Multiple short-term (<10⁵ years) global warming events (“hyperthermals”) occurred throughout the early Eocene. Chemical weathering of continental silicate rocks is considered to have played a key role in recovery from these transient global warming events via consumption of excess atmospheric CO₂. However, although evidence of this negative feedback has been reported for the Paleocene–Eocene Thermal Maximum (PETM), the effectiveness of chemical weathering during other transient hyperthermals remains poorly constrained. Here, we newly report early Eocene marine Os isotope records including Eocene Thermal Maximum 2 (ETM2), the I1 event, and ETM3 at Ocean Drilling Program Site 752 in the southern Indian Ocean. We demonstrate that marine ¹⁸⁷Os/¹⁸⁸Os increased during the hyperthermal events that were less severe than the PETM. The intensity of continental silicate weathering increased by 18%–22%, 17%–21%, and 13%–16% during ETM2, the I1 event, and ETM3, respectively, compared to the background conditions. Based on a reconsidered formulation of an Os mass-balance model, the intensity of continental silicate weathering during the PETM was reassessed to be a 34%–42% increase relative to the pre-PETM level. Thus, the continental chemical weathering flux during the Eocene hyperthermals may have been up to half as large as that of the PETM. It is noteworthy that the ordering of the changes in continental silicate weathering did not agree with the ordering of the seawater temperature rise among these events. This weathering–warming inconsistency might be attributable to (1) potential underestimation of continental silicate weathering due to the emplacement of Large Igneous Provinces (LIPs) and related basalt weathering, such as the North Atlantic Igneous Province and Siletzia in western North America, (2) changes in the background level of weathering intensity, and/or (3) a secular decrease in continental weatherability through the long-lasting early Eocene warming trend.

整个始新世早期都发生了多次短期（<10 ^{5年）全球变暖事件（“高温事件”）。}_{大陆硅酸盐岩石的化学风化被认为在通过消耗大气中过量的 CO 2}从这些短暂的全球变暖事件中恢复过来中发挥了关键作用。然而，尽管已经报道了古新世 - 始新世极热（PETM）这种负反馈的证据，但在其他瞬态过热期间化学风化的有效性仍然受到很少的限制。在这里，我们新报告了早期始新世海洋 Os 同位素记录，包括南印度洋海洋钻探计划站点 752 的始新世热最大值 2 (ETM2)、I1 事件和 ETM3。我们证明了海洋¹⁸⁷ Os/ ¹⁸⁸在不如 PETM 严重的过热事件期间，Os 增加。与背景条件相比，ETM2、I1事件和ETM3期间大陆硅酸盐风化强度分别增加了18%~22%、17%~21%和13%~16%。基于重新考虑的 Os 质量平衡模型的公式，PETM 期间大陆硅酸盐风化的强度被重新评估为相对于 PETM 之前的水平增加了 34%–42%。因此，始新世超高温期的大陆化学风化通量可能高达 PETM 的一半。值得注意的是，大陆硅酸盐风化的变化顺序与这些事件中海水温度升高的顺序不一致。