Mediterranean radiocarbon offsets and calendar dates for prehistory

The timing and magnitude of the episodic offsets match the patterns and associations identified 1600 to 1900 CE from Jordan juniper trees, suggesting a common systemic link over at least the past 3700 years.

“The timing and magnitude of these episodic offsets match the patterns and associations identified 1600 to 1900 CE from Jordan juniper trees (18), suggesting a common systemic link over, at least, the past 3700 years.”

• cites [18] Manning S. W., Griggs C., Lorentzen B., Bronk Ramsey C., Chivall D., Jull A. J. T., Lange T. E., Fluctuating radiocarbon offsets observed in the southern Levant and implications for archaeological chronology debates. Proc. Natl. Acad. Sci. U.S.A. 115, 6141– 6146 (2018). 29844183 PMC6004441 sourceSupported

The positive offsets are typically in the range found previously for substantive seasonal or growing season differences: ~2 to 4‰ (that is, ~16 to 32 14C years).

“The offsets are typically in the range found previously for substantive seasonal or growing season differences: ~2 to 4‰ (that is, ~16 to 32 14C years) (15–18, 23, 26).”

• cites [15] Kromer B., Manning S. W., Kuniholm P. I., Newton M. W., Spurk M., Levin I., Regional 14CO2 offsets in the troposphere: Magnitude, mechanisms, and consequences. Science 294, 2529– 2532 (2001). 11743160 sourceNot checked — no full text of the source
• cites [16] Dee M. W., Brock F., Harris S. A., Ramsey C. B., Shortland A. J., Higham T. F. G., Rowland J. M., Investigating the likelihood of a reservoir offset in the radiocarbon record for ancient Egypt. J. Archaeol. Sci. 37, 687– 693 (2010). sourceNot checked — no full text of the source
• cites [17] Manning S. W., Dee M. W., Wild E. M., Bronk Ramsey C., Bandy K., Creasman P. P., Griggs C. B., Pearson C. L., Shortland A. J., Steier P., High-precision dendro-14C dating of two cedar wood sequences from First Intermediate Period and Middle Kingdom Egypt and a small regional climate-related 14C divergence. J. Archaeol. Sci. 46, 401– 416 (2014). sourceNot checked — no full text of the source
• cites [18] Manning S. W., Griggs C., Lorentzen B., Bronk Ramsey C., Chivall D., Jull A. J. T., Lange T. E., Fluctuating radiocarbon offsets observed in the southern Levant and implications for archaeological chronology debates. Proc. Natl. Acad. Sci. U.S.A. 115, 6141– 6146 (2018). 29844183 PMC6004441 sourcePartly supported

  The Discussion (page unavailable in our copy) reports growing-season-related offsets of about 2–3‰, including approximately 16 and 24 radiocarbon years, and notes a previously observed Egyptian offset of about 2.5‰. It does not establish the claimed typical upper end of 4‰ (32 radiocarbon years). (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [23] Bronk Ramsey C., Dee M. W., Rowland J. M., Higham T. F. G., Harris S. A., Brock F., Quiles A., Wild E. M., Marcus E. S., Shortland A. J., Radiocarbon-based chronology for Dynastic Egypt. Science 328, 1554– 1557 (2010). 20558717 sourceNot checked — no full text of the source
• cites [26] McDonald L., Chivall D., Miles D., Bronk Ramsey C., Seasonal variations in the 14C content of tree rings: Influences on radiocarbon calibration and single-year curve construction. Radiocarbon 61, 185– 194 (2019). sourceNot checked — no full text of the source

Even when subsequent iterations of IntCal (such as the forthcoming IntCal20) are modified to reflect additional data input, the apparent difference of Mediterranean wood versus central European wood in the earlier 16th century BCE observed within the Hd datasets remains real and relevant.

“Thus, even when subsequent iterations of IntCal (such as the forthcoming IntCal20) are modified to reflect additional data input [such as those data in (13)], this apparent difference of Mediterranean wood versus central European wood in the earlier 16th century BCE observed within the Hd datasets remains real and relevant.”

• cites [13] Pearson C. L., Brewer P. W., Brown D., Heaton T. J., Hodgins G. W. L., Jull A. J. T., Lange T., Salzer M. W., Annual radiocarbon record indicates 16th century BCE date for the Thera eruption. Sci. Adv. 4, eaar8241 (2018). 30116779 PMC6093623 sourceSupported

Various small offsets in contemporary (same calendar years) 14C levels are reported for known-age plant material from several areas, including the Mediterranean.

“Various small offsets in contemporary (same calendar years) 14C levels are reported for known-age plant material from several areas, including the Mediterranean (8, 13–19).”

• cites [8] Büntgen U., Wacker L., Galván J. D., Arnold S., Arseneault D., Baillie M., Beer J., Bernabei M., Bleicher N., Boswijk G., Bräuning A., Carrer M., Ljungqvist F. C., Cherubini P., Christl M., Christie D. A., Clark P. W., Cook E. R., D’Arrigo R., Davi N., Eggertsson Ó., Esper J., Fowler A. M., Gedalof Z.’., Gennaretti F., Grießinger J., Grissino-Mayer H., Grudd H., Gunnarson B. E., Hantemirov R., Herzig F., Hessl A., Heussner K. U., Jull A. J. T., Kukarskih V., Kirdyanov A., Kolář T., Krusic P. J., Kyncl T., Lara A., LeQuesne C., Linderholm H. W., Loader N. J., Luckman B., Miyake F., Myglan V. S. sourcePartly supported

  The Discussion (page unavailable) reports a small interhemispheric ¹⁴C offset and a north–south gradient in contemporaneous tree-ring records. The paper does not specifically establish an offset for Mediterranean plant material; its mention of an Albanian sample in Methods concerns a missing ring, not a regional ¹⁴C offset. (LLM, conf=0.80)

  Experimental — accuracy not yet measured
• cites [13] Pearson C. L., Brewer P. W., Brown D., Heaton T. J., Hodgins G. W. L., Jull A. J. T., Lange T., Salzer M. W., Annual radiocarbon record indicates 16th century BCE date for the Thera eruption. Sci. Adv. 4, eaar8241 (2018). 30116779 PMC6093623 sourcePartly supported

  In “Testing the IntCal13 calibration curve with multispecies annual data” (p. 3), the paper reports an offset in radiocarbon measurements from known-age Irish oak and Californian bristlecone pine relative to IntCal13 data from north European oak. This supports the point that small offsets are reported across plant-material records, but the paper does not report a comparable measurement from known-age Mediterranean plant material. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [14] McCormac F. G., Baillie M. G. L., Pilcher J. R., Kalin R. M., Location-dependent differences in the 14C content of wood. Radiocarbon 37, 395– 407 (1995). sourcePartly supported

  The Introduction reports small ¹⁴C offsets between contemporaneous, tree-ring-dated wood from Ireland, Germany, and the western United States. Our copy does not report an offset for Mediterranean plant material, so it supports the general claim but not that geographic example. (LLM, conf=0.87)

  Experimental — accuracy not yet measured
• cites [15] Kromer B., Manning S. W., Kuniholm P. I., Newton M. W., Spurk M., Levin I., Regional 14CO2 offsets in the troposphere: Magnitude, mechanisms, and consequences. Science 294, 2529– 2532 (2001). 11743160 sourceNot checked — no full text of the source
• cites [16] Dee M. W., Brock F., Harris S. A., Ramsey C. B., Shortland A. J., Higham T. F. G., Rowland J. M., Investigating the likelihood of a reservoir offset in the radiocarbon record for ancient Egypt. J. Archaeol. Sci. 37, 687– 693 (2010). sourceNot checked — no full text of the source
• cites [17] Manning S. W., Dee M. W., Wild E. M., Bronk Ramsey C., Bandy K., Creasman P. P., Griggs C. B., Pearson C. L., Shortland A. J., Steier P., High-precision dendro-14C dating of two cedar wood sequences from First Intermediate Period and Middle Kingdom Egypt and a small regional climate-related 14C divergence. J. Archaeol. Sci. 46, 401– 416 (2014). sourceNot checked — no full text of the source
• cites [18] Manning S. W., Griggs C., Lorentzen B., Bronk Ramsey C., Chivall D., Jull A. J. T., Lange T. E., Fluctuating radiocarbon offsets observed in the southern Levant and implications for archaeological chronology debates. Proc. Natl. Acad. Sci. U.S.A. 115, 6141– 6146 (2018). 29844183 PMC6004441 sourceSupported
• cites [19] See supplementary materials.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

There is a long history of even the most accurate 14C laboratories systematically varying in age determinations for contemporary samples compared with other laboratories by up to ~30 14C years.

“There is a long history of even the most accurate 14C laboratories systematically varying in age determinations for contemporary samples compared with other laboratories by up to ~30 14C years (1, 2).”

• cites [1] Stuiver M., Reimer P. J., Braziunas T. F., High-precision radiocarbon age calibration for terrestrial and marine samples. Radiocarbon 40, 1127– 1151 (1998). sourceSupported
• cites [2] Reimer P. J., Baillie M. G. L., Bard E., Bayliss A., Beck J. W., Bertrand C. J. H., Blackwell P. G., Buck C. E., Burr G. S., Cutler K. B., Damon P. E., Edwards R. L., Fairbanks R. G., Friedrich M., Guilderson T. P., Hogg A. G., Hughen K. A., Kromer B., Cormac G. M., Manning S., Ramsey C. B., Reimer R. W., Remmele S., Southon J. R., Stuiver M., Talamo S., Taylor F. W., van der Plicht J., Weyhenmeyer C. E., IntCalo4 terrestrial radiocarbon age calibration, 0–26 cal kyr BP. Radiocarbon 46, 1029– 1058 (2004).Not checked yet

  Not checked in the free run.

The BCP and IrO should offer a dataset similar to those reflecting central and northern European later spring-summer growing seasons, such as the GeO and IrO comprising much of the existing IntCal dataset in this time period.

“Instead, the BCP and the IrO should offer a dataset similar to those reflecting central and northern European later spring-summer growing seasons, such as the GeO and IrO comprising much of the existing IntCal dataset in this time period, despite a history of issues with BCP 14C data in earlier work (2, 14, 25).”

• cites [2] Reimer P. J., Baillie M. G. L., Bard E., Bayliss A., Beck J. W., Bertrand C. J. H., Blackwell P. G., Buck C. E., Burr G. S., Cutler K. B., Damon P. E., Edwards R. L., Fairbanks R. G., Friedrich M., Guilderson T. P., Hogg A. G., Hughen K. A., Kromer B., Cormac G. M., Manning S., Ramsey C. B., Reimer R. W., Remmele S., Southon J. R., Stuiver M., Talamo S., Taylor F. W., van der Plicht J., Weyhenmeyer C. E., IntCalo4 terrestrial radiocarbon age calibration, 0–26 cal kyr BP. Radiocarbon 46, 1029– 1058 (2004).Not checked yet

  Not checked in the free run.

• cites [14] McCormac F. G., Baillie M. G. L., Pilcher J. R., Kalin R. M., Location-dependent differences in the 14C content of wood. Radiocarbon 37, 395– 407 (1995). sourcePartly supported

  The Introduction (page unavailable) documents earlier bristlecone-pine radiocarbon adjustments and compares bristlecone pine with Irish and German oak, supporting the reference to historical data issues. It does not establish that these datasets reflect similar later spring–summer growing seasons or describe their contribution to IntCal in the cited time period. (LLM, conf=0.85)

  Experimental — accuracy not yet measured
• cites [25] Reimer P. J., Hughen K. A., Guilderson T. P., McCormac G., Baillie M. G. L., Bard E., Barratt P., Warren Beck J., Buck C. E., Damon P. E., Friedrich M., Kromer B., Bronk Ramsey C., Reimer R. W., Remmele S., Southon J. R., Stuiver M., van der Plicht J., Preliminary report of the first workshop of the IntCal04 radiocarbon calibration/comparison working group. Radiocarbon 44, 653– 661 (2002). sourcePartly supported

  The 0–12 ka BP section identifies German and Irish oak as radiocarbon calibration chronologies and reports problems with earlier bristlecone pine measurements. It does not establish that bristlecone pine and Irish oak reflect growing seasons similar to those of the existing European datasets; instead, it says bristlecone pine measurements were consistently older and that a regional or growing-season difference was possible. (LLM, conf=0.83)

  Experimental — accuracy not yet measured

Radiocarbon measurements on wood from Turkish pine usually show no apparent offset in the periods of reversals and plateaus in the 14C calibration record identified in the Jordanian juniper time series (~1685 to 1762 CE and 1818 to 1912 CE).

“Radiocarbon measurements on wood from these trees (19, 27) thus usually show no apparent offset in the periods of reversals and plateaus in the 14C calibration record that were identified in the Jordanian juniper time series (~1685 to 1762 CE and 1818 to 1912 CE) (Fig. 1A) (18).”

• cites [19] See supplementary materials.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [27] Manning S. W., Kromer B., Bronk Ramsey C., Pearson C. L., Talamo S., Trano N., Watkins J. D., 14C record and wiggle-match placement for the Anatolian (Gordion Area) juniper tree-ring chronology ~1729 to 751 cal bc, and typical Aegean/Anatolian (growing season related) regional 14C offset assessment. Radiocarbon 52, 1571– 1597 (2010). sourcePartly supported

  The Aegean offset section (Figure 13 and Table 7; page unavailable) reports Turkish-pine measurements from AD 1300–1800 and a very small overall offset from IntCal09. This supports the general point and covers 1685–1762, but the paper does not measure the 1818–1912 interval or assess the specified Jordanian-juniper reversals and plateaus. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [18] Manning S. W., Griggs C., Lorentzen B., Bronk Ramsey C., Chivall D., Jull A. J. T., Lange T. E., Fluctuating radiocarbon offsets observed in the southern Levant and implications for archaeological chronology debates. Proc. Natl. Acad. Sci. U.S.A. 115, 6141– 6146 (2018). 29844183 PMC6004441 sourceSupported

At times when the positive Mediterranean growing season offset might be anticipated as possibly relevant, such as a major reversal and plateau in the 14C calibration curve ~1610 to 1530 BCE, the relevant information likely does not come from BCP or IrO or the current IntCal.

“Therefore, at times when the positive Mediterranean growing season offset might be anticipated as possibly relevant, such as a major reversal and plateau in the 14C calibration curve ~1610 to 1530 BCE (4), the relevant information likely does not come from BCP or IrO or the current IntCal.”

• cites [4] Reimer P. J., Baillie M. G. L., Bard E., Bayliss A., Beck J. W., Blackwell P. G., Ramsey C. B., Buck C. E., Cheng H., Edwards R. L., Friedrich M., Grootes P. M., Guilderson T. P., Haflidason H., Hajdas I., Hatté C., Heaton T. J., Hoffmann D. L., Hogg A. G., Hughen K. A., Kaiser K. F., Kromer B., Manning S. W., Niu M., Reimer R. W., Richards D. A., Scott E. M., Southon J. R., Staff R. A., Turney C. S. M., van der Plicht J., IntCal13 and Marine13 radiocarbon age calibration curves 0–50,000 years Cal BP. Radiocarbon 55, 1869– 1887 (2013). sourcePartly supported

  Split into 2 atoms — 0 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 1 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured

Two episodes of substantial 14C offsets have been observed through comparisons of measurements on known-age wood from southern Jordan versus the record from central and northern Europe.

“Two episodes of substantial 14C offsets have been observed through comparisons of measurements on known-age wood from southern Jordan versus the record from central and northern Europe.”

• cites [18] Manning S. W., Griggs C., Lorentzen B., Bronk Ramsey C., Chivall D., Jull A. J. T., Lange T. E., Fluctuating radiocarbon offsets observed in the southern Levant and implications for archaeological chronology debates. Proc. Natl. Acad. Sci. U.S.A. 115, 6141– 6146 (2018). 29844183 PMC6004441 sourceSupported

The GOR time series was compared with IntCal98 and IntCal04 specifically because they do not include subsequent Hd GeO data, avoiding circularity.

“We compare our data with these two records specifically because they do not include subsequent Hd GeO data (38), avoiding circularity.”

• cites [38] Kromer B., Manning S. W., Friedrich M., Talamo S., Trano N., 14C calibration in the 2nd and 1st millennia BC—Eastern Mediterranean Radiocarbon Comparison Project (EMRCP). Radiocarbon 52, 875– 886 (2010). sourcePartly supported

  The Introduction (page unavailable) says the Anatolian tree-ring series was compared with IntCal98 and IntCal04. But Tree-Ring Series and Methods says earlier Heidelberg German-oak measurements were already part of IntCal04, and the paper does not give avoidance of circularity as the reason for choosing those curves. The claim’s blanket statement that both curves exclude the relevant Hd GeO data is therefore not supported. (LLM, conf=0.87)

  Experimental — accuracy not yet measured

The BCP record of (13) likely exhibits a maximum alternative case for a revised AMS 14C IntCal summer NH baseline.

“The BCP record of (13) likely exhibits a maximum alternative case for a revised AMS 14C IntCal summer NH baseline (Fig. 6, A to C) (19).”

• cites [13] Pearson C. L., Brewer P. W., Brown D., Heaton T. J., Hodgins G. W. L., Jull A. J. T., Lange T., Salzer M. W., Annual radiocarbon record indicates 16th century BCE date for the Thera eruption. Sci. Adv. 4, eaar8241 (2018). 30116779 PMC6093623 sourcePartly supported

  The IntCal13 comparison (p. 3) reports a sustained offset in the annual bristlecone pine record, and Experimental design (p. 6) identifies its short Northern Hemisphere summer growth season. This supports using the record as an alternative calibration case, but the paper does not establish that it represents a *maximum* alternative or an upper bound for a revised AMS IntCal baseline. (LLM, conf=0.82)

  Experimental — accuracy not yet measured
• cites [19] See supplementary materials.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

A tree-ring time series of seven weighted average OxA AMS 14C dates on an oak sample from Miletus in low-elevation western Anatolia offers a close fit to the LLGPC-source IntCal curve, with an OxCal ΔR 0,10 value versus IntCal09 of 4.0 ± 8.3 14C years.

“A tree-ring time series comprising seven weighted average OxA AMS 14C dates on an oak sample from Miletus in low-elevation western Anatolia offers a close fit to the LLGPC-source IntCal curve (27), with an OxCal ΔR 0,10 value versus IntCal09 (μ ± σ) of only 4.0 ± 8.3 14C years.”

• cites [27] Manning S. W., Kromer B., Bronk Ramsey C., Pearson C. L., Talamo S., Trano N., Watkins J. D., 14C record and wiggle-match placement for the Anatolian (Gordion Area) juniper tree-ring chronology ~1729 to 751 cal bc, and typical Aegean/Anatolian (growing season related) regional 14C offset assessment. Radiocarbon 52, 1571– 1597 (2010). sourcePartly supported

  Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured

A comparison of AMS 14C measurements versus Hd measurements on similar Swedish pine samples indicates no substantial difference for the 15th to 17th centuries CE.

“A comparison of AMS 14C measurements (47) versus Hd measurements (table S1) on similar Swedish pine samples also indicates no substantial difference for the 15th to 17th centuries CE (fig. S5).”

• cites [47] Tyers C., Sidell J., Van der Plicht J., Marshall P., Cook G., Bronk Ramsey C., Bayliss A., Wiggle-matching using known-age pine from Jermyn Street, London. Radiocarbon 51, 385– 396 (2009). sourceSupported

The absence of elevated 14C ages for the Mediterranean Hd GOR and NOC samples ~3600 to 3555 cal B.P. is contrary to the AA BCP and IrO dataset.

“At the same time, the absence of elevated 14C ages for the Mediterranean Hd GOR and NOC samples ~3600 to 3555 cal B.P., contrary to the AA BCP and IrO dataset (Fig. 3A) (13), is also important for this topic.”

• cites [13] Pearson C. L., Brewer P. W., Brown D., Heaton T. J., Hodgins G. W. L., Jull A. J. T., Lange T., Salzer M. W., Annual radiocarbon record indicates 16th century BCE date for the Thera eruption. Sci. Adv. 4, eaar8241 (2018). 30116779 PMC6093623 sourceSupported

Maintaining the same LLGPC IntCal04/09 reference value and an OxCal ΔR 0,10 test, the OxA Jordan juniper AMS 14C offset is 18.2 ± 2.8 14C years.

“then the OxA and AA Jordan juniper AMS 14C offsets (18) are (μ ± σ) 18.2 ± 2.8 and 18.1 ± 4.1 14C years, respectively.”

• cites [18] Manning S. W., Griggs C., Lorentzen B., Bronk Ramsey C., Chivall D., Jull A. J. T., Lange T. E., Fluctuating radiocarbon offsets observed in the southern Levant and implications for archaeological chronology debates. Proc. Natl. Acad. Sci. U.S.A. 115, 6141– 6146 (2018). 29844183 PMC6004441 sourcePartly supported

  The Results report an OxA offset for Jordanian juniper, but give 19.1 ± 2.8 radiocarbon years against IntCal13, using a neutral prior of 0 ± 20. Our copy does not support the attributed 18.2 ± 2.8 value under an IntCal04/09 reference and 0 ± 10 test; the Discussion likewise describes calculations against IntCal13. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

Maintaining the same LLGPC IntCal04/09 reference value and an OxCal ΔR 0,10 test, the AA Jordan juniper AMS 14C offset is 18.1 ± 4.1 14C years.

“then the OxA and AA Jordan juniper AMS 14C offsets (18) are (μ ± σ) 18.2 ± 2.8 and 18.1 ± 4.1 14C years, respectively.”

• cites [18] Manning S. W., Griggs C., Lorentzen B., Bronk Ramsey C., Chivall D., Jull A. J. T., Lange T. E., Fluctuating radiocarbon offsets observed in the southern Levant and implications for archaeological chronology debates. Proc. Natl. Acad. Sci. U.S.A. 115, 6141– 6146 (2018). 29844183 PMC6004441 sourcePartly supported

  The Results (page not supplied) report an AA Jordanian juniper offset, but give 20.6 ± 4.5 ¹⁴C years using IntCal13 and an OxCal ΔR prior of 0 ± 20. The cited paper does not report the claimed 18.1 ± 4.1 value under an LLGPC IntCal04/09 reference and 0 ± 10 test. (LLM, conf=0.87)

  Experimental — accuracy not yet measured

In the latter three cases, AMS 14C values are on average more recent than the Hd LLGPC ages.

“In the latter three cases, the AMS 14C values are, on average, more recent than the Hd LLGPC ages [contrary to the findings in the comparison in (43)].”

• cites [43] Hogg A., Turney C., Palmer J., Southon J., Kromer B., Ramsey C. B., Boswijk G., Fenwick P., Noronha A., Staff R., Friedrich M., Reynard L., Guetter D., Wacker L., Jones R., The New Zealand kauri (Agathis Australis) research project: A radiocarbon dating intercomparison of younger dryas wood and implications for IntCal13. Radiocarbon 55, 2035– 2048 (2013). sourceSupported

Much of the current observed variation in AMS 14C-to-LLGPC comparisons is as likely to relate to interlaboratory variations in methods and instruments as to a typical offset.

“Much of the current observed variation is as likely to relate to interlaboratory variations in methods and instruments [an ever-present issue (8, 11, 48)], something only more evident as AMS 14C approaches the precision of LLGPC and LSC datasets.”

• cites [8] Büntgen U., Wacker L., Galván J. D., Arnold S., Arseneault D., Baillie M., Beer J., Bernabei M., Bleicher N., Boswijk G., Bräuning A., Carrer M., Ljungqvist F. C., Cherubini P., Christl M., Christie D. A., Clark P. W., Cook E. R., D’Arrigo R., Davi N., Eggertsson Ó., Esper J., Fowler A. M., Gedalof Z.’., Gennaretti F., Grießinger J., Grissino-Mayer H., Grudd H., Gunnarson B. E., Hantemirov R., Herzig F., Hessl A., Heussner K. U., Jull A. J. T., Kukarskih V., Kirdyanov A., Kolář T., Krusic P. J., Kyncl T., Lara A., LeQuesne C., Linderholm H. W., Loader N. J., Luckman B., Miyake F., Myglan V. S. sourcePartly supported

  The Introduction says modern AMS can be as precise as some traditional decay counters, and Methods > Data uncertainty notes limited accuracy in less precise AMS systems. Methods > Sample preparation also acknowledges possible measurement biases and errors. These passages support instrument-related uncertainty, but do not establish that interlaboratory differences explain the observed AMS-to-LLGPC variation or are as likely an explanation as a typical offset. (LLM, conf=0.76)

  Experimental — accuracy not yet measured
• cites [11] Scott E. M., Cook G. T., Naysmith P., Staff R. A., Learning from the wood samples in ICS, TIRI, FIRI, VIRI, and SIRI. Radiocarbon 61, 1293– 1304 (2019). sourceNot checked — no full text of the source
• cites [48] Bayliss A., Marshall P., Confessions of a serial polygamist: The reality of radiocarbon reproducibility in archaeological samples. Radiocarbon 61, 1143– 1158 (2019). sourceSupported

When the published Santorini eruption dating analyses are rerun with the Hd GOR calibration dataset, the results support a later 17th century BCE date range for the Thera eruption, with entire most likely 68.2% hpd ranges of 1649 to 1617 BCE and 1680 to 1613 BCE.

“If we rerun these analyses with the Hd GOR calibration dataset (as in Fig. 2A) with its revision of the earlier mid–16th century BCE 14C values to reflect Mediterranean conditions and regional offset, we find that the results support a later 17th century BCE date range for the Thera eruption, including the entire most likely 68.2% highest posterior density (hpd) ranges (Fig. 5, A and B; 1649 to 16”

• cites [55] Manning S. W., Ramsey C. B., Kutschera W., Higham T., Kromer B., Steier P., Wild E. M., Chronology for the Aegean Late Bronze Age 1700-1400 B.C. Science 312, 565– 569 (2006). 16645092 sourceNot checked — no full text of the source
• cites [56] Höflmayer F., The date of the Minoan Santorini eruption: Quantifying the “Offset”. Radiocarbon 54, 435– 448 (2012). sourcePartly supported

  Split into 2 atoms — 0 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 1 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured

About 33% of the Hd offset in the first Younger Dryas wood comparison is attributable to one outlying date for mid-ring 376.5.

“~33% of the Hd offset is attributable to one outlying date: for mid-ring 376.5”

• cites [43] Hogg A., Turney C., Palmer J., Southon J., Kromer B., Ramsey C. B., Boswijk G., Fenwick P., Noronha A., Staff R., Friedrich M., Reynard L., Guetter D., Wacker L., Jones R., The New Zealand kauri (Agathis Australis) research project: A radiocarbon dating intercomparison of younger dryas wood and implications for IntCal13. Radiocarbon 55, 2035– 2048 (2013). sourcePartly supported

  Table 1 of the initial kauri intercomparison reports an HD difference of 52 ± 53 radiocarbon years at mid-ring 376.5 and an average HD offset of 8 years. The paper discusses an HD offset, but the passages do not identify that date as an outlier or attribute about 33% of the offset to it. (LLM, conf=0.80)

  Experimental — accuracy not yet measured

The Mediterranean-relevant Hd GOR dataset does not indicate the ambiguous 17th or 16th century calibrated ranges for the Thera eruption proposed from the AA BCP and IrO data.

“Thus, the Mediterranean-relevant Hd GOR dataset does not indicate the ambiguous 17th or 16th century calibrated ranges for the Thera eruption proposed in (13) from the AA BCP and IrO data.”

• cites [13] Pearson C. L., Brewer P. W., Brown D., Heaton T. J., Hodgins G. W. L., Jull A. J. T., Lange T., Salzer M. W., Annual radiocarbon record indicates 16th century BCE date for the Thera eruption. Sci. Adv. 4, eaar8241 (2018). 30116779 PMC6093623 sourcePartly supported

  The Discussion (p. 5) says the paper’s revised ranges extend into the 16th century BCE but do not exclude a late-17th-century eruption, supporting the description of its ranges as spanning both centuries. The paper does not report a finding for the Hd GOR dataset, so it cannot support the claim about what that dataset indicates. (LLM, conf=0.82)

  Experimental — accuracy not yet measured

In the second Younger Dryas wood comparison, Hd data were on average 21 14C years younger than the Waikato LSC laboratory.

“In the second case, the Hd data were, on average, 21 14C years younger than the LSC laboratory (Waikato)”

• cites [43] Hogg A., Turney C., Palmer J., Southon J., Kromer B., Ramsey C. B., Boswijk G., Fenwick P., Noronha A., Staff R., Friedrich M., Reynard L., Guetter D., Wacker L., Jones R., The New Zealand kauri (Agathis Australis) research project: A radiocarbon dating intercomparison of younger dryas wood and implications for IntCal13. Radiocarbon 55, 2035– 2048 (2013). sourceSupported

Despite sometimes marked interannual variation, the AA AMS 14C data are typically ~20 to 40 14C years older than IntCal13 during the period ~1660 to 1540 BCE.

“However, despite sometimes marked interannual variation, the AA AMS 14C data are, as noted above, typically ~20 to 40 14C years older than IntCal13 during the period ~1660 to 1540 BCE (Fig. 3A) (13).”

• cites [13] Pearson C. L., Brewer P. W., Brown D., Heaton T. J., Hodgins G. W. L., Jull A. J. T., Lange T., Salzer M. W., Annual radiocarbon record indicates 16th century BCE date for the Thera eruption. Sci. Adv. 4, eaar8241 (2018). 30116779 PMC6093623 sourceSupported

SUERC AMS 14C dates on single-year known-age U.K. wood differ from Seattle QL LLGPC by 12.1 ± 8.0 14C years (n = 26).

“a difference of Scottish Universities Environmental Research Centre Radiocarbon Dating Laboratory AMS 14C data to QL of 12.1 ± 8.0 14C years (n = 26)”

• cites [48] Bayliss A., Marshall P., Confessions of a serial polygamist: The reality of radiocarbon reproducibility in archaeological samples. Radiocarbon 61, 1143– 1158 (2019). sourceSupported

OxA AMS 14C dates on single-year known-age U.K. wood differ from Seattle QL LLGPC by 1.4 ± 7.9 14C years (n = 25).

“differences of OxA AMS 14C to QL of only 1.4 ± 7.9 14C years (n = 25)”

• cites [48] Bayliss A., Marshall P., Confessions of a serial polygamist: The reality of radiocarbon reproducibility in archaeological samples. Radiocarbon 61, 1143– 1158 (2019). sourceSupported

Groningen AMS 14C dates on single-year known-age U.K. wood differ from Seattle QL LLGPC by −22.5 ± 13.6 14C years (n = 6).

“a difference for Groningen to QL of −22.5 ± 13.6 (n = 6) (48)”

• cites [48] Bayliss A., Marshall P., Confessions of a serial polygamist: The reality of radiocarbon reproducibility in archaeological samples. Radiocarbon 61, 1143– 1158 (2019). sourcePartly supported

  The Additional information section reports a GrA–QL mean offset of −22.5 radiocarbon years for six measurements, matching the direction, magnitude, and sample count. It gives the associated standard error as ±13.8, however, not the cited ±13.6. Page information is unavailable in our copy. (LLM, conf=0.92)

  Experimental — accuracy not yet measured

Many AMS 14C measurement series do not exhibit an unexpected older offset versus comparable samples measured by LLGPC.

“many AMS 14C measurement series do not exhibit such an unexpected older offset versus comparable samples measured by LLGPC (4, 40–42)”

• cites [4] Reimer P. J., Baillie M. G. L., Bard E., Bayliss A., Beck J. W., Blackwell P. G., Ramsey C. B., Buck C. E., Cheng H., Edwards R. L., Friedrich M., Grootes P. M., Guilderson T. P., Haflidason H., Hajdas I., Hatté C., Heaton T. J., Hoffmann D. L., Hogg A. G., Hughen K. A., Kaiser K. F., Kromer B., Manning S. W., Niu M., Reimer R. W., Richards D. A., Scott E. M., Southon J. R., Staff R. A., Turney C. S. M., van der Plicht J., IntCal13 and Marine13 radiocarbon age calibration curves 0–50,000 years Cal BP. Radiocarbon 55, 1869– 1887 (2013). sourceCould not verify

  The Terrestrial 14C Archives section discusses tree-ring measurements, and the Comparison to IntCal09 and Marine09 section discusses differences among calibration datasets; neither compares AMS series with LLGPC measurements. Searches for AMS, LLGPC, gas proportional counting, and laboratory offsets found no passage addressing the claimed absence of an older offset. Page numbers were not available in our copy. (LLM, conf=0.72)

  Experimental — accuracy not yet measured
• cites [40] Taylor R. E., Southon J., Reviewing the mid-first millennium BC 14C “warp” using 14C/bristlecone pine data. Nucl. Instrum. Methods Phys. Res. 294, 440– 443 (2013). sourceNot checked — no full text of the source
• cites [41] Jull A. J., Panyushkina I. P., Lange T. E., Kukarskih V. V., Myglan V. S., Clark K. J., Salzer M. W., Burr G. S., Leavitt S. W., Excursions in the 14C record at A.D. 774–775 in tree rings from Russia and America. Geophys. Res. Lett. 41, 3004– 3010 (2014). sourceNot checked — no full text of the source
• cites [42] Miyake F., Jull A. J. T., Panyushkina I. P., Wacker L., Salzer M., Baisan C. H., Lange T., Cruz R., Masuda K., Nakamura T., Large 14C excursion in 5480 BC indicates an abnormal sun in the mid-Holocene. Proc. Natl. Acad. Sci. U.S.A. 114, 881– 884 (2017). 28100493 PMC5293056 sourcePartly supported

  The Method and Result section (page unavailable) reports that three AMS measurement series agree with one another and that their combined data are almost consistent with IntCal13 and its original data. It does not identify those comparison samples as measured by LLGPC or establish the broader claim about many AMS series lacking an older offset relative to LLGPC. (LLM, conf=0.78)

  Experimental — accuracy not yet measured

The grand solar minimum period 750 ± 60 BCE likely reflects a different process.

“the grand solar minimum period 750 ± 60 BCE (50) likely reflects a different process (15)”

• cites [50] Usoskin I. G., Gallet Y., Lopes F., Kovaltsov G. A., Hulot G., Solar activity during the Holocene: The Hallstatt cycle and its consequence for grand minima and maxima. Astron. Astrophys. 587, A150 (2016). sourceSupported
• cites [15] Kromer B., Manning S. W., Kuniholm P. I., Newton M. W., Spurk M., Levin I., Regional 14CO2 offsets in the troposphere: Magnitude, mechanisms, and consequences. Science 294, 2529– 2532 (2001). 11743160 sourceNot checked — no full text of the source

In most work to date, no general pattern of offsets between AMS 14C measurements and LLGPC 14C measurements at Hd is apparent.

“In most work to date, no general pattern of offsets between AMS 14C measurements and LLGPC 14C measurements at Hd is apparent (19, 43–45)”

• cites [19] See supplementary materials.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [43] Hogg A., Turney C., Palmer J., Southon J., Kromer B., Ramsey C. B., Boswijk G., Fenwick P., Noronha A., Staff R., Friedrich M., Reynard L., Guetter D., Wacker L., Jones R., The New Zealand kauri (Agathis Australis) research project: A radiocarbon dating intercomparison of younger dryas wood and implications for IntCal13. Radiocarbon 55, 2035– 2048 (2013). sourceCould not verify

  The Five-Laboratory intercomparison discusses a possible offset between Heidelberg and other laboratories, including AMS laboratories; it does not compare AMS with LLGPC measurements made at Heidelberg. Searches for that within-laboratory comparison found no passage addressing whether a general pattern of offsets is apparent. Page numbers were not available in our copy. (LLM, conf=0.76)

  Experimental — accuracy not yet measured
• cites [44] Kromer B., Lindauer S., Synal H.-A., Wacker L., MAMS—A new AMS facility at the Curt-Engelhorn-Centre for Archaeometry, Mannheim, Germany. Nucl. Instrum. Methods Phys. Res. 294, 11– 13 (2013). sourceNot checked — no full text of the source
• cites [45] Hammer S., Friedrich R., Kromer B., Cherkinsky A., Lehman S. J., Meijer H. A. J., Nakamura T., Palonen V., Reimer R. W., Smith A. M., Southon J. R., Szidat S., Turnbull J., Uchida M., Compatibility of atmospheric 14CO2 measurements: Comparing the Heidelberg low-level counting facility to international accelerator mass spectrometry (AMS) laboratories. Radiocarbon 59, 875– 883 (2017). sourcePartly supported

  The Results and Conclusions (page not provided) report no significant average offset between Heidelberg low-level counting and the AMS consensus in this study. The paper compared five samples and cautions that they were too few to assess individual laboratories, so it does not establish the claim’s broader characterization of ‘most work to date.’ (LLM, conf=0.83)

  Experimental — accuracy not yet measured

There are nine recurring substantive positive offset episodes in the Hd GOR record relative to Hd GeO and IntCal98/04, defined as offsets where in a contiguous period of ≥20 calendar years, ≥95% of those years exhibit a positive offset.

“However, in detail, there are nine recurring substantive positive offset episodes (defined arbitrarily as offsets where in a contiguous period of ≥20 calendar years, ≥95% of those years exhibit a positive offset, i.e., an offset value above 0)”

In every instance but one, the nine positive offset episodes correspond with major reversals and plateaus in the 14C record.

“—in every instance but one (see below), these correspond with major reversals and plateaus in the 14C record—”

During the nine positive offset episodes, the Hd GOR values are consistently older than those from the parallel Hd GeO time series and the IntCal98 and IntCal04 calibration datasets.

“where the Hd GOR values are consistently older than those from (i) the parallel Hd GeO time series and (ii) the IntCal98 and IntCal04 calibration datasets (table S2).”

These two negative offset occurrences correspond with stronger slopes in the 14C calibration curve with declining 14C ages B.P.

“These two occurrences correspond with stronger slopes in the 14C calibration curve with declining 14C ages B.P.”

At various intervals, particularly where data measured at the same Hd laboratory are compared, there are periods of similar scale substantive negative 14C offsets.

“At the same time, we must also note the reverse observation: At various intervals, particularly where we compare data measured at the same Hd laboratory, there are also some periods of similar scale substantive negative 14C offsets (Fig. 2B).”

The NOC time series covering the mid-17th through early 15th centuries BCE includes the major and sustained 14C reversal in the earlier 16th century BCE, which is clearly evident in the Hd GOR dataset, especially 3549 to 3517 cal B.P. (1600 to 1568 BCE) and generally 3549 to 3487 cal B.P. (1600 to 1538 BCE).

“The NOC time series covering the mid-17th through early 15th centuries BCE includes the major and sustained 14C reversal in the earlier 16th century BCE, which is clearly evident in the Hd GOR dataset, especially 3549 to 3517 cal B.P. (1600 to 1568 BCE) and generally 3549 to 3487 cal B.P. (1600 to 1538 BCE) (Fig. 2B).”

In overall net terms, there is reasonable agreement between the Hd GOR and GeO records over the interval 3655 to 3431 cal B.P.

“We observe that, in overall net terms, there is reasonable agreement between the records.”

The Hd GOR and GrM NOC data indicate that Mediterranean 14C ages in the earlier 16th century BCE are older than the IntCal values.

“In particular, as evident in Figs. 2 (A and B) and 3A, the Hd GOR and GrM NOC data indicate that Mediterranean 14C ages in the earlier 16th century BCE are older than the IntCal values and, thus, are potentially approximately contemporary with 14C ages for the last decades of the 17th century BCE.”

There are several periods where 14C dates on Egyptian samples appear to fit the pattern of the Mediterranean-relevant Hd GOR record much better than the IntCal04 record, as well as without application of a static correction factor.

“There are several periods where the 14C dates on the Egyptian samples, in fact, appear to fit the pattern of the Mediterranean-relevant Hd GOR record much better than the IntCal04 (2) record, as well as without application of a static correction factor (16, 23).”

• cites [2] Reimer P. J., Baillie M. G. L., Bard E., Bayliss A., Beck J. W., Bertrand C. J. H., Blackwell P. G., Buck C. E., Burr G. S., Cutler K. B., Damon P. E., Edwards R. L., Fairbanks R. G., Friedrich M., Guilderson T. P., Hogg A. G., Hughen K. A., Kromer B., Cormac G. M., Manning S., Ramsey C. B., Reimer R. W., Remmele S., Southon J. R., Stuiver M., Talamo S., Taylor F. W., van der Plicht J., Weyhenmeyer C. E., IntCalo4 terrestrial radiocarbon age calibration, 0–26 cal kyr BP. Radiocarbon 46, 1029– 1058 (2004).Not checked yet

  Not checked in the free run.

• cites [16] Dee M. W., Brock F., Harris S. A., Ramsey C. B., Shortland A. J., Higham T. F. G., Rowland J. M., Investigating the likelihood of a reservoir offset in the radiocarbon record for ancient Egypt. J. Archaeol. Sci. 37, 687– 693 (2010). sourceNot checked — no full text of the source
• cites [23] Bronk Ramsey C., Dee M. W., Rowland J. M., Higham T. F. G., Harris S. A., Brock F., Quiles A., Wild E. M., Marcus E. S., Shortland A. J., Radiocarbon-based chronology for Dynastic Egypt. Science 328, 1554– 1557 (2010). 20558717 sourceNot checked — no full text of the source

The Hd GOR dataset indicates a most likely later 17th century BCE date range for the Thera olive branch sample.

“The finding is most likely a later 17th century BCE date range for this sample (19).”

• Also stated in: § Thera/Santorini eruption date · hedged

  “Here, comparison with the Mediterranean relevant Hd GOR dataset indicates a most likely later 17th century BCE date range (Fig. 5C), which is consistent with the analysis of sets of AMS 14C data against the Hd GOR dataset (Fig. 5, A and B).”

• cites [19] See supplementary materials.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Rerunning the Fig. 5 (A and B) analyses with an additional hypothetical +10 14C years adjustment to the Hd GOR dataset does not produce a substantial change.

“If we rerun the analyses in Fig. 5 (A and B) with an additional hypothetical +10 14C years adjustment to the Hd GOR dataset, then we do not find a substantial change (Fig. 5, D and E).”

Our GrM NOC Mediterranean AMS 14C data are 21.1 ± 8.0 14C years older than the corresponding interpolated Hd GOR Mediterranean ages.

“our GrM NOC and GrM OYM Mediterranean AMS 14C data are, respectively, 21.1 ± 8.0 and 28.6 ± 14.4 14C years older than the corresponding interpolated Hd GOR Mediterranean ages.”

Our GrM OYM Mediterranean AMS 14C data are 28.6 ± 14.4 14C years older than the corresponding interpolated Hd GOR Mediterranean ages.

“our GrM NOC and GrM OYM Mediterranean AMS 14C data are, respectively, 21.1 ± 8.0 and 28.6 ± 14.4 14C years older than the corresponding interpolated Hd GOR Mediterranean ages.”

A specific Mediterranean offset in the earlier 16th century BCE is identified in the Hd GOR and GrM NOC datasets.

“The earlier 16th century BCE Mediterranean offset identified above in the Hd GOR and GrM NOC datasets is particularly relevant to a long-running controversy: the dating of the Minoan eruption of the Thera (Santorini) volcano and associated debates around its impacts and the chronology of the beginning of the Aegean Late Bronze Age (13, 19, 54–58).”

An OxA AMS 14C study comparing 18th to 19th century CE annual plant material from Egypt versus the LLGPC NH calibration curve obtained an average offset of 19 ± 5 14C years.

“An OxA AMS 14C study comparing 18th to 19th century CE annual plant material from Egypt versus the LLGPC NH calibration curve (unstated, but IntCal04/09) obtained an average offset of 19 ± 5 14C years (16)”

• cites [16] Dee M. W., Brock F., Harris S. A., Ramsey C. B., Shortland A. J., Higham T. F. G., Rowland J. M., Investigating the likelihood of a reservoir offset in the radiocarbon record for ancient Egypt. J. Archaeol. Sci. 37, 687– 693 (2010). sourceNot checked — no full text of the source

Within our study, eight periods are noted where substantive offsets likely associated with a typical Mediterranean growing season are evident.

“Within our study, eight periods are noted where substantive offsets likely associated with a typical Mediterranean growing season are evident.”

The equivalent comparison of the LLGPC Hd GOR series versus the LLGPC IntCal04 dataset yields an OxCal ΔR value of 9.2 ± 2.5 14C years.

“The equivalent comparison of the LLGPC Hd GOR series versus the LLGPC IntCal04 dataset yields an OxCal ΔR value of 9.2 ± 2.5 14C years.”

UGAMS OYM AMS 14C dates exhibit an opposite shift of −26 ± 7.7 14C years to more recent ages relative to Hd GOR.

“the UGAMS OYM AMS 14C dates exhibit an opposite shift of −26 ± 7.7 14C years to more recent ages.”

A comparison of the large New Kingdom AMS 14C dataset of Egyptian samples found an offset against LLGPC IntCal04 with a mean of ~18 14C years, generalized as ~20 ± 5 14C years.

“with a mean of ~18 14C years (generalized as ~20 ± 5 14C years in the text of ref. (23) ; we use this SD below) against LLGPC IntCal04”

• cites [23] Bronk Ramsey C., Dee M. W., Rowland J. M., Higham T. F. G., Harris S. A., Brock F., Quiles A., Wild E. M., Marcus E. S., Shortland A. J., Radiocarbon-based chronology for Dynastic Egypt. Science 328, 1554– 1557 (2010). 20558717 sourceNot checked — no full text of the source

With the +10 14C years adjustment, the dating probabilities still indicate the later 17th century BCE as the most likely date range.

“The dating probabilities still continue to indicate the later 17th century BCE as the most likely date range.”

Using the information added in the table S1 addendum to (23), we achieved lower values for a ΔR test 0,10 across five runs of μ ± σ: 11.3 ± 5.4 to 12.0 ± 5.9 14C years.

“using the information added in the table S1 addendum to (23), we achieved lower values for a ΔR test 0,10 across five runs of μ ± σ: 11.3 ± 5.4 to 12.0 ± 5.9 14C years”

• cites [23] Bronk Ramsey C., Dee M. W., Rowland J. M., Higham T. F. G., Harris S. A., Brock F., Quiles A., Wild E. M., Marcus E. S., Shortland A. J., Radiocarbon-based chronology for Dynastic Egypt. Science 328, 1554– 1557 (2010). 20558717 sourceNot checked — no full text of the source

A positive average offset of ~21 14C years between the Mediterranean and NH is identified for the period ~3550 to 3486 cal B.P. (1601 to 1537 BCE) from comparison of the Hd datasets.

“We can then, in addition, consider the possible relevance of the positive average offset of ~21 14C years between the Mediterranean and NH in the period ~3550 to 3486 cal B.P. (1601 to 1537 BCE) as identified from the comparison of the Hd datasets (Fig. 2B) and apply this adjustment to the AA BCP data (Fig. 6, D to F).”

Only if the hypothetical adjustment is 20 or 25 14C years does the dating probability switch to indicating that an earlier mid-16th century BCE date range is more likely.

“Only if the hypothetical adjustment is 20 or 25 14C years, does the dating probability switch to indicating that an earlier mid–16th century BCE date range is more likely (Fig. 5, H to K).”

The recurring positive 14C offset episodes range variously from ~13 to 31 14C years.

“This recurring phenomenon, with offset episodes variously from ~13 to 31 14C years (Fig. 2A)”

In five reruns of the New Kingdom model against IntCal04, we achieved ΔR test 0,10 μ ± σ results of 15.0 ± 10.4 to 17.8 ± 4.8 14C years.

“we note that in five reruns of this model against IntCal04, we achieved ΔR test 0,10 μ ± σ results of 15.0 ± 10.4 to 17.8 ± 4.8 14C years”

If the putative AMS to LLGPC offset reached around 15 14C years, the date of the Santorini eruption starts to become more ambiguous.

“If it were to reach around 15 14C years, then the date of the Santorini eruption starts to become more ambiguous.”

For a hypothetical 14C date of 3035 ± 15 14C years B.P., the calendar probability for the critical date range 1260-1200 BCE is 37.9% with the Hd GOR calibration dataset versus 18.7% with IntCal13, approximately double.

“A hypothetical 14C date of 3035 ± 15 14C years B.P. has double the calendar probability (37.9% versus 18.7%) for the critical date range between 1260 and 1200 BCE when contrasting the Hd GOR versus IntCal13 14C calibration datasets (Fig. 4B).”

The coherent weighted average 14C date from a set of samples (using six of seven available dates) from the funerary context of Tutankhamun is 3117 ± 12 14C years B.P.

“weighted average 14C date from a set of samples (using six of seven available dates) from the funerary context of Tutankhamun is 3117 ± 12 14C years B.P.”

Our findings identify and highlight the relevance of a recurring variable growing season positive 14C offset for the lower-elevation Mediterranean.

“Our findings identify and highlight the relevance of a recurring variable growing season positive 14C offset for the lower-elevation Mediterranean.”

These transitions are coeval with periods in the GOR record that are offset from the IntCal records.

“These transitions are coeval with periods in the GOR record that are offset from the IntCal records (Fig. 2A)”

This situation highlights the challenge of interlaboratory variation at high resolution.

“This situation highlights the challenge of interlaboratory variation at high resolution.”

A single "standard" 14C calibration curve built from midlatitude and spring and especially summer growing season-dominated wood (i.e., IntCal) cannot be fully representative, at high resolution, of the Mediterranean at those times when a growing season offset appears to operate at measurable and substantive scale.

“Rather, a single “standard” 14C calibration curve built from midlatitude and spring and especially summer growing season–dominated wood (i.e., IntCal) cannot be fully representative, at high resolution, of the Mediterranean at those times when a growing season offset appears to operate at measurable and substantive scale.”

• AssumptionThe authors state this as an assumption: The instances of substantive offsets occur especially under circumstances that stretch the normal differences in the growing seasons of plants.

The Hd GeO versus GOR comparison in the earlier 16th century BCE highlights a 14C offset that is independent of variations in absolute values achieved by different laboratories.

“The Hd GeO versus GOR comparison in the earlier 16th century BCE highlights a difference, a 14C offset, that is independent of variations in absolute values achieved by different laboratories.”

Comparing Hd GeO and Hd GOR, there is a systematic difference, or offset, based on the source of wood (and thence growing season) and not the laboratory.

“What we have identified instead, comparing Hd GeO and Hd GOR, is a systematic difference, or offset, based on the source of wood (and thence growing season) and not the laboratory.”

The exception is the offset during the grand solar minimum centered ~750 BCE, which reflects another and less common process.

“The exception is the offset during the grand solar minimum centered ~750 BCE, which reflects another and less common process (15).”

• cites [15] Kromer B., Manning S. W., Kuniholm P. I., Newton M. W., Spurk M., Levin I., Regional 14CO2 offsets in the troposphere: Magnitude, mechanisms, and consequences. Science 294, 2529– 2532 (2001). 11743160 sourceNot checked — no full text of the source

Turkish pine (Pinus nigra) from Çatacık in western Turkey grows in a high-elevation context where very cold winters create spring-summer growing conditions and timings similar to central and northern Europe.

“Turkish pine (Pinus nigra) from Çatacık in western Turkey grows in a high-elevation context where very cold winters create spring-summer growing conditions and timings (35) similar to central and northern Europe.”

• cites [35] Köse N., Akkemik Ü., Dalfes H. N., Özeren M. S., Tolunay D., Tree-ring growth of Pinus nigra Arn. subsp. pallasiana under different climate conditions throughout western Anatolia. Dendrochronologia 30, 295– 301 (2012). sourceNot checked — no full text of the source

Other oaks in central and northern Europe generally grow from spring (late April/start of May, but starting a little earlier in some areas) through summer to sometime from late August to mid-September.

“Other oaks in central and northern Europe generally grow from spring (late April/start of May, but starting a little earlier in some areas) through summer to sometime from late August to mid-September (19).”

• cites [19] See supplementary materials.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Consideration of some Mediterranean AMS 14C cases suggested that an additional factor of ≤10 14C years might apply to the LLGPC Hd GOR dataset versus AMS 14C dates.

“Nonetheless, consideration above of some Mediterranean AMS 14C cases suggested that perhaps an additional factor of ≤10 14C years might apply to the LLGPC Hd GOR dataset versus AMS 14C dates.”

The BCP and IrO samples do not reflect the typical Mediterranean growing season.

“However, the identification of a specific Mediterranean offset in the earlier 16th century BCE (Figs. 2, A and B, and 3A) indicates that the correct date will not solely derive from IntCal nor do these BCP and IrO samples reflect the typical Mediterranean growing season (see above).”

There is no possible AMS 14C-to-LLGPC issue in the case of the Thera olive branch sample.

“Hence, there is no possible AMS 14C–to–LLGPC issue in this case.”

The consistency between the olive branch result and the AMS 14C datasets against Hd GOR suggests an additional AMS 14C-to-LLGPC contribution of no more than about ≤10 14C years.

“This suggests the reality of an additional AMS 14C–to–LLGPC contribution of no more than about ≤10 14C years, as discussed above.”

This parallel dating strategy circumvents the problem of being unable, otherwise, to extract signal from the noise of interlaboratory variation, which is often the cause for any apparent differences.

“This parallel dating strategy circumvents the problem of being unable, otherwise, to extract signal from the noise of interlaboratory variation, which is often the cause for any apparent differences.”

We could reasonably generalize all this information as ≤10 14C years.

“We could reasonably generalize all this information as ≤10 14C years.”

The recurring variable growing season positive 14C offset undermines the relevance of the generic midlatitude NH 14C calibration curve for high-resolution chronology in the Mediterranean, especially during offset episodes.

“This recurring phenomenon, with offset episodes variously from ~13 to 31 14C years (Fig. 2A), undermines the relevance of the generic midlatitude NH 14C calibration curve for high-resolution chronology in the Mediterranean and especially during these offset episodes.”

The difference between AA AMS 14C data and IntCal13 during ~1660 to 1540 BCE is a laboratory or method difference.

“Therefore, this is a laboratory or method difference.”

Regardless of the absolute dating accuracy of the Hd laboratory over this period, the relative similarities or differences observed between the two Hd time series are real.

“Thus, regardless of the absolute dating accuracy of the Hd laboratory over this period, the relative similarities or differences observed between the two Hd time series are real.”

Mediterranean 14C ages in the earlier 16th century BCE are potentially approximately contemporary with 14C ages for the last decades of the 17th century BCE.

“In particular, as evident in Figs. 2 (A and B) and 3A, the Hd GOR and GrM NOC data indicate that Mediterranean 14C ages in the earlier 16th century BCE are older than the IntCal values and, thus, are potentially approximately contemporary with 14C ages for the last decades of the 17th century BCE.”

The Thera olive branch comparison uses comparable Mediterranean Hd measurements against Mediterranean Hd measurements.

“Instead, we have comparable Mediterranean Hd measurements against Mediterranean Hd measurements.”

These periods may sometimes be associated with periods of cultural transition.

“and, thus, may sometimes be associated with periods of cultural transition.”

The hypothetical scenario of AA BCP data forming a new IntCal baseline plus a Mediterranean positive offset, or large LLGPC to AMS 14C adjustments, does not return to the traditional "low" archaeological chronology.

“Such a scenario [or the hypothetical large LLGPC to AMS 14C adjustments considered in Fig. 5 (H to K)], interestingly, does not, however, return us to the traditional “low” archaeological chronology (19, 57).”

• cites [19] See supplementary materials.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [57] Warren P., Archaeology: Absolute dating of the Bronze Age eruption of Thera (Santorini). Nature 308, 492– 493 (1984). sourceNot checked — no full text of the source

In each of these cases, the offset includes the Mediterranean offset.

“In each of these cases, this offset includes the Mediterranean offset.”

Rerunning the Tutankhamun data set analysis against IntCal13 and comparing against IntCal04 and Hd GOR shows a likely best fit versus the Hd GOR range.

“The placement of the Tutankhamun data set rerunning the analysis in (24) against IntCal13 and comparing against IntCal04 and Hd GOR similarly shows a likely best fit versus the Hd GOR range (Fig. 4A, inset).”

• cites [24] S. W. Manning, B. Kromer, M. W. Dee, M. Friedrich, T. F. G. Higham, C. B. Ramsey, Radiocarbon calibration in the mid to later 14th century BC and radiocarbon dating at Tell el-Amarna, Egypt, in Radiocarbon and the Chronologies of Ancient Egypt, A. J. Shortland, C. Bronk Ramsey, Eds. (Oxbow Books, 2013), pp. 121–145. sourceNot checked — no full text of the source

The Mediterranean offset could exacerbate the dating ambiguity between the later 17th century BCE and the earlier mid-16th century BCE.

“This could exacerbate the dating ambiguity between the later 17th century BCE and the earlier mid–16th century BCE.”

This offset includes only the Mediterranean offset since it is an LLGPC versus LLGPC comparison.

“This offset includes only the Mediterranean offset since it is an LLGPC versus LLGPC comparison.”

There is a specific Mediterranean context for the Thera dating controversy.

“There is instead a specific Mediterranean context for this controversy.”

Comparing the intersection of the Tutankhamun calendar and 14C ranges shows a better fit with the Hd GOR calibration range than with IntCal04.

“If we compare the intersection of these calendar and 14C ranges, we see a better fit with the Hd GOR calibration range (Fig. 4A).”

The identification of a specific Mediterranean offset in the earlier 16th century BCE indicates that the correct date for the Thera controversy will not solely derive from IntCal.

“However, the identification of a specific Mediterranean offset in the earlier 16th century BCE (Figs. 2, A and B, and 3A) indicates that the correct date will not solely derive from IntCal nor do these BCP and IrO samples reflect the typical Mediterranean growing season (see above).”

No simple static adjustment is possible as a satisfactory solution for the recurring, periodic offsets observed in both the BCE and CE windows reported in works to date.

“No simple static adjustment is possible as a satisfactory solution for the recurring, periodic offsets observed in both the BCE and CE windows reported in works to date.”