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Quantifying major sources of uncertainty in projecting the impact of climate change on wheat grain yield in dryland environments

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Journal of arid Land 2023年第5期15卷 545-561页

作者： Reza DEIHIMFARD Sajjad RAHIMI-MOGHADDAM Farshid JAVANSHIR Alireza PAZOKI Department of Agroecology Environmental Sciences Research InstituteShahid Beheshti UniversityTehran 19839–69411Iran Department of Production Engineering and Plant Genetics Faculty of Agriculture and Natural ResourcesLorestan UniversityKhorramabad 68151–44316Iran Department of Agrotechnology Yadegar-e-Imam Khomeini(RAH)Shahre Rey BranchIslamic Azad UniversityTehran 18151–63111Iran

Modelling the impact of climate change on cropping systems is crucial to support policy-making for farmers and ***,there exists inherent uncertainty in such *** Circulation Models(GCMs)and future climate change scenarios(different Representative Concentration Pathways(RCPs)in different future time periods)are among the major sources of uncertainty in projecting the impact of climate change on crop grain *** study quantified the different sources of uncertainty associated with future climate change impact on wheat grain yield in dryland environments(Shiraz,Hamedan,Sanandaj,Kermanshah and Khorramabad)in eastern and southern *** five representative locations can be categorized into three climate classes:arid cold(Shiraz),semi-arid cold(Hamedan and Sanandaj)and semi-arid cool(Kermanshah and Khorramabad).Accordingly,the downscaled daily outputs of 29 GCMs under two RCPs(RCP4.5 and RCP8.5)in the near future(2030s),middle future(2050s)and far future(2080s)were used as inputs for the Agricultural Production Systems sIMulator(APSIM)-wheat *** of variance(ANOVA)was employed to quantify the sources of uncertainty in projecting the impact of climate change on wheat grain *** from 1980 to 2009 were regarded as the baseline *** projection results indicated that wheat grain yield was expected to increase by 12.30%,17.10%,and 17.70%in the near future(2030s),middle future(2050s)and far future(2080s),*** increases differed under different RCPs in different future time periods,ranging from 11.70%(under RCP4.5 in the 2030s)to 20.20%(under RCP8.5 in the 2080s)by averaging all GCMs and locations,implying that future wheat grain yield depended largely upon the rising CO2 *** results revealed that more than 97.22% of the variance in future wheat grain yield was explained by locations,followed by scenarios,GCMs,and their ***,at the semi-arid climate locations(Hamedan,S

关键词： wheat grain yield climate change Agricultural Production Systems sIMulator(APSIM)-wheat model General Circulation Models(GCMs) arid climate semi-arid climate Iran

Influence of climate and Tectonics on the Crystallization of Carnallite and Related Salts in the Congolese Atlantic Basin during the Lower Cretaceous, Republic of Congo

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Open Journal of Geology 2023年第1期13卷 51-71页

作者： Daphne Steimer Garcia Nkokani Milandou Hilaire Elenga Maurice Dieudonné Malounguila Nganga Mathurin Enama Mengong Center for Geological and Mining Research Brazzaville Republic of Congo Faculty of Science and Technology Geology Course Marien Ngouabi University Brazzaville Republic of Congo Newco Mining SA Pointe-Noire Republic of Congo

Lithological, petrographic, and morphoscopic studies were conducted on cuttings and cores from three boreholes drilled in the Loemé salt, Kanga site, Republic of the Congo, to determine 1) the preferential conditions for crystallization of carnallite and associated salts and 2) to reconstruct paleoenvironmental and paleoclimatic conditions at the time of sedimentation. Sequential analysis of logs, sedimentary structures, carnallitite facies and associated salts concluded to the existence of a potassic carnallitite lagoon basin with low water cover, on a very wide and extensive plateau, affected by coastal waves and swells resulting from successive collapses. This basin evolved in two phases: confined and then open. The regular stratifications of halite, the rhythmicity of the halite-carnallitite elementary sequences are characteristic of salts that precipitated in relatively stable brines. These salts are therefore tectonosedimentary. The brecciated facies of the carnallitites sometimes associated with tachyhydrite result from the evolution of these deposits into salt crusts reworked by the surges into subaquatic allochemical gravelly cords under water. These crusts mark stages of partial and complete drying of the basin in a very hot and arid climate. Prolonged exposure of halite brines as well as their homogenization by surges accelerated evaporation and their abrupt evolution into carnallite brines obstructing the fossilization of sylvite. The precipitation of tachyhydrite marks the final stage of the successive complete drying of the basin.

关键词： Potassium Lagoon Surges Stable Brines Rhythmicity Elementary Sequences Salt Crusts arid climate Republic of the Congo

climate Change and Future Long-Term Trends of Rainfall at North-East of Iraq

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Journal of Civil Engineering and Architecture 2014年第6期8卷 790-805页

作者： Nadhir Al-Ansari Mawada Abdellati Mohammad Ezeelden Salahalddin S. Ali Sven Knutsson Department of Civil Environmental and Natural Resources Engineering Lulea University of Technology Lulea 971 87 Sweden BEST Research Institute Peter Jost Centre Liverpool John Moores University Liverpool L3 3AF UK Department of Dams and Water Resources Engineering Mosul University Mosul 41002 Iraq Department of Geology Sulaimani University Sulaimani 41052 Iraq

Iraq is facing water shortage problem despite the presence of the Tigris and Euphrates Rivers. In this research, long rainfall trends up to the year 2099 were studied in Sulaimani city northeast Iraq to give an idea about future prospects. The medium high （A2） and medium low B2 scenarios have been used for purpose of this study as they are more likely than others scenarios, that beside the fact that no climate modeling canter has performed GCM （global climate model） simulations for more than a few emissions scenarios （HadCM3 has only these two scenarios） otherwise pattern scaling can be used for generating different scenarios which entail a huge uncertainty. The results indicate that the average annual rainfall shows a significant downward trend for both A2 and B2 scenarios. In addition, winter projects increase/decrease in the daily rainfall statistics of wet days, the spring season show very slight drop and no change for both scenarios. However, both summer and autumn shows a significant reduction in maximum rainfall value especially in 2080s while the other statistics remain nearly the same. The extremes events are to decrease slightly in 2080s with highest decrease associated with A2 scenario. This is due to the fact that rainfall under scenario A2 is more significant than under scenario B2. The return period of a certain rainfall will increase in the future when a present storm of 20 year could occur once every 43 year in the 2080s. An increase in the frequency of extreme rainfall depends on several factors such as the return period, season of the year, the period considered as well as the emission scenario used.

关键词： arid climate climate change Iraq rainfall Sulaimani

Geochemical evidences of dry climate in the Mid-Holocene in Gonghe Basin, northeastern Qinghai-Tibetan Plateau

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Research in Cold and arid Regions 2012年第6期4卷 472-483页

作者： Bing Liu HeLing Jin Zhong Sun ZhiZhu Su CaiXia Zhang Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences School of History and Culture Shanxi University

Previous research on climatic change in the Mid-Holocene in China indicates that it was a warm and humid period, accompanied by stronger summer monsoons, and it is defined as the Megatherrnal in the Holocene, or the Holocene Optimum period. However, this conclusion is mainly dh＇eeted at the monsoonal region in eastem China. In this research, we chose the Gonghe Basin in the northeastern Qinghai-Tibetan Plateau as the study area. Geochemical analysis of the profiles of paleosols and aeolian sand in the Santala area in the middle of the Gonghe Basin, along with OSL （optically stimulated luminescence） dating, indicates that the regional climate has experienced several warm-humid and cold-dry cycles since 11.8 ka. In particular, the Mid-Holocene （8.14.6 ka） was relatively cold and dry as evidenced by drastic fluctuations in chemical weathering degree and humidity, a higher aridity index, and sparse vegetation, accompanying increased winter monsoonal strength. In order to clarify whether this is an individual or local signal, we compared our geochemical analysis results with lake and peat records and aeolian de- posits of the monsoonal boundary region. The results indicate that the climate deteriorated widely, with declines in temperature and moisture, in the Mid-Holocene in the modem monsoonal boundary zone. Furthermore, the duration of climate deteriora- tion （relatively dry period） generally decreased from west to east in the aforementioned regions. Therefore, this dry phase in Gonghe Basin may be representative of dry events in Mid-Holocene in northem China. In addition, we discuss the reasons for this dry climate from several perspectives：（1） it probably can be attributed to a decline in summer monsoonal strength; （2） the regional evaporation loss （forced by high temperature） was not compensated by regional precipitation; （3） the thermal dynamic effect of the Qinghai-Tibetan Plateau.

关键词： Mid-Holocene arid climate geochemical elements Gonghe Basin Qinghai-Tibetan Plateau

Desert-steppe migration on the Loess Plateau at about 450 kaBP

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Journal of Geographical Sciences 2005年第1期15卷 115-122页

作者： ZHAOJingbo GeographyDepartmentofShaanxiNormalUniversity Xi＇an710062China／／StateKeyLaboratoryofLoessandQuaternaryInstituteofEarthEnvironmentCASXi＇an710054China

According to the field investigation, observation by an electronic microscope and x-ray identification and chemical analysis, desert-steppe migration in the Loess Plateau at about 450 kaBP was studied. The data show that gypsum illuvial horizon indicating the desert-steppe environment developed in the early stage of the formation of the fifth layer loess in Shaoling tableland in Chang'an and Bailu tableland in Xi'an of Shaanxi are situated in the southern Loess Plateau. This indicates that remarkable drying occurred, a large-scope migration of desert steppe took place toward south and the climate zone migrated 5 degrees in latitude to south which is the largest migration range indicated by geochemical indexes. The desert-steppe and more wild environment distributed widely on the Loess Plateau at that time. The development of gypsum also indicates that the climate changed at 450 kaBP from monsoon climate to nonmonsoon climate in the Loess Plateau, and the region was not affected by summer monsoon and was in the cold and dry environment of nonmonsoon climate. Annual mean precipitation was about 200 mm, 400 mm less at that time than at present.

关键词： the Loess Plateau gypsum arid climate large-scale migration of desert-steppe