Talk:IntCal

Notes and questions

Reading through the draft I have a couple of questions. I don't want to stick my nose in without your OK to add citations while this is still your draft, but if you don't mind, I could add citations in a couple of places.

• "It was recognized in the 1950's that 14C levels in the atmosphere had varied in the past and therefore a correction or calibration was needed." I know Libby pointed out in 1955 that 14C levels might have varied in the past, but I can't find any discussion of the need for a calibration curve before 1960. Suess's 1986 article in Radiocarbon mentions that his lab found irregularities in the historical 14C level, but the first date he gives for a published curve is 1969. I had a quick look at the bibliography in the 1959 first volume of Radiocarbon but didn't see anything obviously discussing calibration.
• "The first curves were published in the 1960's and revised through the 1980's." Does "first curves" refer to pre-IntCal curves? If so it would be good to make this a bit more definite -- were different labs independently producing proposed curves?
• Footnote 1 is to Stuiver & Reimer 1993; is this "Extended ¹⁴C data base and revised CALIB 3.0 ¹⁴C age calibration program"? We should include the article title in the citation. There are a couple of other references that also should have the titles added.
• I know the 1993 article was the first to use the term IntCal but it would be good to find a history that explicitly says this was where the term was created. I had a look in Taylor & Bar-Yosef, and (p. 54) they list the Calibration issues of Radiocarbon starting with 1986. Was there some change that happened in 1993 that means we should consider the modern curves to have begun at that point? Or is it that the name was invented then?

By the way, the markup for Wikipedia references can be a pain in the neck to learn, so if let me know if I can help; and if you don't mind I'll fix any issues I spot. Mike Christie (talk - contribs - library) 01:04, 15 July 2025 (UTC)

Thanks Mike! You make some very good points. In the question about when the need for a correction or calibration was first recognized, I will have to check my paper copy of De Vries H, 1958. Variation in concentration of radiocarbon with time and location on earth. Proceedings of the Koninklijke Nederlandse Akademie Van Wetenschappen Series B-Palaeontology Geology Physics Chemistry Anthropology B61: 94-102. It is in my retirement office so don't have easy access. If it does mention the need for a correction then I should clarify that this is the 'late' 1950s.

I will clarify that 'first curves' refers to pre-IntCal curves which were produced independently by different labs. I think the first published calibration curve was 1966: Stuiver M, Suess HE, 1966. On the relationship between radiocarbon dates and true sample ages. Radiocarbon 8: 534-40, but there were earlier efforts to show the variation in the atmosphere such as Willis EH, Tauber H, Munnich KO, 1960. Variations in the atmospheric radiocarbon concentration over the past 1300 years. American Journal of Science Radiocarbon Supplement 2: 1-4 and Suess produced an extended current in 1967: Suess HE. Bristlecone pine calibration of the radiocarbon time scale from 4100 BC to 1500 BC. Proceedings of the Radioactive dating and methods of low-level counting. , 1967. Monaco: International Atomic Energy Agency. BTW I discussed the early calibration efforts in a recent paper : Reimer PJ, 2022. EVOLUTION OF RADIOCARBON CALIBRATION. Radiocarbon 64: 523-39 but am still learning things about the historical calibration curves.

The Stuiver & Reimer 1993 reference is the 'Extended 14C database etc.' I will update the references to include titles etc. I think I've figured out how to do the reference but will certainly get in touch if I have trouble.

As far as I recall Minze Stuiver and I created the term IntCal for the 1993 paper (although figures in that paper show IntCal92 when as it was being called before the publication). In 1986 we had just used the name 'atm20' for the calibration curve we distributed with the CALIB program. I suppose the major change was that in 1993 non-tree ring data was used (U-Th dated corals) for the first time and it was perhaps a wider international collaboration. Also we had gotten a computer that could handle files names longer than 6 characters!

I'll let you know when I get these changes done!

Thanks very much,

Paula PaulaReimer (talk) 15:05, 15 July 2025 (UTC)

Hi Mike

Just to let you know I am slowly working on the draft in my sandbox. So far I've only modified the first paragraph of the History section and managed to put in references.

Thanks for your offer to submit it when finished.

Paula PaulaReimer (talk) 15:13, 22 July 2025 (UTC)

Hi Mike,

I have updated the information on the curves prior to IntCal and explained that IntCal93 was based on the 1986 curves which were recommended at a business meeting at the International Radiocarbon Conference in 1986. I also explained where the term IntCal came from. I've also inserted the references. I'm not sure if I did this right where 2 citations were used together. Could you please take a look at the draft and see if you have any further questions/suggestions?

Thanks,

Paula PaulaReimer (talk) 09:47, 23 July 2025 (UTC)

Will do -- probably this evening; I'm at work at the moment (US east coast time). Mike Christie (talk - contribs - library) 12:01, 23 July 2025 (UTC)

No rush! I'll probably be headed to bed by then (UK time)! I had to create a new account when I started this page (for some reason email address I used wasn't being recognized). I was just wondering if you knew how to join my old account to current. I created the Minze Stuiver biography under the old account so this is not my first time to make a page.

Thanks PaulaReimer (talk) 13:47, 23 July 2025 (UTC)

Looks like your old user name was User:Radiocarbon? In fact I see I left you a message on your talk page in 2014; that's around the time I was working on the radiocarbon dating article. There's no way to merge two accounts together. What some people do in this situation is change the old user page and talk page to redirect to the new pages. That way anyone who wants to talk to the old editor about an old edit they made will automatically discover your new account. You might also want to add a note to your new user page saying that you used to edit under that old name. I didn't get time to take a look at the draft last night but I have some time before work this morning and will have a quick look. Mike Christie (talk - contribs - library) 10:33, 24 July 2025 (UTC)

The two references you're referring are 9 & 10? They look fine to me. There are still two uncited sentences; I'd guess the very last sentence is covered by the citation to the Marine20 article, so that can be moved to the end of the sentence. The other uncited text is "however, there was insufficient data to supply a separate Southern Hemisphere curve so calibration users were advised to add an offset to radiocarbon ages and uncertainties before calibrating". Does McCormac et al "Variations of Radiocarbon in Tree Rings" cover that? If so it can be repeated at the end of that sentence -- there's a way to use a reference twice by naming it and then referring to the name; I can do that for you if you're not familiar with it. Other than that I think this is ready to be moved into article space; if you agree I'll go ahead and make the move. It needs to have a couple of categories added -- again I can do that if you like. Mike Christie (talk - contribs - library) 10:54, 24 July 2025 (UTC)

Thanks, it sound like trying to merge the old account new is more work than it's worth. I'll take a look a the uncited text - I think that is probably different than the McCormac et al. article. After that I'd be glad to have you add the categories and make the move to article space. Paula PaulaReimer (talk) 17:38, 24 July 2025 (UTC)

Yes the last sentence is covered by the citation to the Marine20 article - I just didn't want people to think it was a link to the ice core CO2 data, but the citation can be moved to the end. The citation for the sentence "however, there was insufficient data to supply a separate Southern Hemisphere curve so calibration users were advised to add an offset to radiocarbon ages and uncertainties before calibrating" is complicated. McCormac et al. don't mention including an offset for calibration. Stuiver & Braziunas say "The regional differences interfere with 14C age calibration. A uniform Southern Hemispheric 14C age correction of 40 year is often applied (Stuiver and Reimer, 1993). Here we find an average 19th century offset of 23 _+ 9 14C yr for S. Chile and Tasmania, and an average 30 _+ 8 14C year for S. Chile, Tasmania and S. Africa combined." However I can't find any mention of an offset in Stuiver & Reimer 1993 - we may have recommended the 40 yr offset to people but it doesn't seem to appear in print. I also can't find any mention of insufficient SH data to build an SH calibration curve so that is probably just from my memory. So perhaps the best thing is to omit ', however, there was insufficient data to supply a separate Southern Hemisphere curve so' and insert 'and' and reference Stuiver & Braziunas a second time. PaulaReimer (talk) 09:40, 25 July 2025 (UTC)

I've made both those edits. I also noticed there was no citation for the sentence about northern tree-ring data being used in SHCal04, but I checked and it's covered by McCormac so I moved that citation down to the end of that sentence. I added one category and have moved the article to article space as IntCal. I left a redirect behind in your sandbox, so if you go to your sandbox it will automatically take you to the new article. Thanks for creating this! Do you have plans to edit any of the other radiocarbon-related articles? Mike Christie (talk - contribs - library) 12:40, 25 July 2025 (UTC)

Thanks very much for your help and for moving this to article space. I have plans to do some editing on the radiocarbon calibration article. PaulaReimer (talk) 13:41, 25 July 2025 (UTC)

Hi Mike

When I'm not in edit mode there are a number of error messages at the bottom of the IntCal article, e.g. Cite error: A list-defined reference named "pjr1" is not used in the content (see the help page).

The "pjrx" must come from when I first copy a word document into my sandbox using the Visual Editor and my comments were picked up as references. I later deleted the pjrx in each case and inserted a reference. From the help page it looks like they still may have ref tags. Do you have any idea how to get rid of those?

Thanks PaulaReimer (talk) 13:18, 26 July 2025 (UTC)

I think it should be fixed now. It looks like you're already familiar with some of the relevant Wikipedia jargon so I'll give you the short explanation; ask if this isn't clear. Citations are within <ref> tags, but ref tags can also be used to create list-defined references (LDR), in which case you can simply name the ref when you do the citation, and don't have to clutter the text with the lengthy details of the cite. Not many editors use LDR, though it has its partisans; most either do what you've done (long-form citations in the text) or use one of the methods of shortening the citations. Typically you then get separate "References" and "Sources" sections. See The Trundle, for example, which I worked on; that uses a form called short citations. There are other methods that also provide a link from the references section to the sources such as sfn, which you can see at Black Prince's chevauchée of 1356. What had happened was your initial version created LDR refs, but then you stopped referencing them, so the page was complaining you had defined some references but then not used them. Mike Christie (talk - contribs - library) 18:41, 26 July 2025 (UTC)

Thanks so much Mike! I didn't know about LDR references and was surprised when the Visual Editor picked up my comments like that. I should have stuck with html which I'm somewhat familiar with. Some of my IntCal colleagues have sent a few corrections/suggestions so I have a few other changes to make to the article but nothing major. PaulaReimer (talk) 08:10, 27 July 2025 (UTC)

Hi Mike, Do you know why citation 12 (the IntCal04 reference) in the IntCal article doesn't include authors? I used the same automatic insert using the doi and it just skips authors. I tried editing but it would only let add 1 author. Thanks! PaulaReimer (talk) 13:59, 28 July 2025 (UTC)

I added a couple of authors without any trouble -- not sure how you're editing, but here's how I did it. If you edit using VE, and double-click on the "[12]", it should bring up a dialog with fieldnames on the left side. You'll see fields named e.g. "last name 3" and "first name 3". Check the boxes against the fields you want to use; they will then appear on the right hand side of the dialog and you can fill them in. When you hit "Apply changes" and save the page the additional authors should show up in the citation. Mike Christie (talk - contribs - library) 17:30, 28 July 2025 (UTC)

Thanks! I didn't notice the list on the left had multiple author fields. It did cut off at 15 even though I change the Display Authors to 30, but I'm happy enough with an 'et al.' after 14. PaulaReimer (talk) 09:37, 29 July 2025 (UTC)