Subfossil trees with their annual rings constitute the most accurate and precise archive to calibrate the radiocarbon (14C) method. The Holocene part of the IntCal curve is based on tree-ring chronologies, absolutely dated by dendrochronological matching. For the Northern Hemisphere, the absolute curve starts at 12,325 cal BP. For the early part of the Younger Dryas (YD) climatic event (≈ 12,850–11,650 cal BP), there are only a few floating dendrochronological sequences, mainly from Switzerland and France. We present new 14C results from subfossil trees (Pinus sylvestris L.) collected from the Barbiers site (southeast French Alps). The dendrochronological series covers 416 years, corresponding to the onset of the YD period. In order to date our sequence, we matched it with the 14C record based on kauri trees from New Zealand. The Barbiers data were first averaged at the same decadal resolution as the kauri record. Statistical comparison of the different averaging options and matching techniques enables dating the Barbiers sequence to 13,008–12,594 ±10 cal BP, which thus includes the boundary between the Allerød and YD events. The new Barbiers record allows to calculate the 14C inter-hemispheric gradient (14C-IHG) during the period overlapping the kauri sequence. For the optimal dating option, the mean 14C-IHG is 37 yr with a standard deviation (SD) of 21 yr based on 43 decadal estimations (−6‰ with SD of 2‰). The 14C-IHG record exhibits minimal values, down to zero, between 12,960–12,840 cal BP. Excluding these minima leads to an average 14C-IHG of 45 yr with a SD of 14 yr based on 33 decadal values, in agreement with observations for the last two millennia. The Barbiers record suggests a 14C-IHG increase between the end of the Allerød period (IHG of 37 yr with SD of 14 yr) and the early part of the YD (IHG of 48 yr with SD of 14 yr), which is compatible with previously reported drop of deep-water convection in the North-Atlantic and the associated increase in wind-driven upwelling in the Southern Ocean.

具有年轮的亚化石树是校准放射性碳（14 C）方法的最准确和最精确的档案。IntCal曲线的全新世部分基于树年轮年代，绝对是通过树轮年代学匹配来确定的。对于北半球，绝对曲线始于12,325 cal BP。对于年轻得里亚斯（YD）气候事件的早期部分（≈12,850–11,650 cal BP），只有少数浮动树轮年代学序列，主要来自瑞士和法国。我们提出了亚化石树（樟子松）的新14 C结果L.）是从Barbiers站点（法国东南阿尔卑斯山）收集的。树木年代学系列涵盖了416年，对应于YD时期的开始。为了更新序列，我们将其与基于新西兰贝壳杉树的14 C记录进行了匹配。Barbiers数据首先以与贝壳杉记录相同的年代际分辨率进行平均。通过统计比较不同的平均选项和匹配技术，可以将Barbiers序列的日期定为13,008–12,594±10 cal BP，从而包括Allerød事件和YD事件之间的边界。新的Barbiers记录允许在与贝壳杉序列重叠的时期内计算14 C半球间梯度（14 C-IHG）。对于最佳约会选项，均值14C-IHG为37年，基于43个年代际估算得出的标准差（SD）为21年（-6‰，SD为2‰）。的14 C-洲际记录表现出最小的值，下降到零，12,960-12,840 BP CAL之间。排除这些极小值，得出的平均14 C-IHG为45年，基于33年代际值的SD为14年，与最近两个千年的观测结果一致。Barbiers记录表明，在Allerød期末（IHG为37年，SD为14年）和YD早期（IHG为48年，SD为14年）之间增加了14 C-IHG，这是可比的先前报道的北大西洋深水对流下降以及南大洋上由风驱动的上升流相应增加。