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See detailClimate and biogeochemical response to a rapid melting of the West-Antarctic Ice Sheet during interglacials and implications for future climate
Menviel, L.; Timmermann, A.; Timm, O. et al

in Paleoceanography (2010), 25

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See detailClimate and emotion regulation: is there a role for “climatotherapy” in the sustainable development of mental health ?
Desseilles, Martin ULg; Duclos, Catherine; Flohimont, Valérie et al

in Behavioral and Brain Sciences (2013), 36(5), 23-24

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See detailClimate and marine carbon cycle response to changes in the strength of the Southern Hemispheric westerlies
Menviel, L.; Timmermann, A.; Mouchet, Anne ULg et al

in Paleoceanography (2008), 23(4),

It has been previously suggested that changes in the strength and position of the Southern Hemisphere westerlies could be a key contributor to glacial-interglacial atmospheric CO2 variations. To test this ... [more ▼]

It has been previously suggested that changes in the strength and position of the Southern Hemisphere westerlies could be a key contributor to glacial-interglacial atmospheric CO2 variations. To test this hypothesis, we perform a series of sensitivity experiments using an Earth system model of intermediate complexity. A strengthening of the climatological mean surface winds over the Southern Ocean induces stronger upwelling and increases the formation of Antarctic Bottom Water. Enhanced Ekman pumping brings more dissolved inorganic carbon (DIC)-rich waters to the surface. However, the stronger upwelling also supplies more nutrients to the surface, thereby enhancing marine export production in the Southern Hemisphere and decreasing the DIC content in the euphotic zone. The net response is a small atmospheric CO2 increase (similar to 5 ppmv) compared to the full glacial-interglacial CO2 amplitude of similar to 90 ppmv. Roughly the opposite results are obtained for a weakening of the Southern Hemisphere westerly winds. [less ▲]

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See detailClimate and Security: Evidence, Emerging Risks and a New Agenda
Gemenne, François ULg; Barnett, Jon; Adger, W. Neil et al

in Climatic Change (2014), 123(1), 1-9

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See detailClimate and Security: Evidence, Emerging Risks and a New Agenda
Gemenne, François ULg; Adger, Neil; Barnett, Jon et al

in Climatic Change (2014)

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See detailClimate change impacts on groundwater resources: modelled deficits in a chalky aquifer, Geer basin, Belgium
Brouyère, Serge ULg; Carabin, Guy; Dassargues, Alain ULg

in Hydrogeology Journal (2004), 12(2), 123-134

An integrated hydrological model (MOHISE) was developed in order to study the impact of climate change on the hydrological cycle in representative water basins in Belgium. This model considers most ... [more ▼]

An integrated hydrological model (MOHISE) was developed in order to study the impact of climate change on the hydrological cycle in representative water basins in Belgium. This model considers most hydrological processes in a physically consistent way, more particularly groundwater flows which are modelled using a spatially distributed, finite-element approach. Thanks to this accurate numerical tool, after detailed calibration and validation, quantitative interpretations can be drawn from the groundwater model results. Considering IPCC climate change scenarios, the integrated approach was applied to evaluate the impact of climate change on the water cycle in the Geer basin in Belgium. The groundwater model is described in detail, and results are discussed in terms of climate change impact on the evolution of groundwater levels and groundwater reserves. From the modelling application on the Geer basin, it appears that, on a pluriannual basis, most tested scenarios predict a decrease in groundwater levels and reserves in relation to variations in climatic conditions. However, for this aquifer, the tested scenarios show no enhancement of the seasonal changes in groundwater levels. [less ▲]

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See detailClimate change simulation in continental Antarctica using Open-Top Chambers
Mano, Marie-José ULg; Namsaraev, Zorigto; Gorodetskaya, Irina et al

Poster (2012, July)

In continental Antarctica, the environnmental conditions are extreme and only microbial organisms can withstand them. Currently, the majority of OTCs experiments are being held in Maritime Antarctica but ... [more ▼]

In continental Antarctica, the environnmental conditions are extreme and only microbial organisms can withstand them. Currently, the majority of OTCs experiments are being held in Maritime Antarctica but it would be interesting to have such data for the continental part of Eastern Antarctica. To monitor the response of the microbial communities to local simulations of climate change, 8 Open-Top Chambers (OTC) were installed close to the Princess Elisabeth station, in the Sor Rondane Mountains in January 2010. They are located on the Utsteinen ridge, the Tanngarden granite outcrop, the Teltet nunatak and the fourth nunatak of the Pingvinane range. In each location, two OTCs and a control area were established. Temperature and humidity loggers were installed inside the OTCs and outside, in the control areas, to estimate the environmental changes induced by the OTCs. [less ▲]

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See detail"Climate change" and vulnerability analysis: poor will become poorer
Ozer, Pierre ULg

Conference (2013, November 07)

The recent Intergovernmental Panel on Climate Change’s Fifth Assessment Report (IPCC-AR5) considers new evidence of climate change based on many independent scientific analyses from observations of the ... [more ▼]

The recent Intergovernmental Panel on Climate Change’s Fifth Assessment Report (IPCC-AR5) considers new evidence of climate change based on many independent scientific analyses from observations of the climate system, paleoclimate archives, theoretical studies of climate processes and simulations using climate models. “Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased”. “Changes in many extreme weather and climate events have been observed since about 1950. It is very likely that the number of cold days and nights has decreased and the number of warm days and nights has increased on the global scale”. “It is likely that the frequency of heat waves has increased”. “There are likely more land regions where the number of heavy precipitation events has increased than where it has decreased”. “The frequency or intensity of heavy precipitation events has likely increased”. In the meantime, it is now well known that climate change consequences (increasing magnitude and frequency of droughts, floods, storms and/or coastal erosion) will mainly impact the most vulnerable. Although there are multiple ways to define vulnerability, we here define vulnerability as the exposure of individuals or collective groups to livelihood stress as a result of the impacts of such climate change and consecutive socioeconomic and environmental changes. In the context of this paper, we will focus on natural disasters induced by “climate change”. We will travel across developing countries to illustrate the increasing vulnerability of the poor and the way they –sometimes– develop effective adaptation responses. We conclude that, for many reasons (mainly the protection of individual, financial and/or political interests), the poor will become poorer. [less ▲]

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See detailClimate control of terrestrial carbon exchange across biomes and continents
Yi, Chuixiang; Ricciuto, Daniel; Li, Runze et al

in Environmental Research Letters (2010), 5(3),

Understanding the relationships between climate and carbon exchange by terrestrial ecosystems is critical to predict future levels of atmospheric carbon dioxide because of the potential accelerating ... [more ▼]

Understanding the relationships between climate and carbon exchange by terrestrial ecosystems is critical to predict future levels of atmospheric carbon dioxide because of the potential accelerating effects of positive climate-carbon cycle feedbacks. However, directly observed relationships between climate and terrestrial CO2 exchange with the atmosphere across biomes and continents are lacking. Here we present data describing the relationships between net ecosystem exchange of carbon (NEE) and climate factors as measured using the eddy covariance method at 125 unique sites in various ecosystems over six continents with a total of 559 site-years. We find that NEE observed at eddy covariance sites is (1) a strong function of mean annual temperature at mid-and high-latitudes, (2) a strong function of dryness at mid-and low-latitudes, and (3) a function of both temperature and dryness around the mid-latitudinal belt (45 degrees N). The sensitivity of NEE to mean annual temperature breaks down at similar to 16 degrees C (a threshold value of mean annual temperature), above which no further increase of CO2 uptake with temperature was observed and dryness influence overrules temperature influence. [less ▲]

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See detailThe climate induced variation of the continental biosphere: A model simulation of the last glacial maximum
Friedlingstein, P.; Delire, C.; Müler, J. F. et al

in Geophysical Research Letters (1992), 19

A simplified three-dimensional global climate model was used to simulate the surface temperature and precipitation distributions for the Last Glacial Maximum (LGM), 18000 years ago. These fields were ... [more ▼]

A simplified three-dimensional global climate model was used to simulate the surface temperature and precipitation distributions for the Last Glacial Maximum (LGM), 18000 years ago. These fields were applied to a bioclimatic scheme which parameterizes the distribution of eight vegetation types as a function of biotemperature and annual precipitation. The model predicts a decrease, for LGM compared to present, in forested area balanced by an increase in desert and tundra extent, in agreement with a reconstruction of the distribution of vegetation based on paleodata. However, the estimated biospheric carbon content (phytomass and soil carbon) at LGM is less reduced than in the reconstructed one. Possible reasons for this discrepancy are discussed. [less ▲]

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See detailA climate model from 200 AD to 1200 AD for the Hautes-Fagnes plateau (East Belgium) : based on pollen grains, testate amoebae, and humification analyses
Beghin, Jérémie ULg; Fagel, Nathalie ULg; Gerrienne, Philippe ULg et al

Poster (2012, September 12)

Several peat cores were extracted from the Misten bog, on the Hautes-Fagnes plateau (East Belgium). Analyses of pollen grains, testate amoebae and the degree of peat humification have been standardised ... [more ▼]

Several peat cores were extracted from the Misten bog, on the Hautes-Fagnes plateau (East Belgium). Analyses of pollen grains, testate amoebae and the degree of peat humification have been standardised and combined into a palaeo-hydro-climatic model from 200 AD to 1200 AD. The reconstruction shows 9 distinctive phases of near-surface water tables, which may be used to infer changes in the atmospheric water balance of eastern Belgium during the Subatlantic stage. [less ▲]

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See detailClimate oscillations evidenced by spectral analysis of Southern Chilean lacustrine sediments: the assessment of ENSO over the last 600 years
Fagel, Nathalie ULg; Boes, X.; Loutre, M. F.

in Journal of Paleolimnology (2008), 39(2), 253-266

The Chilean Lake District (38-42 degrees S) is strongly influenced by Southern westerlies-driven precipitations. At 40 degrees S Lago Puyehue provides high resolution sedimentation rates (similar to 1-2 ... [more ▼]

The Chilean Lake District (38-42 degrees S) is strongly influenced by Southern westerlies-driven precipitations. At 40 degrees S Lago Puyehue provides high resolution sedimentation rates (similar to 1-2 mm/yr) suitable for annual climate reconstruction. Several short and long sediment cores were collected in this lake. Their analysis aim at a better understanding of climate mechanisms related to ENSO in this part of the world. The recognition of ENSO related periodicities and their stability is studied through the analysis of two short varved cores collected from underflow and interflow key sites. According to varve chronology controlled by Cs-137 and Pb-210 profiles and chronostratigraphical markers, the short core from underflow site (PU-I) spans 294 +/- 18 years and the core in the interflow site (PU-II) covers 592 +/- 9 years. Several methods of spectral analysis were applied on the total varve thickness to identify potential periodicities in the signal. Blackman-Tuckey, Maximum Entropy, Multi-Taper Methods (MTM) and singular spectrum analysis were applied on the whole record. In addition, evolutive MTM and wavelet analyses allow to identify temporal influence of some periodicities. In the PU-I studied interval (AD 1700-2000), a period at similar to 3.0 years appears in a large part of the interval, mostly in the recent part. Periods at similar to 5.2 and similar to 23 years also show up. PU-II record (AD 1400-2000) displays the most robust periodicities at around 15, 9, 4.4, 3.2 and 2.4 years. These periodicities are in good agreement with the sub-decadal periods identified by Dean and Kemp (2004) and linked to the El Nino Southern Oscillation and the Pacific Decadal Oscillation. Differences in the recorded periodicities between PU-I and PU-II sites are consistent with different sedimentation processes in the lake. According to climate instrumental data for the last 20 years, varves in PU-I site are mostly related to fluvial dynamics and regional climate factors, i.e., precipitation, temperature and wind. In PU-II site, varves increment is related to both regional and global climate forcing factors, i.e., El Nino Southern Oscillation. The evolutive MTM analysis and the wavelet analysis suggest a striking break in the periodicities at around AD 1820. Finally relationships between El Nino and longer term climate phase like the Little Ice Age (LIA) are also assessed. [less ▲]

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See detailClimate variability of southern Chile since the Last Glacial Maximum: a continuous sedimentological record from Lago Puyehue (40 degrees S)
Bertrand, Sebastien; Charlet, Francois; Charlier, Bernard ULg et al

in Journal of Paleolimnology (2008), 39(2), 179-195

This paper presents a multi-proxy climate record of an 11 m long core collected in Lago Puyehue (southern Chile, 40 degrees S) and extending back to 18,000 cal yr BP. The multi-proxy analyses include ... [more ▼]

This paper presents a multi-proxy climate record of an 11 m long core collected in Lago Puyehue (southern Chile, 40 degrees S) and extending back to 18,000 cal yr BP. The multi-proxy analyses include sedimentology, mineralogy, grain size, geochemistry, loss-on-ignition, magnetic susceptibility and radiocarbon dating. Results demonstrate that sediment grain size is positively correlated with the biogenic sediment content and can be used as a proxy for lake paleoproductivity. On the other hand, the magnetic susceptibility signal is correlated with the aluminium and titanium concentrations and can be used as a proxy for the terrigenous supply. Temporal variations of sediment composition evidence that, since the Last Glacial Maximum, the Chilean Lake District was characterized by three abrupt climate changes superimposed on a long-term climate evolution. These rapid climate changes are: (1) an abrupt warming at the end of the Last Glacial Maximum at 17,300 cal yr BP; (2) a 13,100-12,300 cal yr BP cold event, ending rapidly and interpreted as the local counterpart of the Younger Dryas cold period, and (3) a 3,400-2,900 cal yr BP climatic instability synchronous with a period of low solar activity. The timing of the 13,100-12,300 cold event is compared with similar records in both hemispheres and demonstrates that this southern hemisphere climate change precedes the northern hemisphere Younger Dryas cold period by 500 to 1,000 years. [less ▲]

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See detailClimate-carbon cycle feedback during glacial cycles
Ganopolski, A; Brovkin, V; Calov, R et al

Conference (2011, August 15)

Paleoclimate records reveal a close link between global ice volume and atmospheric CO2 concentration, at least, through the last 800,000 years. Despite many efforts over the last two decades, mechanisms ... [more ▼]

Paleoclimate records reveal a close link between global ice volume and atmospheric CO2 concentration, at least, through the last 800,000 years. Despite many efforts over the last two decades, mechanisms of glacial-interglacial CO2 variability and its role for the glacial cycles remain elusive. Here using the Earth system model of intermediate complexity CLIMBER-2 which includes all major components of the Earth system – atmosphere, ocean, land surface, ice sheets, terrestrial biota, eolian dust and marine biogeochemistry – we performed simulations of the last glacial cycles employing variations in the Earth’s orbital parameters as the only prescribed climatic forcing. In the experiments with constant CO2 concentration, temporal dynamics of the simulated glacial cycles strongly depend on the CO2 level. For CO2 concentrations about and above preindustrial one, the model simulates only short glacial cycles with precessional and obliquity frequencies. However, for lower CO2 concentrations the model simulates long glacial cycles with dominant 100 kyr periodicity. Simulated glacial cycles agreed favorably with paleoclimate reconstructions, but their amplitude is underestimated compared to those of the simulations with time-dependent CO2 concentration. These results confirm that the positive climate-carbon cycle feedback plays an important role in amplification of long glacial cycles. Experiments with fully interactive CO2 shed some light on the mechanism of climate-carbon cycle feedback during glacial cycles. Forced by orbital variations only, the model is able to reproduce the main features of CO2 changes: the 40 ppmv CO2 drop during glacial inception, the minimum concentration at the last glacial maximum being 80 ppmv lower than the Holocene value, and the relatively abrupt CO2 rise during the deglaciation. The main drivers of atmospheric CO2 evolve with time: changes in sea surface temperature and volume of bottom water of southern origin exert CO2 control during glacial inception and deglaciation, while changes in carbonate chemistry and marine biology are dominant during the first and second parts of the glacial cycles, respectively. [less ▲]

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See detailClimate-controlled palynofacies and miospore biostratigraphy of the Early Devonian Jauf Formation, northern Saudi Arabia
Breuer, Pierre; Leszczynski, S.; Miller, M.A. et al

in Review of Palaeobotany and Palynology (in press)

The Jauf Formation miospore succession is synthesized in terms of paleoenvironments and sequence stratigraphy. The data set for this study is obtained from four overlapping, continuously cored, and ... [more ▼]

The Jauf Formation miospore succession is synthesized in terms of paleoenvironments and sequence stratigraphy. The data set for this study is obtained from four overlapping, continuously cored, and extensively sampled, boreholes that for a 940 ft composite section. The Jauf Formation ranges in age from late Pragian to latest Emsian. The palynological assemblages, recognized herein, provide the basis for recognizing depositional environments present in the Early Devonian of northern Saudi Arabia. Transgressive – regressive cycles are indicated, not only by lithology but by marked changes in the marine to terrestrially dominated palynological assemblages. Flooding events are recognized by the replacement of spore dominated assemblages by organic-walled microphytoplankton. The maximum flooding interval for the Jauf is reinterpreted based on a correlative event consisting of diverse acritarchs and abundant chitinozoans. [Add details on the paly and sequence stratigraphy here. No.cycles and order.] The new northern Gondwanan biozonation developed by Breuer and Steemans (2012) and used here allows a high-resolution regional biozonation for the Arabian Plate and more intercontinental [?] correlation of the Jauf Formation with other Gondwanan and Euramerican localities. One new spore genus (Zonohilates) and four spore species (Insculptospora maxima, Camarozonotriletes alruwailii, Devonomonoletes crassus and Zonohilates vulneratus) are newly proposed. [less ▲]

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See detailClimate-driven growth of croplands and grasslands: analysis and modeling at regional scale
Horion, Stéphanie ULg

Doctoral thesis (2012)

Comprehensive understanding of the interactions between climate and vegetation is a key issue in environmental sciences, and especially for researchers studying climate change impacts on terrestrial ... [more ▼]

Comprehensive understanding of the interactions between climate and vegetation is a key issue in environmental sciences, and especially for researchers studying climate change impacts on terrestrial ecosystems. Indeed in order to better predict changes in ecosystems productivity, scientists are investing time and e ort in assessing how environmental changes are influencing - and are going to influence in the near future - the vegetation distribution and dynamics. Temperature, precipitation and atmospheric CO2 are the key determinants of the distribution of vegetation on Earth. Over the last 150 years, it has been reported that the global surface temperature has increased on average by around 0:8 C. Several studies mentioned that this rapid warming has resulted in reduction of climatic constraints to biological activity and shift in growing season. However changes in vegetation dynamics are not uniform spatially. From a methodological point of view, annual and seasonal metrics were commonly used to assess the impact of climate variability on vegetation at global and continental scales. The studies therefore neglected that intra-annual variability in the response of terrestrial ecosystems to such changes may exist. This intra-annual variability can be seen as the difference in vegetation response to a given environmental change according to its phenological development. In this research we investigated the intra-annual variation of the climatic constraints over croplands and grasslands in 25 regions located in Europe and Africa. The central question was: how best can we identify the climate footprint on vegetation development during the growing season, using global datasets of Normalized Difference Vegetation Index (NDVI) and the JRC-MARS meteorological indicators? The structure of this study is as follows. First we provide an overview of major studies linking climate variability and vegetation dynamic at global, continental and regional scales. Then we describe the NDVI and meteorological datasets used in this research, as well as the methodology developed to select optimal regions of interest for the study of 'climate-vegetation' interactions at regional scale. Indeed external factors - such as land cover changes, landscape fragmentation, etc. - need to be minimized to ensure that the variations in the NDVI signal can be attributed to climate variability. Preliminary time series analyses are then performed to characterize the long-term climate and vegetation conditions in each region of interest. We further present the approach developed in this research to decompose and to analyse jointly time series of remote sensing derived observation and climate dataset. We focus specifically on the adjustment of the 'climate-vegetation' relationships for specific periods within the growing season. Indeed we demonstrate that the relationship between NDVI and the meteorological parameters is highly complex and vary significantly trough the phenological cycle of the plants. Hence, interactions between vegetation dynamics and climate variability need to be studied at a smaller time scale than the year or the growing season, in order to identify properly the limiting factors to vegetation growth. Our analysis revealed that, in most of the cases, the best correlations are obtained when we considered the vegetative phase (from green-up to maximum of NDVI) and the reproductive phase (from maximum of NDVI to maturity) separately. We also show that climatic constraints identified using yearly proxies of climate and vegetation do not depict correctly, or completely, the climate control on vegetation development. Finally we evaluate the performance of climate-driven growth models in two sites of croplands and two sites of grasslands. The models were adjusted per phenological phases and set to provide 1-month forecast of NDVI. Pure climatic models (CLIM) were compared to auto-regressive climatic model (CLIM-AR). Apart in the Irish grasslands, the CLIM-AR models were performing better than CLIM models during the vegetative phase. On the other hand, during the reproductive phase, the introduction of the auto-regressive term did not improve significantly the performance of the CLIM model. Moreover the autoregressive term did never appear as first predictor, demonstrating that, in the selected sites, short to medium atmospheric conditions were explaining most of the variance in the 1-month forecast NDVI. [less ▲]

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