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Abstract The Walker circulation is projected to slow down in response to greenhouse gas warming. However, detecting the impact of human activities on changes in the Walker circulation is challenging due to the significant influence of internal variability. Here, based on ensembles of multiple climate models from the Coupled Model Intercomparison Project Phase 6 (CMIP6), we show evidence that the emergence of the human-induced weakening of Walker circulation tends to occur earlier in the middle-upper troposphere than at the surface. This earlier emergence is attributed to a more pronounced initial weakening response of the middle-upper tropospheric Walker circulation to atmospheric CO2 radiative forcing. We further reveal that the emergence time of a weaker Walker circulation varies across models. This intermodel spread is governed by an ocean thermostat that operates by modulating the zonal sea surface temperature gradient over the tropical Indo-Pacific region. Our findings address the key question of whether and how to detect human-induced large-scale atmospheric circulation changes and provide valuable insights for assessing the associated risks.

Abstract Paleoclimate model simulations provide reference data to help interpret the geological record and offer a unique opportunity to evaluate the performance of current models under diverse boundary conditions. Here, we present a dataset of 35 climate model simulations of the warm early Eocene Climatic Optimum (EECO; ~ 50 million years ago) and corresponding preindustrial reference experiments. To streamline the use of the data, we apply standardised naming conventions and quality checks across eight modelling groups that have carried out coordinated simulations as part of the Deep-Time Model Intercomparison Project (DeepMIP). Gridded model fields can be downloaded from an online repository or accessed through a new web application that provides interactive data exploration. Local model data can be extracted in CSV format or visualised online for streamlined model-data comparisons. Additionally, processing and visualisation code templates may serve as a starting point for advanced analysis. The dataset and online platform aim to simplify accessing and handling complex data, prevent common processing issues, and facilitate the sharing of climate model data across disciplines.

Abstract The mid-Piacenzian warm period (MPWP, ~3.264–3.025 Ma) has gained widespread interest due to its partial analogy with future climate. However, quantitative data–model comparison of East Asian Summer Monsoon (EASM) precipitation during the MPWP is relatively rare, especially due to problems in decoding the imprint of physical processes to climate signals in the records. In this study, pollen-based precipitation records are reconstructed and compared to the multi-model ensemble mean of the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2). We find spatially consistent precipitation increase in most simulations but a spatially divergent change in MPWP records. We reconcile proxy data and simulation by decomposing physical processes that control precipitation. Our results 1) reveal thermodynamic control of an overall enhancement of EASM precipitation and 2) highlight a distinct control of thermodynamic and dynamical processes on increases of tropical and subtropical EASM precipitation, reflecting the two pathways of water vapor supply that enhance EASM precipitation, respectively.

Abstract There have been few case studies of the relationship between the Pacific Decadal Oscillation (PDO) and the East Asian climate before the pre-industrial era with limited anthropogenic impacts. Using the CESM Last Millennium Ensemble (CESM-LME) simulation with reconstruction evidence, we showed that there was an interdecadal transition of the summer precipitation in East China, with the pattern of “southern flooding and northern drought” in the mid-18th century. The interdecadal transition was influenced by PDO, as suggested by both the reconstruction evidence and simulation. Corresponding to the positive PDO phase change, the East Asia-Pacific pattern teleconnection wave train propagated northward and modulated the circulation and precipitation in East China, together with the southward movement of the East Asian westerly jet. The volcanic double or clustered eruptions are thought to have played a crucial role on the shift of the PDO phase and the decadal summer climate change over East China during the mid-18th century. Incorporating volcanic activity in a reasonable manner would likely improve decadal simulations of East Asian climate in the past and predictions in the future.

Abstract Extreme heat events (EHEs) often hit North China, resulting in significant losses. The devastating EHE in the 1743 summer, marked as the highest temperature in the past 300 years, led to ∼11,000 fatalities. These historical EHEs prompt us to explore potential mechanisms beyond anthropogenic influences. We employ the Norwegian Earth System Model here to simulate the past millennium climate and then dynamically downscale the July 1743 event using the Weather Research and Forecasting Model. The successful simulation of warming in North China, although it has been a fortunate outcome, is supported by tree‐ring records, providing a compelling case study for the event. Through composite and case analyses, we discover a connection between EHEs and active Northeast China Vortexes (NCVs) which induce warm advection, consequently heating the lower atmosphere. Reanalysis further confirms the connection in the modern era. Our study suggests modeling past EHEs, while challenging, is indeed feasible.

Abstract The complex and contrasted distribution of terrestrial biota in Asia has been linked to active tectonics and dramatic climatic changes during the Neogene. However, the timings of the emergence of these distributional patterns and the underlying climatic and tectonic mechanisms remain disputed. Here, we apply a computational data analysis technique, called redescription mining, to track these spatiotemporal phenomena by studying the associations between the prevailing herbivore dental traits of mammalian communities and climatic conditions during the Neogene. Our results indicate that the modern latitudinal zoogeographic division emerged after the Middle Miocene climatic transition, and that the modern monsoonal zoogeographic pattern emerged during the late Late Miocene. Furthermore, the presence of a montane forest biodiversity hotspot in the Hengduan Mountains alongside Alpine fauna on the Tibetan Plateau suggests that the modern distribution patterns may have already existed since the Pliocene.

Abstract The increased precipitation in the Asian water tower has prompted the abrupt lake expansion and increased runoff, significantly reshaping the water resource redistribution in the Inner Tibetan Plateau (ITP). However, the dynamic attribution behind this decadal increment remains unclear. Here, analysis of observations, large ensemble simulations, and pacemaker experiments indicates that this decadal increase was mainly attributed to the synergistic effects of the external forcing (anthropogenic greenhouse and aerosol emissions) and the Pacific internal variability, while the Atlantic and the Indian Ocean play a secondary role. Observations and simulations show that thermodynamic and dynamic effects work collaboratively to this increase. Remarkably, the upper-level dynamic convergence over the ITP would be enhanced through teleconnection and atmospheric dynamic feedback when involving the Pacific internal variability, resulting in more precipitation occurrence. Further analyses show that the enhanced stationary Rossby wave propagation over Eurasia and strengthened transient eddy activity over North Pacific could contribute to the anomalous cyclone over the ITP and weakened East Asian westerly jet, which built a pathway for the external forcing and Pacific internal variability collaboratively impacting the decadal increase in precipitation in the ITP. These results can improve our understanding of ITP summer precipitation attribution and can be applied to emergent constraints on future decadal precipitation prediction.

Understanding human actions often requires in-depth detection and interpretation of bio-signals. Early eye disengagement from the target (EEDT) represents a significant eye behavior that involves the proactive disengagement of the gazes from the target to gather information on the anticipated pathway, thereby enabling rapid reactions to the environment. It remains unknown how task difficulty and task repetition affect EEDT. We aim to provide direct evidence of how these factors influence EEDT. We developed a visual tracking task in which participants viewed arrow movement videos while their eye movements were tracked. The task complexity was increased by increasing movement steps. Every movement pattern was performed twice to assess the effect of repetition on eye movement. Participants were required to recall the movement patterns for recall accuracy evaluation and complete cognitive load assessment. EEDT was quantified by the fixation duration and frequency within the areas of eye before arrow. When task difficulty increased, we found the recall accuracy score decreased, the cognitive load increased, and EEDT decreased significantly. The EEDT was higher in the second trial, but significance only existed in tasks with lower complexity. EEDT was positively correlated with recall accuracy and negatively correlated with cognitive load. Performing EEDT was reduced by task complexity and increased by task repetition. EEDT may be a promising sensory measure for assessing task performance and cognitive load and can be used for the future development of eye-tracking-based sensors.

Pupil size is a significant biosignal for human behavior monitoring and can reveal much underlying information. This study explored the effects of task load, task familiarity, and gaze position on pupil response during learning a visual tracking task. We hypothesized that pupil size would increase with task load, up to a certain level before decreasing, decrease with task familiarity, and increase more when focusing on areas preceding the target than other areas. Fifteen participants were recruited for an arrow tracking learning task with incremental task load. Pupil size data were collected using a Tobii Pro Nano eye tracker. A 2 × 3 × 5 three-way factorial repeated measures ANOVA was conducted using R (version 4.2.1) to evaluate the main and interactive effects of key variables on adjusted pupil size. The association between individuals’ cognitive load, assessed by NASA-TLX, and pupil size was further analyzed using a linear mixed-effect model. We found that task repetition resulted in a reduction in pupil size; however, this effect was found to diminish as the task load increased. The main effect of task load approached statistical significance, but different trends were observed in trial 1 and trial 2. No significant difference in pupil size was detected among the three gaze positions. The relationship between pupil size and cognitive load overall followed an inverted U curve. Our study showed how pupil size changes as a function of task load, task familiarity, and gaze scanning. This finding provides sensory evidence that could improve educational outcomes.

Abstract Proxy‐based reconstructions show that the climate during the mid‐Holocene (MH) was warmer and wetter than the present day in most regions of China, characterized by a northwestward extension of the East Asian summer monsoon and an increase in woody cover. However, climate simulations that neglect vegetation shifts yield cooler climates than proxy‐based reconstructions for the MH. Here, we simulate MH vegetation cover, productivity, and terrestrial parameters in China using a state‐of‐the‐art land surface model forced with realistic proxy‐based climate data. Our simulations corroborate MH vegetation cover inferred from 246 pollen sites, and indicate a higher vegetation productivity in China, despite the lower CO2 concentration during the MH compared to the present day. Enhanced vegetation growth during the MH could have affected land surface energy and hydrological budgets through biophysical feedbacks. Our findings highlight the impact of vegetation dynamics on the terrestrial carbon cycle and regional climate in China.

Whether there were more extensive glaciations during the Marine Isotope Stage (MIS) 3 relative to MIS 2 across the Tian Shan in Central Asia is intensely debated because of the uncertainty in chronological data and fully understanding the driving mechanisms. To help resolve the ongoing debate, we assess the climate sensitivity of the glaciers and reconstruct the extent of glaciation during MIS 2 and 3 across the Tian Shan, using a glacier-resolving (250 × 250 m) ice sheet model asynchronously coupled with a global climate model. Our results demonstrate that the equilibrium-line altitude (ELA) over the Tian Shan decreases by ∼180 m for every 1 °C cooling under a modern precipitation regime, but precipitation reduction greatly lowers the sensitivity of the glaciers to temperature decrease (e.g., the effect of 2 °C cooling is broadly offset by a 50% decrease in precipitation). Under the modeled colder/drier-than-present climate, the model predicts an ELA depression (∆ELA) of ∼75 m (162 m) over the Tian Shan during MIS 3 interstadials (stadials). The extent of MIS 3 glaciation is much smaller than that during MIS 2 (i.e., ∆ELA = ∼726 m). The more extensive glaciation during MIS 2 is largely attributed to the enhanced summer cooling. Furthermore, through a site-to-site model-data comparison, we find that the closest match between the modeled glacier margin and the locations of the glacial deposits previously argued to be MIS 3 is generally achieved under MIS 2 climatic conditions. These results suggest more extensive glacier advances over the Tian Shan during MIS 2 than MIS 3 on a regional scale, although MIS 3 glaciation may still occur in individual glacier catchments. This pattern suggests general synchronicity with the timing of maximum Northern Hemisphere ice sheets during the last glacial, which should be further tested in a multimodel framework in the future.

Linking human technological and behavioural advances to environmental changes is challenging, as it requires a robust understanding of past climate at local scales. Here, we present results from regional high-resolution numerical simulations along with climate data directly from the archaeological sequence of Blombos Cave (BBC), a well-studied site in coastal southern Africa. The model simulations cover two distinct periods centred at 82 and 70 thousand years (ka) ago (Marine Isotope Stage [MIS] 5 and the onset of MIS 4, respectively), when orbital parameters and global sea level were markedly different from one another. Climatic changes from 82 to 70 ka are determined through four simulations that use past and present-day coastline configurations. The hydrogen isotopic composition of leaf waxes (δ2Hwax) and n-alkane distributions and abundances are used to reconstruct hydroclimate around BBC. The leaf wax n-alkane record, one of the first produced in an archaeological setting in this region to date, can be interpreted as a drying signal from MIS 5c to 4. This agrees with our modelling results, which indicate a drier and more continental climate over coastal southern Africa at 70 ka, compared to 82 ka. The simulated aridification is most evident from the reduced precipitation amounts in both summer (∼20%) and winter (∼30%). The annual number of summer days (Tmax ≥ 25 °C) and cold nights (Tmin < 5 °C) in the vicinity of BBC increases more than 5 and 3-fold, respectively, under the more continental climate at 70 ka. Weaker westerly winds in winter, a cooler Agulhas Current, and a land surface expansion associated with the coastline shift due to lower sea levels at 70 ka all contribute to the simulated climate shift. Our approach highlights the importance of multiple lines of evidence for achieving robust results, while demonstrating how both large-scale forcing and local influences worked together in shaping the local climate that early humans lived in. Adaptation to a drier climate and increased continentality around BBC might have induced greater mobility, which led to increased population interactions, cultural transmission rates, skill exchange, and material complexity during the so-called Still Bay period.

Climate models project a weakening and expansion of the Hadley circulation (HC) under global warming but with considerable spread in the magnitude of these changes. Here, utilizing models from the latest Coupled Model Intercomparison Project Phase 6 (CMIP6), we illustrate how the variance in projected changes in the HC arises from equilibrium climate sensitivity (ECS) uncertainty across models. Models with higher ECS project a greater extent of static stability increase hence larger HC changes. Using the best estimate of ECS with value of 3 K (∼2.5–4.0 K) to constrain the HC projection, we reveal that the constrained projection yields a 15% (11%) decrease in the weakening (poleward shift) of the HC in the Northern (Southern) Hemisphere compared to the multimodel mean under the SSP5-8.5 scenario. The corresponding projection uncertainty is reduced by about 77.4% and 75.6%, respectively. Our results indicate a smaller-than-expected change in the HC in response to increased CO _2 concentrations.

Abstract The role of the mid‐latitude seaway between the proto‐Paratethys and the North Sea on the early Paleogene ocean circulation is examined with a state‐of‐art earth system model. The early Eocene simulations here demonstrate that the open mid‐latitude seaway captures most relatively fresh surface water from the Arctic and Greenland‐Norwegian Sea and prohibits them from leaking into the Labrador Sea, thus benefiting the Atlantic meridional overturning circulation (AMOC). However, the closure of the seaway triggers the AMOC reduction as more relatively fresh surface water enters the Labrador Sea, and the AMOC finally shuts down. Together with geological reconstructions, our results also provide insights into understanding the evolution of the Atlantic‐Arctic oceanic gateways during the Paleogene.

In contrast to future projections, paleoclimate records often find wetter subtropics in tandem with elevated CO2. Here, a compilation of proxies and simulations are used to reveal the climate dynamics and feedbacks responsible for generating wet subtropics during the mid-Pliocene.

Abstract Background Medical trainees are required to learn many procedures following instructions to improve their skills. This study aims to investigate the pupillary response of trainees when they encounter moment of performance difficulty (MPD) during skill learning. Detecting the moment of performance difficulty is essential for educators to assist trainees when they need it. Methods Eye motions were recorded while trainees practiced the thoracostomy procedure in the simulation model. To make pupillary data comparable among trainees, we proposed the adjusted pupil size (APS) normalizing pupil dilation for each trainee in their entire procedure. APS variables including APS, maxAPS, minAPS, meanAPS, medianAPS, and max interval indices were compared between easy and difficult subtasks; the APSs were compared among the three different performance situations, the moment of normal performance (MNP), MPD, and moment of seeking help (MSH). Results The mixed ANOVA revealed that the adjusted pupil size variables, such as the maxAPS, the minAPS, the meanAPS, and the medianAPS, had significant differences between performance situations. Compared to MPD and MNP, pupil size was reduced during MSH. Trainees displayed a smaller accumulative frequency of APS during difficult subtask when compared to easy subtasks. Conclusions Results from this project suggest that pupil responses can be a good behavioral indicator. This study is a part of our research aiming to create an artificial intelligent system for medical trainees with automatic detection of their performance difficulty and delivering instructional messages using augmented reality technology.

The 2021 East Asia sandstorm began from the Eastern Gobi desert steppe in Mongolia on March 14, and later spread to northern China and the Korean Peninsula. It was the biggest sandstorm to hit China in a decade, causing severe air pollution and a significant threat to human health. Capturing and predicting such extreme events is critical for society. The Lagrangian particle dispersion model FLEXPART and the associated dust emission model FLEXDUST have been recently developed and applied to simulate global dust cycles. However, how well the model captures Asian dust storm events remains to be explored. In this study, we applied FLEXPART to simulate the recent 2021 East Asia sandstorm, and evaluated its performance comparing with observation and observation-constrained reanalysis datasets, such as the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) and CAMS global atmospheric composition forecasts (CAMS-F). We found that the default setting of FLEXDUST substantially underestimates the strength of dust emission and FLEXPART modelled dust concentration in this storm compared to that in MERRA-2 and CAMS-F. An improvement of the parametrization of bare soil fraction, topographical scaling, threshold friction velocity and vertical dust flux scheme based on Kok et al. (Atmospheric Chemistry and Physics, 2014, 14, 13023–13041) in FLEXDUST can reproduce the strength and spatio-temporal pattern of the dust storm comparable to MERRA-2 and CAMS-F. However, it still underestimates the observed spike of dust concentration during the dust storm event over northern China, and requires further improvement in the future. The improved FLEXDUST and FLEXPART perform better than MERRA-2 and CAMS-F in capturing the observed particle size distribution of dust aerosols, highlighting the importance of using more dust size bins and size-dependent parameterization for dust emission, and dry and wet deposition schemes for modelling the Asian dust cycle and its climatic feedbacks.

Abstract The winter extreme precipitation over South China (SC) experiences a large year‐to‐year variability, causing uncertainty in its prediction. Here, we find that the boreal winter sea ice concentration (SIC) in the Okhotsk Sea can serve as a precursor to the following winter's extreme precipitation frequency (EPF) over SC, which has important implications for its prediction. Further analysis reveals that the Okhotsk Sea SIC anomalies help to reinforce North Pacific Oscillation‐like atmospheric variability over the North Pacific, which induces the development of El Niño‐Southern Oscillation (ENSO)‐like SST anomalies in the equatorial eastern Pacific. The ENSO may act as a “power amplifier” to boost the impact of the Okhotsk Sea winter SIC anomalies on the following winter EPF over SC via a positive atmosphere–ocean feedback process. Our findings suggest that the Okhotsk Sea SIC may act as a potential precursor for the winter EPF over SC leading by about 1 year, and further improve our understanding of extratropical‐tropical interactions and aid predictability of winter extreme precipitation over SC.

Deep learning has been applied in healthcare, where features of patients are read by the computer to assist with diagnosis and treatment. In sports medicine, kinematic characteristics of injuries need to be defined. Patients' data are then acquired amplified to training deep learning models. In this study, we tracked motions of lower extremities in patients with lateral collateral ligament injuries of the ankle. Key kinematic characteristics of injuries were identified by comparing patients to normal individuals. The deep convolutional generative adversarial networks (DCGANs) was employed to synthesize a modest-sized labeled dataset to avoid the problems raised from using large-scale manual labeling data. We then fed a combination of real and synthesized data to train long short-term memory (LSTM) networks to detect patients with ligament injuries. The results showed that combined data yielded a better outcome, measured by classification accuracy and f1-score, than solely using the patient data or with a large quantity of synthesized single range of motion feature.

Introduction. We evaluated the velocity profiles of patients with lateral collateral ligament (LCL) injuries of the ankle with a goal of understanding the control mechanism involved in walking. Methods. We tracked motions of patients’ legs and feet in 30 gait cycles recorded from patients with LCL injuries of the ankle and compared them to 50 gait cycles taken from normal control subjects. Seventeen markers were placed on the foot following the Heidelberg foot measurement model. Velocity profiles and microadjustments of the knee, ankle, and foot were calculated during different gait phases and compared between the patient and control groups. Results. Patients had a smaller first rocker percentage and larger second rocker percentage in the gait cycle compared to controls. Patients also displayed shorter stride length and slower strides and performed more microadjustments in the second rocker phase than in other rocker/swing phases. Patients’ mean velocities of the knee, ankle, and foot in the second rocker phase were also significantly higher than that in control subjects. Discussion. Evidence from velocity profiles suggested that patients with ligament injury necessitated more musculoskeletal microadjustments to maintain body balance, but these may also be due to secondary injury. Precise descriptions of the spatiotemporal gait characteristics are therefore crucial for our understanding of movement control during locomotion.

Model simulations show that tropical cyclones were preferably formed in the Southern Hemisphere during the warmer Early Eocene, but then shifted along a cooling climate across the Cenozoic to the Northern Hemisphere. Today's conditions favoring the western North Pacific as the largest genesis center is a result of closing tropical seaways during the Pliocene.

Tropical cyclones (TCs) not only passively respond to climate change, but also play an important role in vertical mixing of the upper ocean and in driving oceanic heat transport. Using a fully coupled climate model, the authors investigate the potential effect of TC-induced vertical mixing on the El Niño–Southern Oscillation (ENSO) and East Asian monsoon in the mid-Piacenzian, during which global TCs are estimated to have been stronger. Sensitivity experiments indicate that the TC-induced oceanic mixing over global storm basins leads to additional warming over the eastern tropical Pacific and a deeper thermocline in the mid-Piacenzian, whereas it dampens the interannual variability of ENSO. Regarding the East Asian monsoon circulations, low-level (850 hPa) summer and winter winds are intensified in response to enhanced vertical mixing, with a southward/westward shift of the western North Pacific high and westerly jet in summer and a deepened East Asian trough in winter. These climatic features are largely reproduced in the experiment with enhanced vertical mixing only over the central-eastern North Pacific. These results may shed light on TC feedbacks associated with vertical mixing and advance our understanding on mid-Piacenzian climate.

Abstract Paleobotanical and sedimentological records indicate that marked climatic and environmental transitions had taken place in East China by the early Miocene. These transitions were driven by paleogeographic and global climatic shifts, but the respective roles of these shifts in the Asian climate remain unclear. Here, we use the low‐resolution Norwegian Earth System Model and Community Atmosphere Model version 4 to compare the effects of Tibetan Plateau (TP) growth, Paratethys Sea retreat and global cooling on the East Asian climate change that occurred by the early Miocene. The modeling results indicate that these three factors had clearly different climatic effects in East China. In particular, TP growth increased annual precipitation in East China, while Paratethys Sea retreat and global cooling generally decreased annual precipitation in East China. In addition, the three factors studied all drove aridification in inland Asia. Considering the increased precipitation, arid/semiarid‐to‐humid shift in vegetation and high plant diversity present in East China by the early Miocene, as shown in geological records, TP growth thus played a major role in these respects.

In this study, we present an analysis of warm extremes over monsoonal China (21–45° N, 106–124° E) during the last 600 years based on Chinese historical documents and simulations from the Paleoclimate Modelling Intercomparison Project Phase 3 (PMIP3) and the Coupled Model Intercomparison Project Phase 5 (CMIP5). The Chinese historical documents indicate that extreme warm records become more frequent after ~1650 CE in North China and ~1850 CE in the Yangtze River Valley. Our analyses of two threshold extreme temperature indices also illustrate that warm extremes have become more frequent since the 17th century in North China and the mid-19th century in Yangtze River Valley in good agreement with the changes in warm extremes revealed in the historical documents. This agreement suggests potential mechanisms behind the shift of periods, which should be further investigated in the future.

During the mid-Pliocene (3.264-3.025 Ma), atmospheric CO2 concentrations were approximately 400 ppm and the Antarctic ice sheet was substantially reduced compared to today. Antarctica is surrounded by the Southern Ocean, which plays a crucial role in the global oceanic circulation and climate regulation. Using results from the Pliocene Model Intercomparison Project (PlioMIP2), we investigate Southern Ocean conditions during the mid-Pliocene with respect to the pre-industrial period. We find that the mean sea surface temperature (SST) warming in the Southern Ocean is 2.8°C, while global mean SST warming is 2.4°C. The enhanced warming is strongly tied to a dramatic decrease in sea-ice cover over the mid-Pliocene Southern Ocean. We also see a freshening of the ocean (sub)surface, driven by an increase in precipitation over the Southern Ocean and Antarctica. The warmer and fresher surface leads to a highly stratified Southern Ocean, that can be related to weakening of the deep abyssal overturning circulation. Sensitivity simulations show that the decrease in sea-ice cover and enhanced warming is largely a consequence of the reduction of the Antarctic ice sheet. In addition, the mid-Pliocene geographic boundary conditions are responsible for approximately half of the increase in mid-Pliocene SST warming, sea ice loss, precipitation and stratification increase over the Southern Ocean. From these results, we conclude that a strongly reduced Antarctic Ice Sheet during the mid- Pliocene has a substantial influence on the state of the mid-Pliocene Southern Ocean and exacerbates the changes that are induced by a higher CO2 concentration alone. This is relevant for the long-term future of the Southern Ocean, as we expect melting of the western Antarctic ice sheet in the future, an effect that is not currently taken into account in future projections by CMIP ensembles. [ABSTRACT FROM AUTHOR]