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The tropical Andes has been less studied in terms of erosion processes in comparison to other major mountain ranges in the world. Environmental gradients are steepest along the western flank of the Andes that is characterized by marked differences in vegetation, rough topography with deeply incised canyons, and highly variable and extreme precipitation patterns. Previous efforts mostly focused on sediment fluxes in large rivers draining to e.g. the Amazon basin while small to medium-sized rivers such as the ones flowing towards the Pacific Ocean have been relegated. They highlighted the link between sediment yield, anthropogenic and natural factors, e.g. climate, topography, river runoff, lithology and vegetation cover. In this study, we identified the spatial patterns of specific sediment yield along the western slopes of the Peruvian Andes between 3° and 13° S latitude for 21 catchments. We collected and analysed data from 22 environmental factors to elucidate their importance on spatially varying sediment yield. The sediment load was derived from gauging stations, reservoir sedimentation and water turbidity over a 30-yr period. The specific sediment yield varies strongly along the Peruvian western Andes as a consequence of the spatial variation in climate, topography and land cover controlling sediment production and transport. We reported higher-than-average specific sediment yields for the central part (6°-11°S) with values of 2130 and 2300 t km−2 yr−1 and low and uniform yields of 39 to 551 t km−2 yr−1 in the southern part (11° − 14.5° S). Given the scarcity of data on sediment yield, we included an uncertainty assessment based on bootstrapping approaches as to get a better grasp on the potential range of specific sediment yields in the study region. Using statistical techniques including Spearman correlation rank, univariate and multivariate regression analyses, we were able to determine the importance of the 22 environmental variables on the specific sedimen

Understanding the variations of water cycle on orbital timescale and their response to astronomical parameters, greenhouse gases (GHG) and ice sheets is one of the focuses in paleoclimate study. Sea ice and precipitation, two important components of the water cycle, are paid much attention. A better understanding of their variations on orbital timescale, especially their response to external forcing and related processes and feedbacks, could provide insight on their long-term variations in the future. The latest research results show that, on orbital scale, the Arctic sea ice is more sensitive to insolation, while the Southern Ocean sea ice is more sensitive to GHG. Under the combined influence of insolation and GHG, the last nine interglacials all have much less summer Arctic sea ice, as compared to both the present-day and the future, due to the much higher Northern Hemisphere (NH) summer insolation. As compared to the future, the last nine interglacials all have much more annual and seasonal Southern Ocean sea ice due to their much lower CO2. In terms of the astronomical parameters, the Arctic sea ice is more influenced by precession, whereas obliquity plays a more important role in the Southern Ocean sea ice. The different responses of Arctic and Southern Ocean sea ice to astronomical parameters and CO2 are mainly due to their different geographical locations. The Arctic ocean is relatively closed and it is located in the northern highest latitudes, which make it only receives very little insolation during winter and it is mainly influenced by precession-dominated summer insolation. The summer insolation not only influences the summer Arctic sea ice, but also has an effect on the winter one through the summer remnant effect. In addition, the Arctic sea ice is also affected by the vegetation in the northern mid and high latitudes, which is mainly dominated by precession. As compared to the Arctic, the latitudes of Southern Ocean are lower and it is more open, whi

Quercus robur/Quercus petraea and Pinus sylvestris are widely distributed and economically important tree species in Europe co-occurring on mesotrophic, xeric and mesic sites. Increasing dry conditions may reduce their growth, but growth reductions may be modified by mixture, competition and site conditions. The annual diameter growth in monospecific and mixed stands along an ecological gradient with mean annual temperatures ranging from 5.5 °C to 11.5 °C was investigated in this study. On 36 triplets (108 plots), trees were cored and the year-ring series were cross-dated, resulting in year-ring series of 785 and 804 trees for Q. spp. and P. sylvestris, respectively. A generalized additive model with a logarithmic link was fit to the data with random effects for the intercept at the triplet, year and tree level and a random slope for the covariate age for each tree; the Tweedie-distribution was used. The final model explained 87 % of the total variation in diameter increment for both tree species. Significant covariates were age, climate variables (long-term mean, monthly), local competition variables, relative dbh, mixture, stand structure and interactions thereof. Tree growth declined with age and local density and increased with social position. It was positively influenced by mixture and structural diversity (Gini coefficient); mixture effects were significant for P. sylvestris only. The influence of potential evapotranspiration (PET) in spring and autumn on tree growth was positive and non-linear, whereas tree growth sharply decreased with increasing PET in June, which proved to be the most influential month on tree growth along the whole ecological gradient. Interactions of PET with tree social position (relative dbh) were significant in July and September for Q. spp. and in April for P. sylvestris. Interactions of climate with density or mixture were not significant. Climatic effects found agree well with previous results from intra-annual growth studies and

Predicting the occurrence probability of species is intrinsically dependent on the quality of the training dataset and, in particular, on the sample prevalence (i.e., the ratio between presences and absences). Whenever the number of presences and absences is not equal within the training dataset, the predictions deviate towards higher values as the sample prevalence increases and vice versa. As a result, probability models of species occurrence with different sample prevalence cannot be directly compared. The favourability concept was introduced to amend this limitation. Indeed, the favourability – i.e., the variation in the probability of occurrence regardless the sample prevalence – could reduce the degree of uncertainty when comparing species distributions despite different sample prevalences. To test this hypothesis, we simulated 50 virtual species and compared the predictive performance of four probability-based and favourability-based Species Distribution Models (GLM, GAM, RF, BRT) under a set of different prevalence values and sampling strategies (i.e, random and stratified sampling). Favourability-based models performed slightly better than probability-based models in predicting the species distribution over geographic space, confirming also their capability to reduce the variability of the predictions across different degrees of sample prevalence.

Well-designed land use governance that involves multiple stakeholders is crucial to reducing deforestation in tropical commodity frontiers. The effectiveness of different policy mixes is difficult to assess due to long implementation times and challenges to conducting real-world experiments. Here we introduce an agent-based simulation of land use governance (ABSOLUG) to examine the interactions among governments, commodity producers, and civil society and assess the impacts of different land use governance approaches on deforestation. The model represents a generic commodity producing landscape in the tropics with a central marketplace and features four groups of agents: largeholders, smallholders, NGOs, and a government. The objective of largeholders and smallholders is to generate profits through the production of commodity crops. Statistical evaluation through local and global sensitivity analyses shows that the model is robust, and few parameters show threshold behaviors. We used a hands-off and a proactive-government scenario to evaluate the model operationally. The hands-off scenario was inspired by high rates of tropical deforestation in the second half of the 20th century and the pro-active government scenario by a few recent cases of forest transition countries. The hands-off scenario led to quasi-complete deforestation of the landscape at the end of the simulation period. Deforestation in the proactive-government scenario decreased and eventually stopped in the second half of the simulation period, followed by reforestation.

Various abrupt climate events have been reported during the last glacial period, but their regional expressions and causes remain complex and not fully understood largely due to lack of high-resolution paleoclimate records. In this study, a high-resolution loess sequence is presented from North China which is significantly influenced by the East Asian Summer Monsoon, and its multiple proxies reveal two strong, abrupt cooling-drying events occurring at 48 ka and ∼42 ka. The 48 ka event corresponds to the fifth Heinrich (H5) event that was characterized by catastrophic iceberg discharges into the subpolar North Atlantic Ocean. Our loess and model results suggest that the 48 ka event could result from the unique and extreme orbital configuration at 48 ka, characterized by the smallest latitudinal summer insolation gradient over the last glacial period. This orbital configuration led to a cooling-drying in the low and mid-latitudes but a warming in high latitudes. The ∼42 ka event corresponds to a catastrophic environmental crisis discovered on the Eurasian and Australian continents. It also corresponds to a major reversal of the Earth's magnetic poles, i.e., the Laschamps Excursion. The cosmic ray increase due to this Excursion could affect the pedogenesis and dust deposition of the loess sequence via cloud increase, regional cooling, aerosol increase and local wind strengthening. This study is a clear demonstration that both extreme orbital conditions and the change of the Earth's magnetic field could cause abrupt climate and environmental changes.

The loess-paleosol sequences in the Chinese Loess Plateau (CLP) are an important terrestrial paleoclimate record. However, quantitative understanding of the response of paleosol development to various climate and environmental factors remains poor. Based on simulations with combined soil-climate models (SoilGen2-LOVECLIM1.3), this study investigates the sensitivity of paleosol development to different soil forming factors as well as the influence of ice sheets and astronomical forcing during the interglacials of the past 500 ka. Sensitivity analyses show that precipitation, dust addition and evapotranspiration are the dominant factors controlling the interglacial paleosol formation, but their relative importance varies between intergalcials and for different soil properties such as calcite and clay contents. Our results show that the simulated S1, S2, S3, S5-1 paleosols, which correspond to MIS 5, 7, 9 and 13 respectively, exhibit strong relationship with precession through its control on precipitation, whereas the precession signal is weak in the simulated S4 paleosol, in line with the weak precession variation during MIS 11. The results also show variable length of lags between different soil properties and precession and also in different interglacials. The lag between the simulated calcite and precession is shorter than that of clay. Moreover, clay content also shows strong relation with temperature during MIS 5 and MIS 13. Large ice sheets in the early and late phases of the interglacials have substantial impact on both temperature and precipitation in the CLP and thus on carbonate leaching and clay migration. Therefore, the simulated paleosols result mainly from the joint effect of precession and ice sheets via their control on local climate, and they show qualitative agreement with observations.

Context. The orientation and rotation of Mars can be described by a set of Euler angles (longitude, obliquity, and rotation angles) and estimated from radioscience data (tracking of orbiters and landers), which can then be used to infer the planet's internal properties. The data are analyzed using a modeling expressed within the barycentric celestial reference system (BCRS). This modeling includes several relativistic contributions that need to be properly taken into account to avoid any misinterpretation of the data. Aims. We provide new and more accurate (to the 0.1 mas level) estimations of the relativistic corrections to be included in the BCRS model of the orientation and rotation of Mars. Methods. There are two types of relativistic contributions with regard to Mars's rotation and orientation: (i) those that directly impact the Euler angles and (ii) those resulting from the time transformation between a local Mars reference frame and BCRS. The former contribution essentially corresponds to the geodetic effect, as well as to the smaller Lense-Thirring and Thomas precession effects, and we computed their values assuming that Mars evolves on a Keplerian orbit. As for the latter contribution, we computed the effect of the time transformation and compared the rotation angle corrections obtained, based on the assumption that the planets evolve on Keplerian orbits, with the corrections obtained, based on realistic orbits as described by the ephemerides. Results. The relativistic correction in longitude mainly comes from the geodetic effect and results in a geodetic precession (6.754 mas yr−1) and geodetic annual nutation (0.565 mas amplitude). For the rotation angle, the correction is dominated by the effect of the time transformation. The main annual, semiannual, and terannual terms display amplitudes of 166.954 mas, 7.783 mas, and 0.544 mas, respectively. The amplitude of the annual term differs by about 9 mas from the estimate usually considered by the community.

This introductory chapter describes the science base, objectives, and methods of the “Planetary Exploration, Horizon 2061” foresight exercise. It first describes the class of astrophysical objects whose future investigation and improved understanding are the objective of the Horizon 2061 foresight: planetary systems. It then introduces the four “pillars” of science-driven planetary exploration: (1) the science of planetary systems—six key science questions about planetary systems, their origins, evolution, workings, and habitability, which can be addressed via in situ exploration only in the solar system; (2) the space missions needed to perform the observations that can inform these questions; (3) the technologies needed to fly these challenging space missions; (4) the space-based and ground-based infrastructures and services needed to support these missions to all destinations in the Solar System. It then describes the method followed by the “Horizon 2061” exercise to successively build these four “pillars,” and how this method and work flow are reflected in the structure of the book and translated into each of its seven chapters.

This chapter reviews the way the six key questions about planetary systems, from their origins to the way they work and their habitability, identified in Chapter 1 (Blanc et al., 2021), can be addressed by means of solar system exploration, and how one can find partial answers to these six questions by flying to the different provinces to the solar system: terrestrial planets, giant planets, small bodies, and up to its interface with the local interstellar medium. It derives from this analysis a synthetic description of the most important space observations to be performed at the different solar system objects by future planetary exploration missions. These “observation requirements” illustrate the diversity of measurement techniques to be used as well as the diversity of destinations where these observations must be made. They constitute the base for the identification of the future planetary missions we need to fly by 2061, which are described in Chapter 4.

With the discovery of thousands of extrasolar planetary systems it becomes more and more evident that a large variety of planetary system architectures, including very different types of planets, have been realized in nature. Our solar system is just one among many. We do not know yet whether the evolution of the planets and moons in the solar system is typical for such objects in similar environments, or not. This includes in particular the capability to develop habitable surface conditions, or even life. Planets orbiting host stars different to our Sun can experience very different environmental conditions such as stellar spectral energy distributions and harsh cosmic rays impacting the orbiting planets. The dynamical evolution of planetary systems depends on the formation processes and interactions with the protoplanetary disk as well as migration processes. Looking at extrasolar planets in the sky today, we see systems in different astrophysical environments, at different ages and with different evolutionary histories. As outlined above, the number of processes shaping the characteristics of planets is large. Yet, for extrasolar planets the number of observables is small. Observational constraints are usually limited to orbital parameters, planetary masses, radii, and some of the atmospheric constituents. In fortunate cases additional constraints like magnetic fields and Love numbers will become accessible in the future. Additional constraints are given by the host star characteristics (metallicity, composition, age, temperature, etc.), but the link between stellar properties and planetary characteristics is complex and not fully understood yet. In view of this limited achievable data set, it becomes vital to better understand how we can learn from our detailed knowledge of the bodies in the solar system to better understand the planets and moons in extrasolar systems. Vice versa, extrasolar systems show us the possible variety of planetary systems, which helps

The seasonal cycle of the Antarctic sea ice extent is strongly asymmetric, with a relatively slow increase after the summer minimum followed by a more rapid decrease after the winter maximum. This cycle is intimately linked to the seasonal cycle of the insolation received at the top of the atmosphere, but sea ice processes as well as the exchanges with the atmosphere and ocean may also play a role. To quantify these contributions, a series of idealized sensitivity experiments have been performed with an eddy-permitting (∘) NEMO-LIM3 (Nucleus for European Modelling of the Ocean–Louvain-la-Neuve sea ice model version 3) Southern Ocean configuration, including a representation of ice shelf cavities, in which the model was either driven by an atmospheric reanalysis or coupled to the COSMO-CLM2 regional atmospheric model. In those experiments, sea ice thermodynamics and dynamics as well as the exchanges with the ocean and atmosphere are strongly perturbed. This perturbation is achieved by modifying snow and ice thermal conductivities, the vertical mixing in the ocean top layers, the effect of freshwater uptake and release upon sea ice growth and melt, ice dynamics, and surface albedo. We find that the evolution of sea ice extent during the ice advance season is largely independent of the direct effect of the perturbation and appears thus mainly controlled by initial state in summer and subsequent insolation changes. In contrast, the melting rate varies strongly between the experiments during the retreat, in particular if the surface albedo or sea ice transport are modified, demonstrating a strong contribution of those elements to the evolution of ice coverage through spring and summer. As with the advance phase, the retreat is also influenced by conditions at the beginning of the melt season in September. Atmospheric feedbacks enhance the model winter ice extent response to any of the perturbed processes, and the enhancement is strongest when the albedo is modified. The

Sedimentary rocks can record signals produced by highly complex processes. These signals are generated by a progressive deposition of sediments which can be affected, mainly through the climate system, by regular astronomical cycles (i.e. Milankovitch cycles), and by irregular oscillations like the El Niño-Southern Oscillation. Also, usually through biological, chemical and/or physical post-depositional processes, the sedimentary records can be affected by pattern-creating heterogeneous processes. The noise in the signals further complicates the records, and the deposition rate (or sedimentation rate) can fluctuate, which greatly reduces the effectiveness of the classical stationary time-series analysis methods commonly used in cyclostratigraphy (i.e. the study of the cycles found in the sedimentary records). Faced with this multiplicity of processes, a common approach used in cyclostratigraphy is to reduce each signal to more manageable sub-signals, either over a given range of frequencies (e.g., by filtering), or by considering a continuum of constant frequencies (e.g., using transforms). This makes it possible to focus on the features of interest, commonly astronomical cycles. However, working with sub-signals is not trivial. Firstly, sub-signals have a certain amount of cross-cancellation when they are summed back to reconstruct the initial signal. In extreme cases, this means that in filters and in transforms, wiggles that are not present in the initial signal can appear in the sub-signals. Secondly, the sub-signals considered often cannot be summed to reconstruct the initial signal: implying that processes affecting the signal remain unstudied. It is possible to take cross-cancellation into account and to consider the entire content of a signal by dividing the signal into a decomposition: a set of sub-signals that can be added back together to reconstruct the original signal. We discuss here how to reframe commonly used time-series analysis techniques in the c

Ticks have medical and economic importance due to their ability to transmit pathogens to humans and animals. In tropical and sub-tropical countries, tick-borne diseases (TBD) are among the most important diseases affecting livestock and humans. The fast spread of ticks and TBD requires a quick development and application of efficient prevention and/or control programs. Therefore, prior investigations on TBD and related vectors epidemiology, for instance, through accurate epidemiological models, are mandatory. This study aims to develop models to forecast suitable habitat for Rhipicephalus microplus distribution in West Africa. Tick occurrences were assembled from 10 different studies carried out in six West African countries in the past decade. Six statistical models (maximum entropy in a single model and generalised linear model, generalised additive model, random forest, boosted regression tree and support vector machine model in an ensemble model) were applied and compared to predict the habitat suitability of R. microplus distribution in West Africa. Each model was evaluated with the area under the receiver operating characteristic curve (AUC), the true skill statistic (TSS) and the Boyce index (BI). The selected models had good performance according to their AUC (above .8), TSS (above .7) and BI (above .8). Temperature played a key role in MaxEnt model, whereas normalised difference vegetation index (NDVI) was the most important variable in the ensemble model. The model predictions showed coastal countries of West Africa as more suitable for R. microplus. However, some Sahelian areas seems also favourable. We stress the importance of vector surveillance and control in countries that have not yet detected R. microplus but are in the areas predicted to host suitable habitat. Indeed, awareness-raising and training of different stakeholders must be reinforced for better prevention and control of this tick in these different countries according to their status.

Quaternary monsoon changes in East Asia have been extensively investigated by proxy records from continental and marine archives. However, these proxy indicators often show controversial characteristics in terms of trends and rhythms, perplexing understanding of orbital-scale monsoon dynamics. Here we review the orbital-scale monsoon variability and dynamics in East Asia by comparing multiple proxies from loess, lake, speleothem, and marine records with the HadCM3 modeling result. Evolutionary power spectra of loess grain size and sea surface temperature exhibit a remarkable shift from 41- to 100-kyr cycles across the mid-Pleistocene transition (MPT), whereas other proxy records (e.g. 13C of loess carbonate, pollen concentration in lake sediments, and magnetic mineral compositions in marine sediments) display strong and persistent precession cycles through the Quaternary, along with distinct 100-kyr cycles after the MPT. Simulations with the HadCM3 climate model reveal that the effects of orbital parameters, ice volume, and CO2 concentration on the temperature, precipitation, and southerly winds are seasonally and spatially different in East Asia. In the summer season, orbitally induced insolation plays a dominant role in driving changes in these three climate variables except for summer precipitation in south China (20-30ºN), whilst annual changes in precipitation and temperature are jointly affected by insolation, ice volume, and CO2. Proxy-model comparison suggests that several land-based proxies are sensitive to changes in summer precipitation, annual precipitation, and annual temperature, though their responses to astronomical, ice, and CO2 forcing being quite different between north and south China. Our proxy-model comparison reveals that diverse expression of Quaternary climate periodicities was provoked by different sensitivities of marine and terrestrial proxies to seasonal and/or annual changes in precipitation and temperature, and by different responses

Disentangling the links between terrestrial vegetation changes and astronomical forcing as well as CO2 is of great help to understand the sensitivity of contemporary vegetation and predict future vegetation and climate changes, yet it remains challenging. Given the distinct differences in astronomical configurations and CO2 concentration between Marine Isotope Stage (MIS) 11 and 13, here we investigate the role of astronomical forcing and CO2 on global vegetation changes during these two interglacials based on transient simulations performed with the model LOVECLIM1.3. Our results show that during these two interglacials, astronomical forcing plays a dominant role on the vegetation evolution, with the effect of CO2 being relatively small. The effect of astronomical forcing on vegetation can be explained successively by the relationship between climate (temperature, precipitation) and the astronomical parameters and by the relationship between vegetation and climate. The relative effect of precession and obliquity on vegetation strongly depends on regions and on interglacials. In general, obliquity plays a more important role on vegetation variations during MIS-11, while precession is more important during MIS-13. Our results also reveal a clear half-precession cycle (~ 10 ka) in the variations of temperature, precipitation and vegetation in the tropical area during MIS-13, as a direct response to the tropical insolation. However, no obvious half-precession cycle is simulated during MIS-11 due to its weak precession variation but large obliquity variation, indicating that half-precession cycle is not stable in time.

Understanding the sea ice variability and the mechanisms involved during warm periods of the Earth is essential for a better understanding of the sea ice changes at the present and in the future. Based on simulations with the model LOVECLIM, this study investigates the sea ice variations during the last nine interglacials and focuses on the inter-comparison between interglacials as well as their differences from the present and future. Our results show that the annual mean Arctic sea ice variation is primarily controlled by local summer insolation, while the annual mean Southern Ocean sea ice variation is more influenced by the CO2 concentration but the effect of local summer insolation can’t be ignored. The lowest Arctic sea ice area results from the highest summer insolation at MIS-15, and the lowest Southern Ocean sea ice area at MIS-9 is explained by the highest CO2 concentration and moderate local summer insolation. As compared to the present, the last nine interglacials all have much less sea ice in the Arctic annually and seasonally due to high summer insolation. They also have much less Arctic sea ice in summer than the double CO2 experiment, which makes to some degree the interglacials possible analogues for the future in terms of the changes of sea ice. However, compared to the double CO2 experiment, the interglacials all have much more sea ice in the Southern Ocean due to their much lower CO2 concentration, which suggests the inappropriateness of considering the interglacials as analogues for the future in the Southern Ocean. Our results suggest that in the search for potential analogues of the present and future climate, the seasonal and regional climate variations should be considered.

We introduce PARASO, a novel five-component fully coupled regional climate model over an Antarctic circumpolar domain covering the full Southern Ocean. The state-of-the-art models used are the fast Elementary Thermomechanical Ice Sheet model (f.ETISh) v1.7 (ice sheet), the Nucleus for European Modelling of the Ocean (NEMO) v3.6 (ocean), the Louvain-la-Neuve sea-ice model (LIM) v3.6 (sea ice), the COnsortium for Small-scale MOdeling (COSMO) model v5.0 (atmosphere) and its CLimate Mode (CLM) v4.5 (land), which are here run at a horizontal resolution close to . One key feature of this tool resides in a novel two-way coupling interface for representing ocean–ice-sheet interactions, through explicitly resolved ice-shelf cavities. The impact of atmospheric processes on the Antarctic ice sheet is also conveyed through computed COSMO-CLM–f.ETISh surface mass exchange. In this technical paper, we briefly introduce each model's configuration and document the developments that were carried out in order to establish PARASO. The new offline-based NEMO–f.ETISh coupling interface is thoroughly described. Our developments also include a new surface tiling approach to combine open-ocean and sea-ice-covered cells within COSMO, which was required to make this model relevant in the context of coupled simulations in polar regions. We present results from a 2000–2001 coupled 2-year experiment. PARASO is numerically stable and fully operational. The 2-year simulation conducted without fine tuning of the model reproduced the main expected features, although remaining systematic biases provide perspectives for further adjustment and development.

The Guinea Coast is the southern part of the West African continent. Its summer rainfall variability mostly occurs on interannual timescales and is highly influenced by the sea surface temperature (SST) variability in the eastern equatorial Atlantic, which is the centre of action of the Atlantic Niño mode. Using both historical and scenario (SSP5–8.5) simulations from 31 general circulation models (GCMs) participating in the sixth phase of the Coupled Model Intercomparison Project (CMIP6), we first show that these models present a wet bias during boreal summer. This bias is associated with overly high mean boreal summer SSTs in the eastern equatorial and south Atlantic regions. Next, we analyse the near-term, mid-term and long-term changes of the Atlantic Niño relative to the present-day situation, in a climate with a high anthropogenic emission of greenhouse gases. We find a gradual decrease in the equatorial Atlantic SST anomalies associated with the Atlantic Niño in the future. This result reflects a possible reduction of the Atlantic Niño variability in the future due to a weakening of the Bjerknes feedback over the equatorial Atlantic. In a warmer climate, an anomalous higher sea level pressure in the western equatorial Atlantic relative to the eastern equatorial Atlantic weakens the climatological trade winds over the equatorial Atlantic. As a result, the eastern equatorial Atlantic thermocline is deeper and responds less to the Atlantic Niño events. Among the models that simulate a realistic rainfall pattern associated with the Atlantic Niño in the present-day climate, there are 12 GCMs which project a long-term decrease in the Guinea Coast rainfall response related to the Atlantic Niño. In these models, the zonal 850 hPa wind response to the Atlantic Niño over the equatorial Atlantic is strongly attenuated in the future climate. We also find that 12 other GCMs show no robust change in the patterns associated with the Atlantic Niño. There is a higher confiden

Constraining depositional phases in braided river deposits can be challenging if only based on sedimentology or geochronology. In this paper, we explored how different data sources can provide complementary information on the depositional history of Pleistocene fluvial deposits. The study was realized on the Zutendaal gravels that outcrop in Northeastern Belgium. In an 8 m high exposure of gravel sheets, we collected bulk samples that were processed for grain size, elemental geochemistry and cosmogenic radionuclides. After dry sieving, we derived the D10, D50, D90, gravel and sand content. From the elemental geochemistry of the bulk samples, we calculated the Ti/Zr and Cr/Zr ratios as proxies for provenance, the Al2O3/SiO2 and Ba/Sr ratios for hydrolysis, and the MnO, Fe2O3 concentrations and the ratio for oxidation. The 10Be concentration-depth profiles are informative to identify phases of landscape stability characterized by depositional hiatuses. To verify the existence of any aberrant variation in 10Be concentration associated to provenance, the in-situ 10Be concentrations were contrasted with provenance and weathering indices. Differences in grain size, elemental geochemistry and in-situ 10Be between sedimentary units were evaluated based on Mann-Whitney tests, while Spearman correlation tests informed us on the co-variation between data sources. The outcrop in the Zutendaal gravels contains three depositional units with significant differences in grain size and chemical weathering extent, and representing distinct 10Be accumulation phases. The absence of correlation between provenance and oxidation proxies indicates that weathering is essentially intraformational or post-depositional. Sedimentary hiatuses were identified based on fining upward sequences and 10Be concentration-depth profiles, whereby local deviation in 10Be concentration at the top of the fining upward sequence provided information on the duration of the hiatus. The case study illustrates how

Actor-level data on large-scale commercial agriculture in Sub-Saharan Africa are scarce. The peculiar choice of transnational investing in African land has, therefore, been subject to conjecture. Addressing this gap, we reconstructed the underlying logics of investment location choices in a Bayesian network, using firm- and actor-level interview and spatial data from 37 transnational agriculture and forestry investments across 121 sites in Mozambique, Zambia, Tanzania, and Ethiopia. We distinguish four investment locations across gradients of resource frontiers and agglomeration economies to derive the preferred locations of different investors with varied skillsets and market reach (i.e., track record). In contrast to newcomers, investors with extensive track records are more likely to expand the land use frontier, but they are also likely to survive the high transaction costs of the pre-commercial frontier. We highlight key comparative advantages of Southern and Eastern African frontiers and map the most probable categories of investment locations.

Land use is central to addressing sustainability issues, including biodiversity conservation, climate change, food security, poverty alleviation, and sustainable energy. In this paper, we synthesize knowledge accumulated in land system science, the integrated study of terrestrial social-ecological systems, into 10 hard truths that have strong, general, empirical support. These facts help to explain the challenges of achieving sustainability in land use and thus also point toward solutions. The 10 facts are as follows: 1) Meanings and values of land are socially constructed and contested; 2) land systems exhibit complex behaviors with abrupt, hard-to-predict changes; 3) irreversible changes and path dependence are common features of land systems; 4) some land uses have a small footprint but very large impacts; 5) drivers and impacts of land-use change are globally interconnected and spill over to distant locations; 6) humanity lives on a used planet where all land provides benefits to societies; 7) land-use change usually entails trade-offs between different benefits—"win–wins" are thus rare; 8) land tenure and land-use claims are often unclear, overlapping, and contested; 9) the benefits and burdens from land are unequally distributed; and 10) land users have multiple, sometimes conflicting, ideas of what social and environmental justice entails. The facts have implications for governance, but do not provide fixed answers. Instead they constitute a set of core principles which can guide scientists, policy makers, and practitioners toward meeting sustainability challenges in land use.

Land-use frontiers, such as agriculture expanding into forests, remain a major driver of biodiversity loss, and often lead to conservation responses. To better understand the geographies of conservation, connecting conservation with tools used widely in Land System Science – particularly the frontier concept – allows assessing the patterns, actors, and drivers of conservation. We propose that land conservation can be analysed through three different perspectives. First, conservation can be framed as efforts to slow or stop other frontiers. Second, the expansion of conservation could itself be described as a frontier process, similarly leading to institutional and cultural reorganization, and sometimes conflicts (e.g. green grabbing). Third, frontiers can be seen as spaces where multiple land uses, including conservation, interact. Analysing conservation through these perspectives could be particularly powerful to thoroughly consider the social-ecological contexts in which conservation happens, and thus to bridge the disciplines of Land System Science and Conservation Science.

The Dry Chaco is a semi-arid ecoregion in South America that hosts one of the largest dry forests in the world, but expansion of dryland agriculture and cattle ranching led to gradual conversion of native vegetation to anthro- pogenic land cover. The potential impact of these newly established agricultural lands on the surrounding environment is of great concern. Local studies have shown that deforestation leads to changes in the soil-water balance, and can expedite groundwater rise and mobilization of water-soluble salts to the surface affecting plant growth and crop productivity. This study is a regional assessment of soil salinity and salinization processes in the central Argentinean Dry Chaco. It is based on extensive dataset of 492 surface and 142 subsurface samples taken along east-west transects across the Dry Chaco. Soil electrical conductivity (EC) was used as an indicator of salinity, and supplementary information on salt crusts was derived from Google Earth imagery. Subsurface salinity (i.e., measured at 100 cm depth) showed clear regional patterns in natural soil salinity that are related to the annual water budget and topography. Besides primary salinization due to arrested drainage and landscape stagnation, anthropogenic activities increased secondary salinization, especially in the agricultural areas with shallow groundwater tables and irrigated croplands. In addition, the study demonstrated that remotely-sensed vegetation indices such as the seasonal variation in the density of green vegetation are particularly suitable to monitor regional variation in soil salinity. Our results show that the extent of future dryland salinization in the Dry Chaco will mainly depend on whether areas prone to natural soil salinity are further protected from deforestation, and the magnitude and rate of groundwater rise after deforestation as conditioned by local climate and geomorphology. This better understanding of soil salinity patterns and how they are affected as a

The Andean region is susceptible to soil erosion due to steep topography, prevalent rainfall and high probability of earthquakes and landslides. By its impressive length, continuity and height, the mountain ridges significantly disrupt the atmospheric circulation resulting in a wide variety of environmental conditions. The western flank draining to the Pacific Ocean is characterized by strong environmental gradients, rough topography with deeply incised canyons, and highly variable and extreme precipitation patterns. These environmental conditions pose particular challenges for erosion and sediment flux monitoring. The thesis presents new data on the sediment yield of Andean rivers draining to the Peruvian coast. The dataset is based on time series of river suspended load, discharge and turbidity, and sediment accumulation in reservoirs. About 55% of the observed variance can be explained by hydrometeorology and topography, while anthropogenic factors such as land use marginally improve the model predictions. The effect of climate variability on sediment transport was further studied in the Cañete catchment where the 240MW El Platanal hydropower plant is located. By calibrating a coupled hydrological-sediment transport model for the Cañete River, the effect of precipitation variability on sediment transport and reservoir sedimentation was assessed. Even under the most optimistic scenario, the lifespan of the reservoir is shorter that its officially expected functionality of 50 years. The geomorphic processes driving sediment production and transport were quantified using UAV-PPK-SfM techniques. The processing chain was optimized for 4D geomorphic monitoring in rough terrain by including co-registration techniques. By analyzing the spatial patterns in sediment yield along the western Andes, the thesis enhanced the knowledge base on sediment transport to the Peruvian coastal plain. Besides, it illustrated the vulnerability of hydroelectric facilities to climate variab, (SC - Sciences) -- UCL, 2022

Cosmogenic nuclide dating of glacial landforms on the Kerguelen Archipelago (49°S, 69°E) gives the opportunity to study multi-millennial glacier fluctuations within the sub-Antarctic sector of the Indian Ocean. We here dated such geomorphic features to provide time constraints over the last 17,000 years using in situ-produced 36Cl in three glacial valleys: Val Travers valley, Ampere Glacier valley and Arago Glacier valley. For the first time, a combination of in situ-produced 36Cl and 10Be dating and 26Al/10Be ratios analysis was performed in the quartz-bearing syenite boulders of the Arago Glacier site. In addition, a Bayesian approach was computed to obtain a better constraint on moraine dating. Glacial advances occurred during the Late Glacial at 16.0 ± 1.9 ka and at 12.9 ± 1.7 ka in Val Travers, and at 13.6 ± 1.8 ka in Arago Glacier valley, probably linked to the Heinrich Stadial 1 and/or Antarctic Cold Reversal events, respectively. This suggests that all glaciers at this latitude were broadly sensitive to the large-scale climatic signal of the Antarctic Cold Reversal. So far, no Early nor Mid-Holocene moraines have been found in the glacial valleys on Kerguelen, indicating that the glaciers had probably receded significantly during these periods. This is in agreement with previously determined 14C ages from peat bogs, which suggest extensive deglaciation during several millennia of the Holocene period. Samples from glacially-polished bedrock surfaces (ranging from ∼4.4 ka to ∼14 ka) at Ampere Glacier site also suggest that this valley was ice free for several millennia during the Holocene. Finally, glaciers seem to have re-advanced only during the Late Holocene, especially within the last millennium, at ∼1 ka, ∼ 430 yr and ∼300 yr. A comparison of this new dataset with the available 10Be ages from other southern mid-latitude regions during the Holocene allows the identification of three different glacier evolution patterns. We suspect that variations of Kergue

The Chinese loess-paleosols sequences are important archives of the Quaternary paleoclimate and paleoenvironmental information. Loess was deposited during glacials, with a rate of high dust addition. Paleosols underwent strong pedogenesis during interglacials in response to strong summer monsoon and low dust influx rate. Most previous studies of paleosols in the CLP focused on paleoclimate-paleosol linkages by analyzing bulk paleosol characteristics, however much remains unknown about their relationship in terms of relative contributions of paleoclimatic conditions (e.g. precipitation, temperature, evapotranspiration, vegetation and dust addition). Soil formation is controlled by various environmental factors (e.g. dust input, climatic conditions) over an interglacial period; thereby, deducing such interpretations is complex. This motivates us to quantitatively examine relative contributions of precipitation, temperature, evapotranspiration, vegetation and dust addition on paleosol development in the CLP. As far as climate is concerned, ice sheets play an important role in regulating glacial-interglacial cycles during the Quaternary period and have been found to be closely linked with paleosol development in the CLP. However, how ice sheet-induced climate change has affected paleosol development is still unclear. We use SoilGen2-LOVECLIM process-based soil-climate models to simulate paleosol development using time series of climate data (e.g. precipitation, temperature, dust input) for a given interglacial. A sensitivity analysis was done to quantitatively assess the relative contributions of these factors on paleosol development. The sensitivity experiment includes simulations for each climatic factor alone, combined climatic factors (e.g. precipitation and evapotranspiration) and a reference simulation (Pre-Industrial climate). The results were analyzed by calculating the mean absolute error between each of the sensitivity simulation and the actual simulation (com

We explore a methodology to statistically downscale snowfall – the primary driver of surface mass balance in Antarctica – from an ensemble of historical (1850–present day) simulations performed with an earth system model over the coastal region of Dronning Maud Land (East Antarctica). This approach consists of associating daily snowfall simulations from a polar-oriented regional atmospheric climate model at 5.5 km spatial resolution with specific weather patterns observed over 1979–2010 CE with the atmospheric reanalyses ERA-Interim and ERA5. This association is then used to generate the spatial distribution of snowfall for the period from 1850 to present day for an ensemble of 10 members from the Community Earth System Model (CESM2). The new dataset of daily and yearly snowfall accumulation based on this methodology is presented in this paper (MASS2ANT dataset; https://doi.org/10.5281/zenodo.4287517; Ghilain et al., 2021). Based on a comparison with available ice cores and spatial reconstructions, our results show that the spatio-temporal distribution of snowfall is improved in the downscaled dataset compared with the CESM2 simulations. This dataset thus provides information that may be useful in identifying the large-scale patterns associated with the local precipitation conditions and their changes over the past century.

The retreat of Arctic sea ice is frequently considered to be a possible driver of changes in climate extremes in the Arctic and possibly down to mid-latitudes. However, it remains unclear how the atmosphere will respond to a near-total retreat of summer Arctic sea ice, a reality that might occur in the foreseeable future. This study explores this question by conducting sensitivity experiments with two global coupled climate models run at two different horizontal resolutions to investigate the change in temperature and precipitation extremes during summer over peripheral Arctic regions following a sudden reduction in summer Arctic sea ice cover. An increase in frequency and persistence of maximum surface air temperature is found in all peripheral Arctic regions during the summer, when sea ice loss occurs. For each 1×106 km2 of Arctic sea ice extent reduction, the absolute frequency of days exceeding the surface air temperature of the climatological 90th percentile increases by ∼ 4 % over the Svalbard area, and the duration of warm spells increases by ∼ 1 d per month over the same region. Furthermore, we find that the 10th percentile of surface daily air temperature increases more than the 90th percentile, leading to a weakened diurnal cycle of surface air temperature. Finally, an increase in extreme precipitation, which is less robust than the increase in extreme temperatures, is found in all regions in summer. These findings suggest that a sudden retreat of summer Arctic sea ice clearly impacts the extremes in maximum surface air temperature and precipitation over the peripheral Arctic regions with the largest influence over inhabited islands such as Svalbard or northern Canada. Nonetheless, even with a large sea ice reduction in regions close to the North Pole, the local precipitation response is relatively small compared to internal climate variability.

To expand the knowledge base on natural infrastructure for erosion mitigation in the Andes, it is necessary to move beyond case by case empirical studies to comprehensive assessments. This study reviews the state of evidence on the effectiveness of interventions to mitigate soil erosion by water and is based on Andean case studies published in gray and peer-reviewed literature. Based on a systematic review of 118 case studies from the Andes, this study addressed the following research questions. (1) Which erosion indicators allow us to assess the effectiveness of natural infrastructure? (2) What is the overall impact of working with natural infrastructure on on-site and off-site erosion mitigation? (3) Which locations and types of studies are needed to fill critical gaps in knowledge and research? Three major categories of natural infrastructure were considered: restoration and protection of natural vegetation, such as forest or native grasslands, forestation with native or exotic species and implementation of soil and water conservation measures for erosion mitigation. From the suite of physical, chemical and biological indicators commonly used in soil erosion research, two indicators were particularly relevant: soil organic carbon of topsoil and soil loss rates at plot scale. The protection and conservation of natural vegetation has the strongest effect on soil quality, with 3.01±0.893 times higher soil organic carbon content in the topsoil compared to control sites. Soil quality improvements are significant but lower for forestation and soil and water conservation measures. Soil and water conservation measures reduce soil erosion to 62.1g %g ±g 9.2g %, even though erosion mitigation is highest when natural vegetation is maintained. Further research is needed to evaluate whether the reported effectiveness holds during extreme events related to, for example, El Niño-Southern Oscillation. © 2022 Veerle Vanacker et al.

This study aimed to simulate oak and beech forest growth under various scenarios of climate change and to evaluate how the forest response depends on site properties and particularly on stand characteristics using the individual process-based model HETEROFOR. First, this model was evaluated on a wide range of site conditions. We used data from 36 long-term forest monitoring plots to initialize, calibrate, and evaluate HETEROFOR. This evaluation showed that HETEROFOR predicts individual tree radial growth and height increment reasonably well under different growing conditions when evaluated on independent sites. In our simulations under constant CO2 concentration ([CO2]cst) for the 2071-2100 period, climate change induced a moderate net primary production (NPP) gain in continental and mountainous zones and no change in the oceanic zone. The NPP changes were negatively affected by air temperature during the vegetation period and by the annual rainfall decrease. To a lower extent, they were influenced by soil extractable water reserve and stand characteristics. These NPP changes were positively affected by longer vegetation periods and negatively by drought for beech and larger autotrophic respiration costs for oak. For both species, the NPP gain was much larger with rising CO2 concentration ([CO2]var) mainly due to the CO2 fertilisation effect. Even if the species composition and structure had a limited influence on the forest response to climate change, they explained a large part of the NPP variability (44% and 34% for [CO2]cst and [CO2]var, respectively) compared to the climate change scenario (5% and 29%) and the inter-annual climate variability (20% and 16%). This gives the forester the possibility to act on the productivity of broadleaved forests and prepare them for possible adverse effects of climate change by reinforcing their resilience.

The Totten Glacier in East Antarctica is of major climate interest because of the large fluctuation of its grounding line and of its potential vulnerability to climate change. The ocean above the continental shelf in front of the Totten ice shelf exhibits large extents of landfast sea ice with low interannual variability. Landfast sea ice is either crudely or not at all represented in current climate models. These models are potentially omitting or misrepresenting important effects related to this type of sea ice, such as its influence on coastal polynya locations. Yet, the impact of the landfast sea ice on the ocean–ice shelf interactions is poorly understood. Using a series of high-resolution, regional NEMO-LIM-based experiments, including an explicit treatment of ocean–ice shelf interactions, over the years 2001–2010, we simulate a realistic landfast sea ice extent in the area of Totten Glacier through a combination of a sea ice tensile strength parameterisation and a grounded iceberg representation. We show that the presence of landfast sea ice impacts seriously both the location of coastal polynyas and the ocean mixed layer depth along the coast, in addition to favouring the intrusion of mixed Circumpolar Deep Water into the ice shelf cavities. Depending on the local bathymetry and the landfast sea ice distribution, landfast sea ice affects ice shelf cavities differently. The Totten ice shelf melt rate is increased by 16% on average and its variance decreased by 38%, while the Moscow University ice shelf melt rate is increased by in winter. This highlights the importance of including an accurate landfast sea ice representation in regional and eventually global climate models.

Intra-field heterogeneity of soil properties, such as soil organic carbon (SOC), nitrogen (N), phosphorous (P), exchangeable cations, pH, or soil texture, is a function of complex interactions between biological factors, physical factors, and historic agricultural management. Mapping the crop growth and final yield heterogeneity and quantifying their link with soil properties can contribute to an optimization of amendment/fertilizer application and crop yield in a management variable zones (MVZ) approach. To this end, we studied a field of 17 ha consisting of four former fields that were merged in early 2017 and cropped with winter wheat in 2018. Historical management practices data were collected. The topsoil characteristics were analyzed by grid-based sampling and kriged to create maps. We tested the capacity of a multispectral MicaSense® RedEdge-MTM camera sensor embedded on an unmanned aerial vehicle (UAV) to map in-season growth of winter wheat. Relating several vegetation indices (VIs) to the plant area index (PAI) measured in the field highlighted the red-edge NDVI (RENDVI) as the most suitable to follow the crop growth throughout the growing season. The georeferenced final grain yield of the winter wheat was measured by a combine harvester. The spatial patterns in RENDVI at three phenological stages were mapped and analyzed together with the yield map. For each of these images a conditional inference forest (CI-forest) algorithm was used to identify the soil properties significantly influencing these spatial patterns. Historical management practices of the four former fields have induced significant heterogeneity in soil properties and crop growth. The spatial patterns of RENDVI are rather constant over time and their Spearman rank correlation with yield is similar along the growing season (r ≃ 0.7). Soil properties explain between 87% (mid-March) to 78% (mid-May) of the variance in RENDVI throughout the growing season, as well as 66% of the variance in yiel

Tropical dry woodlands are rapidly being lost to agricultural expansion, but how deforestation dynamics play out in these woodlands remains poorly understood. We have developed an approach to detect and map high-level patterns of deforestation frontiers, that is, the expansion of woodland loss across continents in unprecedented spatio-temporal detail. Deforestation in tropical dry woodlands is pervasive, with over 71 Mha lost since 2000 and one-third of wooded areas located in deforestation frontiers. Over 24.3 Mha of deforestation frontiers fall into what we term ‘rampant frontiers’. These are characterized by drastic woodland loss and conditions favourable for capital-intensive agriculture, as seen in the South American Chaco and Southeast Asia. We have found many active and emerging frontiers (~59% of all frontiers), mostly in the understudied dry woodlands of Africa and Asia, where greater frontier monitoring is needed. Our approach enables consistent, repeatable frontier monitoring, and our global frontier typology fosters comparative research and context-specific policymaking.

The tick Ixodes ricinus is widely distributed across Europe and is responsible for the transmission of several pathogens to humans and animals. In this study, we used a knowledge-based method to map variations in habitat suitability for I. ricinus ticks throughout continental France and Corsica. The multi-criteria decision analysis (MCDA) integrated four major biotic and abiotic factors known to influence tick populations: climate, land cover, altitude and the density of wild ungulates. For each factor, habitat suitability index (HSI) values were attributed to different locations based on knowledge regarding its impact on tick populations. For the MCDA, two methods of factor combination were tested, additive and multiplicative, both which were evaluated at the spatial scales of departments and local municipalities. The resulting habitat suitability maps (resolution=100x100 m) revealed that conditions are suitable for I. ricinus over most of France and Corsica. Particularly suitable habitats were located in central, north-eastern and south-western France, while less-suitable habitats were found in the Mediterranean and mountainous regions. To validate the approach, the HSI scores were compared to field data of I. ricinus nymph abundance. Regardless of scale, the correlation between abundance indicator and HSI score was stronger for the additive than for the multiplicative approach. Overall, this study demonstrates the value of MCDA for estimating habitat suitability maps for I. ricinus abundance, which could be especially useful in highlighting areas of the tick’s distribution where preventive measures should be prioritised.

Smallholders produce about a third of the global crop production. Supporting these smallholder farms is an important lever for poverty alleviation. Farm and field sizes are key indicators of many smallholder dynamics, including fragmentation, farm consolidation, and interactions between smallholders, medium-scale commercial farming, and large enterprises. Despite the socio-economic, environmental, and political importance of these dynamics, spatially explicit data on farms and field sizes are still lacking. Identifying small-scale agriculture using satellite imagery is challenging due to the heterogeneity in the crop types and management practices. This study compared three unsupervised segmentation approaches that have not been widely explored for delineating smallholder fields: mean shift, multiresolution segmentation, and simple non-iterative clustering (SNIC), using PlanetScope imagery. The study area is located in northern Mozambique, where 71% of the farms cover less than 2 ha. The results were evaluated using four segmentation accuracy metrics based on object geometries: Area Fit Index (AFI), Quality Rate (QR), Oversegmentation (OS), and Undersegmentation (US). The results showed that the multiresolution segmentation algorithm outperformed the other methods to delineate smallholder fields. This work will support future regional-scale mapping efforts.

The Southern Hemisphere cryosphere has recently shown regionally-contrasted responses to climate change, in particular to the positive phases of the Southern Annular Mode. However, the understanding of the impacts of this mode on ice-shelf basal melt at a circum-Antarctic scale is still limited. Here, we performed idealized experiments with a pan-Antarctic regional ice-shelf cavity-resolving ocean—sea-ice model for different phases of the Southern Annular Mode. We show that positive phases lead to increased upwelling and subsurface ocean temperature and salinity close to ice shelves, while the opposite occurs for negative phases. A one-standard-deviation increase of the Southern Annular Mode leads to a net basal mass loss of 40 Gt yr−1, with strong regional contrasts: increased ice-shelf basal melt in the Bellingshausen and Western Pacific sectors and the opposite response in the Amundsen sector. Estimates of 1000–1200 and 2090–2100 ice-shelf basal melt changes due to the Southern Annular Mode are −86.6 Gt yr−1 and 55.0 to 164.9 Gt yr−1, respectively, compared to the present.

Volcanic eruptions have been the most dominant natural forcing of climate change over the past millennium, affecting temperature change at multiple timescales. However, how volcanic eruptions affect regional temperature variability on the decadal timescale remains unclear. We analyzed the bidecadal effects of volcanic eruptions in the mid-fifteenth century on two representative regions (the Tibetan plateau [TP] and the Arctic) in the Northern Hemisphere by combining proxy reconstructions, model ensemble simulations, and model sensitive experiments. The results show that the TP experienced bidecadal cooling during the mid-fifteenth century as a result of the long-term heat uptake in the midlatitude ocean that reduced latent heat transfer to the atmosphere. A positive sea ice–albedo feedback led to a bidecadal summer temperature decrease in the Arctic comparable to that on the TP, whereas the Arctic winter experienced stronger bidecadal cooling caused by a reduced ocean–atmosphere energy exchange and atmospheric poleward energy transport. In addition, our results show that it took ∼20 years for the temperature in these two regions to return to the level that existed before the first eruption, and this was linked to the strengthening of the Atlantic Meridional Overturning Circulation and ocean heat transport.

On the Chinese Loess Plateau, the development of the paleosol S3 that was formed during the MIS-9 interglacial is weaker than some other paleosol units such as the S4 soil that was formed during the MIS-11 interglacial, suggesting relatively drier climate condition during MIS-9. By contrast, in Tajikistan of southern central Asia, the S3 is the most developed soil over the past 800 ka, indicating relatively warm and humid climate conditions. The difference in the paleosol formation and the MIS-9 climate between monsoonal China and central Asia is intriguing. In this study, we combine loess records from monsoonal China and central Asia as well as climate simulation results to understand the spatial difference of the MIS-9 climate in particular in comparison with the climate of MIS-11. Our results show that under the combined effects of greenhouse gases (GHGs) and insolation, the simulated effective moisture conditions between northern China and southern central Asia are consistent with the loess records. Insolation leads to much more annual mean precipitation than GHG during MIS-9 in southern central Asia, explaining a much wetter MIS-9 there. By contrast, both insolation and GHG lead to more annual mean precipitation and evaporation during MIS-9 in northern China, leading only to a slight difference in the effective moisture between MIS-9 and MIS-11. In addition, compared to MIS-11, the higher insolation and GHG concentration during MIS-9 generate an anomalous atmospheric circulation pattern similar to negative phase of North Atlantic Oscillation, favoring precipitation increase in southern central Asia.

Marine Isotope Stage (MIS) 5, between about 130 and 70 ka BP, is a relatively long warm period characterized by climate oscillations consisting of three interstadials and two stadials. In this study, two sets of snapshot simulations by a step of 2 ka covering the whole MIS-5 period are performed with the model HadCM3 to investigate the relative impacts of insolation, CO2 and Northern Hemisphere ice sheets on the internal variations within MIS-5 and spatial variations of the East Asian climate, including the East Asian summer monsoon (EASM) intensity. The first set of experiments are forced by varying insolation and GHGs (OrbGHG) and the second ones are forced by varying insolation, GHGs and ice sheets (OrbGHGIce). Results show that a similar trend with precession can be found in the simulated summer precipitation, temperature and EASM index in both OrbGHG and OrbGHGIce, indicating the dominant role of precession on the EASM. Within the range of CO2 variability during MIS-5, the change of CO2 causes similar degree of warming effect, but much lower degree of humidifying effect compared to insolation. Insolation and CO2 change the precipitation through different dynamic and thermodynamic processes. Our results also show that the influence of ice sheets on temperature and precipitation is less important than the effect of insolation and it varies from regions and in time. The effect of ice sheets depends on background insolation and also the location, height and area of ice sheets. The simulated spatial-temporal variations of the EASM climate are compared with proxy records and the mechanisms involved are investigated.

Marine Isotope Stage (MIS) 5, between about 130 and 70 ka BP, characterized by climate oscillations consisting of three interstadials and two stadials. In this study, two sets of snapshot simulations by a step of 2 ka covering the whole MIS-5 period are performed with the model HadCM3 to investigate the relative impacts of insolation, CO2 and Northern Hemisphere ice sheets on the spatial and temporal variations of the East Asian climate, including the East Asian summer monsoon (EASM). Results show that precession plays a dominant role in the simulated summer precipitation, temperature and the EASM index. Within the range of CO2 variability during MIS-5, the change of CO2 causes similar degree of warming effect but much lower degree of humidifying effect compared to insolation. Insolation and CO2 affect the summer precipitation mainly through dynamic and thermodynamic processes, respectively. Our results also show that the influence of ice sheets on temperature and precipitation is less important than the effect of insolation and it varies from regions and in time. The effect of ice sheets depends on background insolation and also the location, height and area of the ice sheets. The simulated spatial-temporal variations of the EASM climate are compared with proxy records and the mechanisms involved are investigated. The simulated MIS-5 climate is also compared with the present and the future to investigate to which degree it can be considered as an analogue for the future in terms of East Asian climate.