it is vital to have the science right on the likely consequences as well as the causes.
  35. Greenland ice loss continues to accelerate
    And the question is, if this iceloss is genuine, why's it happening? Not due to warming. http://www.real-science.com/wp-content/uploads/2011/10/ScreenHunter_39-Oct.-10-22.03.jpg Temps at Nuuk have been steadily declining over the past 80 years.
    Response:

    [DB] See Tom's response to you below.

  36. Pielke Sr. and SkS Warming Estimates
    Dr Pielke @22: 1) The IPCC AR4 writes:
    "The simple formulae for RF of the LLGHG quoted in Ramaswamy et al. (2001) are still valid. These formulae are based on global RF calculations where clouds, stratospheric adjustment and solar absorption are included, and give an RF of +3.7 W m–2 for a doubling in the CO2 mixing ratio. (The formula used for the CO2 RF calculation in this chapter is the IPCC (1990) expression as revised in the TAR."
    (My emphasis) Referring back to the IPCC TAR, we find the adjustment to the simple formula was due to the work of Myhre et al, 1998, which in turn depends on intermodel comparisons performed in Myhre and Stordal, 1997 (hereafter, M&S97). In M&S97, Myhre and Stordal perform a detailed series of comparisons between LBL models and a Broad Band Model used at various resolutions. The most detailed resolution used a 2.50x2.50 grid. The coarsest used a global mean climatology. M&S97 explicitly state that:
    "Overlap is considered between gases that absorb in the same spectral region."
    They go on to describe how the overlap is handled. As the 2.50x2.50 is global in extent, it necessarily includes the highly humid tropics, and more significantly the very cool polar regions. Later M&S97 compare the 2.50x2.50 model to a 100x100, a 2.50 zonal mean model, a 100 zonal mean model, and a global mean climatology model. The difference in forcing between each of these models is less than 1% in all cases. Further on they explicitly compare CO2 radiative forcing with altitude for Tropical, Mid-Latitude Summer, and Sub-Arctic Winter conditions using both the LBL and Broadband model. The Tropical and Mid-Latitude Summer forcings are scarely distinguishable, with the MLS forcing being slightly stronger. The SAW forcing is considerably weaker than either the TROP or MLS forcing. Of course, as the formula is based on a full global comparison, that is of no consequence to the final figure. 2) With regard to whether the IPCC AR4 quotes transient forcings in a given year, or the forcing relative to preindustrial levels, I refer you to this chart: Note the charts heading. For greater clarity, the caption reads:
    "FAQ 2.1, Figure 2. Summary of the principal components of the radiative forcing of climate change. All these radiative forcings result from one or more factors that affect climate and are associated with human activities or natural processes as discussed in the text. The values represent the forcings in 2005 relative to the start of the industrial era (about 1750). Human activities cause significant changes in long-lived gases, ozone, water vapour, surface albedo, aerosols and contrails. The only increase in natural forcing of any significance between 1750 and 2005 occurred in solar irradiance. Positive forcings lead to warming of climate and negative forcings lead to a cooling. The thin black line attached to each coloured bar represents the range of uncertainty for the respective value. (Figure adapted from Figure 2.20 of this report.)"
    (My emphasis) Lest there be any doubt, based on a pixel count the chart shows a CO2 radiative forcing of 1.67 W/m^2, in agreement with the text. As to what difference this makes, not a great deal. Never-the-less, you brought the question up. You have blogged on the issue at least twice, and have claimed repeatedly that the CO2 radiative forcing is over-estimated when you have in fact been under estimating it. And you have presented your significant underestimate based on your back of an envelope calculation in a talk to a scientific conference. I would have thought that, given the circumstances, professional pride alone would make you wish to correct those errors with alacrity.
  37. SkS Weekly Digest #19
    BTW, on the main page, the toon gets stretched out to several screen's worth of height for me, using Chrome. Not sure what's going on there - it looks fine on this page.
  38. Pielke Sr. and SkS Warming Estimates
    Dr. Pielke writes: >>Lets move on. ... >>I also have emphasized that it is not an important issue. It strikes me that you again want to change the conversation when others dispute your claims. The difference between 20% and 50% is quite large, and you in fact brought up this figure to prove your point. You end your posting by saying you will ask more questions, but what are the use of you raising questions, when you simply won't stand for any in depth debate in trying to answer these questions, but want to change the subject each time?
  39. Pielke Sr. and SkS Warming Estimates
    Dr. Pielke writes: >>Where has SkS positively recognized his finding on a larger natural influence, even if you (and I) disagree with Roy that the warming was mostly natural? His basic idea is sound and a significant scientific advancement. It seems you are presenting a moving target argument here. In post 11, you write "this is one reason I recommend you focus on science and not Roy's policy/political statements." When it is pointed out that SkS did review Spencer's work, you move the target to claim that SkS must do so in a positive way. More importantly, Spencer's basic idea is hardly sound and significant, which is why SkS has not reviewed it "positively." However, Roy Spencer is hardly the topic of this thread. If you think that Spencer in any way undermines the post by SkS, could you please cite his specific works in specific ways? That would be helpful to clarifying the "the contribution of CO2 to the net positive anthropogenic radiative forcing," the topic of this discussion.
  40. Pielke Sr. and SkS Warming Estimates
    Tom Curtis - I presented a summary of why I have concluded ~50% is too high. I also have emphasized that it is not an important issue. Part of the difference is that, as reported in http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch2s2-3.html#2-3-1 the contribution due to CO2 has increased 20% just between 1995 to 2005; i.e. "....In the decade 1995 to 2005, the RF due to CO2 increased by about 0.28 W m–2 (20%), an increase greater than that calculated for any decade since at least 1800...." However, in looking through this chapter, I do not see where they considered the water vapor overlap. This would lower the fraction. They also write "Using the global average value of 379 ppm for atmospheric CO2 in 2005 gives an RF of 1.66 ± 0.17 W m–2; a contribution that dominates that of all other forcing agents considered in this chapter." so they do explicitly state that this forcing was for 2005 not the difference from pre-industrial. Also, where is the water vapor/CO2 overlap considered? This would be in the models, but I do not see this evaluation in the IPCC chapter and in the SPM figure. I am hoping someone at SkS can clarify. At a more fundamental level, what difference does it make if it is 25% or 50%? My interpretation of the published papers came up with a smaller fraction. SkS and the IPCC have a larger fraction. Would you propose different policy if it were a lower fraction? It will be increasing in the future in any case. The fraction make no difference in the modeling since it is part of their calculations. Each of the approaches presented so far on SkS and in the IPCC, as well as my back-of-the-envelope list, to estimate these values are inadequate. I have proposed a way to better assess these numbers, but have had no feedback on that so far from SkS. I have also asked a number of other questions and will have more on my weblog tomorrow.
  41. Pielke Sr. and SkS Disagreements and Open Questions
    Eric (Skeptic) @54: The first diagram comes from Royer et al, 2007, and the second from Royer 2008. I find your explanation of the seasonal migration of the Hadley cell and Ferrel cells, and consequently the of the jet streams dubious. Specifically, it is well known that the inter tropical convergence zone follows the sun, and the Hadley cells and Ferrel cells follow the ITCZ. Additional explanation in terms of "temperature contrast" seems unnecessary. It is also well known that the Hadley cells specifically, have expanded in size with increasing global temperature. This is particularly noticable in South West Western Australia. The Westerlies formed by the returning surface winds of the Ferrel Cell are the major source of winter rainfall in southern Western Australia. During winter, the migration of the Ferrel cell brings the westerlies and the rain they bring north to Perth's latitude. During summer they pass south of the continent. Further north the land lies under the dry, returning air of the Hadley cell, and is arid through out the year. Hence West Australia's characteristic rainfall pattern: As previously mentioned, increased temperature expands the Hadley cell, pushing the Ferrel cell and the rain bringing westerlies further south. As a result, they do not come sufficiently north in winter, resulting in dry winters for southern Western Australia: This can be seen to be an effect of the changing size of the Hadley cell because summer rainfall has not been effected: This same trend is probably a significant cause of the repeated droughts in recent years in southern Africa. Turning to the ice age weather effects, you have provided no reason to think the effects are not responsive to temperature. Taking the Sub Tropical Front, the relevant effect on climate is its position relative to the Cape of Good Hope. If it is north of that latitude, the STF, it acts as a barrier to warm water flowing from the Indian Ocean into the Atlantic. Below that latitude, and it presents no barrier. There is nothing in this which prevents its position from being determined by temperature, and hence its being a feedback on temperature. The effect provides a distinct "tipping point", but that in no way obviates its status as a feedback. Similar warming "tipping points" have been postulated in the current circumstances, and while they do mean temperature increases may not by even with increasing CO2, they do not change the basic calculations of climate sensitivity.
    Response:

    [DB] Replaced links to dynamic remote-hosted graphs to static locally-hosted graphs.

  42. Weather vs Climate
    Eric#123: "weather responds to cyclical changes in forcing, diurnal and seasonal being obvious and ENSO being less cyclical and less obvious." Agreed. But your contention was, if I understand correctly, that weather changes are both 'semi-permanent' and a forcing for climate change. Maybe this is a semantic question, but how are seasonal cycles 'semi-permanent'? And how can cycles, which are in response to energy imbalances, be considered 'forcings'? Do you consider ENSO a forcing? If la Nina is a cause for the Texas/New Mexico/Mexico drought, are we now in a 'semi-permanent' drought?
  43. Weather vs Climate
    Eric (skeptic) - "The distinction between weather and climate relevant to global warming is the what affects the mean flow of energy at TOA on a global basis." Please do not forget that changes induced by temperature shifts are feedbacks, not forcings. If long term weather patterns change due to temperature shifts, and (a second step, requiring some evidence) change TOA imbalance, they are feedbacks, part of the climate sensitivity. Which again is estimated by looking at initiating radiative imbalance and the resulting temperature changes, roughly 3-3.5C/doubling of CO2, or 3-3.5C for 3.7 W/m^2 forcing imbalance.
  44. Eric (skeptic) at 13:07 PM on 11 October 2011
    Weather vs Climate
    Muoncounter, thanks for the invitation. The distinction between weather and climate relevant to global warming is the what affects the mean flow of energy at TOA on a global basis. The current change in CO2 forcing and the forcings in this graph: /news.php?n=1025#64969 change the climate. OTOH weather responds to cyclical changes in forcing, diurnal and seasonal being obvious and ENSO being less cyclical and less obvious. The current southward movement of the polar jet is purely weather because it will move back north next spring. If it does indeed move further north in the summer that would be a climate effect of AGW. I do not believe that is yet evident. One of the numerous climate effect of the ice sheets is a southward movement of the polar jets in the NH and northward movement in the SH. This causes various changes in weather which result in permanent (or semi-permanent) changes in the mean flow of energy at TOA. The specific one in the paper I linked here /news.php?p=1&t=55&&n=1025#64963 was that the poleward movement of the polar jet was a large factor in the transition from glacial to interglacial, IOW weather change causes climate change. Editorial note: I agree I should not gum up the Pielke thread debating weather versus climate or forcing versus feedback. However there are points Pielke made that are not being directly addressed, namely his contention that the glacial climate regime (read weather regime) is very different (result is net cooling); and his other contention that the global average temperature (as shown in the diagram (first link above) is skewed by the increase in elevation due to the ice sheets. Each point should be clarified and addressed. His writings may sometimes contain different usages of terms, so I was also trying to clarify terminology with my posts (and I may or may not have been correct).
    Response:

    [DB] Dr. Pielke's points are noted and will be addressed.

  45. Pielke Sr. and SkS Disagreements and Open Questions
    Eric#54: "The effects of weather changes are semi-permanent and not negligible. " I wonder if you would care to explain this statement in terms more substantive than the example you cite here. To avoid interrupting the flow of dialogue with Dr. Pielke, perhaps the thread 'Weather vs Climate' would be appropriate for this sidebar.
  46. Pielke Sr. and SkS Warming Estimates
    How much of the non-CO2 forcing is nevertheless still related to fossil fuels?
  47. Eric (skeptic) at 11:45 AM on 11 October 2011
    Pielke Sr. and SkS Disagreements and Open Questions
    Tom, thanks for your explanation. The effects of weather changes are semi-permanent and not negligible. The effects are manifested in two modes: glacial and interglacial; there is a "cooler weather" effect for the former and "warmer weather" for the latter. Our current NH example is the polar jet starting to migrate south for the winter, but that is not due to average temperature but increased temperature contrast in the NH. When the weather changes in the glacial it is similarly not due to GAT or similar metric. Since it is a response to some original change it is technically a feedback, however, it is not a response to a forcing such as CO2, but rather to a geographic (ice sheet and ocean ice) change. The other Pielke thread had a great argument quoted by Albatross: "Because BC forcing results in a vertical redistribution of the solar forcing, a simple scaling of the forcing with the CO2 doubling climate sensitivity parameter may not be appropriate"." The point here is that the forcings pointed out in post 48 are much more different from CO2 than BC is from CO2 and cannot be simply scaled with a CO2 doubling forcing. Please send a reference for " As it happens, climate sensitivity has been tested across the range of phanerozoic distributions of continents and climate conditions and resulted in very similar values" I am very interested in what kind of model they used.
  48. Pielke Sr. and SkS Warming Estimates
    Dr Pielke, thankyou for the clarification @18. While disagreeing with Albatross's apparent imputation that more recent papers automatically trump earlier papers, never-the-less it seems intemperate to dismiss the Skeie et al values as unreasonable. Given that they are reasonable values, and that the contribution of CO2 to the anthropogenic forcing using Skeie et al values is 48.2%, I do not believe your claim that "the fraction is clearly well less than 50% using reasonable values" is justified. If you disagree that the Skeie et al values are reasonable, perhaps you would have the courtesy to explain why rather than simply dismissing them from the range of "reasonable values".
  49. Pete Dunkelberg at 11:16 AM on 11 October 2011
    Hockey sticks, 'unprecedented warming' and past climate change
    One more Hockey Stick: The climate of North America during the past 2,000 years reconstructed from pollen data A.E. Viau, M. Ladd, K. Gajewski 2011 http://www.sciencedirect.com/science/article/pii/S0921818111001500 Highlights ► We use 748 pollen records from across North America to reconstruct the climatic conditions during the past 2,000 years ► Temperatures during both the Medieval Period (MWP; 650-1050 AD) and the subsequent Little Ice Age (LIA; 1550-1850 AD) appear cooler than the past few decades ► The climate during Medieval times was warmer than the LIA across North America ► Results can be interpreted as due to a poleward shift in the position of Subtropical High Pressure Cells in summer during the MWP ===== With so many records this paper may show the advanced and retreat of the aforementioned Subtropical High Pressure Cells during the MWP. That would be a nice addition to the Hockey literature.
  50. Pielke Sr. and SkS Warming Estimates
    NewYorkJ - In the comments on my earlier posts on SkS, there were quite a few comments on his politics. Where has SkS positively recognized his finding on a larger natural influence, even if you (and I) disagree with Roy that the warming was mostly natural? His basic idea is sound and a significant scientific advancement.

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