scholarly journals Revisiting historical climatic signals to better explore the future: prospects of water cycle changes in Central Sahel

2015 ◽  
Vol 371 ◽  
pp. 195-201 ◽  
Author(s):  
C. Leauthaud ◽  
J. Demarty ◽  
B. Cappelaere ◽  
M. Grippa ◽  
L. Kergoat ◽  
...  
Keyword(s):  
Water Cycle ◽  
Climatic Changes ◽  
Climatic Conditions ◽  
Water Model ◽  
Semiarid Region ◽  
Coupled Models ◽  
The Past ◽  
Precipitation Regimes ◽  
Sahel Region ◽  
Precipitation Changes

Abstract. Rainfall and climatic conditions are the main drivers of natural and cultivated vegetation productivity in the semiarid region of Central Sahel. In a context of decreasing cultivable area per capita, understanding and predicting changes in the water cycle are crucial. Yet, it remains challenging to project future climatic conditions in West Africa since there is no consensus on the sign of future precipitation changes in simulations coming from climate models. The Sahel region has experienced severe climatic changes in the past 60 years that can provide a first basis to understand the response of the water cycle to non-stationary conditions in this part of the world. The objective of this study was to better understand the response of the water cycle to highly variable climatic regimes in Central Sahel using historical climate records and the coupling of a land surface energy and water model with a vegetation model that, when combined, simulated the Sahelian water, energy and vegetation cycles. To do so, we relied on a reconstructed long-term climate series in Niamey, Republic of Niger, in which three precipitation regimes can be distinguished with a relative deficit exceeding 25% for the driest period compared to the wettest period. Two temperature scenarios (+2 and +4 °C) consistent with future warming scenarios were superimposed to this climatic signal to generate six virtual future 20-year climate time series. Simulations by the two coupled models forced by these virtual scenarios showed a strong response of the water budget and its components to temperature and precipitation changes, including decreases in transpiration, runoff and drainage for all scenarios but those with highest precipitation. Such climatic changes also strongly impacted soil temperature and moisture. This study illustrates the potential of using the strong climatic variations recorded in the past decades to better understand potential future climate variations.

scholarly journals Climate Change and Conflict

2019 ◽  
Vol 22 (1) ◽  
pp. 343-360 ◽  
Author(s):  
Vally Koubi
Keyword(s):  
Climate Change ◽  
Climatic Changes ◽  
Climatic Conditions ◽  
Future Research ◽  
General Effect ◽  
Substantial Agreement ◽  
Political Factors ◽  
Academic Literature ◽  
The Past ◽  
Level Of Economic Development

The link between climate change and conflict has been discussed intensively in academic literature during the past decade. This review aims to provide a clearer picture of what the research community currently has to say with regard to this nexus. It finds that the literature has not detected a robust and general effect linking climate to conflict onset. Substantial agreement exists that climatic changes contribute to conflict under some conditions and through certain pathways. In particular, the literature shows that climatic conditions breed conflict in fertile grounds: in regions dependent on agriculture and in combination and interaction with other socioeconomic and political factors such as a low level of economic development and political marginalization. Future research should continue to investigate how climatic changes interact with and/or are conditioned by socioeconomic, political, and demographic settings to cause conflict and uncover the causal mechanisms that link these two phenomena.

Fingerprint-Based Attribution Study of Climatic Changes in the Hai River Basin of China

2012 ◽  
Vol 518-523 ◽  
pp. 5798-5804
Author(s):  
Xiang Yi Ding ◽  
Yang Wen Jia
Keyword(s):  
River Basin ◽  
Meteorological Data ◽  
Moving Average ◽  
Sudden Change ◽  
Temporal Variations ◽  
Climatic Changes ◽  
Climatic Conditions ◽  
Anthropogenic Forcing ◽  
The Past ◽  
Precipitation And Temperature

Many observational facts and studies have shown that the climatic conditions in the Hai River Basin, which is the political and cultural centre of China, changed significantly over last half of the 20th century. This study attempts to evaluate the variability of climatic elements such as precipitation and temperature in the basin based on observed meteorological data, and the temporal variations and sudden changes of precipitation and temperature during past 40 years (1961-2000) are analyzed combining moving-average and linear regression with Mann-Kendall method. In addition, the observed climatic changes are attributed to different factors including natural variability and anthropogenic forcing using the fingerprint-based attribution method. The results indicate that: 1) during 1961-2000, the precipitation slightly decreased and the estimated sudden change time was 1965, the temperature significantly increased and the estimated sudden change time was 1964; 2) natural climate variability may be the factors responsible for the observed precipitation changes during the past 40 years in the basin, while anthropogenic forcing may be the main factors responsible for the observed temperature changes during the past 40 years in the basin.

scholarly journals The Transformation of Agro-Climatic Resources of the Altai Region under Changing Climate Conditions

Agriculture ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 68 ◽  
Author(s):  
Nina Maximova ◽  
Komali Kantamaneni ◽  
Gennady Morkovkin ◽  
Darya Arnaut ◽  
Louis Rice
Keyword(s):  
Growing Season ◽  
Climatic Changes ◽  
Climatic Conditions ◽  
Integrated Analysis ◽  
Published Data ◽  
Climate Conditions ◽  
Related Data ◽  
Growing Season Length ◽  
Altai Region ◽  
The Past

This research examines the transformation of the agro-climatic conditions of the Altai region as a result of climate change. The climate of the Altai region in Russia is sharply continental and characterized by dry air and significant weather variability, both in individual seasons and years. The current study is determined by the lack of detailed area-related analytical generalizations for the territory of the Altai region over the past 30 years. Most of the published data dealing with an integrated analysis of the agro-climatic conditions in the Altai region date back to the late 1960s and early 1970s; in most cases, this data is from climate reference-books based on the generalized data from the first half of the 20th century. To make accurate forecasts and to efficiently manage agricultural production in the Altai region, area-related data on the state and dynamics of agro-climatic changes have been analysed. The results reveal that in the period between 1964 and 2017, significant climatic changes occurred in the territory of the Altai region. These climatic changes affected the growing season length, which increased due to a shift in the dates of the air temperature transition above 10 °C, to earlier dates in spring and to later dates in autumn. Furthermore, the current study also revealed that the foothills of the Altai Mountains are the most moistened parts of the region and the Kulunda lowland is the most arid part. In the Altai region, the accumulated temperatures and amounts of precipitation during the growing season increased significantly, and the values of integrated coefficients and indices that reflect the moisture supply conditions for the territory also changed significantly. Based upon the results, a schematic map of the current precipitation distribution on the Altai region’s territory has been generated. These results and this map may be used to conduct more detailed studies in the field of agro-climatology and to update the current borders of agro-climatic areas and revision of the agro-climatic zonation scheme.

scholarly journals Influence of atmospheric internal variability on the long-term Siberian water cycle during the past two centuries

2017 ◽  
Author(s):  
Kazuhiro Oshima ◽  
Koto Ogata ◽  
Hotaek Park ◽  
Yoshihiro Tachibana
Keyword(s):  
General Circulation ◽  
Water Cycle ◽  
Circulation Model ◽  
Internal Variability ◽  
The Arctic ◽  
Coupled Models ◽  
The Past ◽  
Term Variation ◽  
East West

Abstract. River discharges from Siberia are a large source of freshwater into the Arctic Ocean, although the cause of the long-term variation in discharge is still unclear. The observed river discharges of the Lena in the east and the Ob in the west indicated different relationships in each of the epochs during the past seven decades. The correlations between the two river discharges were negative during the 1980s to mid-1990s, positive during the mid-1950s to 1960s, and became weak after the mid-1990s. Long-term records of tree-ring-reconstructed discharges during the past two centuries have also shown differences in the correlations in each epoch. However, it is noteworthy that the correlations obtained from the reconstructions tend to be negative. Such negative correlations have also been obtained from precipitations over the Lena and Ob in observation, and in simulations with an atmospheric general circulation model (AGCM) and multi-coupled models conducted for the Fourth Assessment Report of the IPCC. The AGCM control simulation further demonstrated that an east–west seesaw pattern of summertime atmospheric large-scale circulation frequently emerges over Siberia as an atmospheric internal variability, resulting in the negative correlation between the Lena and Ob. Consequently, the summertime atmospheric internal variability of east–west seesaw pattern over Siberia is a key factor influencing the long-term variation in precipitation and river discharge, i.e., the water cycle in this region.

scholarly journals Simulating the Effects of Thinning Events on Forest Growth and Water Services Asks for Daily Analysis of Underlying Processes

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1729
Author(s):  
Rasoul Yousefpour ◽  
Marc Djahangard
Keyword(s):  
Soil Water ◽  
Water Cycle ◽  
Average Diameter ◽  
Growth Function ◽  
Climatic Conditions ◽  
Forest Growth ◽  
Water Model ◽  
Water Services ◽  
The Novel ◽  
Monthly Basis

Forest growth function and water cycle are affected by climatic conditions, making climate-sensitive models, e.g., process-based, crucial to the simulation of dynamics of forest and water interactions. A rewarded and widely applied model for forest growth analysis and management, 3PG, is a physiological process-based forest stand model that predicts growth. However, the model runs on a monthly basis and uses a simple soil-water module. Therefore, we downscale the temporal resolution to operate daily, improve the growth modifiers and add a responsive hydrological sub-model to represents the key features of a snow routine, a detailed soil-water model and a separated soil-evaporation calculation. Thereby, we aim to more precisely analyze the effects of thinning events on forest productivity and water services. The novel calibrated 3PG-Hydro model was validated in Norway spruce sites in Southern Germany and confirmed improvements in building forest processes (evapotranspiration) and predicting forest growth (biomass, diameter, volume), as well as water processes and services (water recharge). The model is more sensitive to forest management measures and variability in soil water by (1) individualization of each site’s soil, (2) simulation of percolation and runoff processes, (3) separation of transpiration and evapotranspiration to predict good evapotranspiration even if high thinning is applied, (4) calculation in daily time steps to better simulate variation and especially drought and (5) an improved soil-water modifier. The new 3PG-Hydro model can, in general, better simulate forest growth (stand volume, average diameter), as well as details of soil and water processes after thinning events. The novel developments add complexity to the model, but the additions are crucial and relevant, and the model remains an easy-to-handle forest simulation tool.

Triple isotopic composition of oxygen in water and dioxygen during deglaciations recorded in the EPICA Dome C ice core to link climate, biosphere productivity and water cycle

2020 ◽  
Author(s):  
Amaelle Landais ◽  
Ji-Woong Yang ◽  
Nicolas Pasquier ◽  
Antoine Grisart ◽  
Margaux Brandon ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Hydrological Cycle ◽  
Water Cycle ◽  
Ice Core ◽  
Ice Cores ◽  
Climatic Conditions ◽  
Added Value ◽  
Air Bubbles ◽  
The Past

<p>High precision measurements of triple isotopic composition of oxygen in water is a useful tool to infer the dynamic of past hydrological cycle when measured in ice core together with δ<sup>18</sup>O and δD. In particular, the triple isotopic composition of oxygen in water provides information on the climatic conditions of the evaporative sources. In parallel, it has been shown that the triple isotopic composition of oxygen in the atmospheric dioxygen can be a useful tracer of the global biosphere productivity and hence reconstruct the dynamic of the global biosphere productivity in the past from measurements performed in the air bubbles. Measuring triple isotopic composition of oxygen both in the water and in the atmospheric dioxygen trapped in bubbles in ice cores is thus a strong added value to study the past variability of water cycle and biosphere productivity in parallel to climate change.</p><p>Here, we first present new laboratory experiments performed in closed biological chambers to show how the triple isotopic composition of oxygen in atmospheric dioxygen can be used for quantification of the biosphere productivity with determination of fractionation coefficients. Then, we present new records of triple isotopic composition of oxygen in water and O<sub>2</sub> trapped in bubbles from the EPICA Dome C ice core over the deglaciations of the last 800 ka.</p>

scholarly journals Denitrifying pathways dominate nitrous oxide emissions from managed grassland during drought and rewetting

2021 ◽  
Vol 7 (6) ◽  
pp. eabb7118
Author(s):  
E. Harris ◽  
E. Diaz-Pines ◽  
E. Stoll ◽  
M. Schloter ◽  
S. Schulz ◽  
...  
Keyword(s):  
Growth Rate ◽  
Nitrous Oxide ◽  
N Fertilization ◽  
High Variability ◽  
Nitrous Oxide Emissions ◽  
Severe Drought ◽  
Total N ◽  
The Past ◽  
Precipitation Changes ◽  
Isotopic Measurements

Nitrous oxide is a powerful greenhouse gas whose atmospheric growth rate has accelerated over the past decade. Most anthropogenic N2O emissions result from soil N fertilization, which is converted to N2O via oxic nitrification and anoxic denitrification pathways. Drought-affected soils are expected to be well oxygenated; however, using high-resolution isotopic measurements, we found that denitrifying pathways dominated N2O emissions during a severe drought applied to managed grassland. This was due to a reversible, drought-induced enrichment in nitrogen-bearing organic matter on soil microaggregates and suggested a strong role for chemo- or codenitrification. Throughout rewetting, denitrification dominated emissions, despite high variability in fluxes. Total N2O flux and denitrification contribution were significantly higher during rewetting than for control plots at the same soil moisture range. The observed feedbacks between precipitation changes induced by climate change and N2O emission pathways are sufficient to account for the accelerating N2O growth rate observed over the past decade.

scholarly journals Millennial-scale precipitation changes in southern Brazil over the past 90,000 years

2007 ◽  
Vol 34 (23) ◽  
pp. n/a-n/a ◽  
Author(s):  
Xianfeng Wang ◽  
Augusto S. Auler ◽  
R. L. Edwards ◽  
Hai Cheng ◽  
Emi Ito ◽  
...  
Keyword(s):  
Southern Brazil ◽  
The Past ◽  
Precipitation Changes ◽  
Millennial Scale

scholarly journals Orbital forcing of terrestrial mollusks and climatic changes from the Loess Plateau of China during the past 350 ka

2001 ◽  
Vol 106 (D17) ◽  
pp. 20045-20054 ◽  
Author(s):  
Naiqin Wu ◽  
D. D. Rousseau ◽  
Tungsheng Liu ◽  
Houyuan Lu ◽  
Gu Zhaoyan ◽  
...  
Keyword(s):  
Loess Plateau ◽  
Climatic Changes ◽  
Orbital Forcing ◽  
The Loess Plateau ◽  
The Past ◽  
Terrestrial Mollusks

Tree line shifts, changing vegetation assemblages and permafrost dynamics on Galdhøpiggen (Jotunheimen, Norway) over the past ~4400 years

The Holocene ◽  
2021 ◽  
pp. 095968362110665
Author(s):  
Helen Hallang ◽  
Cynthia A Froyd ◽  
John F Hiemstra ◽  
Sietse O Los
Keyword(s):  
Scots Pine ◽  
Late Holocene ◽  
Accumulation Rate ◽  
Climatic Changes ◽  
Climatic Conditions ◽  
Tree Line ◽  
Peat Core ◽  
Modern Pollen ◽  
Modern Analogue ◽  
Downy Birch

An environmental reconstruction based on palynological evidence preserved in peat was carried out to examine late-Holocene alpine tree line dynamics in the context of past climatic changes on Galdhøpiggen (Jotunheimen, southern Norway). We analysed a peat core taken from a mire at the present-day tree line (1000 m a.s.l.), c. 450 m downslope from the lower limit of sporadic permafrost. We adopted a combination of commonly used indicators of species’ local presence to reconstruct past vegetation assemblages, such as the relative pollen abundance (%), pollen accumulation rate (PAR), and presence of indicator species. Additionally, fossil pollen from the peat sequence was compared to modern pollen from a surface moss polster to establish a modern analogue. The results were compared with studies covering the late-Holocene climatic changes in the area. The reconstruction demonstrates that a pine-dominated woodland reached above the present-day tree line at c. 4300 cal. yr BP, suggesting a warmer climate suitable for Scots pine ( Pinus sylvestris) growth at this altitude. Scots pine retreated to lower altitudes between c. 3400 and 1700 cal. yr BP, accompanied by the descent of the low-alpine shrub-dominated belt, in response to cooling climatic conditions. The colder period covered c. 1700–170 cal. yr BP, and an open downy birch ( Betula pubescens) woodland became widespread at 1000 m a.s.l., whilst pine remained sparse at this altitude. From c. 170 cal. yr BP onwards, warming allowed pine to re-establish its local presence alongside downy birch at 1000 m a.s.l.

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