The trigger, pace, and nature of the intensification of Northern Hemisphere Glaciation (iNHG) are uncertain, but can be probed by study of ODP Site 1208 North Pacific marine sediments. Herein, we present magnetic proxy data that indicate a 4-fold increase of dust between ~ 2.73 and ~ 2.72 Ma, with subsequent increases at the start of glacials thereafter, indicating a strengthening of the mid-latitude westerlies. Moreover, a permanent shift in dust composition after 2.72 Ma is observed, consistent with drier conditions in the source region and/or the incorporation of material which could not have been transported via the weaker Pliocene winds. The sudden increase in our dust proxy data, a coeval rapid rise in dust recorded by proxy dust data in the North Atlantic (Site U1313), and the Site 1208 shift in dust composition, suggest that the iNHG represents a permanent crossing of a climate threshold toward global cooling and ice sheet growth, ultimately driven by lower atmospheric CO₂.

北半球冰川作用 (iNHG) 加剧的触发因素、速度和性质尚不确定，但可以通过对 ODP 站点 1208 北太平洋海洋沉积物的研究进行探索。在此，我们提供的磁代理数据表明，在约 2.73 Ma 和约 2.72 Ma 之间，尘埃增加了 4 倍，随后在冰川期开始时增加了 4 倍，表明中纬度西风带的加强。此外，在2.72 Ma之后观察到灰尘成分发生永久性变化，这与源区的干燥条件和/或无法通过较弱的上新世风输送的物质的结合相一致。我们的尘埃代理数据突然增加，北大西洋代理尘埃数据（站点 U1313）记录的同期尘埃快速上升，以及站点 1208 尘埃成分的变化，₂ .