Talk:Ice core/Archive 1

Invitation
Work is currently in progress on a page entitled Views of Creationists and mainstream scientists compared. Also currently being worked upon is NPOV (Comparison of views in science) giving guidelines for this type of page. It is meant to be a set of guidelines for NPOV in this setting. People knowledgable in many areas of science and the philosophy of science are greatly needed here. And all are needed to ensure the guidelines correctly represent NPOV in this setting. :) Barnaby dawson 21:33, 27 Dec 2004 (UTC)

Leaded gasoline
Anyone know if Antarctic bases are still using gasoline with lead additives? (SEWilco 20:55, 18 May 2005 (UTC))


 * (William M. Connolley 21:17, 18 May 2005 (UTC)) For the UK, I'd doubt it, since its banned here (is it banned? Its certainly little used).


 * Leaded gasoline is also little used in the USA, although sparsely available for vehicles (such as collector cars) which require it. That's why it took me a while to realize that there was the possibility of local lead emissions around the bases.  Although I'm not underestimating the sensitivity of modern equipment and being able to detect a penguin rubbing lead off rocks.  (SEWilco 03:17, 19 May 2005 (UTC))


 * I've been told that there is no leaded gasoline at McMurdo, and that there is in fact no gasoline at South Pole Station, where all the equipment is modified to run on either diesel fuel or jet fuel. Dragons flight 21:59, May 19, 2005 (UTC)

(William M. Connolley 22:34, 19 May 2005 (UTC)) Is this anything to do with The levels of lead on the outside of ice cores is much higher than on the inside.[2]. That reads like a rather odd statement. Ice cores are plastic-bagged as they are taken (at least nowadays) so I really can't see how this could occur.


 * Yes, that is what got me wondering about the source. I found one set of numbers: Antarctic Peninsula 1984-1985: Pb 4.7, Cu 1.0, Zn 6.1, Cd 0.06 (atmospheric pg m&sub3;).  But with an ice core, a closer possible source is lead in the coring machinery (traditionally, lead in solder) or drilling fluid (including fluid containers).  Looks also like penguins and rocks may be less of a source than their droppings. .  Oh, but never mind lead; the sulfur emissions look more interesting.  (SEWilco 04:50, 20 May 2005 (UTC))


 * Stumbled across more while looking for something else. (SEWilco 05:31, 20 May 2005 (UTC))
 * "In the 1940s in Antarctica the lead concentration in snow was already approximately ten times greater than the one present in ice some thousands years ago. Between 1940 and 1980 its concentration has further increased, showing that the man contribution to the lead emissions into the atmosphere has also been significant in the austral hemisphere, even if on a smaller scale than in the north hemisphere. Our recent studies have proved that even in the Antarctic snow the lead concentration has quickly decreased during the 1980s, showing that the reduction of this toxic metal in petrol has dramatically improved the air quality on a global level."


 * I hadn't seen the plastic mentioned. If you know when that started, please update article. (SEWilco 04:50, 20 May 2005 (UTC))
 * Speaking of plastic bags, I do hope they are not the type of white plastic bags which use white lead paint, and ditto for the white boxes used for transport. :-) (SEWilco 05:05, 20 May 2005 (UTC))
 * Groan. Lead has often been used as a stabilizer in PVC.  Vinyl, including wire insulation, too.  Clear plastics seem to tend to use tin compounds rather than lead. Looks like cores rest on straight sheets of something, and I assume those are foam sheets, and I don't immediately find mention of lead in foams. (SEWilco 06:07, 20 May 2005 (UTC))

(William M. Connolley 14:02, 20 May 2005 (UTC)) I've revised the text of the page to something that seems more in tune with current practice. I'm not quite sure what you're getting at with all of the above. There seems to be a lack of a certain basic assume-people-are-competent.

There are a number of studies I have by Eric Wolff about lead in Antarctic snow, demonstrating the extreme care required to analyse the trace amounts and determine the increase to 1980 and somewhat decline since. See-also. Pb is about 4 ng/kg in Coats land. Not sure where it would fit in though, since its snow not ice core.


 * Lead has been found in low-density polyethylene bottles. I haven't found mention of lead content in poly bags.  But at least one study found LDPE levels were too low to be source of ice core contamination, and this study was examining cores stored in LDPE bottles rather than poly bags. (SEWilco 16:18, 23 May 2005 (UTC))


 * I moved your material to the "Core processing" section, where there is already material about the current practices. As for atmospheric lead levels: Maybe it doesn't fit here; here so far all we have is curiosity about the ice lead levels.  Recent lead levels won't be in ice cores yet.  The firn description from the lead study may be of interest, as the depth and pattern of lead should be useful as a recent tracer, particularly if lead particles are involved rather than a diffusable gas.  The article Lead doesn't really cover this subtopic, but such info may be relevant to Tetra-ethyl lead or Lead poisoning. Or create a "Lead in the environment" section in Lead, as I recently had to do in Mercury (element) when cleaning up a dental amalgam POV mess. (SEWilco 14:48, 20 May 2005 (UTC))

(William M. Connolley 18:39, 20 May 2005 (UTC)) The core contamination bit is out of context and misleading - it refers to early cores. I'll remove it once I've got the refs for it. Putting it back wasn't helpful.


 * Oh, it was helpful and relevant. (SEWilco 02:43, 21 May 2005 (UTC))

[J. Daniels, 25 November 2005] I believe it is particularly important in this politically charged area of science to maintain a clearer separation between the data and the interpretation of the data. In this article, the focus is apparently on the methods and practices of data gathering. That is, only to determine the constituent substances contained in the ice and other situational data about the ice, like geographic locations, depths, etc. A discussion of the potential for contamination of the data is also probably relevant in a general article about ice core samples. And while some mention of the types of conclusions that may potentially be drawn from the data, such as air temperature, other climatic conditions, solar activity, etc., is interesting and worthy of mention for completeness and to convey a basic understanding of the intent and thrust of the experiment as a whole, it is probably best separated wholly from the main body of the article, as it should be separated in the scientific process. When conclusions are incorporated into the process of data gathering or even into the discussions of data gathering, subsequent conclusions become more open to doubt than they would have otherwise been due to the potential for observational bias.

I think that the “Ice Core Data” section ought to be further sub-divided to break out conclusion-bearing statements from the specifics of core processing.

Statements like:


 * "Analysis of the Upper Fremont Glacier ice core showed large levels of chlorine-36 that definitely correspond to the production of that isotope during atmospheric testing of nuclear weapons."

and


 * "Dust in the core can be linked to increased desert area or wind speed."

ought to be in a separate analysis or theory section that links them directly to the studies or discussions that drew those connections: a “What is being done with ice core data” section, if you will.


 * Thanks for the comment. We don't have any ice core experts here, so feel free to try to improve the article. As you see, it hasn't been updated for a while William M. Connolley 20:07, 25 November 2005 (UTC).

Glaciers

 * however since the 1980s glacier ice has been found that is older, some cores dating as far back as 400,000 years.

Is there a ref for that? It sounds unlikely William M. Connolley 10:14, 20 February 2006 (UTC)


 * Well I was also surprised by this assertion, but it does indeed seem that Lonnie Thompson's group are claiming ca. 750,000 years for their oldest glacier ice core to date (cited on many web pages but mostly originating from a single press release). I don't know how they date their ice (haven't been keeping up), but here is a paper that contains this claim in its abstract .  Can't access Web of Science right now so can't find any more than this. Actinide 12:43, 20 February 2006 (UTC)


 * ..originating from a single press release.. Here is the Science Magazine abstract for the first report of the Guliya glacier core. Tropical Climate Instability: The Last Glacial Cycle from a Qinghai-Tibetan Ice Core. -- Stbalbach 15:44, 20 February 2006 (UTC)


 * Hmm, I think the real point may be the useable climate signal. Very old ice is one thing; in sequence is quite another. William M. Connolley 13:46, 20 February 2006 (UTC).


 * Information is from Thin Ice: Unlocking the Secrets of Climate in the World's Highest Mountains, a fascinating account of Lonnies career and discoveries. Once the layer count runs out, they use "flow models", chlorine-36 dating and carbon dating, correlation with other records, some other methods to piece together a chronology, cross checking each other. In the end they concur with the results from the poles (with some important differences). Actually Actinide is right it's around 760,000 is the oldest, found at Guliya in 1997. The field is so focused on the poles that most people don't realize Guliya even exists. But its importance is not so much the age but the data they have found in the tropics which has been important in our understanding of climate change (which is for another day to explain!). -- Stbalbach 15:40, 20 February 2006 (UTC)


 * The science paper says:


 * An ice core record from the Guliya ice cap on the Qinghai-Tibetan Plateau provides evidence of regional climatic conditions over the last glacial cycle. 36Cl data suggest that the deepest 20 meters of the core may be more than 500,000 years old. The delta 18O change across Termination I is ~5.4 per mil, similar to that in the Huascarán (Peru) and polar ice cores. Three Guliya interstadials (Stages 3, 5a, and 5c) are marked by increases in delta 18O values similar to that of the Holocene and Eemian (~124,000 years ago). The similarity of this pattern to that of CH4 records from polar ice cores indicates that global CH4 levels and the tropical hydrological cycle are linked. The Late Glacial Stage record contains numerous 200-year oscillations in delta 18O values and in dust, NH4+, and NO3- levels.


 * "may be more than 500 kyr" - not 760 kyr. William M. Connolley 17:27, 20 February 2006 (UTC).

Yes, but there is a reason for that: the tropical cores aren't usable very far down. There is also a problem with their isotope thermometry, since there is no eq-to-pole fractionation in them William M. Connolley 16:52, 20 February 2006 (UTC).


 * A reason for what? "usable" in what sense? -- Stbalbach 17:00, 20 February 2006 (UTC)


 * Well, what do people use ice cores for? Primarily, to produce climate records. AS in the pic on the ice core page. Those long records come from Antarctica, where the accumulation rate is low. If your accumulation rate is higher, then the lower ice gets squashed very very thin - it must. Which means you don't get a usable signal from the older ice. Even the last interglacial isn't very usable from the mountain glaciers/icecaps (or even much from GRIP/GISP, if it comes to that). William M. Connolley 17:11, 20 February 2006 (UTC).

OTOH, this:


 * Glacier ice cores are more compact than polar cores, packing more years into a length, thus requiring shorter cores.

is garbled. Glacier cores *are* shorter; but this is not a virtue. They are shorter just for geometrical reasons: mid-lat and tropical ice just never gets as thick as polar ice. "packing more years into a length" is close to false. Because they are high accumulation, they pack *fewer* years into a given length near the top of the core. Only at the very compressed stuff at the bottom do they have lots of years-per-length; and this is then a Bad Thing. William M. Connolley 17:16, 20 February 2006 (UTC).

Your the expert. Ill leave it to you. I just read Thin Ice and there's much more to the story, there is usable climate data in the older ice. I'm in no position to summarize it here. BTW the Bowen ref is for the whole section. -- Stbalbach 17:32, 20 February 2006 (UTC)


 * I'm only a humble climate modeller, but I did go ask an ice corer :-) I have the science paper now, so I'll try to add some more from that. I suspect that mid-lat/tropical cores are quite diverse. Is Guliya the pre-eminent deep core? William M. Connolley 17:41, 20 February 2006 (UTC).


 * Well your the Real Climate guy which is pretty cool in my book (or Bloglines account). Ill finish Thin Ice in the next day or two and have a better handle on where things stand, Lonnie went to Kenya and another mt in the Andes which I have not gotten to yet. -- Stbalbach 17:57, 20 February 2006 (UTC)


 * How kind, thanks. I've finished the Science paper; its interesting. I'm not sure I'm ready to edit much yet, I may even think about it... Some interesting points: the Guliya core is very much dated by comparing it to the GRIP2 core. It would be undatable, probably, without the polar cores. Also the delta-O-18 signal in it is... curious. It seems to me that there are some issues the Science paper evades. The DO18 from GISP2, for example, is clearly lower in the last glacial, with dansgaard-oeschger event spikes; but even the spikes are clearly below the Holocene values. Yet at G, DO18 was higher 30kyr ago (and at other glacial times) than now! There is no clear plateau for the holocene. The obvious interpretation (partly supported by conversation with a friend) is that much of the G DO18 signal is not temperature, but is probably the "amount effect", ie precipitation (there is some techical stuff hidden there in the way equ-pole fractionation occurs, which I don't fully understand).


 * The climate signal at G "only" goes back about 110 kyr. The very old ice is dated, indeed, from Cl36, and apparently there is so little Cl36 at the bottom that half-life arguments indicate that its > 500 kyr old. But... there is no evidence in the Science paper, at least, that this old ice is useful for anything! Apart from knowing the ice cap has been there that long, but I doubt that is new info. William M. Connolley 23:07, 20 February 2006 (UTC)

Also: I changed "glacier" into "non-polar". I would be fairly sure that most of them were done into ice-caps: the Guliya and Dunde certainly were. Which makes sense: the flow you get in a glacier would make the core nearly unusable. William M. Connolley 23:15, 20 February 2006 (UTC).

Also, I created an LT stub. If there is any decent biog info in the book, could you put some in? His home page is *not* informative... William M. Connolley 23:31, 20 February 2006 (UTC)

Gas age / pore close off
I removed the existing table, which was clearly wrong. Some of it was based on misinterpretation of. The table asserted that Estimated air ages at firn closeoff was 6 years for GISP2. I don't believe that. Firn depth at GISP2 is 80m; accumulation must be about 0.1 m/y; which suggests a value more like 800 y. The above ref also sez ''At Vostok, for example, the bubble closeoff zone is about 8 m thick. A single layer of ice traps bubbles throughout the ≈300 yr it moves through this zone.'' so the previously claimed max of 156 years must be wrong (as well as far too precise).

If anyone knows this better, please comment William M. Connolley 20:28, 24 February 2006 (UTC)


 * Ah, browsing the same I found The gas age–ice age difference ([Delta]age) is as great as 7 kyr in glacial ice from Vostok. William M. Connolley 20:29, 24 February 2006 (UTC)


 * Ah #2: the ref sez The diffusivity of the firn is such that air at the base of the stagnant column today has a “CO2 age” ranging from about 6 yr for the GISP2 core (central Greenland) to about 40 years at Vostok (East Antarctica).  which I think someone has misinterpreted: it doesn't mean the gas-ice age diff is 6yr; it means the air is 6yr old relative to the sfc, and therefore is much younger than the surrounding ice. William M. Connolley 20:33, 24 February 2006 (UTC).

Vostok Ice Core Graph
I've been reading a lot on global warming lately and I always come across this Vostok graph which is supposed to show how our current warming trend and increase in atmospheric CO2 concentrations is unprecedented in history. I went to the NOAA web site to find the source data for this graph and found that many of the samples are 1000 or more years apart, yet the points are connected as though there's a linear increase between those to points. This is very misleading unless the data I'm looking at is incomplete. Shouldn't the graph be a scatter plot instead of a linear graph?Jimberg98 00:02, 20 January 2007 (UTC)


 * I doubt it makes much difference. You can see he higher-rez EPICA data at ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/epica_domec/edc-ca-na.txt if you like William M. Connolley 12:00, 20 January 2007 (UTC)


 * That's sodium and calcium data. Is that the data used to determine CO2 levels? Jimberg98 04:51, 21 January 2007 (UTC)


 * Oops, sorry, how about ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/epica_domec/domec_co2.txt ? William M. Connolley 12:47, 21 January 2007 (UTC)


 * No problem and thanks. The new data only covers about 10,000 years with the majority of the numbers spanning 90 years or more.  Some spans are over 200 years.  Again, I think it's misleading to show the data as though it's linear.  My biggest concern, obviously, is that I read a bunch of articles where the authors draw comparisons between this data and data that was directly observed and truly is linear.  Would a CD sound the same if you only used only 490 samples per second instead of 44100?Jimberg98 00:12, 22 January 2007 (UTC)


 * Technically you're correct - it's misleading to use a solid line which suggests continuous measurement. However, this is palaeoclimate data. Consequently, and regardless of the archive (ice, marine or lacustrine sediments etc..) it's not possible to avoid sampling to some level. Given the length of the record it's unlikely that any significant changes haven't been picked up within the intervals used. Additionally, a solid line helps those not used to interpreting graphed data pick up any trends. Making comparisons with modern records is perfectly valid so long as the source of the data is explicit (as in scientific papers). I'm not sure how else we could to do it. NickW 09:42, 22 January 2007 (UTC)
 * My problem is that if you go over to the global warming page, you see directly measured data included in the graph that has samples that can be as far apart as 6000 years. Who's to say that there weren't periods in that missing data that are comparable to today's measurements?Jimberg98 17:31, 26 January 2007 (UTC)


 * hypothising non-observed continuities in basically chaotic system, hmm, the simplest model is usually the best (at least most easily applicable), but concerning this i'm not so certain. 91.153.52.32 10:41, 27 September 2007 (UTC)

Melting cores/Core Sampling Rate?
I'm not sure where this question belongs, so I'll ask it here and maybe someone can move it to the correct location when they answer it. If there is significant melting of ice caused by global warming resulting from increased CO2 and other greenhouse gases, how can that quantity of CO2 be taken from ice cores if there was no ice to trap the air bubble? Wouldn't it stand to reason that the bubbles trapped are the ones that could be trapped once the temperature levels dropped to a point that ice could reform? I'm sure there are ways that they can age a bubble by examining something, but how can they know what CO2 levels were in a period where ice was melting? Take what's happening currently. If the poles keep melting as scientists predict, how would scientists 400,000 years from now know what levels of CO2 we actually reached? What if all the ice on earth melted and then it refroze? Is there a way they can tell that from the ice core samples? I'd like to see this explained in the article. Thanks. Jimberg98 22:00, 4 January 2007 (UTC)


 * Cores are only usable from locations where there is (little or no) melting. This is true for all the major cores from Greenland and Antarctica. As for the future... we currently have much better mreasurements from direct atmospheric sampling William M. Connolley 22:08, 4 January 2007 (UTC)


 * So there are some locations where we know they never melt? Ever?  I understand that we take do direct atmospheric sampling now.  That's because we can.  If ice is melting now, or 100 years from now, or 500 years from now, no data is being gathered by the ice, right?  I guess an easier question would be, what is the sampling rate of ice core data?  Is it constant?  Thanks. Jimberg98 22:29, 4 January 2007 (UTC)


 * Yes (ie, that they haven't in the past). Certainly the ones in the interior of Antarctica. If the ice is melting, then the core won't be much use. Sampling rate depends on precipitation rate. But since there is the pore close-off problem, the resolution for gases is poor - decades, depending on the site William M. Connolley 22:50, 4 January 2007 (UTC)


 * When you say decades, are you talking 20 years, 40 years, 80 years? What about rates of sublimation in the locations that never melted in the past?  How does one determine that ice has never melted or sublimated in the past if the evidence could have melted or sublimated?  I'm not a skeptic about global climate change.  I would expect that the earth would continue on a warming trend after coming out of an ice age just like it has always done in the past.  I'm just wondering if we're like creatures that live for 30 minutes wondering about how we're causing summer and how to prevent it.  How can we compare data with a daily sampling rate to data having an uncertain rate of decades?  What's the margin of error for ice core samples? Jimberg98 15:15, 5 January 2007 (UTC)


 * Ice that has melted and refrozen has a very different crystal structure than that formed from compacted snow. If you are familiar with the problem, you can tell if there was melt just from looking at the core.  On any given measurement, the uncertainty is likely to be few percent in age (for samples older than a couple thousand years) and a few to several ppm in concentration.  Changes of 100 ppm (such as has occurred since 1800) are many times larger than the uncertainty in past concentration.  Dragons flight 15:33, 5 January 2007 (UTC)


 * What about the crystal structure of ice that sublimated? Jimberg98 17:55, 5 January 2007 (UTC)

Maybe I asked about resolution in the wrong way so I just want to confirm what you're saying. I went to download the CO2 data collected from the Vostok cores and noticed that there are a couple thousand years between some sample ages. Some seemed to be 6 years. What is the average sample rate of data stretching back 400,000 years? When you answered about resolution, was that the accuracy of aging a sample? Thanks. Jimberg98 22:12, 16 January 2007 (UTC)

Random comment that may/not have to do with this: I don't have the exact cited sources, but the pattern of rings in an ice core is NOT summer-winter-summer-winter. It's warm-cold-warm-cold. I live in Muchigan. In January, we can have five of those warm-cold periods in a week. So any 'evidence' collected using the summer-winter thing would be wrong, if the warm-cold thing is correct.Could somebody maybe do some research on this? I don't have any time, but I think it's worth adding to the article if it's a valid theory. 204.38.47.171 16:21, 26 October 2007 (UTC)

What exactly does the proxy temperature data represent?
When using isotopes to determine temperatures from the ice cores, what does it represent? Average over a certain amount of time? Peak temperatures? 150.228.40.142 (talk) 23:52, 17 December 2007 (UTC)

What is the margin of Error of Ice Core Samples?
every measurement has a Margin of Error, but my google-fu can not locate this...--65.107.88.154 14:10, 26 October 2007 (UTC)
 * The margin of error is probably not very small, just because these are sampled measurements, and for that reason the Nyquist–Shannon sampling theorem applies. This means that the process should have been filtered for variations above half the sample frequency. If this is not done in advance of the sampling, aliasing will occur and distort the dynamic information of the measurements. And since there is no possibility of filtering in advance of sampling, the measurements are by nature distorted. Unfortunately, it is not possible to tell how big this distortion is, because there is no way of knowing how influential the dynamic behavior above half the sampling frequency is, compared to the frequencies below this frequency. But typically, the Vostok core is sampled at a rate of one sample per 1000 years (approx.), so if filtered correctly the Vostok core would have given dynamic information of variations up to 1 per 2000 years. It is not realistic to assume that earth's weather system could not have changed considarably within periods of 2000 years. Therefore, the error could be considerable. Arconada (talk) 20:48, 6 May 2008 (UTC)
 * There are at least two different questions here. First, what is the margin of error of an individual measurement of, say, d-o-18. Second, what processes are missed by only having a sample rate of, say, 1 per kyr. For the first, I think that many cores are repeat sampled (at least the recent ones?) and the error bars are much smaller than the variation displayed. For the second, there is diffusion within the cores (certainly of the gases included, perhaps rather less of the ice content itself) so smaller subsampling wouldn't help. Actually, that was probably a third... William M. Connolley (talk) 21:12, 6 May 2008 (UTC)
 * I cannot give you the margin of error of an individual measurement, but the fact that many cores are repeatedly sampled, as you said, does not impress me: similar measurements result in similar errors.  It is simply necessary to find an entirely different and totally independent way to confirm the measurements of the climate down to 400.000 years ago.  To your second question, what processes are missed by having a sample rate of 1 per 1000 years? Well, all the processes, random or cyclic that are above the frequency 1 per 2000 years.  And looking at the last 2000 years, a lot of variation can occur in this time span. Actually, the processes are not really missed, but irreversably mixed into the frequency spectrum of 0 to 1 per 2000 years. To your third remark, I suppose there is diffusion in the ice core, and it acts as a filter, but that is not enough for two reasons. You’re a mathematician so you will probably know that aliasing is not prevented by ‘some’ form of filtering, but by a rigorous form of filtering.  But even if you could design a filter to eliminate all the frequencies above the Nyquist frequency in the ice core, or the other way around, if you could sample at a high enough sample-rate(whatever it may be), theoretically it would not help, because aliasing is part of the process: aliasing already took place at the very beginning. Some measurements or processes are sampled by its nature. A sample of the atmosphere was taken at intervals every time a snow-shower took place. Maybe a day passed before another shower, maybe a week, or a month or even a year.  The bottom line is, the ice core is a sampled measurement of the atmosphere at that time. The variations of the atmosphere were not recorded in between samples, therefore aliasing took already place then.  This is not an uncommon paradox. Many measurements take place without being able to filter for aliasing, many processes are typically sampled. What to think of opinion polls, where every month voters are asked to say what they will vote in the next elections.  We all know that the time-line that is produced in this way, does not predict the result of the election, and this is partly caused by the fact that we are unable to prevent aliasing.  Or what about the stock market? The price of a commodity is only determined at the exact moment when a buyer and a seller agree about the price, and a trade takes place. In between trades the price could be anything: we don’t know what the price is, because there is no agreement. The point is, the price is sampled at trade-moments, so in the graph of the price the aliasing error is included because we are not able to filter against it anymore. Maybe this is one of the reasons why we perceive some processes as chaotic.  But back to the question, measuring the climate by ice is a process of sampling, from the very beginning to the end. Aliasing is an important and unpredictable factor. So in response to the original question, I said the margin of error is probably not very small. Arconada (talk) 15:05, 7 May 2008 (UTC)
 * It is worth keeping in mind that not all techniques are the same. For recent cores, some of the chemistry (e.g. sulfate) and stable isotopes (deuterium) are gathered through a nearly continuous sampling process that generates data much more densely, and rarely skips more than a few hundred years.  Some physical measurements (e.g. conductivity [proxy for ion concentration] and optical scattering [proxy for dust]) are even done truly continuously so that every inch of core is scanned.  Unfortunately the gas data (e.g. CO2) is much more complicated to collect and hence is often sampled with skips of a few thousand years.  To the extent that the more densely studied proxies are tightly correlated to gases and don't show large fluctations, it suggests (but does not prove) that there is not a lot being missed in the sampling of gases.  Also, for the record, gaseous diffision of the interesting species operates at a rate of tens of centimeters per 100,000 years, and for most of the core would not have a major role when gases are sampled every couple meters.  Dragons flight (talk) 15:58, 7 May 2008 (UTC)
 * Still, sampling related errors do occur. "Nearly continuous sampling", as you said, is sampling, not a continuous measurement. And even if the conductivity and optical measurements are truly continuous, the precipitation isn't. The ice is sheet is created by discontinuous snow falls, samples. So the history of the atmosphere is sampled and aliasing is part of that. It’s a paradox. Arconada (talk) 10:09, 17 May 2008 (UTC)

How Many Annual Cycles Can Be Visually Identified?
Could anyone tell how many annual cycles can be visually counted from the top of the ice core downward? Is it on the order of hundreds, thousands, or tens of thousands,or more?

Thank you!

--Roland 07:47, 4 March 2008 (UTC)


 * It depends on the area where the core was laid down. In greenland, they can layer-count 10,000 years and possibly more. This is because accumulation rates are (comparatively) high so you get a lot of layer to count each year. In Antarctica, rates are typically lower, and you can't count so far (but in exchange you get cores that cover a longer timespan). See for example the most recent RC . BTW, I'm fairly sure that what is counted are not visual layers, but seasonally varying chemical traces William M. Connolley (talk) 08:23, 4 March 2008 (UTC)


 * Actually, layer counting is often based on a combination of annual variations in chemistry, optical layers(influenced by ice crystal size, and ultimately temperature at time of precipitation), and electrical conductivity. The use of multiple proxies helps to resolve layers when a single proxy may be ambiguous.  As can be seen in images like Image:GISP2D1837 crop.jpg, annual layers do have a distinctive visual trace.  At GISP2, the layer counters claimed to reach over 40,000 years if I recall correctly (with increasing uncertainty in the deep portions).  Dragons flight (talk) 16:06, 7 May 2008 (UTC)


 * Glaciers have been created with ice sand —Preceding unsigned comment added by 74.166.237.24 (talk) 01:40, 28 October 2008 (UTC)

Lost Squadron Discussion and Request
Came here looking for information on the Lost Squadron and wanted to know if any work as been done on this subject in relation to ice layers. The Lost Squadron is a group of P-38's that made and emergency landing on the eastern coast of Greenland on July 15th, 1942. The pilots were rescued after several days but the planes were abandoned. They were found again in 1992 under 268 feet (~75 Meters) of ice. The planes are now in a museum. The team that recovered the planes reported seeing hundreds and hundreds of visible layers of ice. Since a known time frame can be associated with the formation of the ice layers on the top of the planes, has any work been done to correlate the layers with other Ice Core projects? First ever Wikipedia edit so please forgive or correct my mistakes and I am not nearly knowledgeable enough to edit the main article or any Wikipedia article. I have been unable to find any work on this subject thus far. If any has been done wouldn't it be appropriate to add it to this article as it gives a known date and time frame for the formation of this thickness of ice with x amount of precipitation and also known climate conditions. Pnpjunction 23:56, 13 November 2007 (UTC)pnpjunction


 * I saw a NOVA show about this where the rescuers pointed out that the planes were buried under hundreds of layers snow, and that the way scientists count layers must be tremendously wrong, since the planes were there only 50 years. This wiki article says basically there's 1 foot of snow for every year. This would indicate that the planes were buried 250 years ago!  All of the talk about global warming based on Greenland ice cores must be incorrect.  Scientists simply surmised one layer corresponded to 1 year or 1 season.  But the scientists never had anything to base this estimate on.  Now that they have something to base it on, they simply ignore it because it doesn't fit their theory, much like a lot of things in modern science.173.76.90.12 (talk) 00:36, 1 September 2009 (UTC)

Additional corings for Greenland
I've added some information on corings in Greenland that I've found while researching hopefully interesting content for the Dye 3 article. Opinions, comments, questions, please. Marshallsumter (talk) 23:26, 5 September 2009 (UTC)

Notes vs References
Does anyone know why there are references under both Notes and References? Technically, this is because two different sets of codes are used

&lt;ref name=abc> &lt;/ref>

But why? I want to fix this, but I don't want to edit against consensus, particularly if there is some reason I don't understand. As it now stands, there are 2 references with the same numbers from 1 to 18.

In addition, the note numbers were one off the numbers used in the text. (I fixed that.) In addition, the numbers in the text are sequential. The numbers in the Notes section are also sequential. However, the two sets of numbers don't match unless they are in exactly the same order. I found this because the first two notes were swapped. (I also fixed that).

Q Science (talk) 06:06, 7 November 2011 (UTC)

Grammar clarification
Please note that I have re-instated my edit fixing the grammar here. In English, the verb "lag" is used after a plural noun or noun phrase, and not "lags", which would be used after a singular noun or phrase. So, "carbon dioxide increases lag temperature increases", but "the carbon dioxide increase lags the temperature increase". -84user (talk) 21:37, 15 January 2013 (UTC)

No evidence of a greater temperature cycle in relation to Vostok Ice Core data.
According to the Vostok Ice Core Data, Antartica was ice free around half a million years ago, even though their own data shows no greater temperature cycle in play. Where is the evidence the Earth was vastly warmer half a million years ago when ice began accumulating in the Antartic?

If there was no ice accumulation, then there would be no ice core data. The Vostok Ice Core Data is about to hit rock bottom. Only 300 meters to go. Or maybe it already has.

Half a million years ago, Antartic is still smack dab in the middle of the Southern Pole, receiving just as little sunlight as it is today. What changed?

Where is the evidence of a greater temperature cycle?

How was it so vastly warmer half a million years ago that ice began to accumulate at the Vostok Lake basin?

Why is it that over the last half a million years to present, that ice NEVER melted, giving perfect little layers for the Ice Core gatherers to gather Ice Cores?

70.176.5.79 19:45, 8 February 2007 (UTC) lml suckerrrrrrrrrrrrrrr suck off this crap this no helpp — Preceding unsigned comment added by 184.88.171.194 (talk) 00:03, 22 February 2013 (UTC)

Poor reference
In the dating section it says:

Quote: "differences such as 300 years per meter at 100 m depth, 600yr/m at 200 m, 7000yr/m at 400 m, 5000yr/m at 800 m, 6000yr/m at 1600 m, and 5000yr/m at 1934 m."

However the reference (ref 24) does not conform with this assertion, it is just a generic NOAA page. Could the proper reference be inserted, because I cannot confirm this claim.

The same section also says:

Quote: "Deeper into the core the layers thin out due to ice flow and high pressure and eventually individual years cannot be distinguished."

But the image above this in the 'structure of ice sheets' section, shows yearly ice layers at 1837 meters. Could these claims be checked and properly referenced.

95.19.208.12 (talk) 13:46, 2 December 2015 (UTC)

The “Ice Core” Wikipedia page explains very well the use of the proxy to understand the past climate. With sections about how it is sampled, and how there is differing data from Greenland, Antarctica, and Non-Polar cores. The article provides the reader with a section about ice core data in which explains and shows graphs for the amount of CO2, dust, and reconstructed temperature found in the cores. The article does not mention really any disadvantages to using coring as a method of adequate proxy data, however, it does discuss “core contamination” due to being drilled out and handled by humans. Most of the articles present on the Wikipedia page are from 2010-2016, and are therefore present and up to date. However, I have found two articles that are not mentioned in the Wikipedia article in which look over one of which looks at records of carbon dioxide and how they will conduct new things to get better measurements of CO2. The article also gives very good information on the data retrieved from ice cores in regard to the makeup of CO2 in the ice. The other article also discusses radiocarbon dating in ice, as well as explains that radiocarbon dating is very useful, however there are not enough matter to sample to get super accurate results. It also goes into some depth about the WIOC 14C method when dating ice. It ultimately just reinforces that ice proxy dating is a very good determiner of the amount of gasses in the atmosphere, and show how the earth’s climate has changed through many millennia. A few recommendations I have for the Ice Core Wikipedia page is that under “Core processing” there could be a little more pictures, and perhaps links to videos perhaps describing and showing what process scientists put the ice through to obtain data through melting the ice and measuring the air bubbles that come out. Graphs are accurate, however some are more than ten years old (Paleoatmospheric firn studies section).

Uglietti, Chiara, et al. "Radiocarbon Dating of Glacier Ice: Overview, Optimisation, Validation And Potential." Cryosphere 10.6 (2016): 3091-3105. Academic Search Complete. Web. 10 Feb. 2017.

Jenk, Theo Manuel, et al. "A New Set-Up For Simultaneous High-Precision Measurements Of CO2, Δ13c-CO2 And Δ18o-CO2 On Small Ice Core Samples." Atmospheric Measurement Techniques 9.8 (2016): 3687-3706. Academic Search Complete. Web. 10 Feb. 2017.

EmsenDK (talk) 01:29, 16 February 2017 (UTC)

Authorship and implications of lede sentence

 * AD HOC COMMITTEE REPORT ON THE ‘HOCKEY STICK’ GLOBAL CLIMATE RECONSTRUCTION

That's the title of the source of our lede sentence. You know, over the years at Wikipedia, I've developed a sense for when a passage is just too well-worded to have come from our collaborative work. We're pretty good, of course, but usually not that good. So I googled this and found to my astonishment that it matched Wegman word for word here.

I'm just not sure how prominently to tag this quote, since I've been called to task for pointing out the existence of scientists who disagree with the "mainstream" view of AGW.

I seem to recall that there are some scientists - possible even having published article in peer-reviewed journals - who assert that the ice cores positively refute the notion that carbon dioxide is as much a driver of temperature as the other way around.

Now, don't misunderstand me. I'm not trying to push a point of view. I even wrote a guideline (which was later AfD'ed into my userspace) condemning POV-pushing (see User:Ed Poor/POV pushing). If you think I'm violating my own guideline, or any WP rule, please stop me now.

I don't want WP to endorse the "anti-AGW" POV of scientists like Roy Spencer, et al. My desire is only to see that their views, and the evidence and arguments they advance in support of these views, are given as much space in articles like this one as is needed to ensure that we are in compliance with WP:NPOV. If this means no space at all, that's fine. But IMHO "describe all views fairly" would seem to merit some mention of anti-mainstream scientific ideas. --Uncle Ed (talk) 17:51, 20 October 2010 (UTC)


 * When that data was added, it was referenced, but, like you say, should have been quoted. The link failed and was repaired Nov 2007. WMC deleted it 7 hours later as not necessary - rm weg rep - not a sensible source. I agree with WMC that we should not use blogs as sources, but he should have left it in this case or found a better source. Q Science (talk) 18:35, 20 October 2010 (UTC)
 * I don't think we really need a quote for the lead. We can summarize the ideas ourselves without referring to deprecated sources and allowing them to act as coatracks. Would you help me workshop this, Q Science? ScienceApologist (talk) 18:55, 20 October 2010 (UTC)

Plagiarism and troubling discovery
This is highly unseemly.

Ed, you added this very line:

. Now, you're claiming "astonishment" that the plagiarism you included is somehow matched to Wegman?

Please explain yourself.

ScienceApologist (talk) 18:46, 20 October 2010 (UTC)


 * diff. I don't think this is an appropriate source for a scientific article. What do others say? ScienceApologist (talk) 18:32, 20 October 2010 (UTC)

I've sourced from the British Antarctic Survey instead of a blog-mounted copy of a report by a statistician. --TS 19:01, 20 October 2010 (UTC)
 * I just rewrote it to avoid the direct quotation. ScienceApologist (talk) 19:09, 20 October 2010 (UTC)


 * Sorry, SA. I completely forgot that I had copied that from a public domain source. I should have used quotation marks, so an embarassing flap like this could not occur. Just imagine my embarassment at forgetting that I myself made that edit! The only silver lining to this dark cloud is that I did remember (then) to credit the source:  (from public domain Wegman report) --Uncle Ed (talk) 22:06, 20 October 2010 (UTC)


 * What makes it public domain? Guettarda (talk) 22:52, 20 October 2010 (UTC)


 * Given that the Wegman report itself contained massive plagiarism, this is somewhat fitting! Though I too am curious why it's claimed to be public domain. --18.111.89.11 (talk) 14:15, 21 October 2010 (UTC)


 * Double oops! As I told Stephan on my talk page just now, I simply assumed it was a product of the US government and this in the public domain. My bad.


 * Next time I think something is in the public domain, I'm going to ask Guettarda or Stephan to double-check.


 * But I don't think it was "plagiarism", since I did not try to palm it off as my own work. I am willing to plead guilty to "wrongful appropriation", if it should have been placed in quotation marks.


 * Anyway, I think we have decided after 4 1/2 years that the Wegman report definition of ice core isn't as good as something we can craft ourselves, though God only knows why all of a sudden it's no longer a good definition. --Uncle Ed (talk) 16:05, 21 October 2010 (UTC)

According to this blog post (yes, I know, but bear with me) Wegman has explicitly denied that his report was federally funded. It would certainly give me pause, if I intended to copy extensive quotes into Wikipedia, on the question of whether the item I wanted to copy was truly public domain material.

It may be a perfectly good description, but it probably isn't ours to use. --TS 00:07, 25 October 2010 (UTC)


 * Even if it were federally funded, that still wouldn't make it public domain. That only applies to work performed by employees of the federal government in the course of their normal duties. Since Wegman isn't an employee of the US federal government, it's not even close. Now, had it been funded by the government it might be considered work for hire, but even then you need to explicitly surrender your rights. Our default assumption here would have to be that copyright resides with Wegman (or jointly with Wegman and JMU). Guettarda (talk) 00:22, 25 October 2010 (UTC)
 * Quite. I offered my observation as a counter-example. Wegman's denial that it's federally funded is the giveaway. Once you've got that information, and Wegman not running around declaring the work to be public domain, you have the presumption of international copyright. --TS 00:56, 25 October 2010 (UTC)

The line in the article "The gas age–ice age difference is as great as 7 kyr in glacial ice from Vostok" is lifted directly from the source, no paraphrasing, quotation, etc. Not sure if that constitutes plagiarism in some peoples' eyes but it definitely isn't good. Also, it should be clarified what a kyr is as the average reader may not infer it means kiloyear. -- Jriley97 (talk) 00:43, 22 February 2017 (UTC)

Paleoatmosoheric Sensing
Much of the paleoatmospheric sensing section is cited improperly with in text citations and no actual references -- Jriley97 (talk) 00:44, 22 February 2017 (UTC)

Request for More Graphs/Figures
Data seems to be analyzed and displayed in this article clearly and correctly. Under the ice core data section, there are a series of graphs featuring data collected on carbon dioxide, reconstructed temperature, and dust over the past 420,000 years. The article assumes the ice core method is a consistently perfect measure of past climate which is untrue because proxies are not always exactly accurate. This article comments on the strengths of the proxy method ("[ice cores] can be used to reconstruct an uninterrupted and detailed climate record extending over hundreds of thousands of years, providing information on a wide variety of aspects of climate at each point in time.") but fails to mention any flaws or weaknesses with the proxy method of determining climate.

I examined several sources on the reference section of the ice core article and they all seemed to be both current and accurate. I also identified two current journal articles through Web of Science, a peer reviewed scientific journal data base. One was actually already listed under references of the article but the other, an article entitled "On the utility of proxy system models for estimating climate states over the common era" had not been included in the references section of the article and I highly suggest that it is added.

I recommend that my suggested article is added in the references and mentioned in the original ice core article as well. I also think this page could use some more figures or graphs. There are a few graphs given in the Ice Core Data section but there are no graphs displayed for each individual region in Greenland, Antarctica, or the listed non polar regions where ice cores are obtained. Beccaswift (talk) 05:16, 22 February 2017 (UTC) Beccaswift

Detailed Information That Is Backed Up By Useful Sources
This article is heavy relies on details information, statistics, and explanation. Where this article excels is the use of images of ice cores sided with graphs to help the reader visually understand the subject. Understand the graphs and images are sentences where it explains what the reader is seeing in the image. An example is this: we see a sheet of ice and standing alone we don't really know what to make of the image. Under the image, a description explains "19 cm long section of GISP 2 ice core from 1855 m showing annual layer structure illuminated from below by a fiber optic source". The article points on the strengths, but not the weaknesses of the researching that goes into ice cores and the information that comes out of the findings. This should always need to be included in an article pertaining to science because it reminds the reader that science isn't always right and it isn't perfect. This show honesty.

Much of the information in the references are great indicators of a trustworthy source. One of the sources it the National Centers for Environmental Information and has an entire page on Ice Cores where a lot of the data is pulled. Another helpful source pulled from the Science Magazine where the discussion about Tibet's primeval ice is based on. A worry about this article is it's not locked so anyone can add information, no matter what their source or background.

Most of the article revolves around ice core sites. Some go into great detail while others are given the little detail. I'd like to see more information on those sites less covered, including graphs and pictures. Also, include more cited information when discussing ice core sites. It is important to know where much of the data and information is coming from. User: vogelj265 (talk) 19:43, 22 February 2017 (UTC)

After reading about how ice cores are used as proxies in "Introduction to Modern Climate Change" by Andrew Dessler I thought I had a pretty good idea about what they were and how they were used to tell us about climates in the way past. This article though does a pretty good job of explaining the use of ice cores of a proxy and going into more detail than the textbook or lecture slides from class did. Their explanation of how the data retrieved form the ice core was analyzed was detailed but fairly easy to understand. They also gave a small chart to the right of the section to help readers get a visual of what they were trying to explain. I also thought it was interesting how they went made a sub section about how cores get contaminated. I never thought about how easily the cores could become contaminated and put to no use. The article does not really address assumptions. It explains each part as if the reader would have no background knowledge which is nice because the article was then easier to understand. They were able to explain ice cores as a proxy without too much complicated detail. The article really went in depth about how the core is processed and how they really try to make it a reliable measurement of past climate. There is even a lengthy list of all the measures scientists take to not contaminate the ice cores. When it comes to writing about weaknesses entailed with using ice cores as a proxy not much was said about that. There was a lot of information about how reliable the ice cores were and the steps taken to make sure they were reliable but there wasn't much said about the faults when using an ice core as a proxy. ''' Two Peer Reviewed Articles: "Ice Cores and the Age of the Earth." Ice Cores and the Age of the Earth | The Institute for Creation Research. N.p., n.d. Web. 22 Feb. 2017. .

Alley, Richard B. "Reliability of Ice-core Science: Historical Insights." Journal of Glaciology 56.200 (2010): 1095-103. Web. 22 Feb. 2017. .

While the two peer reviewed articles I found were not used in the Wikipedia article I did click through a few of their references which deemed to be credible for giving good information about how to use ice cores as a proxy.

Improvements: 1.Now that were in 2017 some of the articles that were used as a reference should be updated. A majority of the source references were from 2005 so to research and get more recent information could make the article more credible.

2.Along with more updated references maybe use more updated graphs and pictures since technology has changed and new data has too. It would then correlate to the new material referenced. — Preceding unsigned comment added by Pawlak.30 (talk • contribs) 22:25, 22 February 2017 (UTC)

Request for further definitions and citation fixes
1. This Wikipedia page for Ice Core does a great job explaining the use of proxy for understanding past climate. In the opening paragraph, the article explains how the ice core and its properties are used to reconstruct climate records through isotopic analysis. Links are provided to further define climatic records and isotopic analysis. The article also explains how data analyses allow scientists to reconstruct local temperature records and atmospheric composition. Reading on, one will learn that that ice cores hold a ton of information about climate, and the variety of ice proxies is greater than any other natural recorder. Under the header “Ice core data” the article describes how ice layers can be measured in many ways in order to record changes in composition.

The page mentions that a strength characteristic of ice core proxies is that they can be used to “reconstruct an uninterrupted and detailed climate record extending over hundreds of thousands of years, providing information on a wide variety of aspects of climate at each point in time”. A weakness of ice core proxies listed is that the deeper we go into the ice, the thinner the layers get, and the more indistinguishable they become. Later on in the article, it is mentioned that meltwater can damage ice core records from penetrating into the snow, thus another weakness. Moreover, the chemicals in which they use to fill the ice core hole, in order to prevent it from closing, are described as flammable, aggressive in nature, and toxic.

Overall, I think the Wikipedia page for Ice Core does a great job explaining the use of proxy for understanding past climate, in terms of data analyses and strengths and weaknesses. However, I think the article could add some information about the assumptions of ice core proxies.

2. After doing my own research for useful peer-reviewed articles on ice cores, I found two articles that are not currently on this page. Their citations are below. The first is titled “Ice core and climate reanalysis analogs to predict Antarctic and Southern Hemisphere climate changes”, and it is from the Quaternary Science Reviews Journal. The second is titled, “Decadal-Interdecadal Climate Variability over Antarctica and Linkages to the Tropics: Analysis of Ice Core, Instrumental, and Tropical Proxy Data”, and is from the Journal of Climate.

3. One recommendation I have for the Ice Core Wikipedia page is that it defines “recrystallization” in the opening paragraph. There is a link next to the word asking for clarification, so I recommend adding a small definition or simplifying the term.

Another recommendation I have for this page is to fix the broken citation references (#4 and #5). Cunningham.734 (talk) 23:59, 22 February 2017 (UTC)

Article Critique
The first paragraph which covers the definition of an Ice core is very simply put and easy to understand but the definition did lack a citation. I noticed that the following paragraphs contained little citations and there are numerous red highlighted links, indicating that the page no longer exist, still have not been addressed. The layout and contents of this page is very well organized and addresses data analysis, strengths and weaknesses well. Most of the sections had images that helped contribute to the clarity of the information. I do think adding an image to the coring section could help make it easier to understand. Clicking through a couple of the references I found that some need to be updated as some of the links leads to a page that does not exist and found a source that I do not think is peer-reviewed and could potentially be biased by its nature because it is from BBC news. Rdaugherty347 (talk) —Preceding undated comment added 00:19, 23 February 2017 (UTC)

Ice Core Topic Critique
This article on using ice cores as a proxy was excellent in providing the necessary information and elaborating fully on what ice core proxies are and how useful to geologists and climatologist they are. Being general, its readability was easy. By this I mean if someone not familiar with the topic or who was not currently enrolled in a climate class were to read this, it would be very useful in providing them will the overall facts and terminology without leading to confusion. It was very specific it how ice cores are used to analyze general global climate change, going so far as to have separated subsections for each use of analysis of ice. Furthermore, in the very beginning they mentioned the primary uses for ice coring, in determining the climate, dust levels, atmospheric make up and volcano activity of Earth at the given level/ layer of ice. Though the article was easy to read, there is the basic assumption that the reader is somewhat familiar with climate research and that things ,like ice do in fact layer and actually can be used to study the climate. Furthermore it appears that they find this article/ proxy to be very useful and important when determining global climate makeup. Taking a quick look at the articles and sources provided, we can see that the oldest one is from the 80's while the majority are from the early 2000s to now. Knowing that a normal period is 30 years we can accept that the articles are all current. For the most part they seem to generally give and overall explanation of what proxies are and how ice coring is done and how it is analyzed. One source that I used as a benchmark was a researcher article from the International Journal of Climatology and another study from Jouzel et al. Interestingly enough both of the contributors that I mention were listed in the articles further readings, but for a different study that they worked on together. The only recommendations that I would have would be to find more article that were even more up to date, as well as fixing the two broken sources listed and to also expand upon and find more info on the many different ice core sites, for example try to find recent studies published from current scientists conducting research at said locations or to expound upon the info given allowing people to learn more about the many active coring sites. Peralta.21 (talk) 03:30, 23 February 2017 (UTC)

Ice Core Eval and Commentary
After reading this article I would consider my knowledge of ice cores as a proxy greatly supplemented. In our introduction to Modern Climate Change textbook ice cores were briefly mentioned as proxy’s but we weren’t given much insight into how exactly scientists extracted this information from the cores. In the Article about ice cores the process is explained very thoroughly. I believe that the article addresses data analyses in a very clear and concise manner. In the ice core structure section, I do they could have given more specific measurements to help the reader better visualize the many layers of ice and its composition. Overall I think the article does a good job of not making assumptions and making sure that all of their info was linked to reliable sources. In the first section explaining Ice cores, in the sentence “The properties of the ice and the recrystallized” the definition of recrystallized does not lead to a valid link and the author should make sure that is fixed because he should not assume his readers will already know the definition. Other than that one error the article as a whole dealt with assumptions well. I think that the article did a better job of addressing the weaknesses of using proxy’s than the benefits. For example, there was a whole paragraph explaining the difficulties scientists face looking for a sustainable, safe fluid to use when drilling for ice cores. There were no specific areas of the article devoted to the upsides of using proxy’s, I suppose that Is because its implied but it would have been nice to read more about the benefits of using proxy’s (specifically ice cores) in comparison to other proxy’s to learn about the previous state of global climate. 2. The two peer reviewed articles on the Wikipedia page are accurate and up to date. When I searched for two articles using my proxy I found -http://research.bpcrc.osu.edu/resources/pfp/ice_cores.php -http://www.antarcticglaciers.org/glaciers-and-climate/ice-cores/ice-core-basics/ Neither of these articles were used on the Wikipedia page but these are both good peer reviewed articles that help to further explain ice cores as a proxy.

3. I think that the ice core article I read could have done a better job of giving depth data for the different types of ice and the different time periods that each depth relates back to. This data would have helped me visualize just how deep scientists must drill for information about the climate in different time periods. There is also a link in the second sentence of the article that doesn’t lead anywhere, this needs to be fixed so that readers can get an accurate description of the word that is supposed to be getting defined so they can understand the words relevance in the opening paragraph. I would also recommend adding in better quality pictures of the ice layers when firn is visible. I think that would really help readers to gain a clear understanding of just what firn actually is. ChloeSmeltzer (talk) 05:41, 23 February 2017 (UTC)

Article Critique: Geog 3900
The article does a good job explaining how ice coring works, but doesn’t elaborate much on why it is important. The article could much more in depth on modeling of ice core data. There should also be more information on the weaknesses of using this method of paleoclimatology.

It seems like the articles used for referencing are good, reliable sources, but there could be more. The two sources I came across (https://www-ncbi-nlm-nih-gov.proxy.lib.ohio-state.edu/pmc/articles/PMC33751/, http://osu.worldcat.org.proxy.lib.ohio-state.edu/oclc/438968138 ) relate to this subject. The first one (Bender) is actually used as a reference in this article.

A few suggestions for the article in general, there needs to be more citations. A lot of information in this article is stated with no sources to back it up. There are a few sections that could use more elaboration and attention. The section that could use the most help is the section on dating cores. This is a very important aspect of ice coring and receives little attention, especially in comparison to coring locations. The section on Ice Core transportation does not tell us much and could use more information, especially from external sources (it has no citations).

4timothyduncan (talk) 15:58, 23 February 2017 (UTC)

Ice Core: This article is well constructed, neutral, the use of proxy is well explained. There are plenty of references. After reading several articles about this topic and with my general understanding on the subject the only suggestion I have is to add a few more graphs. For example, figure 5.1 has a map of the ice cores locations, “Paleoclimatology: Reconstructing Climate of the Quaternary” by R. Bradley. I think it’ll be helpful to have a link to, or general information about the different ice cores around the globe that are used for paleoclimatology purposes. The ice core data section could use additional information such as recent findings on dust and sea salt concentration. Even though dust is not the most accurate isotope on ice core chronologies, but combined with other data it can be useful for paleoclimatology. Petit and Delmonte introduce new ice core isotopes from the Antarctic. Reference: Bradley, Raymond S. Paleoclimatology: Reconstructing Climates of the Quaternary. (2015): 137-194. Internet resource. PETIT, J R, and B DELMONTE. "A Model for Large Glacial-Interglacial Climate-Induced Changes in Dust and Sea Salt Concentrations in Deep Ice Cores (central Antarctica): Palaeoclimatic Implications and Prospects for Refining Ice Core Chronologies." Tellus B. 61.5 (2009): 768-790. Print. Rauch.94 (talk) 05:31, 28 February 2017 (UTC)

1) The article knocks data analysis out of the park, giving detailed descriptions of the methods used in the extraction and analysis of the cores, relevant durations and ranges of data which represents time, length, and several other measurements. The article manages to do so without straying from a neutral tone, making the data all the more effective. One major assumption which stood out to me was that the proxy represents what it measures with perfect accuracy when, in reality, there is a confidence interval in which each proxy (including ice cores) operates. Other than this, the topic is described from a very scientific standpoint, making only assumptions which are related to the accuracy of scientific measurement and the ability of the tools used to accurately measure data. Nowhere in this article could I find a section which sought to explain any potential downfalls or weaknesses of the ice core method. Even if there are no major weaknesses, there should be mention of potential inaccuracies or comparisons with other proxy methods.

2) The references used are accurate and up to date, but there are several areas which could use more references to back up the information given. The references below are not used in the article, but do confirm the accuracy of the described methods and analysis of ice cores. Under the “Ice Core Data” heading, the process of paleoatmospheric sampling is described, which aligns with the sample taken recently (2016) in the first link below. The second reference also deals with atmospheric content, but focuses on Ca2+ concentration in the Tibetan Plateau http://science.sciencemag.org/content/353/6306/1427.full https://www.researchgate.net/publication/225121711_Relationship_between_calcium_and_atmospheric_dust_recorded_in_Guliya_ice_core 3) The article is very well-designed for the most part although it could use several more citations to back up its claims. The only section I would recommend adding to would be the section involving specific sites (which could use more graphics). There is a massive list of specific sites from which ice cores have been taken, and only a single photo of a site is given. There are a few graphs as well as pictures of unspecific ice cores, but photos of the given locations would do wonders for readability. Jamesoneric (talk) 20:54, 28 February 2017 (UTC)

Article Analysis
This article does a very good job of explaining what an ice core is, but it does not dive deep into how they are used as proxies in climate studies. The article briefly mentions this in the “Ice Core Data” section, but it is not as in depth as it should be. Also, I feel that another section should be added to compare this proxy to other ones to further show its (un)reliability. Here are some sources that could help with both these things:

https://books.google.com/books?hl=en&lr=&id=lhzK1-woaiQC&oi=fnd&pg=PA403&dq=ice+cores&ots=Ol7QTgq0Zk&sig=1p25MSVivKkgEEQKpZYaE6QTqvI#v=onepage&q=ice%20cores&f=false

http://onlinelibrary.wiley.com/doi/10.1029/1999JD900084/full

Rpwis (talk) 17:00, 2 March 2017 (UTC)

Review for Geog 3900
The article does a great job at explaining what an ice core is and how it is used to determine the climate of the past. It does a good job at explaining the data analyses by showing what they look at when examining ice cores and how they use this information. All of the information seems accurate as well, based on what we have learned in class and is consistent with that. This article does a really great job at explaining the strengths of the proxy method by giving examples of data they’ve found and why it’s right. It also does a good job at pointing out its weaknesses and assumptions they have made. This is seen especially when they address ice core contamination and how sometimes sunlight triggers chemical the composition in the top levels of the ice cores. After reading this, if you didn’t know anything about ice cores, you would have a significant base of knowledge on it. I like how it gave simple and also in-depth information and for the beginner and scholar alike. Dprov24 (talk) 00:32, 3 March 2017 (UTC)

History of ice core sites
I'm tentatively planning to expand the section on ice core sites to include a history of ice core drilling. So far I have the following sources: If anyone has any additional sources, or suggestions for how to approach this, I'd be glad to hear them; I have no academic background in the topic and would be glad to have either some help or someone to point out my mistakes. Mike Christie (talk - contribs - library) 15:03, 2 April 2017 (UTC)

Plans to work on this article
I plan to do some work on this article over the next two or three months, if I have time. Here's a possible revised table of contents; comments are welcome.
 * Structure of ice sheets
 * Layers of snow; Firn; gas circulation; bubbles; issues with summer melting
 * Flow from summits; deformation due to bedrock; temperature at the base
 * Coring
 * Basic idea of a core; vertical cross-section is a temporal cross-section
 * Pits, augers and drills
 * Drilling – need for fluid, contamination risk, methods of drilling with pros and cons
 * Dating cores
 * Core processing and uses of cores
 * Recovery and handling; storage and transport
 * Ice relaxation and brittle ice
 * Methods of processing
 * Ice core data
 * History of ice core drilling

Most of these major sections either have or should have sub-articles, so this would eventually be in summary style. Mike Christie (talk - contribs - library) 01:13, 8 May 2017 (UTC)
 * Modified to move brittle ice into the core processing section. Mike Christie (talk - contribs - library) 11:08, 18 May 2017 (UTC)
 * Also need to add notes on the need for casing in snow/firn; the density at which firn is considered to have turned to ice (both Talalay p. 263); reaming when necessary; use of liners for brittle ice -- advantages and disadvantages; problems with warm ice (have something on this alread in). The Sounier article has details on the WAIS divide core processing; can use that but would be ideal to find discussion of those issues in a summary elsewhere. Mike Christie (talk - contribs -  library) 21:58, 20 May 2017 (UTC)

Core handling unsourced material
There are a couple of sentences I'm having trouble sourcing: "Current practices to avoid contamination of ice include...wearing special clean suits over cold weather clothing; mittens or gloves; filtered respirators; ...use of laminar-flow bench to isolate core from room particulates". I suspect the laminar-flow bench and respirators refer to clean room practices, which the article does not to cover too, of course. I plan to rework this section in the next few days -- if anyone has good sources for this material please let me know. Mike Christie (talk - contribs - library) 00:52, 21 May 2017 (UTC)

References/notes structure
The current references and notes structure seems unnecessarily messy; half are in one format and half in another. I plan to eventually move to one format; probably not using note. Pinging, , and , as the three most active editors of this page who are still around; please let me know if you disagree. Mike Christie (talk - contribs - library) 10:45, 8 May 2017 (UTC)
 * Yes - do it :) Vsmith (talk) 11:44, 8 May 2017 (UTC)
 * Some very confused Administrators might have decided that they don't want me fixing references. So they decided to screw you. -- SEWilco (talk) 23:48, 21 May 2017 (UTC)

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New database
Not sure if this news item (or links within it) is of any use to article... http://www.abc.net.au/news/2017-06-01/greenhouse-gases-database-shows-co2-ch4-n2o-rising-relentlessly/8578918 JennyOz (talk) 06:50, 1 June 2017 (UTC)
 * Interesting, but I think it'll make it's way into one of the climate change articles. Ice cores are one of the data sources for this database, but I don't think the database needs to be mentioned in this article specifically. Mike Christie (talk - contribs - library) 10:23, 1 June 2017 (UTC)

Ice core data section
I'm going to try to organize the data section by type of analysis. Here's a list that can be turned into the subheadings for that section. -- Mike Christie (talk - contribs - library) 13:19, 22 May 2017 (UTC)
 * Visual stratigraphy, included scanned images
 * Electrical conductivity
 * Physical properties
 * Isotopes
 * Water isotopes
 * Other isotopes -- see Landais et al 2012 p. 192 gives refs for Ar/Ar and U/Th dating.
 * Gases
 * Palaeoatmosphere
 * Fugitive gas
 * Radionuclides
 * Cosmogenic radionuclides
 * Radionuclides from atmospheric bomb testing
 * Microparticles and tephra
 * Hydrogen peroxide; other molecular species
 * Contamination

Notes from Legrand & Mayewski for glaciochemistry section: -- Mike Christie (talk - contribs - library) 00:15, 3 June 2017 (UTC)
 * 222
 * Calcium and ammonium strong seasonal cycles
 * Sodium tracer of sea salt winter maxima; Cl-
 * Components can be from marine air masses or from dust.
 * Reference horizons from volcanic eruptions e.g. 1815; Laki not in Antarctic snow
 * 222-3
 * Further back, it's in reverse; ice helps reconstruct volcanic ihstory e.g. 1259; Toba at 72kya
 * Seasonal signals can be erased by wind scour at the surface in areas of low precip
 * 227
 * Some unreactive in ice; some react, causing extra complexity in analysis. Implies that the appearance of some species such as HCHO and H2O2 in firn or ice does not imply they were in the atmosphere.
 * Table based on 228, also 232

Also need something on radiocarbon dating of CO2 from ice cores, CFC gases, helium, micrometeorites, and physical properties. Mike Christie (talk - contribs - library) 02:14, 3 June 2017 (UTC)

What's left to do
I'd like to take this article to PR and then to FAC, if all goes well. Remaining tasks: -- Mike Christie (talk - contribs - library) 12:13, 3 June 2017 (UTC)
 * Review comments and suggestions on the talk page
 * Rewrite lead
 * References check -- formatting, all refs cited, all cites have a ref listed
 * Copyedit
 * Review see also, external links for more that could be cut
 * Wikilink pass
 * PR now opened. Mike Christie (talk - contribs - library) 19:29, 3 June 2017 (UTC)