Qingzhen Hao

The impact of rapid climate change on civilizations is of global concern. The Western Zhou (1045–771 BC) was ancient China’s third dynasty and one of the most powerful empires of its time. After a 274-year reign, the dynasty collapsed, accompanied by significant population migration. Various factors have been proposed to explain its fall, while the role of climate change has been largely ignored. Here we present well-dated, high-resolution stalagmite records from Northeast and Southeast China, along with other paleoclimatic and archaeological evidence, to demonstrate the critical role of the 2.8 ka climatic event in the dynasty’s collapse and subsequent migration. Our results indicate a “north dry–south wet” dipolar pattern in the Chinese monsoon region during this event. The drought and cold severely affected the Western Zhou core areas and exacerbated invasions by northern nomads, contributing to its collapse. The resulting environmental stresses and conflicts likely triggered substantial southward migration.

Northwest Pacific Ocean sedimentary eolian records preserve abundant information about the temporal evolution of Northern Hemisphere atmospheric circulation. The large spatial scale of these wind systems means that they play key roles in driving dust transportation from inland areas to the open ocean. However, the altitudinal range of dominant wind systems that produce Northwest Pacific eolian records remains unclear on orbital timescales. To address this uncertainty, we conducted an integrated study of Northwest Pacific Ocean Drilling Program Hole 1210B eolian deposition between 1.5 and 1.0 Ma. Based on our reconstructed environmental magnetic, sedimentological, and geochemical records, modern observational analyses and paleoclimate model results, we propose that eolian variations at Hole 1210B mainly indicate stronger glacial mid‐tropospheric (∼300–500 hPa) wind intensities over the Northwest Pacific. These results improve our understanding of Northern Hemisphere wind system evolution over Northwest Pacific pelagic areas on glacial‐interglacial timescales.

The intensification of Northern Hemisphere Glaciation (iNHG) with the onset of glacial‐interglacial cycles at ∼2.7 Ma had a profound impact on the global climate system. However, there have been few systemic assessments of the response of orbital‐scale East Asian summer monsoon (EASM) variability to the iNHG, partly due to controversies regarding the interpretation of the dominant orbital rhythms of the EASM. Here, we present grain size and other proxy records from mainly silt‐sized lacustrine‐fluvial deposits in northern China. The results shows that the EASM underwent stepwise weakening at ∼2.7 and ∼1.8 Ma, coincident with two major cooling steps of the global climate and that its dominant orbital periodicity changed from ∼41 kyr during ∼3.6–2.7 Ma, to ∼100 kyr during ∼2.7–1.8 Ma. However, these findings are inconsistent with the strengthening of the 41‐kyr cyclicity in marine δ¹⁸O records after the iNHG, whereas they are consistent with northern high‐latitude sea surface temperature records that bear the imprint of local climate signals when the Arctic ice sheets were of limited extent during the Early Pleistocene. We propose that the dominant ∼41‐kyr cyclicity during the Late Pliocene resulted from obliquity‐induced changes in the meridional insolation gradient, or in heat and moisture transport from low latitudes; whereas the dominant ∼100‐kyr cyclicity during ∼2.7–1.8 Ma reflects an increased response to northern high‐latitude forcing. Our findings, combined with previous studies, highlight the importance of eccentricity in modulating the EASM and other key climate system components prior to the Mid‐Pleistocene Transition during the course of Northern Hemisphere Glaciation.

Northwest Pacific sedimentary eolian dust flux records have long been used to make direct inferences about Asian interior aridity. However, factors other than aridity can impact dust production rate. We present here an integrated environmental magnetic, electron microscopic, sedimentologic, and geochemical investigation of eolian dust records from Northwest Pacific Ocean Drilling Program Hole 1207A between 1.0 and 1.5 Ma. Reconstructed fluxes of bulk eolian dust and illite, the predominant clay mineral (>72% proportion), are both higher and lower during glacials and interglacials, respectively. Lower illite chemical index values reflect stronger physical weathering during glacials. We attribute eolian flux peaks to increased availability of wind‐erodible particles caused by enhanced physical weathering in dust source areas due to strengthened Asian interior glacial activity in response to glacial cooling. This evidence demonstrates that Northwest Pacific eolian flux does not only reflect persistent Asian interior aridity on orbital timescales.

East Asian winter monsoon (EAWM) activity has had profound effects on environmental change throughout East Asia and the western Pacific. Much attention has been paid to Quaternary EAWM evolution, while long-term EAWM fluctuation characteristics and drivers remain unclear, particularly during the late Miocene when marked global climate and Asian paleogeographic changes occurred. To clarify understanding of late Miocene EAWM evolution, we developed a high-precision 9-million-year-long stacked EAWM record from Northwest Pacific Ocean abyssal sediments based on environmental magnetism, sedimentology, and geochemistry, which reveals a strengthened late Miocene EAWM. Our paleoclimate simulations also indicate that atmospheric CO ₂ decline played a vital role in this EAWM intensification over the Northwest Pacific Ocean compared to other factors, including central Asian orogenic belt and northeastern Tibetan Plateau uplift and Antarctic ice-sheet expansion. Our results expand understanding of EAWM evolution from inland areas to the open ocean and indicate the importance of atmospheric CO ₂ fluctuations on past EAWM variability over large spatial scales.

We present data on molluscan fauna within the L3 loess unit (and partially within the S3 paleosol) from the key loess section of Veliki Surduk in Serbia. The section correlates to Marine Isotope Stage (MIS) 8 and late MIS 9 and, thus, spans the time frame from ~350 to 250 ka. The Veliki Surduk loess–paleosol sequence (LPS) is located on the northwestern margin of the Titel loess plateau and comprises ~30 m of sediments. Our focus is on a 5.4 m thick sedimentary interval, which was sampled at 20 cm increments, each sample covering approximately 2 ky. Nine mollusk species were identified in the loess sequence: Granaria frumentum, Helicopsis striata, Pupilla triplicata, Chondrula tridens, Pupilla muscorum, Succinella oblonga, Punctum pygmaeum, Vallonia costata, and Vitrina pellucida, as well as a few unidentified slug taxa (Limacidae, Agriolimacidae, and Milacidae). The majority of the snail assemblage occurs at the transition between MIS 9 and MIS 8, suggesting a mostly dry climate and an open and steppe-like habitat. The fauna identified in the upper part of the paleosol layer S3, below the L3 unit, indicated aridification.

Past intervals of warming provide the unique opportunity to observe how the East Asia monsoon precipitation response happened in a warming world. However, the available evaluations are primarily limited to the last glacial-to-interglacial warming, which has fundamental differences from the current interglacial warming, particularly in changes in ice volume. Comparative paleoclimate studies of earlier warm interglacial periods can provide more realistic analogs. Here, we present high-resolution quantitative reconstructions of temperature and precipitation from north-central China over the past 800 thousand years. We found that the average precipitation increase, estimated by the interglacial data, was only around one-half of that estimated for the glacial-to-interglacial data, which is attributed to the amplification of climate change by ice volume variations. Analysis of the interglacial data suggests an increase in monsoon precipitation of ~100 mm for a warming level of 2°C on the Chinese Loess Plateau.

The North Atlantic jet stream (NAJ) has a profound impact on the climate of the North Atlantic−European sector, especially in winter. Observations show that the winter NAJ (NAJ_w) has strengthened over the past ∼140 yr. However, it remains unclear whether this long-term trend has deviated from the natural variability. Here, we present a 2500-yr-long reconstruction of NAJ_w strength using high-quality stalagmite δ¹⁸O records from southeastern Europe. Our results show that the NAJ_w weakened during both the Roman Warm Period (B.C. 300−A.D. 200) and the Medieval Warm Period (A.D. 900−1250) but that it has strengthened under anthropogenic warming (since A.D. 1850). This indicates that its current trend has already deviated from the natural variability. The best explanation for this present anomalous trend of NAJ_w strength is that it was triggered by the appearance of the North Atlantic warming hole under anthropogenic forcing. This anomalous trend suggests that continued global warming may further strengthen the NAJ_w in the future.