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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 24101 to 24150:

  1. The Grand Oil Party: House Republicans denounce a carbon tax

    This was just a blanket anti-carbon tax Resolution.  I think many have long suspected that Exxon's carbon tax support is just lip service while they work against the policy behind the scenes. 

  2. Extreme weather isn't caused by global warming

    John Hartz @86, I find the IPCC glossaries sufficiently exact and easy to access.  In the case of "extreme weather event", so also did meteoterm:

    "extreme weather event
    SOURCE:
    IPCC 4th Assessment Report, WG 1 Glossary
    RELIABILITY:
    Verified
    DEFINITION:
    An extreme weather event is an event that is rare at a particular place and time of year. Definitions of rare vary, but an extreme weather event would normally be as rare as or rarer than the 10th or 90th percentile of the observed probability density function. By definition, the characteristics of what is called extreme weather may vary from place to place in an absolute sense. Single extreme events cannot be simply and directly attributed to anthropogenic climate change, as there is always a finite chance the event in question might have occurred naturally. When a pattern of extreme weather persists for some time, such as a season, it may be classed as an extreme climate event, especially if it yields an average or total that is itself extreme (e.g., drought or heavy rainfall over a season).
    DEFINITION SOURCE:
    IPCC 4th Assessment Report, WG 1 Glossary"

  3. Extreme weather isn't caused by global warming

    dvaytw @85:

    In my opinion, the World Meterological Organization (WMO) sets the "gold standard" with respect to meterological terms. You can access the definition of "extreme weather" and other terms by going to the WMO's Metroterm* webpage. 

    *METEOTERM is WMO terminology database. It contains specialized terminology in six languages: Arabic, Chinese, English, French, Russian and Spanish. It includes the International Meteorological Vocabulary, the International Glossary of Hydrology and terms from related sciences that appear in WMO documents.

  4. Extreme weather isn't caused by global warming

    Thanks, Tom.  I appreciate the immense patience you folks have with my endless queeries.  Your answer is very informative, but can you help me with a specific point?  The guy has this inane idea that extremes are defined nowhere in the literature.  He asks, 

    "So, what is the threshold variable for extreme rain events in Sydney? How would that be calculated?"

    Can you answer this, or at least point me to a definition of "extreme rain" in an individual study?  It sounds ridiculous, but he seems to think this is all just smoke and mirrors.  I want to point him to something very concrete and graspable.

  5. Climate scientists have warned us of coral bleaching for years. It's here

    Many Australians are now resisting the establishment of a coal mine in Queensland that will export coal to India as this acivity will add to the problems harming the Great Barrier Reef.

  6. Trump and global warming: Americans are failing risk management

    The comic has too many low risk examples. There's not a small chance the house will burn down - we've thrown a party with 20 toddlers and are letting them all play with lighters.

  7. Most of the last 10,000 years were warmer

    I am unsure Mike Hillis what point Hillis is arguing with respect to the GISP2 d18O proxy.  Is it that it represents "much of the world's climate", or that it represents Northern Hemisphere temperatures, or that it represents North Atlantic temperatures.  Whichever is the case he is shown to be wrong by the ice core records.  Consider for example the difference between GISP2 and Guliya (from the Tibetan plateau) as shown in this graph of various polar and tropical ice cores:

    It is quite clear that if either is representative of the Northern Hemisphere, then both should be highly correlated given that both are NH ice cores.  But clearly they are not.  Ergo neither is reprentative of NH temperatures.  Still less are either representative of "much of the world's" temperature.

    By similar reasoning, neither can GISP2 be representative of North Atlantic temperatures.  Here are the Holocene d18O  records of six Greenland ice cores:

    As all draw their precipitation from the North Atlantic, if all represented North Atlantic temperatures they would by isomorphic.  Again, clearly they are not, having distinctly different holocene slopes and inflection points.  In particular DYE-3 shows a warming trend through the Holocene, while Agassiz and Renland show a more rapid cooling trend.  Camp Century warms until 5-6 thousand years before 2000 AD, while the other records show much earlier (although not synchronous) inflection points.

    A similar point can be made from the famous Global Warming Art Graphic:

    The wide divergence of shapes of the curves preclude any from being a proxy of global temperature except on the coarsest of resolutions.  However, even the GISP2 (light blue), North Atlantic sediment core (specified as yellow, but which I see as a very light lime green), and European pollen data (orange) show distinctly different shapes, even though all are Northern Hemisphere records, and all are significantly influenced by North Atlantic temperatures.

    Part of Mike Hillis' problem is that North Atlantic temperatures do not vary synchronously.  While one part of the NA may be warming, another may be cooling  As the precipitation on Greenland comes from a small part of the North Atlantic, not the whole of it; that means Greenland ice cores can only represent the temperature of the whole of the North Atlantic, but only small parts of it.  In the case of GISP2 and GRIP, zone of the North Atlantic from which precipitation is drawn varies, shifting to a more southerly (and distant) location when the North Atlantic Oscillation is negative.  That means the GISP2 record cannot even be of a single region within the NA (based on Hillis's suppositions), but from two different locations with distinct mean temperatures, leading to an exagerated temperature seesaw based on changes in the NAO.

    Further, even close locations such as GISP2 and GRIP (just 28 kms apart) show variations in the detail of the d18O record (See figure 3 here).  This may not be due to site specific factors, however.  Of five ice cores from the GISP site, the cross correlations over the period 1770-1987 show a high value of 0.552 and a low value of 0.464 (Table 1 here).  GISP2 shows a correlations ranging from 0.408 to 0.549 to those GRIP cores.   Interestinly White et al show the highest correlation with the mean of the 6 stacks to be with the mean of the coastal temperature record, with a correlation of 0.471 (Table 2, above link).  The individual isotope records have correlations ranging from 0.172 to 0.502 (mean: 0.363, data from Table 1).  For comparison, there is only a 0.279 correlation to the annual NAO index.  The later suggest to me that temperatures over the Greenland Ice Sheet are a more significant factor in the d18O record then are sea surface temperatures at the site of evaporation, although that is still a significant factor.    

  8. The Grand Oil Party: House Republicans denounce a carbon tax

    KR @5, Thanks again! ... Well put! Hansen calls it 'greenwashing'. With some of their shareholders publicly speaking up, there are some signs of hope.

  9. Most of the last 10,000 years were warmer

    And if are dO18 values of -25 to -45 in greenland ice core are supposed to be representative of NH, then how are these values (-6.8 to -8.6) in Fig 1B in this paper of dO18 measurements from Central Alps not also representative?

  10. The Grand Oil Party: House Republicans denounce a carbon tax

    Sauerj - Exxon talks a great talk, but they don't walk the walk. I suspect much of their underemphasized position on carbon taxes boils down to PR, rather than actual intention.

  11. The Grand Oil Party: House Republicans denounce a carbon tax

    KR @2, Thanks! ... But, ExxonMobil has publicly unequivocally stated they support a carbon tax (not sure if they distinguish between rev-neu or not). My assumption was that they would support anything that puts the economic burden, by all industries, on a level playing field (which a carbon tax would). Why would they care if FF products are burdened? Could they not invest in renewables as much as the next guy? Heck they could maybe buy out the entire renewable industry if they wanted.

    Is ExxonMobil saying one thing, but secretly telling politicians the opposite? I know I'm naive, but I have trouble believing that ExxonMobil execs would purposely lie boldly that much. Something tells me to give them more credit than that.

  12. The Grand Oil Party: House Republicans denounce a carbon tax

    One more question: Do you know if there was any discussion (in session) to tailor the wording of this resolution (by either party member) so to ONLY target NON-revenue neutral taxes? Hopefully so.

    It would be heartening to know if at least an attempt was made (by someone) to specifically keep the rev-neu option available. If the ratified resolution had been worded like this, then this would have been a nod of acceptance toward the rev-neu option.

  13. The Grand Oil Party: House Republicans denounce a carbon tax

    Sauerj - I'm afraid given the sponsorship by fossil fuel interested that the push is against any pricing of externalities whatsoever. And given the current influence of big money on US politics, I don't see any forthcoming effort by Congressional Republicans to do anything sensible.

  14. The Grand Oil Party: House Republicans denounce a carbon tax

    A Few Questions: Did the resolution distinguish the difference between revenue-neutral & non-revenue neutral tax? And, thus leave a door open for the GOP to accept a revenue-neutral tax?

    If no distinction was made, then was this 1) by accident (maybe not knowing the difference) or 2) was this detail proposely left 'in the dark' so to cleverly lump rev-neu taxes in with the same anti-tax politics as the non-rev neu taxes? And, thus cleverly poison rev-neu tax initiatives from gaining any further ground.

    Regardless of this resolution, do you think the GOP members will still have enough political freedom to move toward the 'light' of the rev-neu initiatives, OR do you think this resolution will have enough political grip to stall both CCL lobby attempts & the growth of the BCSC for at least the next 12 months (next congress)?

    The article questions if the BCSC members who are GOP are not really serious and may only be members to put on a show, so to pick up more middle-ground voters in districts where CC sensitivities may be above average. ... The realism of politics can be so depressing.

  15. Will Fossil Fuel Prices Fully Recover?

    As noted in the article, fossil fuels can, to some extent, substitute for each other. The on-going natural gas (methane) glut is expected to result in depressed prices for years to come. This could result in prolonged low price of coal, particularly for electricity generation, resulting in closure of less efficient smaller coal mines.

    As an interim measure electricity generators may convert from coal to gas before converting from fossil fuels to renewables – or going out of business as solar develops into a 24/7 reliable and cheaper, source of energy.

  16. Glenn Tamblyn at 08:29 AM on 14 June 2016
    Most of the last 10,000 years were warmer

    Mike Hillis

    Here is some more info from the same site scaddenp linked to. Interesting stuff. Read particularly the link about deuterium excess.

    Wikipedia has a brief discussion here.

    This paper also discusses this and the fact the 18O and Deuterium are well correlated with surface temperatures at the depositing location whereas deuterium excess is correlated with temperatures at the evaporative source.

    As the first link points out, D excess actually allowed the glaciologists to detect a transition in the source temperature in the ice core record that occurred within 1-3 years!. This is interpreted as a change in weather patterns so the water was coming from a different location. This rapid transition in the ice core record is actually used as the marker to define the start of the Holocene.

    Your point about deposition vs condensation and that thus the main fractionation occurs at the evaporative source seems to be drawing too long a bow. That assumes that the only precipitation that occurs after initial evaporation all occurs as the final fall of snow. When in fact, as the schematic on my first link indicates, precipitation would likely occur at multiple stages over the journey of the moist air mass, much ot it as rain. Hail also would be based on condensation based fractionation. Snow that forms around water droplets would be a compound of deposition and condensation fractionation. Only snow that forms from pure deposition around CCN's woukld be pure deposition fractionation.

    So the picture is much more of a hybrid than what you suggest.

    With Deuterium excess available to determine the proportion of fractionation due to evaporation, that leaves the pure 18O and deuterium readings available tothen unpack the fractionation that occurs over the journey of the air mass.

    Importantly, there is one piece of evidence suggesting ice cores are regional/local not hemispheric, which is average residence time for water in the atmosphere. This is estimated at around 9 days. In contrast intra-hemispheric mixing time - how long air takes to mix around within one hemisphere - is estimated at 1-2 months. This strongly suggests that most evaporated water falls out again on scales below hemispheric. 

  17. Most of the last 10,000 years were warmer

    Mike, I am in SH, but I am pretty sure that a temperature range of -10 to -45C determined bydO18 is representative of Greenland and not the NH.

    Your assertion that fractionation is primarily at evaporative source does not appear to be supported in literature (here and here for example).

    Source:

    If you have new research that contradicts, then please provide a cite.

  18. Most of the last 10,000 years were warmer

    sacddenp, your link to the graph:

    http://www.iceandclimate.nbi.ku.dk/images/images_research_sep_09/GRIP_93_pit.png

    shows correlation between Greenland ice core temps and d18O, on a monthly basis. That means higher temperatures in July, for example, than April. This of course applies to everywhere in the Northern Hemisphere.

    If the ice isotope proxy corresponds to temps in Greenland, and not everywhere else in the NH, then we can consider it a local proxy. It does not.

    Now let's get back to my point about how snowfall results, not from condensation, but rather from deposition, which I point out is a much weaker fractionation force, for the reason I stated, than evaporation/condensation. This means the main fractionation happens at the evaporative source.

  19. Extreme weather isn't caused by global warming

    dvaytw @83, you might find that individual studies use their own statistical cutoff points for what counts as "extreme weather".  As the IPCC itself does not do research, they must rely on those studies, and therefore cannot use a specific cut off point, but must rely on those that exist in the literature.  If you look at Box 3.1 in the SREX, the IPCC says:

    "A large amount of the available scientific literature on climate extremes is based on the use of so-called ‘extreme indices’, which can either be based on the probability of occurrence of given quantities or on threshold exceedances (Section 3.1.2). Typical indices that are seen in the scientific literature include the number, percentage, or fraction of days with maximum temperature (Tmax) or minimum temperature (Tmin), below the 1st, 5th, or 10th percentile, or above the 90th, 95th, or 99th percentile, generally defined for given time frames (days, month, season, annual) with respect to the 1961-1990 reference time period. Commonly, indices for 10th and 90th percentiles of Tmax/Tmin computed on daily time frames are referred to as ‘cold/warm days/nights’ (e.g., Figures 3-3 and 3-4; Tables 3-1 to 3-3, and Section 3.3.1; see also Glossary). Other definitions relate to, for example, the number of days above specific absolute temperature or precipitation thresholds, or more complex definitions related to the length or persistence of climate extremes. Some advantages of using predefined extreme indices are that they allow some comparability across modelling and observational studies and across regions (although with limitations noted below). Moreover, in the case of observations, derived indices may be easier to obtain than is the case with daily temperature and precipitation data, which are not always distributed by meteorological services. Peterson and Manton (2008) discuss collaborative international efforts to monitor extremes by employing extreme indices. Typically, although not exclusively, extreme indices used in the scientific literature reflect ‘moderate extremes,’ for example, events occurring as often as 5 or 10% of the time. More extreme ‘extremes’ are often investigated using Extreme Value Theory (EVT) due to sampling issues (see below)."

    This does not mean that "extreme values" are not precisely defined in original research.  Nor does it mean the IPCC treats the issue imprecisely.  However, to not overstate the case, they cannot use a precise common definition where one does not exist in the literature.  What they do do is take the relative rigour of the statistical cut offs used in individual studies in weighing the evidence from the literature.

    As noted on the bottom of the quoted section above, there are often very good reasons for the different cutoffs in different studies.  Specifically, if the phenomenon in question has a limited data set, using a 2.5% cut off may result in insufficient data for normal statistical methods.  EVT can be used in these cases sometimes, but is not as robust.  Droping the cut off may allow the scientists to note, and discuss changes in frequencies that actually exist even when the change is not yet robustly detectable in "extreme extremes".

    On top of that, some events are extreme events, and known to be extreme events even when no precise statistical criteria is defined.  An example is any hurricane/cyclone/typhoon.  Any such is an extreme event with regard to wind speed, and probably precipitation and storm surge as well.  To expect the IPCC's discussion of extreme events to exclude all cyclones except the 5% of strongest cyclones would be absurd, but the statistical cut off based just on wind speed for cyclones will not be precisely known (even though clearly it will meet any reasonable such cutoff).  The IPCC definition, by not specifying precise values allows discussions of the frequencies and strengths of all cyclones (and tornadoes, and floods) without arbitrary cutoffs being used to exclude relevant data.

  20. Extreme weather isn't caused by global warming

    PS - I'm wondering, though: can anyone show me where to find the definition the IPCC uses for actual calculation of its probabilities regarding the contribution of ACC to extreme precipitation?  Or if not that, at least, how to find this definition on one particular study of extreme precipitation?

    I took Eclectic's point back to the argument, but he maintains that nevertheless a definition must be chosen if calculations are going to be made from it, and this makes sense to me with my child's understanding of the topic, at least.  

    And in case anyone is wondering, no, I am not a denialist troll trying to covertly advance these arguments myself.  Personally I think the argument is ridiculous; I am just trying to solve the puzzle of how to defeat it without simply dismissing it out of hand.

  21. Most of the last 10,000 years were warmer

    scaddenp @90,

    Your assessment of δ18O data is surely indisputable.

     

    Mike Hillis @89,

    I note that unsnipped @89 you restate what I branded @70 as your proposition (E), an unsupported assertion that the climate myth addressed by the OP is no myth. That is you tell us that, apparently, once "everybody knew that most of the Holocene was warmer than today" and add (now snipped) the implication that you believe (why we know not) that they were correct in that erstwhile position. All very "grassy knoll."

    On more particular matters, if I read you right, while you said previously "Easterbrook correctly uses it (ie GISP2 ice core δ18O data) as much more than a local proxy, as does Alley," what you now mean is that "Easterbrook is wrong about the GISP2" and that Alley, who doesn't actually agree with Easterbrook's use of theGISP2 ice core δ18O data after all. is also himself wrong as he is happy to see the GISP2 ice core δ18O data as “a local record“ of temperature at “one site,” an idea that you brand as being “utterly and stupidly wrong.” So you thus presently consider that they are both utterly wrong. (I'm not sure if the use of adjectives “utterly” and “stupidly” are intended to have meaning or have purely an expletive role as you are on record informing the world that “wrong and utterly wrong are the same thing.”) Whatever, both Easterbrook & Alley are now wrong but for different reasons.

    Instead, we now have a replacement for your now-defunct proposition (G) which is:- (H) “One thing we do know is that NONE of the moisture that falls on Greenland comes from Greenland, so it (ie. GISP2 ice core δ18O data) is anything BUT a local proxy.” That is, you are saying the data does not provide a record of the site's temperature history. Noting the comment @90, best of luck with that.

  22. Most of the last 10,000 years were warmer

    I would say dO18 as a local temperature measurement is well established in theory and in measurement. See here especially the figure comparing dO18 temperature to Greenland temperature.

  23. 2016 SkS Weekly News Roundup #24

    Comments on Washinton post articles are depressingly full of denialist rehtoric and missinformation. Meanwhile there are many exellent commenters on The Guardian who debunk myths and inform readers with a high degree of knowledge and patience. It would be nice if some of them could take some time and go over to see what is happening on the Wapo site.

  24. No warming in 16 years
    Instead of giving the number of years since 1998 for the "pause" the title should be "There has been no global warming since 1998." Otherwise the title would be outdated within a year.
  25. Mars is warming

    Dutchwayne@49:
    "There is little heat being generated in the planet unlike Earth and therefore virtually all the thermal impact comes from only one driver: Solar radiance."

    That is also true for our own planet! The sun delivers about 240 watts/m2 or at least 2600 times more than the tiny 0.09 watts/m2 trickling out from the interior of Earth. The corresponding number for Mars is probably about ¼ of that. Only the gas giants have enough internal heat to make a large impact on their climate.

    "Mars is in fact a better indicator of Solar activity variation than Earth…"

    Maybe, but if we can measure the solar activity directly from Earth much more precisely, what’s the point in making a poor estimate based on very incomplete temperature data from Mars? Those measurements clearly show a reduction of the total solar irradiance (TSI) over the last 35 years or so, especially during the last solar cycle. (see the last chart in @51). In addition, the recent warming on Earth has certain fingerprints that don’t match what to expect from a warming caused by increased solar activity. Some of these fingerprints are more warming in winters and at high latitudes and a cooling of the upper atmosphere.

    If Mars actually has undergone a warming caused by the reasons mentioned by Tom in @51, it’s just a coincident and certainly not related to the warming on Earth, as there is no way albedo changes on one planet can have an impact on another.

  26. Most of the last 10,000 years were warmer

    Easterbrook is an old man. He went to school (and taught school) when the spaghetti graphs looked like this:

    https://www.ipcc.ch/ipccreports/far/wg_I/ipcc_far_wg_I_chapter_07.pdf

    And everybody knew that most of the Holocene was warmer than today (back then). In those days, the temperature reconstructions (same link) showed only 0.4 C rise from the depths of the LIA to today (then). Now, due to all the GISS and NOAA data tampering, the erasure of the 1970's cooling, etc. they are saying 0.8 C or more.  But 0.8 isn't enough for alarmists so they project another 2.0 or 3.0 degrees in the next 10 years and add it to the hockey stick to scare everybody, but we won't get into that. (-Snip-)

    Easterbrook is wrong about the GISP2 being global, it's NH, as there is very little circulation between the two hemispheres. Werner et al 2001 shows that 96% of the snow that falls on Greenland comes from the NH and only 4% from the SH. Link here: http://epic.awi.de/18985/1/Wer2001b.pdf with similar percentages for Vostok in reverse.

    Easterbrook says global, Alley says north Atlantic, Werner says NH. One thing we do know is that NONE of the moisture that falls on Greenland comes from Greenland, so it is anything BUT a local proxy. If you think Greenland ice cores only tell the temperatures of Greenland, you are quite mistaken.

    Still digesting my comment about deposition vs condensation? All these scientists are treating snowfall in Greenland as if it results from condensation. Am I the only one smart enough to see why this is utterly and stupidly wrong? No, meteorologists all know it, and work with this daily (in the winter).

    Moderator Response:

    [RH] Accusations of data tampering snipped. Please go back and read the SkS commenting policies. This is not allowed on this website. Also warning snipped comment for tone.

    Please note that posting comments here at SkS is a privilege, not a right.  This privilege can be rescinded if the posting individual treats adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.

    Please take the time to review the policy and ensure future comments are in full compliance with it.  Thanks for your understanding and compliance in this matter.

  27. Most of the last 10,000 years were warmer

    Mike Hillis @87/88.

    I see you're back with two new bold assertions.

    (F) You tell us "Easterbrook used Cuffey and Clow." Your statement directly contradicts the OP (a point you fail to mention) which points out that while Easterbrook claims his Figure 4 is "Modified from Cuffy and Clow, 1997," it is in truth "a graph ... almost certainly copied and altered from ... Richard Alley’s 2000 paper." With regard to Figure 4, you are ignoring the nature of that 'modification'. Mind, you may be describing other data presented by Easterbrook but if so it would help greatly if you could identified what data it is that you are blathering about. If it is graphs other than that Figure 4, it will be interesting as the graphs presented by Easterbrook in that particular thesis are a seriously odd set.

    (G) You are now suddenly telling us with some emphasis of the GISP2 ice core data "Easterbrook correctly uses it as much more than a local proxy, as does Alley." Again you contradict the OP and even contradict yourself. Concerning what is meant by "much more than a local proxy," Easterbrook is on record presenting GISP2 data as showing "global warming," a position you are presumably telling us is "correct." Alley, as the OP says, considers this wrong, saying in the citation"no single temperature record from anywhere can prove or disprove global warming, because the temperature is a local record, and one site is not the whole world"He describes in that citation how and when a local record can be used for wider regions, but note the point he makes is that using GISP2 as a global record (à la Easterbrook) is utterly wrong.

  28. Most of the last 10,000 years were warmer

    And this says nothing about the main problem with the OP, which is the elephant in the room, namely, the claim that ice cores are only a local proxy of paleotemperature. Easterbrook correctly uses it as much more than a local proxy, as does Alley, who says in "Two Mile Time Machine"

    p. 114 "Much of the world's climate is coupled to that of Greenland"

    p. 121 "The surface of the north Atlantic was cold whenever Greenland was cold, and the north Atlantic surface was warm whenever Greenland was warm."

    Anybody can see that Greenland is not the source of the moisture that falls on it. Furthermore, the snow that falls on Greenland is not due to condensation of water vapor, but the deposition (the opposite of sublimation) of water vapor, in other words, from the vapor state directly to the solid. Since there is no liquid phase in between, in the formation of snow, the fractionation of condensation is not relevant in snow production. Only the fractionation of freezing. And since the freezing point of water and that of 180 water are only 0.23C apart, there is very little fractionation at the precipitation site, compared to the much greater fractionation due to evaporation, because of the much greater difference in the boiling/condensation points between the two species. It follows that the temperature proxy demonstrated by the ice cores reflects temperatures at the evaporation site much more than at the deposition site.

  29. Most of the last 10,000 years were warmer

    Easterbrook used Cuffey and Clow 1997 who I cite presently:

    "In this paper, we treat our calibrated isotopic history as synonymous with temperature"

    and

    "We have found the calibrated d18O record to be a good proxy for environmental temperature.....with the following calibration: T = 3.05 d18O + 75.4 for t = 8,000 years,"

    and 3 similar calibration equations for different levels of t, with no factors in any of the equations other than the ice isotopes d18O. No factor for any adjustments for elevation using total gas content in the bubbles, and although these were discussed  in the paper, the discussion was limited to why this information could not be used. No mention of gas isotopes in the equations either, and although I appreciate your correction of your use of the word "diffraction" when you meant "fractionation" of the gas isotopes, the bubbles were still not used. As much as you stretch your arguments to the several imagined or pretended ways the bubbles were used, extending even to the citing of papers written years after Easterbrook's, they were not.

    And since the bubbles were not used, the time it takes for consolidation of snow into firn and ice is not germain to the proxy used by Easterbrook.

    And as much as MA Rogers tries a "gotcha" gambit by pointing to the Alley paper, claiming that he used the gas isotopes in the temperature proxy, Easterbrook used Cuffey and Clow, who never did.

    In other words, the phrase in question in the OP, about how it takes decades for the snow to consolidate, should be removed. For my reasons, not yours.

  30. Most of the last 10,000 years were warmer

    MA Rodger @82, the sentence,  "The reason is straightforward enough — it takes decades for snow to consolidate into ice" is quoted from the OP, and is now shown to not be straight forward, but straight forwardly false.  From the OP, the "reason" is the reason why 1855 is the terminal point of the data.  If the reason for that terminal point is a smoothing of the data, that may be a sufficient reason for the 1855 terminal point, and would also be reason as to why the 1855 represents a function of actual data both prior to and after that date.  From the description of the data, that is at least part of the reason as to why the terminal point in the data is 1855 rather than 1987 (the terminal point of the d18O data).  There may, however, be some further reason as to why data used in the smooth was terminated prior to 1987 as well.

    I am not convinced that the smooth did not us all the post 1855 data.  That is because any increase in the post 1855 data is likely to have had a equivalent increase in pre 1855 data for that data point.  Had data to 1987 been used, then data from 1723 would have been used in generating the smoothed 1855 data point.  The lower temperatures in 1723 relative to 1855 would have approximately balanced the higher temperatures in 1987 relative to 1855.

  31. Most of the last 10,000 years were warmer

    Mike Hillis @80, yes, "here we go again with the air bubbles".  Just because you do not understand the mechanisms involved does not mean they are invalid, nor that they have not been properly explained in Alley (2000a) and (2000b), as noted @69 above.

    Specifically, Alley (2000a) states:

    "Temperature gradients cause gas-isotope fractionation by the process of thermal diffusion, with heavier isotopes migrating toward colder regions. Diffusion of gases through pore spaces in firn is faster than diffusion of heat, so the isotope signal reaches the bubble-trapping depth before the heat does, and the isotope anomaly is recorded as the air is trapped in the bubbles (8). The degree of enrichment reveals how big the temperature difference was, and thus the magnitude of any abrupt climate change. In addition, the number of annual layers between the record in the ice and in the bubbles of an abrupt climate change is a known function of temperature and snow accumulation; using snow-accumulation data, one can learn the absolute temperature just before the abrupt climate change (8)."

    Alley (200b) states:

    "New gas-isotope techniques pioneered by Severinghaus, Sowers, Brook et al., (1998) o!er this high-frequency calibration at important transitions. On cold ice sheets with little or no melting, the transformation of snow to ice takes decades to millennia, and there are tens of meters of old snow called firn above the depth at which bubbles are formed. Wind-mixing is limited to the top few meters, so tens of meters of firn exist in which gases exchange with the free atmosphere by di!usion alone.

    Gravitational fractionation causes the gases trapped by bubbles forming at the bottom of the firn to be very slightly heavier than the free atmosphere, in predictable and regular ways (Sowers et al., 1989). However, following abrupt climate changes, the trapped-gas composition is also perturbed slightly by thermal di!usion."

    Reference 8 in Alley (2000a) is just Severinghaus, Sowers, Brook et al., (1998), which states:

    "Observations of thermal diffusion in nature have thus far been limited to gas-filled porous media such as sand dunes and firn, where advective mixing is inhibited by the small pore size such that transport is mainly by diffusion. These observations confirm that transient seasonal and geothermal temperature gradients fractionate air approximately as predicted.


    After an abrupt climate warming, transient temperature gradients lasting several hundred years should arise in the upper part of the firn owing to the thermal inertia of the underlying firn and ice. The heavy gas species such as 15N 14N and 40Ar should therefore be preferentially driven downwards, towards the cold deeper firn, relative to the lighter species (14N2 and 36Ar). An important point is that gases diffuse about 10 times faster than heat in firn, so the thermally fractionated gas will penetrate to the bottom of the firn long before the temperature equilibrates, and the gas composition will closely approach a steady state with respect to the firn temperature such that equation (1) should be valid."

    Your gross misunderstanding of the process involved clearly shows that you did not read the linked references (which are only the scientific articles we are discussing in the first place).  Your strongest argument appears to be your invincible ignorance.

    By 2010 this method was sufficiently refined that Kobashi et al (2010) and Kobashi et al (2011) could use it to construct an independent GISP 2 paleo temperature record.  In 2000, however, Alley only used it as a supplement to his basic d18O paleothermometer.  But because he used it as a supplementary thermometer, the depth at which the nitrogen and argon isotopes can be used to effectively provide a temperature record becomes important.

    I will note that I have incorrectly used the term "diffraction" when I should have used the term "fractionation".  That is a massive error compared to your identifying the wrong isotopes, the wrong method, and falsely claiming the gas isotopes would equilbriate with the ice isotopes that it must obviously prove your point /sarc

    Your compete befuddlement with regard to the gravitational fractionation as a paleothermometer is as nothing compared to your comments on total gas content.  You are very specific that "[Cuffey and Clow] found that the elevation of the Greenland Summit did not change at all during the Holocene."  This is a point you are so secure on that you make it the foundation of your claim that you had the relevant knowledge to exclude any possible elevation correction in the recent record.

    It even has some basis in Cuffey and Clow, who state, "The corresponding elevation (relative to sea level)
    histories show a near-constant Holocene elevation".  The only problem is that the full sentence states, "The corresponding elevation (relative to sea level) histories show a near-constant Holocene elevation for AL = 50 km, and a decreasing Holocene elevation for larger retreats (Figure 2b)."  (My emphasis)  This relates to the discussion of three assumptions about modeling of elevation based on marginal retreats of the ice.  As is clear, they are only committed to "near-constant Holocene elevation" if marginal retreats match the 50 km assumption, however they find that:

    "Which of these elevation curves is most reasonable?  Geologic evidence indicates the Greenland Ice Sheet margin had extended about 200 km in the southwest part of the island and about 150 km eastward during the last glacial [Funder, 1989; Funder and Larsen, 1989]. At the latitude of Summit, the western margin position is not well known but was probably at least 100 km extended. Thus we expect the histories with 100 km > AL > 200 km to be most appropriate."

    They go on to say:

    "The GRIP data of Raynaud and colleagues likewise show a large decrease in gas content during deglaciation, and in addition show a sizable gas content increase from early to late Holocene (Raynaud et al., this issue). If elevation changes of the ice sheet are responsible for these trends, then the ice sheet surface must have been at lower elevation during the glacial, have risen during deglaciation, and have decreased elevation again through the Holocene. This pattern compares best with our elevation curves for marginal retreat distances of 100 to 150 km. However, problems with interpretation of total gas content as elevation preclude a firm conclusion at this time."

    In otherwords, "[Cuffey and Clow] found that the elevation of the Greenland Summit did not change at all during the Holocene" only if you assume they found marginal retreats nearly a third less than those they actually found, and totally ignore the gass content data, which was reproduced in Vinther et al (2009):

     

    So, your defence against my claim that you certainly did not consider elevation changes is to assert that Cuffey and Clow did not find any elevation changes so that your failure to consider them was entirely justified.  By that defence you prove that you did not consider elevation changes, which Cuffey and Clow found to exist, and which gas data show to have fluctuated significantly in recent times (see GRIP total gas content in the graph above).  You thereby prove, not only that you are wrong about the elevation changes, but that you indeed did not consider them as I originally asserted.  Your defence merely proves my assertion justified. LOL

    For the record, the most recent air content data for the GRIP ice core is 169 BP (ie, 1781), and indicates an elevation at the Greenland Summit over 100 meters above current levels (as seen above).

    Also for the record, I note that Mike Hillis continues to argue by mere assertion; and has now resorted to asserting findings for scientific papers that are directly contradicted by those papers.  Just how much sloganeering is permissible at Sks?

  32. Mars is warming

    Dutchwayne @49, it is difficult to take seriously a comment that says, "The biggest weakness though is on the side of the critics of Mars warming"  while ignoring that the evidence put forward for Mars warming by AGW "skeptics"  seems primarilly to be evidence of changing seasons.  See my comments at 29, and at 31, along with HK's comment at 40.

    If we consider the more serious evidence of a warming Mars, it comes in two forms.  The first is the study by Fenton (2007) that showed changes in albedo on the Mars surface:

    Averaged across all areas, the surfuce darkened, implying a greater absorption of sunlight.  From this, Fenton deduced a global warming on Mars of surface by approximately 0.6 C.  Note that we do not possess independent measurements of Global Mean Surface Temperature of Mars of sufficient duration to independently confirm the magnitude of that increase.  Rather, from a change in albedo, we deduce a change in GMST for Mars.

    This immediately suggests a problem with your claim that we use Mars as "a cleaner way to determine the true solar radiation impact on Earth".  The GMST of Mars is not effected by incoming sunlight alone, as you claim, but also by changes in albedo.  Worse, while we know of the changes in albedo, we do not know the value of the change in GMST on Mars in any event in order to make your indirect measure.

    There is some direct, but inconclusive evidence of warming on Mars.  Specifically there have been reductions in the amount of CO2 ice at the South Pole, shown here:

     

    (See also here and here.)

    This evidence does show that there is polar warming at the South Pole of Mars, but does not show conclusively a reduction of martian GMST, as it may be matched by cooling elsewhere (particularly tropical regions, in some of which there are significant increases in albedo).  However, it also shows an increase in CO2 in the martian atmosphere - and consequently an increase in the martian greenhouse effect.  This introduces a second confounding factor to the martian GMST proxy of changes in insolation, measurements of which we do not have in any event.

    Given these two confounding factors (changes in martian albedo, and changes in martian atmospheric CO2) and the lack of long term temperture measurements on Mars, perhaps (as Eclectic sugggests @50) we should relly on the satellite record of Total Solar Irradiance.  That record, of course, shows an overall decline in TSI since the 1980s:

     

  33. Most of the last 10,000 years were warmer

    Correction @82 - (ie the Alley (2004) rise 1750-1855 of 0.4ºC is too small given the full data).

  34. Most of the last 10,000 years were warmer

    Tom Curtis @79,

    I agree that the Alley (2004) data is almost certain to have used post-AD1855 data and that such data (indeed even the measurements at AD1855) would not be from layers that had by the time of their sampling been truly 'consolidated into ice'. Yet I do not believe that the data used by Alley (2004) included all the data up to that measured at AD1987. That is why I hedge my bet @76 & suggest the post 'may not be strictly correct'.

    Note too that the "reason" which is described as being "straightforward enough" concerns either (1) why the data that Easterbrook was "not from the top of the core" or (2) why it comes "from layers dated to 1855."  Which it is? That is not clear.

    The one circumstance that would make this "reason" wrong in any circumstance would be if the reason was wholly a need to smooth the data. That is if all the data was used up to "the top layer" but this resulted in the latest data point being AD1855, then the length of time for 'consolidation into ice' is an irrelevance & the "reason" given by the post would be incorrect.

    My reasons for believing that some data has not been used from the most recent layers is that plots of the Alley (2004) data and a smoothed plot of the d18O data to 1987 appears to show that the AD1855 data point would have given a higher value if all the post-AD1855 data was used (ie the Alley (2004) rise 1970-1855 of 0.4ºC is too small given the full data). I suspect that up to 100 years may have been shorn from the measurements and their absence is preventing temperature calculations for years later than AD1855. Also, one worrying feature of the latest data is the increase in inferred annual temperature cycle, an increase that starts to show itself for measurements from the 1890s. And other calibration data which relies on ice formation will become more raggedy as the layers of consolidated ice are left behind.

    Such "reasons" would amply explain why the 'top of the core' was not used (as (1) above). I consider however that it is not semantically true for (2) as the "layers" are not dated to AD1855 but rather it is the average of the usable layers (that have been adequately consolidated) that date to AD1855. Add in a discomforting amount of supposition in this discourse, and the matter does require a mention.

    Mind, I would not consider the audience of Mike Hillis as approporiate for this matter. He may feel he has hit the target but in truth he tramples the target. As stated @79, his reasoning is invalid.

    For him, the point to mention is that his interpretation of this ice core data surely shows that the four warmest summers of the years for which we have adequate data (the last 1,000 years) apparently occurred in the last 10 years of GISP2 ice/snow data with half the top 30 warmest summers occuring since 1950. So would he be happy proposing such a hockey-stick-like finding? Or would he wish to revise his position?

  35. Climate scientists have warned us of coral bleaching for years. It's here

    Nice article but the comment that the Great Barrier Reef is (or was recently) "close to pristine" is completely wrong. At best one might say the northern quarter was relatively pristine (and unfortunately this experienced the worst bleaching) but the southern three quarters was already heavily degraded with more than 50% of the coral lost, dugong populations in severe decline, seagrass in episodic die-offs, and other issues. I can't believe this statement came from John Bruno who published some of the earliest papers showing the state of decline of the coral on the GBR. So I assume it came from elsewhere but should be corrected.

  36. Greenland’s Melt Season Started Nearly Two Months Early
    " ... sees the graph shoot way up from the current minimal levels ... "

    check the nsidc link, june spike is here

  37. Mars is warming

    Dutchwayne @49 - you are certainly correct that Mars is a far simpler climate system.  But given the very great differences between it and Earth, it is therefore a much poorer comparison to Earth's system.  So therefore what useful information can be gained in the comparison, which could not be better obtained elsewhere?

    For instance: solar activity is better measured directly by Earth satellite, rather than by observation of its effects on a planet which is (varyingly) 60 million to 400 million Km from Earth.

  38. Extreme weather isn't caused by global warming

    Well said, Eclectic.  And this person isn't my friend.  

  39. Mars is warming
    The problem with a lot of these arguments on Mars heating is there is no clear effort to account for the distance greater distance and size of the orbit. Yes mars wobbles and it has an impact, but the orbit is longer and the changes happen slower. The thinner atmosphere works both ways in the argument as does the smaller planet size. The intensity of the solar radiation is also less. I have looked over the reports and I do not see any real attempt to make this an apples to apples comparison that actually proves either case decisively. The biggest weakness though is on the side of the critics of Mars warming. The simple truth is mars has a solid core and no magnetic field worth mentioning. There is little heat being generated in the planet unlike Earth and therefore virtually all the thermal impact comes from only one driver: Solar radiance. the thin atmosphere eliminates the green house effect meaning there is little to temper the solar variations. by logic, Mars is in fact a better indicator of Solar activity variation than Earth and that is a critical point. It is a simpler problem to study with less variables and close enough to the Earth to have real value. There is some indication in the report the authors are working toward that conclusion. However, the outright assault on their idea by the factions supporting man made global warming are clearly based on neutralizing the argument. Their objections are not based on data nor are they refuting the evidence. The logical approach should be to ask for clarification and specific results and a clear definition of the relationship between the effects on Mars and the Earth. Instead, it is a "shut up it doesn't matter" approach normally seen in politics,not science. It is pretty clear the problem is difficult to solve on Earth which is a far more complex system than Mars. Mars offers us a cleaner way to determine the true solar radiation impact on Earth. Rejecting the idea is foolish.
  40. Most of the last 10,000 years were warmer

    Mike Hillis - I've looked over this thread a couple of times, and I one major question for you:

    What is your point?

    The archived and published temperature data for Alley 2000, using "...ice-isotopic ratios, borehole temperatures, and gas-isotopic ratios" (emphasis added), indeed starts at 1855 and goes back, entirely appropriate for examining the Younger Dryas cold period - the entire point of the Alley 2000 paper. 

    Gas-isotopic ratios aren't usable until the firn packs, borehole temps near the surface become increasingly noisy due to local weather, and most of all, Alley wasn't using paleo data for the last few hundred years of temperatures. Whether or not it's possible to extract paleotemperatures from the top few meters of recent snow is simply immaterial - you don't need paleotemperatures when there's an existing instrumental record, and Tom Curtis and others have correctly pointed out that recent years aren't in the published data from that ice core. Easterbrook, Monckton, and others (mis)using the Alley 2000 and GISP2 data made fundamental dating errors in their arguments, local temps aren't global temps, and so the myth discussed in the OP is, indeed, busted. 

    IMO you made some extremely strong and unsupported claims against the OP in your first post ("this fabrication"), and have since been dancing around the corrections provided to you; trying to retain some kind of issue to be "shocked" about. As far as I can see there is no issue with the OP, and you are now arguing about (possible) data of no interest to Alley 2000, data that wasn't collected or published, data irrelevant to either the paper or to the dating errors made by (among others) Easterbrook and Monckton. 

    Arguing about the number of angels that could dance on the head of a pin would be just as relevant to the opening post. If you have an actual issue with the OP, please state it - otherwise, you're just making noise. 

  41. Extreme weather isn't caused by global warming

    Dvaytw, it is interesting that your "friend" demands that climate change should have an "all or zero" effect on extreme weather events, and that extreme weather events themselves be "all or zero" extreme/non-extreme, with no fuzziness of inbetween status.

    Your "friend" is playing word-games to deceive you and/or himself.  Some things can be defined precisely, but some (just as valid in concept) can only be defined with fuzzy logic.

    When is sunset exactly - when the sun first touches the horizon / when it is halfway below the horizon / or when the final bright limb of the sun is occluded by the horizon?  And mean sea-level horizon? : viewed from what altitude?  Five-foot or fifty-foot eye-point?

    When does full night start? At sunset, or after the "civil" twilight finishes - or after the "astronomical" twilight?  It is all rather arbitrary and imprecise, to a greater or lesser degree.  Fuzzy.  But it is crazy to deny the real usefulness of concepts such as sunset and twilight.

    Does your "friend" think that men and women are separate concepts?  Can he tell them apart?  Always?  How precisely does he define the difference?  Appearance is sometimes confusing or deceptive.  Sometimes  in rare cases for a newborn, the expert paediatricians can be perplexed in making the male/female decision - even with the closest examination of the genitals.  Blood hormonal levels can be indecisive.  Even when the genome is clearly XX or XY, the outcome can sometimes be apparently "wrong".

    Or does your "friend" maintain there is no difference between man and woman?

  42. Extreme weather isn't caused by global warming

    Hey SkS'ers.  I've been engaging in my guilty hobby of debating denialist trolls again.  Have been having a pretty lengthy one on Quora.   Basically the only point he continues to give me trouble on is on the question of definitions.  He claims that in "real science", terms are defined precisely.  He then goes on to say that this doesn't happen in climatology; he uses the example of "extreme weather".  If one goes to SREX, 3.1.2., one gets the following definition:

    This report defines an ‘extreme climate or weather event’ or ‘climate extreme’ as “the occurrence of a value of a weather or climate variable above (or below) a threshold value near the upper (or lower) ends of the range of observed values of the variable” 

    It goes on to explain a lot of issues, advantages, disadvantages etc with the different methods of determining threshold values.  His argument is that with such a broad definition (he refuses to even call it a definition), they can basically call anything they want "extreme weather".  

    I have responded that the IPCC isn't dictating definitions to scientists; further that the broadness of the definition isn't a problem with the science but a feature of reality that scientists must deal with.  He claims that it should be easy to come up with a clear and precise definition (he suggests the standard deviation of the index).  He asks me how, for example, the IPCC can give a probability that ACC is affecting extreme precipitation when they can't even precisely define what extreme precipitation is.

    Can anyone offer help on this?   An example in another science where a definition is range migh be very helpful, or anything else y'all can offer.

  43. There's no empirical evidence

    Maybe I miss something but there seems to be something wrong with the line of argument.
    First argument “we’re raising CO2 levels” seems plausible, there is a clear exponential rise of CO2 that correlates to the increase in population.
    Second argument “CO2 traps heat”: that is probably true but irrelevant for the reasoning before we have established that there is a phenomenon that we need to explain.
    Third argument: “The planet is accumulating heat”: yes, the diagram clearly shows a drastic increase. But the time period starts 1960, if you instead look from 1880 you get a slightly different picture: the temperature has increased during the 20 century but in more of a linear fashion. If the heating of the planet was caused by human action then the smoking gun would be a correlation between CO2 levels and temperature but there is none. the number of people and emission of greenhouse gases are increasing exponentially, air and sea temperatures are increasing linearly.
    I don’t have a personal opinion in this, but from a purely logical standpoint there seems not to be any evidence that climate change is man made.

     

    Moderator Response:

    [PS] What theory would predict, is that climate moves in response to NET forcings, not just CO2. Please these articles here and here for further discussion. You might also like to review basic, laboratory-based physics in a textbook to review your assessment that CO2 trapping heat is only "probable".

  44. Trump and global warming: Americans are failing risk management

    Despite all the contrary views, irreversible rapid climate disruption and ocean acidification is under way due largely tothe emissions from fossil fuel usage. That is the stark reality.The most society can do is adopt as rapidly as physically possible measures that will reduce the rate of greenhouse gas emissions, so slow down what is happening in the atmosphere and oceans, while adopting measures to cope as far as it may be possible with such consequences as sae level rise and additional storms. Thta will have to be done even as the services provided by the existing aging infrastructure declines as the natural resources it uses runs out. 

  45. Most of the last 10,000 years were warmer

    Here we go again with the air bubbles. We are measuring the oxygen isotopes in the ice crystals, the O in the H2O, not in the O2 of the air bubbles. Nobody cares about the air bubble entrapment when measuring the isotopes in the ice. You keep talking about the isotopes in the gas bubbles. Do you think that air passing in and around snowflakes and uncompacted firn somehow changes the isotope contant of the snow? Are you suggesting the 18O and 16O in the ice diffuse differently into the air during sublimation of the ice? Not going to happen. Or maybe the 18O and 16O in the oxygen of the air diffuse into the ice somehow, and differently for the two species? I doubt it, but so what if they did? The isotope content of the O2 in the atmosphere has been stable for millions of year, and any change it effects on the 18O/16O ratio of the ice would be the same for every age of ice, and it would make no difference whether the air was trapped or not. Gravitational diffraction of isotopes? You can diffract light, how the heck can you diffract an isotope? I think you made that up. It's not a typo because you said it twice. You can't diffract an isotope with gravity. Makes no sense.

    If what you are talking about is dating the air bubbles trapped in the ice, or analyzing the atmospheric gas content over time, via those bubbles, that's one thing, and yes the air in the ice is newer that the snow it's trapped in, because of diffusion, but this is not related to paleothermometry. To get a temperature proxy, isotopes are measured by taking ice, firn, or snow from the cores, and melting them, and testing the isotopes in the water. Nothing is done with the air during that test. The oxygen is passed to CO2 and bombarded with electrons so they have a charge, and the charged CO2 is accelerated past a magnet which bends the path, and the CO2 with 18O goes one way and the regular CO2 goes the other way.

    As for measuring the total gas content of the ice related to altitude, that's another thing, which I never mentioned, purposely. Here's how it works anyway...The atmosphere is thinner with altitude so less air will be trapped in high altitude snow, so Cuffey and Clow measured total gas content released from the ice as it melted (not pressure of the air bubbles, as you say. Pressure? Nobody measures pressure of gas bubbles in ice. They melt the ice.) They found that the elevation of the Greenland Summit did not change at all during the Holocene. So why would they use total gas content of the ice (not pressure) to adjust for elevation? I will quote you now:

    "Evidently no such correction can have been made for the most recent data in the record, but Mike Hillis certainly did not know that"

    Really? I certainly did not know that? I did not know they would never adjust for elevation that did not change? Hmmmm.

  46. Scientists: 2016 likely to be hottest year on record despite looming La Niña

    william @3, the amount of CO2 that can be drawn down into surface waters of the ocean reduces with increased temperatures, all else being equal.  That means that on a subdecadal scale, change in CO2 content from year to year is as much a function of changes in Global Mean Surface Temperature as of net emissions.  The decadal trend is still a function of emissions.  Consequently, the record hot April just experienced will have resulted in a near record increase in atmospheric CO2, even with no increase in, or even slightly declining CO2 emissions.  However, this will be countered by much reduced atmospheric increase with essentially the same emissions next april, which is likely to be effected by a La Nina.

    There is no indication that, and it is certainly too little data to conclude that, there has been a shut down of any carbon sink beyond the temperature dependence of absorption of excess emissons that has been observed since 1850.

  47. Most of the last 10,000 years were warmer

    MA Rodger @78, I have done some further investigation and found out that Mike Hillis is correct on one key point.  Specifically, when comparing the Alley (2004) data to the Washington University measured samples data, it becomes evident that the first few samples in the Alley data are at approximately:

    1. 51.39 meters
    2. 55 meters
    3. 57 meters
    4. 58 meters
    5. 58 meters
    6. 61 meters
    7. 62 meters
    8. 64 meters
    9. 66 meters
    10. 68 meters
    11. 68 meters
    12. 70 meters
    13. 72 meters
    14. 74 meters

    (All values other than the first rounded to the nearest meter.)

    The issue here is that while all values are well inside the diffusion zone (below the first 20 meters of firn) where diffusive and gravitational diffraction of isotopes occurs, it is not until the 14th (or possibly 13th) value that we find a value below the close off depth at which the firn closes to form bubbles in the ice (specified as 72 meters fo GISP 2 in table 1 of Schwander et al (1997)).  Arguable the 8th through 13th values come from the non-diffusive zone of the firn, where "air is not able to equilibriate with the overlying diffusive zone because of the tortuous nature of the firn" (Schander et al 1997), and hence where included air is effectively sealed from the atmosphere even thought not yet enclosed in ice bubbles.  It remains that the first seven values are from the diffusive zone where air content is essentially modern, though with some diffraction of heavier isotopes.  Ergo it is not possible that the explanation given in the OP (and by myself @ 53) for the 1855 terminal data of the Alley (2004) record as related to the closure of the firn is correct, even in principle.

    Of even greater concern is that the Alley values do not allign precisely with the "measured values".  Given that Alley (2000a) and (2000b) (of which Alley (2004) is the data record) are derived from Cuffey and Clow (1997), who derive their oxygen isotope data from Grootes et al (1993) of which the "measured values" are the record.  It may be that this is because the measured data has been updated for some of the later studies of which it represents the cached data.  However, annually resolved oxygen isotope data were available as early as 1995 (indeed, earlier given time from submission to publication), so that is unlikely to be the reason.

    The discrepancy is more likely to be due to the fact that in Alley (2004) "Data are smoothed from original measurements published by Cuffey and Clow (1997)" (my emphasis).  That being the case, the 1855 terminal data point may include data from later than 1855, as well as earlier.  I say "may" because at that point at that time in the "measured values"  there are several values per annum so that the smoothed values may come from entirely within 1855, and are unlikely to include values earlier than 1861 (based on the interval to the next value).  Regardless, I think the nature of the smooth, and if possible the original data values need to be clarrified with Richard Alley, and the OP corrected to account for that information.  This is even more necessary than the need to delete the straight forwardly erronious claim that "The reason is straightforward enough — it takes decades for snow to consolidate into ice".

    While I don't mind admitting errors, I must admit some chagrin to discover that Mike Hillis has made true claim based on invalid reasoning (ie, the assumption that only oxygen isotope data goes into the temperature determination).  In particular, air pressure in enclosed ice was used to confirm the altitude correction in Cuffey and Clow (1997), for which the relevant data clearly does not come up to the present (see Raynaud et al (1997) figure 1).  Evidently no such correction can have been made for the most recent data in the record, but Mike Hillis certainly did not know that.

    In passing, my discussion above presents evidence that shows a couple of his more recent claims to be false.  His claim @75 that "the core study at the University of Washington was started around 1997" is shown to be egregiously in error, given that the first published paper from that core study was in 1993. His explanation that "Alley stopped his temperature data at 1855 in his paper on the Younger Dryas, not because that's the latest data he had, but more likely because he was writing about an event at the beginning of the Holocene and anything after 1855 was not relevant to the Younger Dryas" is also shown to be false.  Alley (2004) does not represent just the data for Alley (2000b), which discusses the younger Dryas, but also Alley (2000a), and more importantly Cuffey and Clow (1997) which discusses the temperature record from the GISP 2 ice core, and which therefore had every reason to be brought as close to the present as possible.

  48. Scientists: 2016 likely to be hottest year on record despite looming La Niña

    Something else rather curious is happening.  If you look at the Mana Loa Carbon dioxide readings from April, the increase from the previous April is 4.16ppm.  If you look at the series starting from December they are 2.91, 2.56, 3.76, 3.31, 4.16 and May to May, 3.76. Is this some effect of El Nino (less biological activity off the West Coast of South America), the shut down of a carbon sink or two or something else entirely.

  49. Trump and global warming: Americans are failing risk management

    Tom Curtis@3:  Regarding Duterte,  I think John Oliver said it best: "When you don't know how many people you've killed, it's 'Too Many' !"

  50. Trump and global warming: Americans are failing risk management

    Jaimesaid @4, the IPCC defines "climate", saying:

    "Climate in a narrow sense is usually defined as the average weather, or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period for averaging these variables is 30 years, as defined by the World Meteorological Organization. The relevant quantities are most often surface variables such as temperature, precipitation and wind. Climate in a wider sense is the state, including a statistical description, of the climate system."

    That is clear and concise, but if you want a more concise gloss on that definition, "Climate is the 30 year mean, and distribution of all meteorological values."  If follows from that definition of "climate" that if the 30 year mean and/or distribution exhibit a statistically significant change, the climate has changed.  From that you have a clear and precise definition of "climate change".

    You can assert there is a problem with the definitions here, but that represents a rhetorical stance, not a rational one. 

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