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Deciphering the Meiyu behavior during the Last Interglacial (∼127 ka; LIG) may deepen our understanding of drought and flooding events over East Asia in a warmer‐than‐present world induced by Earth's orbit. Based on dynamical downscaling simulations, we suggested a 15‐ and 30‐day earlier onset and retreat of the Meiyu during the LIG relative to preindustrial, respectively, leading to a shortened Meiyu season. Meantime, extreme precipitation in the Meiyu season became stronger and occurred more frequently. Intensified monsoonal circulation, poleward‐located western North Pacific subtropical high, and poleward shift of East Asian westerly jet during the LIG provided favorable moisture conditions for earlier onset and retreat of the Meiyu. The variations of atmospheric circulations were further regulated by the joint effect of the three oceans and diabatic heating over Tibetan Plateau. Our results highlight an important role of Earth's orbit in the Meiyu and imply more flooding events in a warmer world. Plain Language Summary: The record‐breaking Meiyu in 2020 reemphasizes the importance of investigating the evolution of the rainy season in East Asia. This study reveals the response of the Meiyu to changes in the Earth's orbit during the Last Interglacial (LIG, 130–115 ka)—the warmest interglacial of the past 800 ka and a warmer world comparable to the low emission scenarios at the end of the 21st century. The Meiyu season occurred and ended earlier compared with the present day, and the duration was shortened. Additionally, more frequent and intense extreme precipitation events occurred in the Meiyu season during the LIG. The enhanced East Asian summer monsoonal flow, strengthened western North Pacific subtropical high, and poleward shift of the East Asian westerly jet in June provided favorable conditions for the earlier occurrence and termination of the Meiyu during the LIG. Moreover, changes in the sea surface temperature over the three oceans can jointly influence the Meiyu via triggering Kelvin waves, Rossby waves, and teleconnections by atmospheric circulations, with the contribution from the diabatic heating over the Tibetan Plateau. The results of this study help us better understand the evolution of the rainy season over East Asia in a warmer world. Key Points: Earlier onset and shortened duration of Meiyu season during the Last Interglacial (LIG)Stronger and more frequent extreme precipitation events occurred in Meiyu season during the LIGIntensified monsoonal circulation, poleward‐located subtropical high and westerly jets led to changes in Meiyu during the LIG [ABSTRACT FROM AUTHOR]

Records from a wide range of geological archives covering the last few glacial‐interglacial cycles show large inconsistencies in the East Asian summer monsoon variability, which severely hampers our understanding of the evolution and potential mechanisms of the regional East Asian climate on orbital timescales. Here, we examine the simulated temperature and precipitation in East Asia based on a series of equilibrium simulations conducted for the past 425 ka, and we investigate the sensitivity of temperature and precipitation to potential forcings. Our simulations show that, in East Asia, the seasonal mean temperature is dominated by a ∼20‐kyr cycle, and the annual mean temperature (AMT) is dominated by a ∼100‐kyr cycle, which is consistent with previous modeling efforts and geological reconstructions. Additional sensitivity experiments indicate that the greenhouse gas concentration, in combination with the ice volume, is the dominant force for the variations of AMT in East Asia on orbital timescales. For the precipitation in East Asia, our equilibrium simulations and additional sensitivity experiments, together with comprehensive model‐data intercomparison analysis, suggest that the cycles of simulated annual mean precipitation over East Asia are highly model‐dependent, although the dominant ∼20‐kyr cycle in summer precipitation appears to be a robust feature. Overall, the results highlight the large model uncertainty with regard to the relative roles of forcings in hydroclimate variations in East Asia on orbital time scales. There is, therefore, an urgent need to implement more realistic precipitation schemes in models in order to decrease the model spread in simulated precipitation. Plain Language Summary: Investigating the dominant cycles of the East Asian climatic elements over past glacial‐interglacial cycles is always an important issue for palaeoclimatologists. To better examine the cycles of temperature and precipitation in East Asia, we conducted a series of equilibrium simulations over the past 425 ka. And we investigate the sensitivity of temperature and precipitation to potential forcings by using several sensitivity experiments. There are two main findings in our study. The annual mean temperature in East Asia is dominated by the ∼100‐kyr cycle, which is forced by the greenhouse gas concentration and ice volumes. However, our simulation results and further investigations together suggest that the cycles of simulated annual mean precipitation over East Asia are highly model‐dependent, though the dominant ∼20‐kyr cycle in summer precipitation remains a robust feature over East Asia. Therefore, there is an urgent need to reduce the uncertainty for the cycles of simulated precipitation in the future. Key Points: In East Asia, the annual and seasonal mean temperatures are dominated by the ∼100‐kyr cycle, and the ∼20‐kyr cycle, respectivelyThe CO2 combined with the ice volume, is the dominant forcing for the variations of annual temperature in East Asia on orbital timescalesThe cycles of simulated annual mean precipitation are highly model‐dependent [ABSTRACT FROM AUTHOR]

Investigation of the evolution of summer Asian westerly jet (AWJ) in Earth history may deepen our understanding of the behavior of AWJ in the present and future. Here, the variation of summer westerlies and the associated mechanisms over West and East Asia are examined using the last millennium simulations from the Paleoclimate Modeling Intercomparison Project Phase III (PMIP3). The multimodel ensemble mean of 11 PMIP3 models reproduces the spatial distribution of modern zonal wind at 200 hPa and captures the location and intensity of the summer AWJ well. The results illustrate that the location of summer westerlies over West and East Asia shows no clear long-term trend over the last millennium, whereas there is an enhancing trend for the intensity, but with significant interannual and multidecadal variability. Summer westerlies over West Asia mainly oscillate within ~25-year band in terms of the location and intensity, while the principal periodicity over East Asia oscillate within ~25- and ~15-year band, respectively. Moreover, summer AWJ broadly moves poleward and weakens during the 'Medieval Climate Anomaly' (MCA, AD 1000–1200) relative to the 'Little Ice Age' (LIA, AD 1400–1600), which is attributed to the reduced meridional temperature gradient during the MCA. This poleward shift is consistent with the reconstructed moisture conditions over Central Asia, but the lack of direct proxy for westerlies restricts detailed model–data comparisons. Nevertheless, a possible scenario is presented on the spatiotemporal variation of summer AWJ over the last millennium, which may shed light on the response of the AWJ to natural forcings. [ABSTRACT FROM AUTHOR]

The Arctic plays a fundamental role in the climate system and has shown significant climate change in recent decades, including the Arctic warming and decline of Arctic sea-ice extent and thickness. In contrast to the Arctic warming and reduction of Arctic sea ice, Europe, East Asia and North America have experienced anomalously cold conditions, with record snowfall during recent years. In this paper, we review current understanding of the sea-ice impacts on the Eurasian climate. Paleo, observational and modelling studies are covered to summarize several major themes, including: the variability of Arctic sea ice and its controls; the likely causes and apparent impacts of the Arctic sea-ice decline during the satellite era, as well as past and projected future impacts and trends; the links and feedback mechanisms between the Arctic sea ice and the Arctic Oscillation/North Atlantic Oscillation, the recent Eurasian cooling, winter atmospheric circulation, summer precipitation in East Asia, spring snowfall over Eurasia, East Asian winter monsoon, and midlatitude extreme weather; and the remote climate response (e.g., atmospheric circulation, air temperature) to changes in Arctic sea ice. We conclude with a brief summary and suggestions for future research. [ABSTRACT FROM AUTHOR]

The East Asian summer monsoon affects precipitation and hence vegetation in the densely populated Northwest Pacific region, yet a long-standing controversy exists concerning the spatial and temporal dynamics of the Holocene Optimum (HO) in the East Asian Monsoon Region. Here we use a detailed 14,000-year record reconstructing vegetation variations from a strategically selected crater lake from Northeast China, as well as a compilation of previous paleoclimatic studies, to show that the HO began around 6,000 Cal a BP in Northeast China, significantly later than generally recognized. By comparing our paleoenvironmental data with Holocene vegetation records from other regions of East Asia, we identified a marked northward shift for the onset of the HO from ∼ 10 , 260 Cal a BP in South China to ∼ 6 , 000 Cal a BP in Northeast China. The gradual northward transgression of the vegetation change could be caused by both the temperature and precipitation changes in different regions. Finally, we fitted a regression model of the start of the HO period versus latitude, which allowed us to make predictions for the beginning of the HO at different geographical locations. This study reveals a strong relationship between latitude and the initiation of the HO, and provides a window towards better understanding the forcing of vegetation changes in the East Asian monsoon region. [ABSTRACT FROM AUTHOR]