Wikipedia:Peer review/Ice core/archive1

Ice core

I've listed this article for peer review because I would like to take it to WP:FAC. I've completely rewritten it over the last month, and I think it's getting close, but I'm not a subject matter expert and would like input from editors knowledgeable in the subject as well as any other comments. Thanks for any feedback. Mike Christie (talk - contribs - library) 18:44, 3 June 2017 (UTC)

Comments by Andrew Gray

Key disclaimer: I am not an ice core scientist! But with that in mind...

Structure

• How long does it take to compact firn and turn it to ice? A year? A decade? A century? No doubt varies dramatically but would be good to give the reader a general sense rather than just an accumulation depth.

  I've added some example ages; 230 years at Summit and 2500 years at Dome C. Mike Christie (talk - contribs - library) 11:16, 17 June 2017 (UTC)

• One issue I've seen discussed, though I can't find a reference just now, is melting/refreezing at the base - see Ice-sheet dynamics#basal melt. This can mean that the deepest ice is messy and contains no useful information, and presumably (though I don't have a source to hand) the faster the flow the bigger a problem this can be. Might be worth mentioning.

  I added a couple of sentences on basal ice, including a comment that the stratigraphic information is lost. The second paragraph in the "Structure" section mentions that cores are ideally drilled at places with little flow; should this be made more explicit? Mike Christie (talk - contribs - library) 18:23, 17 June 2017 (UTC)

Coring

• This talks about "thermal drills", but it's unclear how these work - the text implies they are electrically heated, which the citations support. It would be good to discuss these in a little more detail to clarify that they're thermal-electric, to distinguish them from...

  I added a few words; is that enough? Mike Christie (talk - contribs - library) 21:49, 17 June 2017 (UTC)

• Hot-water drills, which are mostly used for rapidly drilling access boreholes but have also been used for coring; see this paper for an outline of their early use (proof of concept in 1992/3). I haven't been able to find much on their use in the last decade or so, though, so maybe they've fallen out of fashion.

  Added a couple of sentences from a 2007 source that talks about hot-water drilling and its drawbacks. Mike Christie (talk - contribs - library) 17:51, 17 June 2017 (UTC)

• There is also some work going on to do some coring-type research without actually extracting a core - eg this recent story - which might be worth touching on here (or somewhere else in the article). It's not quite coring, but it's aiming to answer some of the same questions in a different fashion.

  Interesting; I hadn't heard about those projects. I think there should be an ice drilling article at some point which would be a good place for that information, but I don't think there's anything needed here, is there? All I would be able to say is that other ice drilling projects exist that don't retrieve cores, and maybe a couple of examples. Is that relevant enough for this article? Mike Christie (talk - contribs - library) 19:07, 17 June 2017 (UTC)

• IPICS have a working paper outlining future challenges for drilling, which might be worth discussing either here or in a general "future work" section (see below).

  I like the idea, but that paper is over ten years old, so I don't think I can use it -- I know from other reading that at least some of those challenges, such as the search for an ideal drilling fluid, remain priorities for ice drilling communities, but I think I'd need a current summary of the future challenges to include something like that in the article. Mike Christie (talk - contribs - library) 19:13, 17 June 2017 (UTC)

  After looking at the IPICS website I realized they say they keep the white papers up to date, so I've created a new section for this at the end of the article. Mike Christie (talk - contribs - library) 21:44, 17 June 2017 (UTC)

• This might be a good point to discuss the practical complexity of the deep coring projects, which often take several years to complete a long core because it's simply such a long process - I think Dome C took five years. This is referred to in the Antarctic section below but the practicalities involved aren't mentioned, and I think this could be very interesting for readers. Perhaps a note about the time taken to drill a certain distance? I'll see if I can find any accessible end-of-project reports for the very large programs that might talk about this.

  Good idea. I've added a short section based on a recent EastGRIP field plan; how does that look? Mike Christie (talk - contribs - library) 22:24, 17 June 2017 (UTC)

Brittle ice

• "Brittle cores are also often allowed to rest for some time, for up to a full year between drilling seasons, in order to let the ice gradually relax" - it's not quite clear what this means. Rest in storage before being transported out?

  Yes, that's correct. I've clarified this in the text. Mike Christie (talk - contribs - library) 11:19, 17 June 2017 (UTC)

Glaciochemistry

• "This was done, for example, for an eruption thought to date to 1259 A.D., which has since been identified in ice cores from both polar regions" - I am guessing this is the 1257 Samalas eruption, which the WP article suggests has only been reliably dated in the last few years, since the source was written. There is a good recent article on this sort of dating - using cores + tree ring data + historical observations to shed light on the extreme weather events of 535–536, identifying two eruptions where historians had only assumed one. Might be worth bringing in here rather than the older work.

  Done -- I replaced that sentence with one source to the article you mention; thanks for the pointer. Mike Christie (talk - contribs - library) 17:16, 17 June 2017 (UTC)

Radionuclides

• There has been work on identifying plutonium directly deposited from nuclear tests, as well as tritium.

  Added a mention, sourced to the article you linked to. Mike Christie (talk - contribs - library) 21:17, 17 June 2017 (UTC)

Other inclusions

• Do meteorites/micrometeorites actually turn up in cores? The examples here talk about ways they can be recovered from ice sheets, but don't seem to be core-specific.

  I finally got around to addressing this. The numbers given in the cited CRREL article make it clear they are common enough that they are sure to turn up in cores, but the water well collection method finds many more of them because of the width of the well. The CRREL article does point out that a sort of stratification is possible; two consecutive runs at different well depths will collect all the micrometeorites that fell while that depth of snow fell. I changed the article to make this clearer. I agree it's somewhat tangential, but I think it's close enough to use. Mike Christie (talk - contribs - library) 13:05, 30 July 2017 (UTC)

General thoughts

• There has been a lot of interest in recent years on "oldest ice" (see eg this study and the IPICS project generally; working paper). You mention the 800k year core at Dome C, but if you wanted to have a general discussion about future work it could bring in the attempts to get a core stretching back over a million years.

  I added a list of future plans in a new section at the end, based on the IPICS website. Mike Christie (talk - contribs - library) 21:44, 17 June 2017 (UTC)

Possible additional sources

• There is an excellent site at antarcticglaciers.org, with a good section on ice cores. Probably worth putting in as an external link if not citing directly.

Overall, a pretty good article - it flows quite clearly and I definitely learned a good bit from it that I didn't already know. Andrew Gray (talk) 17:38, 14 June 2017 (UTC)

Thanks for the review! These comments are very helpful. I will try to get to these points this weekend and will ping you when I'm done. Mike Christie (talk - contribs - library) 11:10, 15 June 2017 (UTC)

Andrew, I think I've now responded to everything above. Your comments were very helpful; please let me know if you think I've addressed everything adequately. Mike Christie (talk - contribs - library) 22:25, 17 June 2017 (UTC)