Papers by parminder ranhotra
Theoretical and Applied Climatology
Frontiers in Ecology and Evolution
We reviewed the available climate records for the past 2 millennia based on the analyzed sediment... more We reviewed the available climate records for the past 2 millennia based on the analyzed sediment and speleothem archives from different regions of South Asia. Speleothem records from the core-monsoon regions of the Indian sub-continent have revealed the Little Ice Age (LIA) as a climatically dry phase, whereas the same from the western and central Himalaya recorded LIA as wet. Moreover, the sediment-derived vegetation proxy records [pollen-spores and stable organic carbon isotope (δ13Corg)] from the western Himalaya also reported LIA as a dry phase. Heterogeneous results by different proxies during LIA enhanced our interest to understand the response of the proxies toward the primary precipitation sources, Indian summer monsoon (ISM) and winter westerly disturbances (WDs), over the Himalaya. We emphasize that in the Himalayan region, the vegetation predominantly responds to the ISM dynamics, whereas speleothem also captures the WD effect.
Forests, 2022
We analyzed the tree-rings δ18O of Abies spectabilis (fir) growing at the subalpine treeline ecot... more We analyzed the tree-rings δ18O of Abies spectabilis (fir) growing at the subalpine treeline ecotone in the Magguchatti valley. The valley is located in the Indian summer monsoon (ISM) dominated region of western Himalaya and also receives snow precipitation derived by westerly disturbances (WDs) during the winter months. The 60 year developed (1960–2019 CE) tree-ring δ18O chronology revealed a strong positive correlation with the temperature of late winter and spring months (February to April). Strong negative correlations are also apparent for snowcover, soilmoisture, and relative humidity for the same spring season. Our findings partly contrast the significant correlation results of tree-ring δ18O with summer precipitation and drought indices recorded from other summer monsoon-dominated regions in the Himalayas. The spatial correlation analyses with sea surface temperatures (SSTs) and climate parameters showed subdued signals of tropical Pacific at the site, but with a shift to m...
Journal of Asian Earth Sciences, 2022
SSRN Electronic Journal, 2021
Journal of Asian Earth Sciences, 2022
S. P. Singh*, A. Bhattacharyya, Amit Mittal, Aseesh Pandey, Ashish Tewari, Avantika Latwal, Bency... more S. P. Singh*, A. Bhattacharyya, Amit Mittal, Aseesh Pandey, Ashish Tewari, Avantika Latwal, Bency David, Bhupendra S. Adhikari, Devendra Kumar, G. C. S. Negi, Ishfaq Ahmad Mir, Krishna Kumar Tamta, Kumar Sambhav, Mayank Shekhar, Mohit Phulara, Munisa Manzoor, Nandan Singh, Pankaj Tewari, Parminder S. Ranhotra, Pradeep Singh, Pratap Dhaila, Priyanka Sah, Rahul Kumar, Rajesh Joshi, Ranbeer S. Rawal, Renu Rawal, Ripu Daman Singh, Shruti Shah, Subrat Sharma, Subzar Ahmad Nanda, Surabhi Gumber, Utsa Singh and Zafar Reshi Central Himalayan Environment Association, 6 Waldorf Compound, Mallital, Nainital 263 001, India Birbal Sahni Institute of Palaeosciences, 53, University Road, Lucknow 226 007, India Department of Forestry and Environmental Science, D.S.B. Campus, Kumaun University, Nainital 263 001, India G.B. Pant National Institute of Himalayan Environment and Sustainable Development, Sikkim Regional Centre, Pangthang, Gangtok 737 101, India G. B. Pant National Institute of Himalayan ...
Palynological analyses from exposed palaeolacustrine deposits located at the flanks of Damavand v... more Palynological analyses from exposed palaeolacustrine deposits located at the flanks of Damavand volcano, in the central AlborzMountains in Northern Iran, provide a broad idea of the temporal variation of vegetation according to climate changes during a rangeof limited time intervals during the Quaternary period. This research reveals that the regional vegetation of the study area had been asemi-arid mountain steppe since the early Quaternary. However, moderate expansions of open woodlands and aquatic/marshy taxaindicate less arid climatic conditions. Some of these comparatively less arid phases during the last 70 ka are contemporaneous with theclimatic amelioration phases during previous glacial periods in the Himalayan region. Although the results are scattered through time,they clearly show the potential of the study area for further palynological investigations with the aim of understanding the regionalvegetation response on global climate changes in Northern Iran
Journal of the Geological Society of India, 2013
Modern pollen-vegetation relationship has been analyzed in respect to vegetational distribution a... more Modern pollen-vegetation relationship has been analyzed in respect to vegetational distribution and pollen dispersal from sub-alpine and alpine ecological regimes within the higher reaches of the Gangotri glacier valley. The results in general cope with the local ecological conditions of the sites within the valley. Above the tree line limits, the pollen frequency of arboreal taxa is found lower than those of non-arboreal taxa. In contrast the pine-birch forest area at Chirbasa represented the frequency of arboreal pollen (AP) more than that of non-arboreal pollen (NAP) due to over representation of Pinus wallichiana (conifer). Pollen grains of extra-local arboreal elements, mostly conifers have also been recorded here with fair amount of temperate broad-leaved arboreal taxa viz. Quercus, Alnus, Corylus, Carpinus, Ulmus, Juglans etc. that have been transported by the upthermic winds from their growing limits at lower altitudes to the study sites at higher altitudes. Non-arboreal taxa viz. marshy/aquatic, steppe and of other herbaceaous taxa, represents the existing ecological regimes of their respective sites within the valley. Differential pollen preservation has been observed between the moss cushion and sediment samples from the same site that may be due to the direct exposure of moss cushions to air, thus showing more concentration of wind pollinated pollen-spores as compared to surface sediments.
CURRENT SCIENCE, 2011
Palynological studies have provided a good overview of the palaeovegetational and palaeoclimatic ... more Palynological studies have provided a good overview of the palaeovegetational and palaeoclimatic scenario of the Indian subcontinent. However, little has been explored in this regard from the glaciated sites of the Himalayan region. In recent years, some palynological data have been generated from a few glaciated sites of Western Himalaya and it has been found that other than palaeoclimatic reconstruction, spores-pollen can be used as an important parameter to know the possible extent of the glaciers during Late Quaternary. Glacier dynamics plays an important role in carving and consequent modification of the various geomorphic features, which are the characteristic of various stages of glacial fluctuations. Because the distribution of spores-pollen of the type vegetation is ubiquitous, collection of subsurface sediments from the depositional geomorphic features, for palynological study as well as dating, is important to get the chronological history of various glacial stages.
Current Science, 2002
... 18. Fort, M., J. Nepal Geol. Soc., 1995, 11, 257272. 19. Singh, J. and Yadav, R., Curr. Sci.... more ... 18. Fort, M., J. Nepal Geol. Soc., 1995, 11, 257272. 19. Singh, J. and Yadav, R., Curr. Sci., 2000, 79, 15981601. ACKNOWLEDGEMENTS. We are indebted to Prof. ... carbon dioxide emissions.' Remembering Satish Dhawan Amulya KN Reddy [Curr. Sci., 2002, 82, 226] ...
Trees, Forests and People, 2022
Journal of the Geological Society of India
This study highlights the modern pollen-vegetation relationships along an altitudinal gradient co... more This study highlights the modern pollen-vegetation relationships along an altitudinal gradient covering the lower temperate (∼2,000 masl) to alpine vegetation zones (∼3,800 masl) in the Bhagirathi valley, western Himalaya. The pollen dispersal dataset compared with the altitudinal vegetation distribution in the valley shows incoherency between the arboreal taxa and their respective pollen proportions. Discriminant analysis (DA) revealed the role of diurnal valley winds in pollen mixing between altitudinal vegetation zones. Pollen of arboreal taxa are transported profusely from the lower temperate vegetation zones to alpine zone. Whereas pollen of non-arboreal taxa, dominantly growing in the sub-alpine and alpine meadows, remain close to their source and represent the prevailing localized environmental conditions in the valley. Study revealed Pinus and Quercus as dominant arboreal pollen taxa throughout the altitudinal transect with a distinct transition in their representation between ∼2,500 and 2,600 masl. High percentage of Pinus (Quercus) pollen below (above) this transition zone nearly corresponds with the present distribution of conifer (pine-oak) and broadleaved (oak-pine) forests in the valley and can be taken as a marker zone to infer palaeoecological changes. The sub-alpine and alpine krummholz, Juniperus and Ericaceae are found autochthonous in their pollen distribution that can serve as good indicators of relative tree-line and glacier dynamics in past. This pollen-vegetation relationship dataset could be an analogue for the interpretation of fossil pollen records in terms of extant vegetation in the mountain regions.
上新世-更新世过渡期是新生代全球气候变化的重要拐点之一,此期气候经历了由＂暖室＂向＂冰室＂的转变。研究该气候转型期的特征可为科学界和国家层面应对现在和未来的全球气候变暖提供理论基础和实践指导。通... more 上新世-更新世过渡期是新生代全球气候变化的重要拐点之一,此期气候经历了由＂暖室＂向＂冰室＂的转变。研究该气候转型期的特征可为科学界和国家层面应对现在和未来的全球气候变暖提供理论基础和实践指导。通过深入研究中国华北山西榆社盆地张村组上新世-更新世过渡期地层中保存的植物大化石、孢粉以及硅藻组合,为重建该时段陆地生态系统中植被演替和气候变化提供坚实的生物学证据。在综合回顾张村组化石植物研究历史的基础上,侧重介绍最近5年在古植被、古气候、古环境以及古大气CO2浓度重建等方面的最新进展。这些新成果定性及定量地刻画了第三纪-第四纪之交中国北方黄土高原东南缘气候变干、变凉的转型过程及其陆地生态系统中大气CO2浓度先升后降的变化趋势。
Quaternary International
Abstract This article presents a reconstruction of winter (November–March) drought by using the S... more Abstract This article presents a reconstruction of winter (November–March) drought by using the Standardized Precipitation Evapotranspiration Index (SPEI) based on the tree-ring width data of Pinus roxburghii (Chir pine) growing near Uttarkashi, Garhwal region, western Himalaya. This is based on a significant negative correlation between growth of Chir pine and SPEI of November–March (N-M) months. This relationship might be linked with the low rate of photosynthesis during low or freezing temperature when roots unable to take soil moisture, an analogous to drought situation as in the cold desert. The reconstructed winter SPEI record extends from 1767 to 2013 CE. It explains 30.5% of the variance for the calibration period (1903–2013 CE). The regression model was tested using Correlation Coefficient (r), Coefficient of Determination (R2), Reduction of Error (RE), Coefficient of efficiency (CE) and Durbin-Watson test (DW). The extended SPEI time series has revealed several intervals of high and low intensity drought since the 17th century. There is also a linkage between (N-M) months SPEI and Western Disturbance (WD). This connection indicates that the WD may have a role in modulating droughts in the Indian region.
Scientific reports, Jan 4, 2017
To date, there is a gap in the data about the state and mass balance of glaciers in the climate-s... more To date, there is a gap in the data about the state and mass balance of glaciers in the climate-sensitive subtropical regions during the Little Ice Age (LIA). Here, based on an unprecedented tree-ring sampling coverage, we present the longest reconstructed mass balance record for the Western Himalayan glaciers, dating to 1615. Our results confirm that the later phase of LIA was substantially briefer and weaker in the Himalaya than in the Arctic and subarctic regions. Furthermore, analysis of the time-series of the mass-balance against other time-series shows clear evidence of the existence of (i) a significant glacial decay and a significantly weaker magnitude of glaciation during the latter half of the LIA; (ii) a weak regional mass balance dependence on either the El Niño-Southern Oscillation (ENSO) or the Total Solar Irradiance (TSI) taken in isolation, but a considerable combined influence of both of them during the LIA; and (iii) in addition to anthropogenic climate change, the...
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Papers by parminder ranhotra