The Antarctic Ice Core Chronology 2023 (AICC2023) chronological framework and associated timescale for the European Project for Ice Coring in Antarctica (EPICA) Dome C ice core

<p>The EPICA (European Project for Ice Coring in Antarctica) Dome C (EDC) ice core drilling in East Antarctica reaches a depth of 3260 m. The reference EDC chronology, the AICC2012 (Antarctic Ice Core Chronology 2012), provides an age vs. depth relationship covering the last 800 kyr (thousands of years), with an absolute uncertainty rising up to 8000 years at the bottom of the ice core. The origins of this relatively large uncertainty are twofold: (1) the <span class="inline-formula"><i>δ</i>¹⁸</span>O<span class="inline-formula">_atm</span>, <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi mathvariant="italic">δ</mi><mrow class="chem"><msub><mi mathvariant="normal">O</mi><mn mathvariant="normal">2</mn></msub></mrow><mo>/</mo><mrow class="chem"><msub><mi mathvariant="normal">N</mi><mn mathvariant="normal">2</mn></msub></mrow></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="41pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="846b6f765641c697b19d3c3c2c555269"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cp-19-2257-2023-ie00001.svg" width="41pt" height="14pt" src="cp-19-2257-2023-ie00001.png"/></svg:svg></span></span> and total air content (TAC) records are poorly resolved and show large gaps over the last 800 kyr, and (2) large uncertainties are associated with their orbital targets. Here, we present new highly resolved <span class="inline-formula"><i>δ</i>¹⁸</span>O<span class="inline-formula">_atm</span>, <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi mathvariant="italic">δ</mi><mrow class="chem"><msub><mi mathvariant="normal">O</mi><mn mathvariant="normal">2</mn></msub></mrow><mo>/</mo><mrow class="chem"><msub><mi mathvariant="normal">N</mi><mn mathvariant="normal">2</mn></msub></mrow></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="41pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="26bb89727c0d5d655d1ccea7435b6d94"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cp-19-2257-2023-ie00002.svg" width="41pt" height="14pt" src="cp-19-2257-2023-ie00002.png"/></svg:svg></span></span> and <span class="inline-formula"><i>δ</i>¹⁵</span>N measurements for the EDC ice core covering the last five glacial–interglacial transitions; a new low-resolution TAC record over the period 440–800 ka BP (ka: 1000 years before 1950); and novel absolute <span class="inline-formula">⁸¹</span>Kr ages. We have compiled chronological and glaciological information including novel orbital age markers from new data on the EDC ice core as well as accurate firn modeling estimates in a Bayesian dating tool to construct the new AICC2023 chronology. For the first time, three orbital tools are used simultaneously. Hence, it is possible to observe that they are consistent with each other and with the other age markers over most of the last 800 kyr (70 %). This, in turn, gives us confidence in the new AICC2023 chronology. The average uncertainty in the ice chronology is reduced from 1700 to 900 years in AICC2023 over the last 800 kyr (<span class="inline-formula">1<i>σ</i></span>). The new timescale diverges from AICC2012 and suggests age shifts<span id="page2258"/> reaching 3800 years towards older ages over marine isotope stages (MISs) 5, 11 and 19. But the coherency between the new AICC2023 timescale and independent chronologies of other archives (Italian Lacustrine succession from Sulmona Basin, Dome Fuji ice core and northern Alpine speleothems) is improved by 1000 to 2000 years over these time intervals.</p>