Pre-industrial Period Research Articles

Attribution of Last Glacial Maximum precipitation change in Northern Hemisphere monsoon and arid regions

Based on reconstructions from geological records, the precipitation during the Last Glacial Maximum (LGM) was markedly different from that of the preindustrial (PI) period. Especially in the terrestrial monsoon regions and arid regions of the Northern Hemisphere (hereafter referred to as NHTMR and NHTAR, respectively), the precipitation is more sensitive to changes in boundary conditions. However, the relative contributions of individual LGM forcings to precipitation in NHTMR and in NHTAR are still unclear. In this study, a series of climate model experiments were carried out to evaluate their contributions. The results showed that, compared with the PI period, the precipitation and area of NHTMR were both reduced in the LGM. In NHTAR, the precipitation was significantly reduced, but there was an increase in total area. Sensitivity experiments demonstrated that a decrease in sea surface temperature and an expansion of the ice sheet were the two principal contributors to lessening NHTMR precipitation, while the decrease in precipitation in NHTAR can be mainly attributed to ice-sheet-induced albedo and topography changes. Comparatively, the ice-sheet albedo effect had a greater impact on precipitation change than the topographic effect. The atmospheric circulation anomalies associated with the individual forcings were the underlying dynamic mechanism that drive the precipitation changes.

Climatological Changes in Soil Moisture during the 21st Century over the Indian Region Using CMIP5 and Satellite Observations

Climate data records of soil moisture (SM) are fundamental for improving our understanding of long-term dynamics in the coupled water, energy, and carbon cycles over land. However, many of these studies rely on models for which the errors are not yet fully understood over a region. This may have a considerable impact on the economic growth of the country if the model’s future predictions are used for studying long-term trends. Here we examined the spatial distribution of past, present, and future predictions of SM studied using the Coupled Model Intercomparison Project Phase5 (CMIP5) simulations for the historical period (1850–2005) and future climate projections (2006–2099) based on Representative Concentration Pathways (RCP-RCP2.6, RCP4.5, RCP6.0, and RCP8.5). Furthermore, the performance of modeled SM with the satellite AMSR-E (Advanced Microwave Scanning Radiometer-Earth observation system) was studied. The modeled SM variations of 38 Global Climate Models (GCMs) show discreteness but still we observed that CESM1-CM5, CSIRO-MK3-6-0, BCC-CSM1-1, and also BCC-CSM1-1-M, NorESM1-M models performed better spatially as well as temporally in all future scenarios. However, from the spatial perspective, a large deviation was observed in the interior peninsula during the monsoon season from model to model. In addition, the spatial distribution of trends was highly diversified from model to model, while the Taylor diagram presents a clear view of the model’s performance with observations over the region. Skill score statistics also give the accuracy of model predictions in comparison with observations. The time series was estimated for the future trend of the SM along with the past few decades, whereas the preindustrial and industrial period changes were involved. Significant positive anomaly trends are noticed in the whole time series of SM during the future projection period of 2021–2099 using CMIP5 SM model datasets.

Mechanisms of Reduced Mid‐Holocene Precipitation in Arid Central Asia as Simulated by PMIP3/4 Models

AbstractWe investigated the precipitation changes in mid‐latitude arid central Asia (ACA, including Central Asia and Xinjiang) and the related mechanisms in the mid‐Holocene using the output from the Paleoclimate Modeling Intercomparison Project phases 3 and 4 (PMIP3/4). The annual precipitation in ACA was decreased in the mid‐Holocene compared with the preindustrial period, consistent in direction with reconstruction records. Such change was mainly due to deficient winter and spring (December‐May) precipitation in the mid‐Holocene. The decrease in incoming solar radiation in the mid‐Holocene winter and spring caused stronger surface and tropospheric cooling in the northern low latitudes. It reduced the meridional temperature gradient in the troposphere, thereby weakening the westerly winds and related transport of water vapor. More importantly, the cooling weakened the local water cycle in ACA. Finally, the precipitation decreased over almost all of ACA. In the mid‐Holocene summer (June‐August), the meridional temperature gradient and related westerly winds were also reduced. It was mainly caused by stronger surface and tropospheric warming in the northern mid‐ to high latitudes. The stronger warming was due to increased summer incoming solar radiation in the mid‐Holocene. This process differed from that occurred in winter and spring. Therefore, the water vapor transport was weakened, and the summer precipitation was deficient in northern ACA. At the same time, strengthened descending motions contributed to the decrease in summer precipitation in most parts of Central Asia. On the contrary, intensified ascending motions increased summer precipitation in southeastern Xinjiang.

An energy budget approach to understand the Arctic warming during the Last Interglacial

Abstract. The Last Interglacial period (129–116 ka) is characterised by a strong orbital forcing which leads to a different seasonal and latitudinal distribution of insolation compared to the pre-industrial period. In particular, these changes amplify the seasonality of the insolation in the high latitudes of the Northern Hemisphere. Here, we investigate the Arctic climate response to this forcing by comparing the CMIP6 lig127k and piControl simulations performed with the IPSL-CM6A-LR (the global climate model developed at Institut Pierre-Simon Laplace) model. Using an energy budget framework, we analyse the interactions between the atmosphere, ocean, sea ice and continents. In summer, the insolation anomaly reaches its maximum and causes a rise in near-surface air temperature of 3.1 ∘C over the Arctic region. This warming is primarily due to a strong positive anomaly of surface downwelling shortwave radiation over continental surfaces, followed by large heat transfer from the continents to the atmosphere. The surface layers of the Arctic Ocean also receive more energy but in smaller quantity than the continents due to a cloud negative feedback. Furthermore, while heat exchange from the continental surfaces towards the atmosphere is strengthened, the ocean absorbs and stores the heat excess due to a decline in sea ice cover. However, the maximum near-surface air temperature anomaly does not peak in summer like insolation but occurs in autumn with a temperature increase of 4.2 ∘C relative to the pre-industrial period. This strong warming is driven by a positive anomaly of longwave radiation over the Arctic Ocean enhanced by a positive cloud feedback. It is also favoured by the summer and autumn Arctic sea ice retreat (-1.9×106 and -3.4×106 km2, respectively), which exposes the warm oceanic surface and thus allows oceanic heat storage and release of water vapour in summer. This study highlights the crucial role of sea ice cover variations, Arctic Ocean, as well as changes in polar cloud optical properties on the Last Interglacial Arctic warming.

Strong increase in thawing of subsea permafrost in the 22nd century caused by anthropogenic climate change

Abstract. Most earth system models (ESMs) neglect climate feedbacks arising from carbon release from thawing permafrost, especially from thawing of subsea permafrost (SSPF). To assess the fate of SSPF in the next 1000 years, we implemented SSPF into JSBACH, the land component of the Max Planck Institute Earth System Model (MPI-ESM). This is the first implementation of SSPF processes in an ESM component. We investigate three extended scenarios from the 6th phase of the Coupled Model Intercomparison Project (CMIP6). In the 21st century only small differences are found among the scenarios, but in the upper-end emission scenario SSP5–8.5 (shared socio-economic pathway), especially in the 22nd century, SSPF ice melting is more than 15 times faster than in the pre-industrial period. In this scenario about 35 % of total SSPF volume and 34 % of SSPF area are lost by the year 3000 due to climatic changes. In the more moderate scenarios, the melting rate maximally exceeds that of pre-industrial times by a factor of 4, and the climate change induced SSPF loss (volume and area) by the year 3000 does not exceed 14 %. Our results suggest that the rate of melting of SSPF ice is related to the length of the local open-water season and thus that the easily observable sea ice concentration may be used as a proxy for the change in SSPF.

Trace metals enrichment and potential ecological risk in sediments of the Sepetiba Bay (Rio de Janeiro, SE Brazil)

The Sepetiba Bay (SB; SE Brazil) has been severely affected by growing of urbanization and industrial activity. This work aims to analyze the evolution of contamination by metals of sediments in SB. The results show a marked increasing trend in the concentrations of potentially toxic elements (PTEs), which is consistent with the rapid populational and industrial growth, mostly since 1970 CE. The remobilization and redistribution of sediments by currents have contributed to the dispersion of metals from the main source of pollutants to relatively distant regions. “Moderately to strongly polluted” sediments are also recorded in some sites in deeper sedimentary layers (namely in preindustrial periods), probably due to lithologic sources of the sediments. The concentrations of PTEs in SB are relatively high when compared with those found globally and in other Brazilian water bodies. Samples of high-resolution sediment cores confirmed that potential ecological risk to the coastal system is influenced not only through human actions but also by natural causes.

Counting the missing poor in pre-industrial societies

Under income-differentiated mortality, poverty measures suffer from a selection bias: they do not count the missing poor (i.e., persons who would have been counted as poor provided they did not die prematurely). The Pre-Industrial period being characterized by an evolutionary advantage (i.e., a higher number of surviving children per household) of the non-poor over the poor, one may expect that the missing poor bias is substantial during that period. This paper quantifies the missing poor bias in Pre-Industrial societies, by computing the hypothetical headcount poverty rates that would have prevailed provided the non-poor did not benefit from an evolutionary advantage over the poor. Using data on Pre-Industrial England and France, we show that the sign and size of the missing poor bias are sensitive to the degree of downward social mobility.

How Reliable Are Global Temperature Reconstructions of the Common Era?

Global mean annual temperature has increased by more than 1 °C during the past 150 years, as documented by thermometer measurements. Such observational data are, unfortunately, not available for the pre-industrial period of the Common Era (CE), for which the climate development is reconstructed using various types of palaeoclimatological proxies. In this analysis, we compared seven prominent hemispheric and global temperature reconstructions for the past 2000 years (T2k) which differed from each other in some segments by more than 0.5 °C. Whilst some T2k show negligible pre-industrial climate variability (“hockey sticks”), others suggest significant temperature fluctuations. We discuss possible sources of error and highlight three criteria that need to be considered to increase the quality and stability of future T2k reconstructions. Temperature proxy series are to be thoroughly validated with regards to (1) reproducibility, (2) seasonal stability, and (3) areal representativeness. The T2k represents key calibration data for climate models. The models need to first reproduce the reconstructed pre-industrial climate history before being validated and cleared for climate projections of the future. Precise attribution of modern warming to anthropogenic and natural causes will not be possible until T2k composites stabilize and are truly representative for a well-defined region and season. The discrepancies between the different T2k reconstructions directly translate into a major challenge with regards to the political interpretation of the climate change risk profile. As a rule of thumb, the larger/smaller the pre-industrial temperature changes, the higher/lower the natural contribution to the current warm period (CWP) will likely be, thus, reducing/increasing the CO2 climate sensitivity and the expected warming until 2100.

Farklı Sosyo-Ekonomik Gruplara Göre Osmanlı Bireylerinin Zenginliği, 1650-1918: Kurumsal Değişim Bağlamında Betimsel Bir Analiz

The study offers a descriptive analysis of individual wealth in the Ottoman Empire, employing a new dataset from inheritance records of 36 different provinces located in Anatolia. The main purpose is to contribute to the discussion on the relationship between wealth inequality and changing institutional structures, spanning from 1650 to 1918. The limitations of data entail restrictions to construct a quantitative research, and hence, the study provides an implicit analysis on this relationship. A new dataset on individual wealth, however, allow to present a descriptive analysis in a long-term perspective. Establishing information on individual wealth by socio-economic groups, the study estimates wealth inequality according to Gini coefficients. This estimates also include a comparative analysis among different groups, including four quartiles starting from the wealthiest 25 percent. Our findings underlie the importance of the role of institutional change over the wealth inequality. We suggest the wealth inequality is higher under the periods of decentralized institutions, particularly during the pre-industrial period. This trend has become better with series of political, economic and institutional reforms towards centralization during the second half of the nineteenth century.

Impacts of 1.5 °C and 2 °C global warming on Eucalyptus plantations in South America

Even if the maximum global warming thresholds established by the Paris Agreement (1.5 and 2 °C relative to pre-industrial levels) are not exceeded, part of the climate system impacts resulting from this warming will be unavoidable. Forestry industries may be especially vulnerable, due to water shortages and the inability of growing certain forest species. An important part of the South American economy depends on the forestry sector (between 2 to ~7% of the Gross Domestic Product), mainly products derived from Eucalyptus, and so evaluating water availability considering the temperature thresholds established by the Paris Agreement will be fundamental. This study analyzed increased global average temperatures at 1.5 °C and 2 °C, and the impacts on water availability, using the Climatic Water Balance (CWB), and also studied possible impacts on Eucalyptus plantations in South America. Monthly temperature and precipitation data obtained from a set of simulations and projections of 26 General Circulation Models (GCMs) were used, in four Representative Concentration Pathway (RCP) scenarios. The CWB was calculated for three periods: i) the pre-industrial period (1861–1890), ii) the present period (1975–2005), and iii) the period when temperature projections are expected to reach global average increases of 1.5 °C and 2 °C. Due to changes in the CWB, with increases in actual evapotranspiration, water deficits, and a reduced water surplus, Eucalyptus plantations will be negatively affected and economically unfeasible for about 49.2% to 56.7% of all of South America, including a large part of the Amazon region, northern South America, midwestern and northeastern Brazil, western portions of Bolivia, Paraguay, central/northern Argentina, and northern Chile. Only some parts of South America, like the southern and southeastern regions of Brazil, Uruguay, southern Argentina and Chile, Andes Mountain Range, and northwestern South America, will not suffer water deficits, and Eucalyptus plantations will be less impacted in these regions. Large parts of South America will suffer from changes in water availability. The future of the forestry industry, and especially Eucalyptus plantations in these regions, will depend on urgent and effective adaptation measures.

Impact of deforestation on moisture evaporation from soil and canopy for the territory of Ukraine based on data of numerical experiment LUMIP

The study presents results of analysis of the impact of partial deforestation on spatio-temporal distribution of the outflow part of water balance, namely evaporation from soil and canopy. The data of 6 Global climate models of theoretical experiment Land Use Model Intercomparison Project (LUMIP) was used in the research. The aim of this experiment is to reveal the influence of global deforestation with further replacement by grass cover on distribution of climate characteristics. It was done for the period 1850—1929, where the first part 1850—1899 refers to the pre-industrial period or period with minimal mostly constant anthropogenic influence; the second part is the next 30 years — 1900—1929. During the pre-industrial period 1850—1899 land cover was reduced globally with a trend of 400 thousand km2 per year and during 1900—1929 it was stable. Defining the impact of deforestation, the normalization over the first 20 years (1850—1869) was performed and there were found anomalies of climatic characteristics as difference to this basic period. Deforestation with further replacement of the forest cover by grass causes an increase in soil evaporation with the trend up to 1.6 mm/10 years in the warm season with more significant changes in April —July, as deforestation reveals more of the soil. Thus, the correlation was −0.8 ...−0.4 between forest cover and soil evaporation with maximal changes in April. It can be connected with grass being sparse in this period but later on covering more soil and preventing intensive evaporation. On the contrary, evaporation from canopy in global climate models is reduced with deforestation as the evaporation area is shrunk. This effect was revealed during all seasons in most grid points, where deforestation occurs. But the biggest change is found in spring and summer months with values up to −0.8 mm/10 years and correlation r = 0.4 ... 0.9 depending on the model and the season. Thus, we found an effect of increasing evaporation from soil while decreasing evaporation from canopy in climate modeling as the effect of partial deforestation on the territory of Ukraine. These changes can cause redistribution in water balance components of the territory and have consequences for hydrological regime, agrometeorology etc. In particular, the increase in soil evaporation due to deforestation can provoke more intensive soil aridization and degradation. The influence of deforestation on total soil moisture and regime of precipitation will be presented in the next publication.

The Lower Havel River Region (Brandenburg, Germany): A 230-Year-Long Historical Map Record Indicates a Decrease in Surface Water Areas and Groundwater Levels

Instrumental data show that the groundwater and lake levels in Northeast Germany have decreased over the past decades, and this process has accelerated over the past few years. In addition to global warming, the direct influence of humans on the local water balance is suspected to be the cause. Since the instrumental data usually go back only a few decades, little is known about the multidecadal to centennial-scale trend, which also takes long-term climate variation and the long-term influence by humans on the water balance into account. This study aims to quantitatively reconstruct the surface water areas in the Lower Havel Inner Delta and of adjacent Lake Gülpe in Brandenburg. The analysis includes the calculation of surface water areas from historical and modern maps from 1797 to 2020. The major finding is that surface water areas have decreased by approximately 30% since the pre-industrial period, with the decline being continuous. Our data show that the comprehensive measures in Lower Havel hydro-engineering correspond with groundwater lowering that started before recent global warming. Further, large-scale melioration measures with increasing water demands in the upstream wetlands beginning from the 1960s to the 1980s may have amplified the decline in downstream surface water areas.

Effects of solar radiation modification on the ocean carbon cycle: An earth system modeling study

Solar radiation modification (SRM, also termed as geoengineering) has been proposed as a potential option to counteract anthropogenic warming. The underlying idea of SRM is to reduce the amount of sunlight reaching the atmosphere and surface, thus offsetting some amount of global warming. Here, the authors use an Earth system model to investigate the impact of SRM on the global carbon cycle and ocean biogeochemistry. The authors simulate the temporal evolution of global climate and the carbon cycle from the pre-industrial period to the end of this century under three scenarios: the RCP4.5 CO2 emission pathway, the RCP8.5 CO2 emission pathway, and the RCP8.5 CO2 emission pathway with the implementation of SRM to maintain the global mean surface temperature at the level of RCP4.5. The simulations show that SRM, by altering global climate, also affects the global carbon cycle. Compared to the RCP8.5 simulation without SRM, by the year 2100, SRM reduces atmospheric CO2 by 65 ppm mainly as a result of increased CO2 uptake by the terrestrial biosphere. However, SRM-induced change in atmospheric CO2 and climate has a small effect in mitigating ocean acidification. By the year 2100, relative to RCP8.5, SRM causes a decrease in surface ocean hydrogen ion concentration ([H+]) by 6% and attenuates the seasonal amplitude of [H+] by about 10%. The simulations also show that SRM has a small effect on globally integrated ocean net primary productivity relative to the high-CO2 simulation without SRM. This study contributes to a comprehensive assessment of the effects of SRM on both the physical climate and the global carbon cycle.摘要太阳辐射干预地球工程是应对气候变化的备用应急措施. 其基本思路是通过减少到达大气和地表的太阳辐射, 从一定程度上抵消温室效应引起的全球变暖. 本研究使用地球系统模式模拟理想化太阳辐射干预方法对海洋碳循环的影响. 模拟试验中, 通过直接减少太阳辐射将RCP8.5 CO2排放情景下的全球平均温度降低到RCP4.5情景下的温度. 模拟结果表明, 到2100年, 相对于RCP8.5情景, 减少太阳辐射通过增加陆地碳汇, 使大气CO2浓度降低了65 ppm. 减少太阳辐射对海洋酸化影响很小. 到 2100 年, 相对于RCP8.5情景, 减少太阳辐射使海表平均氢离子浓度减少6%, pH上升0.03, 同时使海表平均氢离子浓度的季节变化振幅衰减约10%. 模拟结果还表明, 减少太阳辐射对全球海洋净初级生产力的影响较小. 本研究有助于深化我们对太阳辐射干预地球工程的气候和碳循环效应的认知和综合评估.

ВКУСОВЫЕ ПРЕДПОЧТЕНИЯ В КОНТЕКСТЕ ТРАНСФОРМАЦИИ КУЛЬТУРЫ (ПОРРИДЖ И ШОТЛАНДСКИЕ ТРАДИЦИИ)

Investigation of the dynamics of cultural transformations is one of the basic directions of cultural studies. Changes in the life of society set a coordinate system that allows us to reveal, by the example of individual elements of culture, the essential features of the functioning of cultural traditions. Post-industrial society demonstrates examples when cultural traditions actively influence on the structures of everyday life. This article examines the functioning of «food» (oat dishes) in the life of Scottish society in the past and today. The author analyzes «food» as a sign that has many meanings. When revealing this topic, the author turns to the analysis of the natural and climatic conditions of Scotland, the peculiarities of the culture of the Scots in the pre-industrial period and modern everyday practices. Exam-ples illustrating the complex semantic meaning of «food» in different contexts demonstrate that this «sign» is confined to certain conditions and, at the same time, the transformation and evolution of the perception of «food» is noted in the context of current problems of society and existence, in particular, nostalgic reminiscent moods in society. The author analyzes the semantic content of «food», determining the value of the emotional response in the process of functioning of «food» in society. The author notes the multiplicity of meanings of the sign «food», which ensures the continuity of attention to it in different epochs, as well as the transformation of interest in it. Special attention is paid to the analysis of «food» as a factor that has an indirect influence on the formation of a person's attitude to the sphere of everyday life. National «food», as an element of everyday culture, contains many meanings and, in a post-industrial society, serves to strengthen cultural identity. The article outlines the direction of research on the semantic ambiguity of «food», which can become the basis for understanding the role of cultural traditions in the discourse of modernity.

МИФОЛОГИЧЕСКИЕ АРХЕТИПЫ КАК ОСНОВА НАЦИОНАЛЬНОГО САМОСОЗНАНИЯ РУССКОГО НАРОДА

The article analyzes the basic provisions of understanding myths and mythological archetypes that are typical for ps ychoanalysis, analytical and post-Jungian psychology. The generalizing analysis of the main works of authoritative specialists in mythology (J. Campbell and M. Eliade) is presented. The functions of the universal mythological archetypes of mankind are revealed. National archetypes, which are the ideological dominants of the national identity of the Russian people in the pre-industrial period, are considered. The main characteristics of modern myth-making are identified.

Mercury in bottom sediments of Russian Arctic lakes

Abstract. This article presents the results of studying the distribution of mercury in the cores of bottom sediments of both background and technogenic Arctic lakes in three regions: the Kola North, Malozemelskaya tundra and northwest Siberia. For all cores, the elemental composition, granulometry, and loss on ignition (LOI) were determined layer by layer. Mercury showed a significant excess of the local background in the near-surface sedimentary layers of most lakes. Fluxes of mercury from the pre-industrial period to the present were calculated. We discuss the possibility of technogenic pollution due to transboundary transfer.

THE EVOLUTION OF HUMAN CAPITAL THEORY

The development of the leading countries of the world has led to the formation of a post-industrial economic system based on knowledge, innovation, global information systems, a new quality of education, and new technologies. One of the pillars of the new economy is human capital, which is an important factor in the socio-economic development of modern society. There are many definitions of the term "human capital". Summarizing the definitions existing in the economic literature, we can say that human capital is a stock of health, knowledge, skills, motivation accumulated as a result of investments, which is used in the labor process, ensuring productivity and income growth. The theory of human capital was formed within the framework of the conceptual foundations of the new classical theory and was further developed by various researchers who enriched the theory of human capital with the achievements of institutional, behavioral, evolutionary and synergetic theories. The origin of the theory of human capital was associated with a rethinking of the role of man in the post-industrial economy, since a person could no longer be considered as an "appendage" of capital. If in the pre-industrial period land was the most important factor of production, and capital in the industrial economy, then human capital becomes the most important factor in the post-industrial economy as the paradigm of development of economic growth, human intellectual and creative potential changes. abilities become a source of development.

Future Changes in δ13C of Dissolved Inorganic Carbon in the Ocean

AbstractEmissions of carbon dioxide from fossil fuel combustion are reducing the ratio 13C/12C, δ13C, in atmospheric CO2 and in the carbon in the ocean and terrestrial biosphere that exchanges with the atmosphere on timescales of decades to centuries. Future changes to fossil fuel emissions vary across different scenarios and may cause decreases of more than 6% in atmospheric δ13CO2 between 1850 and 2100. The effects of these potential changes on the three‐dimensional distribution of δ13C in the ocean have not yet been investigated. Here, we use an ocean biogeochemical‐circulation model forced with a range of Shared Socioeconomic Pathway (SSP)‐based scenarios to simulate δ13C in ocean dissolved inorganic carbon from 1850 to 2100. In the future, vertical and horizontal δ13C gradients characteristic of the biological pump are reduced or reversed, relative to the preindustrial period, with the reversal occurring in higher emission scenarios. For the highest emission scenario, SSP5‐8.5, surface δ13C in the center of Pacific subtropical gyres falls from 2.2% in 1850 to −3.5% by 2100. In lower emission scenarios, δ13C in the surface ocean decreases but then rebounds. The relationship between anthropogenic carbon (Cant) and δ13C in the ocean shows a larger scatter in all scenarios, suggesting that uncertainties in δ13C‐based estimates of Cant may increase in the future. These simulations were run with fixed physical forcing and ocean circulation, providing a baseline of predicted δ13C. Further work is needed to investigate the impact of climate‐carbon cycle feedbacks on ocean δ13C changes.

Projected changes in global terrestrial near-surface wind speed in 1.5 °C–4.0 °C global warming levels

Understanding future changes in global terrestrial near-surface wind speed (NSWS) in specific global warming level (GWL) is crucial for climate change adaption. Previous studies have projected the NSWS changes; however, the changes of NSWS with different GWLs have yet to be studied. In this paper, we employ the Max Planck Institute Earth System Model large ensembles to evaluate the contributions of different GWLs to the NSWS changes. The results show that the NSWS decreases over the Northern Hemisphere (NH) mid-to-high latitudes and increases over the Southern Hemisphere (SH) as the GWL increases by 1.5 °C–4.0 °C relative to the preindustrial period, and that these characteristics are more significant with the stronger GWL. The probability density of the NSWS shifts toward weak winds over NH and strong winds over SH between the current climate and the 4.0 °C GWL. Compared to 1.5 °C GWL, the NSWS decreases −0.066 m s−1 over NH and increases +0.065 m s−1 over SH with 4.0 °C GWL, especially for East Asia and South America, the decrease and increase are most significant, which reach −0.21 and +0.093 m s−1, respectively. Changes in the temperature gradient induced by global warming could be the primary factor causing the interhemispheric asymmetry of future NSWS changes. Intensified global warming induces the reduction in Hadley, Ferrell, and Polar cells over NH and the strengthening of the Hadley cell over SH could be another determinant of asymmetry changes in NSWS between two hemispheres.

Climate and ice sheet evolutions from the last glacial maximum to the pre-industrial period with an ice-sheet–climate coupled model

Abstract. The last deglaciation offers an unique opportunity to understand the climate–ice-sheet interactions in a global warming context. In this paper, to tackle this question, we use an Earth system model of intermediate complexity coupled to an ice sheet model covering the Northern Hemisphere to simulate the last deglaciation and the Holocene (26–0 ka). We use a synchronous coupling every year between the ice sheet and the rest of the climate system and we ensure a closed water cycle considering the release of freshwater flux to the ocean due to ice sheet melting. Our reference experiment displays a gradual warming in response to the forcings, with no abrupt changes. In this case, while the amplitude of the freshwater flux to the ocean induced by ice sheet retreat is realistic, it is sufficient to shut down the Atlantic meridional overturning circulation from which the model does not recover within the time period simulated. However, with reduced freshwater flux we are nonetheless able to obtain different oceanic circulation evolutions, including some abrupt transitions between shut-down and active circulation states in the course of the deglaciation. The inclusion of a parameterisation for the sinking of brines around Antarctica also produces an abrupt recovery of the Atlantic meridional overturning circulation, absent in the reference experiment. The fast oceanic circulation recoveries lead to abrupt warming phases in Greenland. Our simulated ice sheet geometry evolution is in overall good agreement with available global reconstructions, even though the abrupt sea level rise at 14.6 ka is underestimated, possibly because the climate model underestimates the millennial-scale temperature variability. In the course of the deglaciation, large-scale grounding line instabilities are simulated both for the Eurasian and North American ice sheets. The first instability occurs in the Barents–Kara seas for the Eurasian ice sheet at 14.5 ka. A second grounding line instability occurs ca. 12 ka in the proglacial lake that formed at the southern margin of the North American ice sheet. With additional asynchronously coupled experiments, we assess the sensitivity of our results to different ice sheet model choices related to surface and sub-shelf mass balance, ice deformation and grounding line representation. While the ice sheet evolutions differ within this ensemble, the global climate trajectory is only weakly affected by these choices. In our experiments, only the abrupt shifts in the oceanic circulation due to freshwater fluxes are able to produce some millennial-scale variability since no self-generating abrupt transitions are simulated without these fluxes.