B-isotope and Mg/Ca ratios of planktonic foraminifera from ODP Hole 108-668B and esimates of salinity, alkalinity and pCO2 (Table 1)

Knowledge of past atmospheric pCO2 is important for evaluating the role of greenhouse gases in climate forcing. Ice core records show the tight correlation between climate change and pCO2, but records are limited to the past ~900 kyr. We present surface ocean pH and pCO2 data, reconstructed from boron isotopes in planktonic foraminifera over two full glacial cycles (0-140 and 300-420 kyr). The data co-vary strongly with the Vostok pCO2-record and demonstrate that the coupling between surface ocean chemistry and the atmosphere is recorded in marine archives, allowing for quantitative estimation of atmospheric pCO2 beyond the reach of ice cores.过去大气二氧化碳分压（pCO2）的相关认知，对于评估温室气体在气候强迫（climate forcing）中的作用具有关键意义。冰芯记录揭示了气候变化与pCO2之间的紧密关联，但现有冰芯记录仅覆盖距今约900 kyr以内的时段。本研究报道了基于浮游有孔虫（planktonic foraminifera）硼同位素重建得到的表层海水pH与pCO2数据，其覆盖两个完整冰期旋回（0~140 kyr与300~420 kyr时段）。该数据集与沃斯托克（Vostok）冰芯pCO2记录呈现极强的协同变化特征，证实表层海水化学与大气之间的耦合关系可保存在海洋沉积记录中，从而实现冰芯记录覆盖范围之外的大气pCO2定量估算。