1
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Thirumalai K, DiNezio PN, Partin JW, Liu D, Costa K, Jacobel A. Future increase in extreme El Niño supported by past glacial changes. Nature 2024:10.1038/s41586-024-07984-y. [PMID: 39322673 DOI: 10.1038/s41586-024-07984-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 08/21/2024] [Indexed: 09/27/2024]
Abstract
El Niño events, the warm phase of the El Niño-Southern Oscillation (ENSO) phenomenon, amplify climate variability throughout the world1. Uncertain climate model predictions limit our ability to assess whether these climatic events could become more extreme under anthropogenic greenhouse warming2. Palaeoclimate records provide estimates of past changes, but it is unclear if they can constrain mechanisms underlying future predictions3-5. Here we uncover a mechanism using numerical simulations that drives consistent changes in response to past and future forcings, allowing model validation against palaeoclimate data. The simulated mechanism is consistent with the dynamics of observed extreme El Niño events, which develop when western Pacific warm pool waters expand rapidly eastwards because of strongly coupled ocean currents and winds6,7. These coupled interactions weaken under glacial conditions because of a deeper mixed layer driven by a stronger Walker circulation. The resulting decrease in ENSO variability and extreme El Niño occurrence is supported by a series of tropical Pacific palaeoceanographic records showing reduced glacial temperature variability within key ENSO-sensitive oceanic regions, including new data from the central equatorial Pacific. The model-data agreement on past variability, together with the consistent mechanism across climatic states, supports the prediction of a shallower mixed layer and weaker Walker circulation driving more frequent extreme El Niño genesis under greenhouse warming.
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Affiliation(s)
| | - Pedro N DiNezio
- Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, CO, USA
| | - Judson W Partin
- The University of Texas Institute for Geophysics, The University of Texas, Austin, Austin, TX, USA
| | - Dunyu Liu
- The University of Texas Institute for Geophysics, The University of Texas, Austin, Austin, TX, USA
| | - Kassandra Costa
- Geology and Geophysics Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Allison Jacobel
- Department of Earth and Climate Sciences, Middlebury College, Middlebury, VT, USA
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2
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Bradshaw CJA, Saltré F, Crabtree SA, Reepmeyer C, Moutsiou T. Small populations of Palaeolithic humans in Cyprus hunted endemic megafauna to extinction. Proc Biol Sci 2024; 291:20240967. [PMID: 39288802 DOI: 10.1098/rspb.2024.0967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 07/26/2024] [Accepted: 08/19/2024] [Indexed: 09/19/2024] Open
Abstract
The hypothesized main drivers of megafauna extinctions in the late Quaternary have wavered between over-exploitation by humans and environmental change, with recent investigations demonstrating more nuanced synergies between these drivers depending on taxon, spatial scale, and region. However, most studies still rely on comparing archaeologically based chronologies of timing of initial human arrival into naïve ecosystems and palaeontologically inferred dates of megafauna extinctions. Conclusions arising from comparing chronologies also depend on the reliability of dated evidence, dating uncertainties, and correcting for the low probability of preservation (Signor-Lipps effect). While some models have been developed to test the susceptibility of megafauna to theoretical offtake rates, none has explicitly linked human energetic needs, prey choice, and hunting efficiency to examine the plausibility of human-driven extinctions. Using the island of Cyprus in the terminal Pleistocene as an ideal test case because of its late human settlement (~14.2-13.2 ka), small area (~11 000 km2), and low megafauna diversity (2 species), we developed stochastic models of megafauna population dynamics, with offtake dictated by human energetic requirements, prey choice, and hunting-efficiency functions to test whether the human population at the end of the Pleistocene could have caused the extinction of dwarf hippopotamus (Phanourios minor) and dwarf elephants (Palaeoloxodon cypriotes). Our models reveal not only that the estimated human population sizes (n = 3000-7000) in Late Pleistocene Cyprus could have easily driven both species to extinction within < 1000 years, the model predictions match the observed, Signor-Lipps-corrected chronological sequence of megafauna extinctions inferred from the palaeontological record (P. minor at ~12-11.1 ka, followed by P. cypriotes at ~10.3-9.1 ka).
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Affiliation(s)
- Corey J A Bradshaw
- Global Ecology | Partuyarta Ngadluku Wardli Kuu, College of Science and Engineering, Flinders University, GPO Box 2100 , Adelaide, South Australia 5001, Australia
- Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage , Wollongong, New South Wales, Australia
| | - Frédérik Saltré
- Global Ecology | Partuyarta Ngadluku Wardli Kuu, College of Science and Engineering, Flinders University, GPO Box 2100 , Adelaide, South Australia 5001, Australia
- Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage , Wollongong, New South Wales, Australia
| | - Stefani A Crabtree
- Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage , Wollongong, New South Wales, Australia
- Department of Environment and Society, Utah State University, 5200 Old Main Hill , Logan, UT 84322, USA
- The Santa Fe Institute, 1399 Hyde Park Road , Santa Fe, NM 87501, USA
| | - Christian Reepmeyer
- Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage , Wollongong, New South Wales, Australia
- Commission for Archaeology of Non-European Cultures, German Archaeological Institute, Dürenstr. 35-37 , Bonn 53173, Germany
- College of Arts, Society and Education, James Cook University Cairns, Nguma-bada campus, GPO Box 6811 Cairns , Queensland 4870, Australia
| | - Theodora Moutsiou
- Archaeological Research Unit, University of Cyprus, 12 Gladstone Street , Nicosia 1095, Cyprus
- College of Arts, Society and Education, James Cook University Cairns , Cairns, Queensland 4870, Australia
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3
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Freeman J, Gil AF, Peralta EA, Franchetti F, López JM, Neme G. A model of long-term population growth with an application to Central West Argentina. PLoS One 2024; 19:e0307703. [PMID: 39110658 PMCID: PMC11305588 DOI: 10.1371/journal.pone.0307703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Accepted: 07/09/2024] [Indexed: 08/10/2024] Open
Abstract
We propose an Ideal Specialization Model to help explain the diversity of population growth trajectories exhibited across archaeological regions over thousands of years. The model provides a general set of expectations useful for guiding empirical research, and we provide a concrete example by conducting a preliminary evaluation of three expectations in Central West Argentina. We use kernel density estimates of archaeological radiocarbon, estimates of paleoclimate, and human bone stable isotopes from archaeological remains to evaluate three expectations drawn from the model's dynamics. Based on our results, we suggest that innovations in the production of food and social organization drove demographic transitions and population expansion in the region. The consistency of population expansion in the region positively associates with changes in diet and, potentially, innovations in settlement and social integration.
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Affiliation(s)
- Jacob Freeman
- Anthropology Program, Utah State University, Logan, UT, United States of America
- The Ecology Center, Utah State University, Logan, UT, United States of America
| | - Adolfo F. Gil
- Instituto de Evolución, Ecología Histórica y Ambiente, Consejo Nacional de Investigaciones Científicas y Técnicas (IDEVEA, CONICET & UTN). J. J. Urquiza 314, San Rafael, Mendoza, Argentina
- Facultad de Filosofía y Letras, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Eva A. Peralta
- Instituto de Evolución, Ecología Histórica y Ambiente, Consejo Nacional de Investigaciones Científicas y Técnicas (IDEVEA, CONICET & UTN). J. J. Urquiza 314, San Rafael, Mendoza, Argentina
| | - Fernando Franchetti
- Instituto de Evolución, Ecología Histórica y Ambiente, Consejo Nacional de Investigaciones Científicas y Técnicas (IDEVEA, CONICET & UTN). J. J. Urquiza 314, San Rafael, Mendoza, Argentina
| | - José Manuel López
- Instituto Argentino de Investigaciones de las Zonas Áridas (IADIZA, CCT CONICET Mendoza), Mendoza, Argentina
| | - Gustavo Neme
- Instituto de Evolución, Ecología Histórica y Ambiente, Consejo Nacional de Investigaciones Científicas y Técnicas (IDEVEA, CONICET & UTN). J. J. Urquiza 314, San Rafael, Mendoza, Argentina
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4
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Bradshaw CJA, Reepmeyer C, Saltré F, Agapiou A, Kassianidou V, Demesticha S, Zomeni Z, Polidorou M, Moutsiou T. Demographic models predict end-Pleistocene arrival and rapid expansion of pre-agropastoralist humans in Cyprus. Proc Natl Acad Sci U S A 2024; 121:e2318293121. [PMID: 38753504 PMCID: PMC11126943 DOI: 10.1073/pnas.2318293121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Accepted: 04/09/2024] [Indexed: 05/18/2024] Open
Abstract
The antiquity of human dispersal into Mediterranean islands and ensuing coastal adaptation have remained largely unexplored due to the prevailing assumption that the sea was a barrier to movement and that islands were hostile environments to early hunter-gatherers [J. F. Cherry, T. P. Leppard, J. Isl. Coast. Archaeol. 13, 191-205 (2018), 10.1080/15564894.2016.1276489]. Using the latest archaeological data, hindcasted climate projections, and age-structured demographic models, we demonstrate evidence for early arrival (14,257 to 13,182 calendar years ago) to Cyprus and predicted that large groups of people (~1,000 to 1,375) arrived in 2 to 3 main events occurring within <100 y to ensure low extinction risk. These results indicate that the postglacial settlement of Cyprus involved only a few large-scale, organized events requiring advanced watercraft technology. Our spatially debiased and Signor-Lipps-corrected estimates indicate rapid settlement of the island within <200 y, and expansion to a median of 4,000 to 5,000 people (0.36 to 0.46 km-2) in <11 human generations (<300 y). Our results do not support the hypothesis of inaccessible and inhospitable islands in the Mediterranean for pre-agropastoralists, agreeing with analogous conclusions for other parts of the world [M. I. Bird et al., Sci. Rep. 9, 8220 (2019), 10.1038/s41598-019-42946-9]. Our results also highlight the need to revisit these questions in the Mediterranean and test their validity with new technologies, field methods, and data. By applying stochastic models to the Mediterranean region, we can place Cyprus and large islands in general as attractive and favorable destinations for paleolithic peoples.
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Affiliation(s)
- Corey J. A. Bradshaw
- Global Ecology | Partuyarta Ngadluku Wardli Kuu, College of Science and Engineering, Flinders University, Adelaide, SA5001, Australia
- Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage, Wollongong, NSW2522, Australia
| | - Christian Reepmeyer
- Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage, Wollongong, NSW2522, Australia
- Commission for Archaeology of Non-European Cultures, German Archaeological Institute, Bonn53173, Germany
- College of Arts, Society and Education, James Cook University Cairns, Cairns, QLD4870, Australia
| | - Frédérik Saltré
- Global Ecology | Partuyarta Ngadluku Wardli Kuu, College of Science and Engineering, Flinders University, Adelaide, SA5001, Australia
- Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage, Wollongong, NSW2522, Australia
| | - Athos Agapiou
- Cyprus University of Technology, Lemesos3036, Cyprus
| | | | - Stella Demesticha
- Archaeological Research Unit, University of Cyprus, Nicosia1095, Cyprus
| | - Zomenia Zomeni
- Geological Survey Department, Ministry of Agriculture, Rural Development and the Environment of the Republic of Cyprus, Nicosia1301, Cyprus
| | | | - Theodora Moutsiou
- College of Arts, Society and Education, James Cook University Cairns, Cairns, QLD4870, Australia
- Archaeological Research Unit, University of Cyprus, Nicosia1095, Cyprus
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5
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Geng J, Yan H, Liu C, Han T, Liu S, Zhao N, Wen H, Yang H, Zhou P, Wang G, Dodson J. Reconstruction of ENSO variability using the standardized growth index of a Tridacna shell from Yongshu Reef, South China Sea. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169118. [PMID: 38065507 DOI: 10.1016/j.scitotenv.2023.169118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 12/01/2023] [Accepted: 12/03/2023] [Indexed: 12/23/2023]
Abstract
El Niño-Southern Oscillation (ENSO) is the strongest signal of global interannual climate anomaly and reconstructing past ENSO variations using high-resolution paleoclimate archives can improve our understanding of ENSO variability, as well as improve our ability to predict future climate changes. Here, a daily resolution standardized growth index (SGI) was established using a giant clam (Tridacna spp.) shell specimen MD2 (life span: 1994-2013 CE), collected from the Yongshu Reef, southern South China Sea (SCS). The cross-spectral and correlation analysis indicated that the SGI variation of MD2 was strongly influenced by ENSO variability on an interannual timescale. Tridacna spp. is in symbiosis with zooxanthellae, and its growth index is usually modulated by the photosynthetic efficiency of zooxanthellae. During the El Niño (La Niña) period, the convective anomalies stimulated in western Pacific would increase (decrease) the effective solar radiation on Yongshu Reef, and in turn influence the photosynthesis rate of zooxanthellae and enzyme activity for the calcification site and thus the SGI of giant clam MD2. The SGI can explain 54.7 % of ENSO variance, demonstrating the potential for Tridacna SGI in ENSO reconstruction. Compared with conventional ENSO reconstruction using high-resolution geochemical proxies, the method of giant clam SGI is rapid and economical.
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Affiliation(s)
- Jun Geng
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hong Yan
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; Open Studio for Oceanic-Continental Climate and Environment Changes, Laoshan Laboratory, Qingdao 266237, China; Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Chengcheng Liu
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; Xi'an Institute for Innovative Earth Environment Research, Xi'an 710061, China
| | - Tao Han
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; Xi'an Institute for Innovative Earth Environment Research, Xi'an 710061, China
| | - Shan Liu
- Xi'an Institute for Innovative Earth Environment Research, Xi'an 710061, China
| | - Nanyu Zhao
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China
| | - Hanfeng Wen
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Haotian Yang
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an 710049, China
| | - Pengchao Zhou
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China
| | - Guozhen Wang
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - John Dodson
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia
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6
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Yang Y, Zhang L, Yi L, Zhong F, Lu Z, Wan S, Du Y, Xiang R. A contracting Intertropical Convergence Zone during the Early Heinrich Stadial 1. Nat Commun 2023; 14:4695. [PMID: 37542043 PMCID: PMC10403598 DOI: 10.1038/s41467-023-40377-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 07/14/2023] [Indexed: 08/06/2023] Open
Abstract
Despite the fact that the response of tropical hydroclimate to North Atlantic cooling events during the Heinrich Stadial 1 (HS1) has been extensively studied in African, South American and Indonesia, the nature of such responses remains debated. Here we investigate the tropical hydroclimate pattern over the Indo-Asian-Australian monsoon region during the HS1 by integrating hydroclimatic records, and examining a δ18Oseawater record from Globigerinoides ruber (white) in the tropical Indian Ocean. Our findings indicate that tropical hydrological conditions were synchronously arid in both hemispheres during the early HS1 (~18.3-16.3 ka) in the Indo-Asian-Australian monsoon region, except for a narrow, wet hydrological belt in northern low latitudes, suggesting the existence of a contracted tropical precipitation belt at that time. This study reveals that the meltwater discharge and resulting changes in global temperatures and El Niño exerted a profound influence on the tropical hydroclimate in the Indo-Asian-Australian monsoon region during the early HS1.
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Affiliation(s)
- Yiping Yang
- Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
| | - Lanlan Zhang
- Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China.
| | - Liang Yi
- State Key Laboratory of Marine Geology, Tongji University, Shanghai, 200092, China
| | - Fuchang Zhong
- Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
| | - Zhengyao Lu
- Department of Physical Geography and Ecosystem Science, Lund University, 22362, Lund, Sweden
| | - Sui Wan
- Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
| | - Yan Du
- State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Rong Xiang
- Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China.
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7
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Wörmer L, Wendt J, Boehman B, Haug GH, Hinrichs KU. Deglacial increase of seasonal temperature variability in the tropical ocean. Nature 2022; 612:88-91. [DOI: 10.1038/s41586-022-05350-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 08/17/2022] [Indexed: 12/02/2022]
Abstract
AbstractThe relatively stable Holocene climate was preceded by a pronounced event of abrupt warming in the Northern Hemisphere, the termination of the Younger Dryas (YD) cold period1,2. Although this transition has been intensively studied, its imprint on low-latitude ocean temperature is still controversial and its effects on sub-annual to decadal climate variability remain poorly understood1,3,4. Sea surface temperature (SST) variability at these timescales in the tropical Atlantic is expected to intensify under current and future global warming and has considerable consequences for environmental conditions in Africa and South America, and for tropical Pacific climate5–8. Here we present a 100-µm-resolution record obtained by mass spectrometry imaging (MSI) of long-chain alkenones in sediments from the Cariaco Basin9–11 and find that annually averaged SST remained stable during the transition into the Holocene. However, seasonality increased more than twofold and approached modern values of 1.6 °C, probably driven by the position and/or annual range of the Intertropical Convergence Zone (ITCZ). We further observe that interannual variability intensified during the early Holocene. Our results demonstrate that sub-decadal-scale SST variability in the tropical Atlantic is sensitive to abrupt changes in climate background, such as those witnessed during the most recent glacial to interglacial transition.
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8
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Thermal coupling of the Indo-Pacific warm pool and Southern Ocean over the past 30,000 years. Nat Commun 2022; 13:5457. [PMID: 36115856 PMCID: PMC9482618 DOI: 10.1038/s41467-022-33206-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 09/06/2022] [Indexed: 11/08/2022] Open
Abstract
The role of the tropical Pacific Ocean and its linkages to the southern hemisphere during the last deglacial warming remain highly controversial. Here we explore the evolution of Pacific horizontal and vertical thermal gradients over the past 30 kyr by compiling 340 sea surface and 7 subsurface temperature records, as well as one new ocean heat content record. Our records reveal that La Niña-like conditions dominated during the deglaciation as a result of the more intense warming in the western Pacific warm pool. Both the subsurface temperature and ocean heat content in the warm pool rose earlier than the sea surface temperature, and in phase with South Pacific subsurface temperature and orbital precession, implying that heat exchange between the tropical upper water column and the extratropical Southern Ocean facilitated faster warming in the western Pacific. Our study underscores the key role of the thermal coupling between the warm pool and the Southern Ocean and its relevance for future global warming. The mechanism of the last deglacial global warming is key for future climate. Here, the authors shed light on the pivotal role of the thermal coupling between the western Pacific warm pool and the Southern Ocean.
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9
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Broughton JM, Codding BF, Faith JT, Mohlenhoff KA, Gruhn R, Brenner-Coltrain J, Hart IA. El Niño frequency threshold controls coastal biotic communities. Science 2022; 377:1202-1205. [PMID: 36074861 DOI: 10.1126/science.abm1033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
El Niño has profound influences on ecosystem dynamics. However, we know little about how it shapes vertebrate faunal community composition over centennial time scales, and this limits our ability to forecast change under projections of future El Niño events. On the basis of correlations between geological records of past El Niño frequency and the species composition of bird and fish remains from a Baja California bone deposit that spans the past 12,000 years, we documented marked faunal restructuring when major El Niño events occurred more than five times per century. This tipping point has implications for the past and future ecology of eastern Pacific coastal environments.
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Affiliation(s)
- Jack M Broughton
- Department of Anthropology and Archaeological Center, University of Utah, Salt Lake City, UT, USA
| | - Brian F Codding
- Department of Anthropology and Archaeological Center, University of Utah, Salt Lake City, UT, USA
| | - J Tyler Faith
- Department of Anthropology and Archaeological Center, University of Utah, Salt Lake City, UT, USA.,Natural History Museum of Utah, Salt Lake City, UT, USA.,Origins Centre, University of the Witwatersrand, Johannesburg, South Africa
| | | | - Ruth Gruhn
- Department of Anthropology, University of Alberta, Edmonton, Alberta, Canada
| | - Joan Brenner-Coltrain
- Department of Anthropology and Archaeological Center, University of Utah, Salt Lake City, UT, USA
| | - Isaac A Hart
- Department of Anthropology and Archaeological Center, University of Utah, Salt Lake City, UT, USA.,Department of Geography, University of Utah, Salt Lake City, UT, USA
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10
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Lawman AE, Di Nezio PN, Partin JW, Dee SG, Thirumalai K, Quinn TM. Unraveling forced responses of extreme El Niño variability over the Holocene. SCIENCE ADVANCES 2022; 8:eabm4313. [PMID: 35245112 PMCID: PMC8896782 DOI: 10.1126/sciadv.abm4313] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 01/12/2022] [Indexed: 06/14/2023]
Abstract
Uncertainty surrounding the future response of El Niño-Southern Oscillation (ENSO) variability to anthropogenic warming necessitates the study of past ENSO sensitivity to substantial climate forcings over geological history. Here, we focus on the Holocene epoch and show that ENSO amplitude and frequency intensified over this period, driven by an increase in extreme El Niño events. Our study combines new climate model simulations, advances in coral proxy system modeling, and coral proxy data from the central tropical Pacific. Although the model diverges from the observed coral data regarding the exact magnitude of change, both indicate that modern ENSO variance eclipsed paleo-estimates over the Holocene, albeit against the backdrop of wide-ranging natural variability. Toward further constraining paleo-ENSO, our work underscores the need for multimodel investigations of additional Holocene intervals alongside more coral data from periods with larger climate forcing. Our findings implicate extreme El Niño events as an important rectifier of mean ENSO intensity.
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Affiliation(s)
- Allison E. Lawman
- Department of Earth, Environmental and Planetary Sciences, Rice University, Houston, TX, USA
- Institute for Geophysics, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX, USA
- Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX, USA
| | - Pedro N. Di Nezio
- Department of Atmospheric and Oceanic Sciences, The University of Colorado, Boulder, CO, USA
| | - Judson W. Partin
- Institute for Geophysics, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX, USA
| | - Sylvia G. Dee
- Department of Earth, Environmental and Planetary Sciences, Rice University, Houston, TX, USA
| | | | - Terrence M. Quinn
- Institute for Geophysics, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX, USA
- Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX, USA
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11
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Climate and demography drive 7000 years of dietary change in the Central Andes. Sci Rep 2022; 12:2026. [PMID: 35132100 PMCID: PMC8821598 DOI: 10.1038/s41598-022-05774-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 01/13/2022] [Indexed: 12/31/2022] Open
Abstract
Explaining the factors that influence past dietary variation is critically important for understanding changes in subsistence, health, and status in past societies; yet systematic studies comparing possible driving factors remain scarce. Here we compile the largest dataset of past diet derived from stable isotope δ13C‰ and δ15N‰ values in the Americas to quantitatively evaluate the impact of 7000 years of climatic and demographic change on dietary variation in the Central Andes. Specifically, we couple paleoclimatic data from a general circulation model with estimates of relative past population inferred from archaeologically derived radiocarbon dates to assess the influence of climate and population on spatiotemporal dietary variation using an ensemble machine learning model capable of accounting for interactions among predictors. Results reveal that climate and population strongly predict diet (80% of δ15N‰ and 66% of δ13C‰) and that Central Andean diets correlate much more strongly with local climatic conditions than regional population size, indicating that the past 7000 years of dietary change was influenced more by climatic than socio-demographic processes. Visually, the temporal pattern suggests decreasing dietary variation across elevation zones during the Late Horizon, raising the possibility that sociopolitical factors overrode the influence of local climatic conditions on diet during that time. The overall findings and approach establish a general framework for understanding the influence of local climate and demography on dietary change across human history.
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12
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Enhanced North Pacific subtropical gyre circulation during the late Holocene. Nat Commun 2021; 12:5957. [PMID: 34642314 PMCID: PMC8511172 DOI: 10.1038/s41467-021-26218-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 09/14/2021] [Indexed: 11/08/2022] Open
Abstract
The North Pacific Subtropical Gyre circulation redistributes heat from the Western Pacific Warm Pool towards the mid- to high-latitude North Pacific. However, the driving mechanisms of this circulation and how it changed over the Holocene remain poorly understood. Here, we present alkenone-based sea surface temperature reconstructions along the Kuroshio, California and Alaska currents that cover the past ~7,000 years. These and other paleorecords collectively demonstrate a coherent intensification of the boundary currents, and thereby the basin-scale subtropical gyre circulation, since ~3,000-4,000 years ago. Such enhanced circulation during the late Holocene appears to have resulted from a long-term southward migration of the Intertropical Convergence Zone, associated with Holocene ocean cooling. Our results imply that the North Pacific Subtropical Gyre circulation could be weakened under future global warming.
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González-Pinilla FJ, Latorre C, Rojas M, Houston J, Rocuant MI, Maldonado A, Santoro CM, Quade J, Betancourt JL. High- and low-latitude forcings drive Atacama Desert rainfall variations over the past 16,000 years. SCIENCE ADVANCES 2021; 7:eabg1333. [PMID: 34533988 PMCID: PMC8448445 DOI: 10.1126/sciadv.abg1333] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Accepted: 07/27/2021] [Indexed: 06/13/2023]
Abstract
Late Quaternary precipitation dynamics in the central Andes have been linked to both high- and low-latitude atmospheric teleconnections. We use present-day relationships between fecal pellet diameters from ashy chinchilla rats (Abrocoma cinerea) and mean annual rainfall to reconstruct the timing and magnitude of pluvials (wet episodes) spanning the past 16,000 years in the Atacama Desert based on 81 14C-dated A. cinerea paleomiddens. A transient climate simulation shows that pluvials identified at 15.9 to 14.8, 13.0 to 8.6, and 8.1 to 7.6 ka B.P. can be linked to North Atlantic (high-latitude) forcing (e.g., Heinrich Stadial 1, Younger Dryas, and Bond cold events). Holocene pluvials at 5.0 to 4.6, 3.2 to 2.1, and 1.4 to 0.7 ka B.P. are not simulated, implying low-latitude internal variability forcing (i.e., ENSO regime shifts). These results help constrain future central Andean hydroclimatic variability and hold promise for reconstructing past climates from rodent middens in desert ecosystems worldwide.
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Affiliation(s)
- Francisco J. González-Pinilla
- Centro UC Desierto de Atacama and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- Institute of Ecology and Biodiversity (IEB), Santiago, Chile
| | - Claudio Latorre
- Centro UC Desierto de Atacama and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- Institute of Ecology and Biodiversity (IEB), Santiago, Chile
| | - Maisa Rojas
- Center for Climate and Resilience Research (CR) and Departamento de Geofísica, Universidad de Chile, Santiago, Chile
| | | | - M. Ignacia Rocuant
- Centro UC Desierto de Atacama and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Antonio Maldonado
- Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Universidad de La Serena, La Serena, Chile
- Departamento de Biología Marina, Universidad Católica del Norte, Coquimbo, Chile
| | - Calogero M. Santoro
- Instituto de Alta Investigación (IAI), Universidad de Tarapacá, Arica, Chile
| | - Jay Quade
- Department of Geosciences, The University of Arizona, Tucson, AZ, USA
| | - Julio L. Betancourt
- Scientist Emeritus, U.S. Geological Survey, Science and Decisions Center, Reston, VA, USA
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14
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Zhang M, Bu Z, Li H, Liu S, Chen J, Cui Y. Hydrological variation recorded in a subalpine peatland of Northeast Asia since the Little Ice Age and its possible driving mechanisms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 772:144923. [PMID: 33578159 DOI: 10.1016/j.scitotenv.2020.144923] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 12/19/2020] [Accepted: 12/29/2020] [Indexed: 06/12/2023]
Abstract
Hydrological characteristics since the Little Ice Age (LIA) could provide a good reference for current climate analysis and future climate prediction. However, the hydrological variation since the LIA and its driving mechanisms in Northeast Asia remain unclear, which has severely restricted our understanding on the past, present and future hydroclimate changes in these regions. Here we reconstruct the hydrological dynamics over the past 700 years using samples from the Hani peatland a subalpine peatland of Changbai Mountains to reveal these issues. The analytical results from plant macrofossil and grain-size of the HN-1 core and the integrated moisture/precipitation records across the entire Northeast Asia indicate that the hydrological environments in Northeast Asia were wetter conditions during the period of 1300-1700 AD, dry conditions during the period of 1700-1850 AD, and wet conditions during the period of 1850-2018 AD, respectively. The possible driving mechanisms for the hydrological variations in Northeast Asia since the LIA can be divided into three models. La Niña-like conditions induced wetter conditions in Northeast Asia from 1300 to 1700 AD. From 1700 to 1850 AD, strong volcanic aerosol effects superimposed on weaker La Niña-like conditions, resulting in dry conditions in Northeast Asia. However, El Niño-like conditions induced wet conditions in Northeast Asia from 1850 to 2018 AD. These driving models suggest that the teleconnected influence of solar activity/sunspot could control the hydrological dynamics in Northeast Asia on a decadal-centennial scale through the ENSO activities and Walker Circulation changes since the LIA. Based on the periodicity relationship between hydrological conditions and sunspot, it can be predicted that the moisutre conditions in Northeast Asia would gradually decrease from 2030 to 2085 AD, and gradually increase from 2085 to 2140 AD.
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Affiliation(s)
- Mingming Zhang
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Changchun 130024, China; State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Institute for Peat and Mire Research, Northeast Normal University, Changchun 130024, China; Jilin Provincial Key Laboratory for Wetland Ecological Processes and Environmental Change in the Changbai Mountains, Changchun 130024, China.
| | - Zhaojun Bu
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Changchun 130024, China; State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Institute for Peat and Mire Research, Northeast Normal University, Changchun 130024, China; Jilin Provincial Key Laboratory for Wetland Ecological Processes and Environmental Change in the Changbai Mountains, Changchun 130024, China
| | - Hongkai Li
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Changchun 130024, China; State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Institute for Peat and Mire Research, Northeast Normal University, Changchun 130024, China; Jilin Provincial Key Laboratory for Wetland Ecological Processes and Environmental Change in the Changbai Mountains, Changchun 130024, China
| | - Shasha Liu
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Changchun 130024, China; State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Institute for Peat and Mire Research, Northeast Normal University, Changchun 130024, China; Jilin Provincial Key Laboratory for Wetland Ecological Processes and Environmental Change in the Changbai Mountains, Changchun 130024, China
| | - Jie Chen
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Changchun 130024, China
| | - Yaxin Cui
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Changchun 130024, China
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15
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Vegetation feedback causes delayed ecosystem response to East Asian Summer Monsoon Rainfall during the Holocene. Nat Commun 2021; 12:1843. [PMID: 33758179 PMCID: PMC7988120 DOI: 10.1038/s41467-021-22087-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Accepted: 02/26/2021] [Indexed: 12/25/2022] Open
Abstract
One long-standing issue in the paleoclimate records is whether East Asian Summer Monsoon peaked in the early Holocene or mid-Holocene. Here, combining a set of transient earth system model simulations with proxy records, we propose that, over northern China, monsoon rainfall peaked in the early Holocene, while soil moisture and tree cover peaked in the mid-Holocene. The delayed ecosystem (soil moisture and tree cover) response to rainfall is caused by the vegetation response to winter warming and the subsequent feedback with soil moisture. Our study provides a mechanism for reconciling different evolution behaviors of monsoon proxy records; it sheds light on the driving mechanism of the monsoon evolution and monsoon-ecosystem feedback over northern China, with implications to climate changes in other high climate sensitivity regions over the globe.
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16
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Rustic GT, Polissar PJ, Ravelo AC, White SM. Modulation of late Pleistocene ENSO strength by the tropical Pacific thermocline. Nat Commun 2020; 11:5377. [PMID: 33097727 PMCID: PMC7584583 DOI: 10.1038/s41467-020-19161-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 09/25/2020] [Indexed: 11/09/2022] Open
Abstract
The El Niño Southern Oscillation (ENSO) is highly dependent on coupled atmosphere-ocean interactions and feedbacks, suggesting a tight relationship between ENSO strength and background climate conditions. However, the extent to which background climate state determines ENSO behavior remains in question. Here we present reconstructions of total variability and El Niño amplitude from individual foraminifera distributions at discrete time intervals over the past ~285,000 years across varying atmospheric CO2 levels, global ice volume and sea level, and orbital insolation forcing. Our results show a strong correlation between eastern tropical Pacific Ocean mixed-layer thickness and both El Niño amplitude and central Pacific variability. This ENSO-thermocline relationship implicates upwelling feedbacks as the major factor controlling ENSO strength on millennial time scales. The primacy of the upwelling feedback in shaping ENSO behavior across many different background states suggests accurate quantification and modeling of this feedback is essential for predicting ENSO’s behavior under future climate conditions. How the El Niño Southern Oscillation depends on the background conditions is not well known. Here, the authors present individual foraminifera distributions which show that central Pacific variability is related to the warmth and depth of the thermocline across varying climate background conditions over the past ~285,000 years.
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Affiliation(s)
- Gerald T Rustic
- Department of Geology, School of Earth and Environment, Rowan University, 600 Whitney Ave, Glassboro, NJ, 08028, USA. .,Lamont-Doherty Earth Observatory, Columbia University, 61 Route 9W, Palisades, NY, 19604, USA.
| | - Pratigya J Polissar
- Lamont-Doherty Earth Observatory, Columbia University, 61 Route 9W, Palisades, NY, 19604, USA.,Ocean Sciences Department, University of California at Santa Cruz, Santa Cruz, CA, 95064, USA
| | - Ana Christina Ravelo
- Ocean Sciences Department, University of California at Santa Cruz, Santa Cruz, CA, 95064, USA
| | - Sarah M White
- Earth and Planetary Sciences Department, University of California at Santa Cruz, Santa Cruz, CA, 95064, USA.,Department of Geography, University of California at Berkeley, Berkeley, CA, 94720, USA
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17
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Jalihal C, Srinivasan J, Chakraborty A. Different precipitation response over land and ocean to orbital and greenhouse gas forcing. Sci Rep 2020; 10:11891. [PMID: 32681072 PMCID: PMC7367857 DOI: 10.1038/s41598-020-68346-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 06/18/2020] [Indexed: 12/04/2022] Open
Abstract
Various proxies suggest a nearly in-phase variation of monsoons with local summer insolation. Oceanic proxies of monsoons document a more complex response. Climate model simulations also indicate that the response is different over land and ocean. Here using a transient simulation by a climate model over the last 22,000 years we have unraveled the factors that lead to these differences within the Indian subcontinent. We show that during the deglacial (22–12 ka) precipitation over India and the Bay of Bengal (BoB) are in phase, whereas they are out of phase across the Holocene (\documentclass[12pt]{minimal}
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\begin{document}$$\sim$$\end{document}∼ 12 ka to 0 ka). During the deglacial, water vapor amplifies the effect of solar forcing on precipitation over both the regions, whereas contributions from surface latent heat fluxes over the BoB drive an opposite response across the Holocene. We find that greenhouse gas forcing drives similar precipitation response over land and ocean, whereas orbital forcing produces a different response over land and ocean. We have further demonstrated that during periods of abrupt climate change [such as the Bølling–Allerød (\documentclass[12pt]{minimal}
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\begin{document}$$\sim$$\end{document}∼ 14 ka)], water vapor affects precipitation mainly through its influence on the vertical stability of the atmosphere. These results highlight the complex nature of precipitation over the BoB and thus has implications for the interpretation of monsoon proxies.
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Affiliation(s)
- Chetankumar Jalihal
- Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore, 560012, India. .,Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, 560012, India.
| | - Jayaraman Srinivasan
- Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, 560012, India
| | - Arindam Chakraborty
- Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore, 560012, India.,Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, 560012, India
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The Role of El Niño in Driving Drought Conditions over the Last 2000 Years in Thailand. QUATERNARY 2020. [DOI: 10.3390/quat3020018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Irregular climate events frequently occur in Southeast Asia due to the numerous climate patterns combining. Thailand sits at the confluence of these interactions, and consequently experiences major hydrological events, such as droughts. Proxy data, speleothem records, lake sediment sequences and tree ring chronologies were used to reconstruct paleo drought conditions. These trends were compared with modelled and historic El Niño Southern Oscillation (ENSO) data to assess if the ENSO climate phenomena is causing droughts in Thailand. Drought periods were found to occur both during El Niño events and ENSO neutral conditions. This indicates droughts are not a product of one climate pattern, but likely the result of numerous patterns interacting. There is uncertainty regarding how climate patterns will evolve under climate change, but changes in amplitude and variability could potentially lead to more frequent and wider reaching hydrological disasters. It is vital that policies are implemented to cope with the resulting social and economic repercussions, including diversification of crops and reorganisation of water consumption behaviour in Thailand.
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Racimo F, Woodbridge J, Fyfe RM, Sikora M, Sjögren KG, Kristiansen K, Vander Linden M. The spatiotemporal spread of human migrations during the European Holocene. Proc Natl Acad Sci U S A 2020; 117:8989-9000. [PMID: 32238559 PMCID: PMC7183159 DOI: 10.1073/pnas.1920051117] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The European continent was subject to two major migrations of peoples during the Holocene: the northwestward movement of Anatolian farmer populations during the Neolithic and the westward movement of Yamnaya steppe peoples during the Bronze Age. These movements changed the genetic composition of the continent's inhabitants. The Holocene was also characterized by major changes in vegetation composition, which altered the environment occupied by the original hunter-gatherer populations. We aim to test to what extent vegetation change through time is associated with changes in population composition as a consequence of these migrations, or with changes in climate. Using ancient DNA in combination with geostatistical techniques, we produce detailed maps of ancient population movements, which allow us to visualize how these migrations unfolded through time and space. We find that the spread of Neolithic farmer ancestry had a two-pronged wavefront, in agreement with similar findings on the cultural spread of farming from radiocarbon-dated archaeological sites. This movement, however, did not have a strong association with changes in the vegetational landscape. In contrast, the Yamnaya migration speed was at least twice as fast and coincided with a reduction in the amount of broad-leaf forest and an increase in the amount of pasture and natural grasslands in the continent. We demonstrate the utility of integrating ancient genomes with archaeometric datasets in a spatiotemporal statistical framework, which we foresee will enable future studies of ancient populations' movements, and their putative effects on local fauna and flora.
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Affiliation(s)
- Fernando Racimo
- Lundbeck GeoGenetics Centre, The Globe Institute, University of Copenhagen, 1350 Copenhagen, Denmark;
| | - Jessie Woodbridge
- School of Geography, Earth, and Environmental Sciences, University of Plymouth, Plymouth PL4 8AA, United Kingdom
| | - Ralph M Fyfe
- School of Geography, Earth, and Environmental Sciences, University of Plymouth, Plymouth PL4 8AA, United Kingdom
| | - Martin Sikora
- Lundbeck GeoGenetics Centre, The Globe Institute, University of Copenhagen, 1350 Copenhagen, Denmark
| | - Karl-Göran Sjögren
- Department of Historical Studies, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Kristian Kristiansen
- Department of Historical Studies, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Marc Vander Linden
- Department of Archaeology, University of Cambridge, Cambridge CB2 1TN, United Kingdom
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20
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Half-precessional cycle of thermocline temperature in the western equatorial Pacific and its bihemispheric dynamics. Proc Natl Acad Sci U S A 2020; 117:7044-7051. [PMID: 32179673 DOI: 10.1073/pnas.1915510117] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The El Niño-Southern Oscillation (ENSO), which is tightly coupled to the equatorial thermocline in the Pacific, is the dominant source of interannual climate variability, but its long-term evolution in response to climate change remains highly uncertain. This study uses Mg/Ca in planktonic foraminiferal shells to reconstruct sea surface and thermocline water temperatures (SST and TWT) for the past 142 ky in a western equatorial Pacific (WEP) core MD01-2386. Unlike the dominant 100-ky glacial-interglacial cycle recorded by SST and δ18O, which echoes the pattern seen in other WEP sites, the upper ocean thermal gradient shows a clear half-precessional (9.4 ky or 12.7 ky) cycle as indicated by the reconstructed and simulated temperature (ΔT) and δ18O differences between the surface and thermocline waters. This phenomenon is attributed to the interplay of subtropical-to-tropical thermocline anomalies forced by the antiphased meridional insolation gradients in the two hemispheres at the precessional band. In particular, the TWT shows greater variability than SST, and dominates the ΔT changes which couple with the west-east SST difference in the equatorial Pacific at the half-precessional band, implying a decisive role of the tropical thermocline in orbital-scale climate change.
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22
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Modulation of Indian monsoon by water vapor and cloud feedback over the past 22,000 years. Nat Commun 2019; 10:5701. [PMID: 31836715 PMCID: PMC6911089 DOI: 10.1038/s41467-019-13754-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 11/26/2019] [Indexed: 11/08/2022] Open
Abstract
To predict how monsoons will evolve in the 21st century, we need to understand how they have changed in the past. In paleoclimate literature, the major focus has been on the role of solar forcing on monsoons but not on the amplification by feedbacks internal to the climate system. Here we have used the results from a transient climate simulation to show that feedbacks amplify the effect of change in insolation on the Indian summer monsoon. We show that during the deglacial (22 ka to 10 ka) monsoons were predominantly influenced by rising water vapor due to increasing sea surface temperature, whereas in the Holocene (10 ka to 0 ka) cloud feedback was more important. These results are consistent with another transient simulation, thus increasing confidence despite potential model biases. We have demonstrated that insolation drives monsoon through different pathways during cold and warm periods, thereby highlighting the changing role of internal factors.
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Synchronous 500-year oscillations of monsoon climate and human activity in Northeast Asia. Nat Commun 2019; 10:4105. [PMID: 31511523 PMCID: PMC6739325 DOI: 10.1038/s41467-019-12138-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 08/23/2019] [Indexed: 11/25/2022] Open
Abstract
Prehistoric human activities were likely influenced by cyclic monsoon climate changes in East Asia. Here we report a decadal-resolution Holocene pollen record from an annually-laminated Maar Lake in Northeast China, a proxy of monsoon climate, together with a compilation of 627 radiocarbon dates from archeological sites in Northeast China which is a proxy of human activity. The results reveal synchronous ~500-year quasi-periodic changes over the last 8000 years. The warm-humid/cold-dry phases of monsoon cycles correspond closely to the intensification/weakening of human activity and the flourishing/decline of prehistoric cultures. Six prosperous phases of prehistoric cultures, with one exception, correspond approximately to warm-humid phases caused by a strengthened monsoon. This ~500-year cyclicity in the monsoon and thus environmental change triggered the development of prehistoric cultures in Northeast China. The cyclicity is apparently linked to the El Niño-Southern Oscillation, against the background of long-term Holocene climatic evolution. These findings reveal a pronounced relationship between prehistoric human activity and cyclical climate change. Long-term climate cycles can potentially influence population dynamics, including those of humans. Here, the authors combine climate and archaeological records from Northeast China over the past 8000 years and demonstrate ~500 year cycles in both the monsoon and human activity.
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The Asian Summer Monsoon: Teleconnections and Forcing Mechanisms—A Review from Chinese Speleothem δ18O Records. QUATERNARY 2019. [DOI: 10.3390/quat2030026] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Asian summer monsoon (ASM) variability significantly affects hydro-climate, and thus socio-economics, in the East Asian region, where nearly one-third of the global population resides. Over the last two decades, speleothem δ18O records from China have been utilized to reconstruct ASM variability and its underlying forcing mechanisms on orbital to seasonal timescales. Here, we use the Speleothem Isotopes Synthesis and Analysis database (SISAL_v1) to present an overview of hydro-climate variability related to the ASM during three periods: the late Pleistocene, the Holocene, and the last two millennia. We highlight the possible global teleconnections and forcing mechanisms of the ASM on different timescales. The longest composite stalagmite δ18O record over the past 640 kyr BP from the region demonstrates that ASM variability on orbital timescales is dominated by the 23 kyr precessional cycles, which are in phase with Northern Hemisphere summer insolation (NHSI). During the last glacial, millennial changes in the intensity of the ASM appear to be controlled by North Atlantic climate and oceanic feedbacks. During the Holocene, changes in ASM intensity were primarily controlled by NHSI. However, the spatio-temporal distribution of monsoon rain belts may vary with changes in ASM intensity on decadal to millennial timescales.
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25
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Runoff events and related rainfall variability in the Southern Carpathians during the last 2000 years. Sci Rep 2019; 9:5334. [PMID: 30926945 PMCID: PMC6440959 DOI: 10.1038/s41598-019-41855-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 03/15/2019] [Indexed: 11/28/2022] Open
Abstract
The occurrence of heavy rainfall events is expected to undergo significant changes under increasing anthropogenic forcing. South-eastern Europe is reacting rapidly to such changes, therefore understanding and forecasting of precipitation variability is vital to better comprehending environmental changes in this area. Here we present a sub-decadal reconstruction of enhanced rainfall events for the past 2000 years from the Southern Carpathians, Romania using peat geochemistry. Five clear periods of enhanced rainfall are identified at 125–250, 600–900, 1050–1300, 1400–1575 and 1725–1980 CE. Significant runoff is observed during the second half of the Medieval Warm Period, whilst the Little Ice Age was characterised by significant variability. The North Atlantic Oscillation appears to be the main control on regional precipitation, but changes in solar irradiance also seem to play a significant role, together with the Siberian High. Comparison of the data presented here with model outputs confirms the ability of models to predict general trends, and major shifts, but highlights the complexity of the region’s hydrological history.
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Affiliation(s)
- Zhengyao Lu
- Department of Physical Geography and Ecosystem Science, Lund University, Sweden
| | - Zhengyu Liu
- Department of Geography, Ohio State University, USA
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Oluwole OSA. Dynamic Regimes of El Niño Southern Oscillation and Influenza Pandemic Timing. Front Public Health 2017; 5:301. [PMID: 29218303 PMCID: PMC5703710 DOI: 10.3389/fpubh.2017.00301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 10/30/2017] [Indexed: 12/03/2022] Open
Abstract
El Niño southern oscillation (ENSO) dynamics has been shown to drive seasonal influenza dynamics. Severe seasonal influenza epidemics and the 2009-2010 pandemic were coincident with chaotic regime of ENSO dynamics. ENSO dynamics from 1876 to 2016 were characterized to determine if influenza pandemics are coupled to chaotic regimes. Time-varying spectra of southern oscillation index (SOI) and sea surface temperature (SST) were compared. SOI and SST were decomposed to components using the algorithm of noise-assisted multivariate empirical mode decomposition. The components were Hilbert transformed to generate instantaneous amplitudes and phases. The trajectories and attractors of components were characterized in polar coordinates and state space. Influenza pandemics were mapped to dynamic regimes of SOI and SST joint recurrence of annual components. State space geometry of El Niños lagged by influenza pandemics were characterized and compared with other El Niños. Timescales of SOI and SST components ranged from sub-annual to multidecadal. The trajectories of SOI and SST components and the joint recurrence of annual components were dissipative toward chaotic attractors. Periodic, quasi-periodic, and chaotic regimes were present in the recurrence of trajectories, but chaos-chaos transitions dominated. Influenza pandemics occurred during chaotic regimes of significantly low transitivity dimension (p < 0.0001). El Niños lagged by influenza pandemics had distinct state space geometry (p < 0.0001). Chaotic dynamics explains the aperiodic timing, and varying duration and strength of El Niños. Coupling of all influenza pandemics of the past 140 years to chaotic regimes of low transitivity indicate that ENSO dynamics drives influenza pandemic dynamics. Forecasts models from ENSO dynamics should compliment surveillance for novel influenza viruses.
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Greening of the Sahara suppressed ENSO activity during the mid-Holocene. Nat Commun 2017; 8:16020. [PMID: 28685758 PMCID: PMC5504352 DOI: 10.1038/ncomms16020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 05/23/2017] [Indexed: 11/23/2022] Open
Abstract
The evolution of the El Niño-Southern Oscillation (ENSO) during the Holocene remains uncertain. In particular, a host of new paleoclimate records suggest that ENSO internal variability or other external forcings may have dwarfed the fairly modest ENSO response to precessional insolation changes simulated in climate models. Here, using fully coupled ocean-atmosphere model simulations, we show that accounting for a vegetated and less dusty Sahara during the mid-Holocene relative to preindustrial climate can reduce ENSO variability by 25%, more than twice the decrease obtained using orbital forcing alone. We identify changes in tropical Atlantic mean state and variability caused by the momentous strengthening of the West Africa Monsoon (WAM) as critical factors in amplifying ENSO’s response to insolation forcing through changes in the Walker circulation. Our results thus suggest that potential changes in the WAM due to anthropogenic warming may influence ENSO variability in the future as well. Evolution of the El Niño-Southern Oscillation through the Holocene remains uncertain. Here, via fully coupled model simulations, the authors show that increased Saharan vegetation and reduced dust emissions 6 kyr BP significantly affect ENSO variability through changes in the West African Monsoon strength.
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Holocene ENSO-related cyclic storms recorded by magnetic minerals in speleothems of central China. Proc Natl Acad Sci U S A 2017; 114:852-857. [PMID: 28096384 DOI: 10.1073/pnas.1610930114] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Extreme hydrologic events such as storms and floods have the potential to severely impact modern human society. However, the frequency of storms and their underlying mechanisms are limited by a paucity of suitable proxies, especially in inland areas. Here we present a record of speleothem magnetic minerals to reconstruct paleoprecipitation, including storms, in the eastern Asian monsoon area over the last 8.6 ky. The geophysical parameter IRMsoft-flux represents the flux of soil-derived magnetic minerals preserved in stalagmite HS4, which we correlate with rainfall amount and intensity. IRMsoft-flux exhibits relatively higher values before 6.7 ky and after 3.4 ky and lower values in the intervening period, consistent with regional hydrological changes observed in independent records. Abrupt enhancements in the flux of pedogenic magnetite in the stalagmite agree well with the timing of known regional paleofloods and with equatorial El Niño-Southern Oscillation (ENSO) patterns, documenting the occurrence of ENSO-related storms in the Holocene. Spectral power analyses reveal that the storms occur on a significant 500-y cycle, coincident with periodic solar activity and ENSO variance, showing that reinforced (subdued) storms in central China correspond to reduced (increased) solar activity and amplified (damped) ENSO. Thus, the magnetic minerals in speleothem HS4 preserve a record of the cyclic storms controlled by the coupled atmosphere-oceanic circulation driven by solar activity.
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Zhang Y, Zhang X, Chiessi CM, Mulitza S, Zhang X, Lohmann G, Prange M, Behling H, Zabel M, Govin A, Sawakuchi AO, Cruz FW, Wefer G. Equatorial Pacific forcing of western Amazonian precipitation during Heinrich Stadial 1. Sci Rep 2016; 6:35866. [PMID: 27779213 PMCID: PMC5078807 DOI: 10.1038/srep35866] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 10/07/2016] [Indexed: 11/09/2022] Open
Abstract
Abundant hydroclimatic evidence from western Amazonia and the adjacent Andes documents wet conditions during Heinrich Stadial 1 (HS1, 18–15 ka), a cold period in the high latitudes of the North Atlantic. This precipitation anomaly was attributed to a strengthening of the South American summer monsoon due to a change in the Atlantic interhemispheric sea surface temperature (SST) gradient. However, the physical viability of this mechanism has never been rigorously tested. We address this issue by combining a thorough compilation of tropical South American paleorecords and a set of atmosphere model sensitivity experiments. Our results show that the Atlantic SST variations alone, although leading to dry conditions in northern South America and wet conditions in northeastern Brazil, cannot produce increased precipitation over western Amazonia and the adjacent Andes during HS1. Instead, an eastern equatorial Pacific SST increase (i.e., 0.5–1.5 °C), in response to the slowdown of the Atlantic Meridional Overturning Circulation during HS1, is crucial to generate the wet conditions in these regions. The mechanism works via anomalous low sea level pressure over the eastern equatorial Pacific, which promotes a regional easterly low-level wind anomaly and moisture recycling from central Amazonia towards the Andes.
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Affiliation(s)
- Yancheng Zhang
- MARUM - Center for Marine Environmental Sciences, University of Bremen, Germany
| | - Xu Zhang
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Cristiano M Chiessi
- School of Arts, Sciences and Humanities, University of São Paulo, São Paulo, Brazil
| | - Stefan Mulitza
- MARUM - Center for Marine Environmental Sciences, University of Bremen, Germany
| | - Xiao Zhang
- MARUM - Center for Marine Environmental Sciences, University of Bremen, Germany
| | - Gerrit Lohmann
- MARUM - Center for Marine Environmental Sciences, University of Bremen, Germany.,Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Matthias Prange
- MARUM - Center for Marine Environmental Sciences, University of Bremen, Germany
| | - Hermann Behling
- Department of Palynology and Climate Dynamics, Albrecht-von-Haller-Institute for Plant Sciences, University of Göttingen, Germany
| | - Matthias Zabel
- MARUM - Center for Marine Environmental Sciences, University of Bremen, Germany
| | - Aline Govin
- IPSL/LSCE, Laboratoire des Sciences du Climat et de l'Environnement (CEA-CNRS-UVSQ), Université Paris Saclay, Gif sur Yvette, France
| | - André O Sawakuchi
- Institute of Geosciences, University of São Paulo, São Paulo, Brazil
| | - Francisco W Cruz
- Institute of Geosciences, University of São Paulo, São Paulo, Brazil
| | - Gerold Wefer
- MARUM - Center for Marine Environmental Sciences, University of Bremen, Germany
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Using seafaring simulations and shortest-hop trajectories to model the prehistoric colonization of Remote Oceania. Proc Natl Acad Sci U S A 2016; 113:12685-12690. [PMID: 27791145 DOI: 10.1073/pnas.1612426113] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The prehistoric colonization of islands in Remote Oceania that began ∼3400 B.P. represents what was arguably the most expansive and ambitious maritime dispersal of humans across any of the world's seas or oceans. Though archaeological evidence has provided a relatively clear picture of when many of the major island groups were colonized, there is still considerable debate as to where these settlers originated from and their strategies/trajectories used to reach habitable land that other datasets (genetic, linguistic) are also still trying to resolve. To address these issues, we have harnessed the power of high-resolution climatic and oceanographic datasets in multiple seafaring simulation platforms to examine major pulses of colonization in the region. Our analysis, which takes into consideration currents, land distribution, wind periodicity, the influence of El Niño Southern Oscillation (ENSO) events, and "shortest-hop" trajectories, demonstrate that (i) seasonal and semiannual climatic changes were highly influential in structuring ancient Pacific voyaging; (ii) western Micronesia was likely settled from somewhere around the Maluku (Molucca) Islands; (iii) Samoa was the most probable staging area for the colonization of East Polynesia; and (iv) although there are major differences in success rates depending on time of year and the occurrence of ENSO events, settlement of Hawai'i and New Zealand is possible from the Marquesas or Society Islands, the same being the case for settlement of Easter Island from Mangareva or the Marquesas.
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Wen X, Liu Z, Wang S, Cheng J, Zhu J. Correlation and anti-correlation of the East Asian summer and winter monsoons during the last 21,000 years. Nat Commun 2016; 7:11999. [PMID: 27328616 PMCID: PMC4917960 DOI: 10.1038/ncomms11999] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Accepted: 05/19/2016] [Indexed: 11/10/2022] Open
Abstract
Understanding the past significant changes of the East Asia Summer Monsoon (EASM) and Winter Monsoon (EAWM) is critical for improving the projections of future climate over East Asia. One key issue that has remained outstanding from the paleo-climatic records is whether the evolution of the EASM and EAWM are correlated. Here, using a set of long-term transient simulations of the climate evolution of the last 21,000 years, we show that the EASM and EAWM are positively correlated on the orbital timescale in response to the precessional forcing, but are anti-correlated on millennial timescales in response to North Atlantic melt water forcing. The relation between EASM and EAWM can differ dramatically for different timescales because of the different response mechanisms, highlighting the complex dynamics of the East Asian monsoon system and the challenges for future projection. Future projection of changes in the East Asia Summer and Winter Monsoon are hindered by a lack of understanding of past variability. Here, using longterm transient simulations, the authors show that the monsoons respond in phase to precessional forcing, yet out of phase millennial-scale North Atlantic forcing.
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Affiliation(s)
- Xinyu Wen
- Department of Atmospheric and Oceanic Sciences &Laboratory for Climate and Ocean-Atmosphere Studies, School of Physics, Peking University, Beijing 100871, China
| | - Zhengyu Liu
- Department of Atmospheric and Oceanic Sciences &Laboratory for Climate and Ocean-Atmosphere Studies, School of Physics, Peking University, Beijing 100871, China.,Department of Atmospheric and Oceanic Sciences &Center for Climatic Research, Nelson Institute for Environmental Studies, University of Wisconsin-Madison, WI 53706, USA
| | - Shaowu Wang
- Department of Atmospheric and Oceanic Sciences &Laboratory for Climate and Ocean-Atmosphere Studies, School of Physics, Peking University, Beijing 100871, China
| | - Jun Cheng
- Polar Climate System and Global Change Laboratory, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Jiang Zhu
- Department of Atmospheric and Oceanic Sciences &Center for Climatic Research, Nelson Institute for Environmental Studies, University of Wisconsin-Madison, WI 53706, USA
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Hinsley SA, Bellamy PE, Hill RA, Ferns PN. Recent Shift in Climate Relationship Enables Prediction of the Timing of Bird Breeding. PLoS One 2016; 11:e0155241. [PMID: 27182711 PMCID: PMC4868293 DOI: 10.1371/journal.pone.0155241] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 04/26/2016] [Indexed: 12/02/2022] Open
Abstract
Large-scale climate processes influence many aspects of ecology including breeding phenology, reproductive success and survival across a wide range of taxa. Some effects are direct, for example, in temperate-zone birds, ambient temperature is an important cue enabling breeding effort to coincide with maximum food availability, and earlier breeding in response to warmer springs has been documented in many species. In other cases, time-lags of up to several years in ecological responses have been reported, with effects mediated through biotic mechanisms such as growth rates or abundance of food supplies. Here we use 23 years of data for a temperate woodland bird species, the great tit (Parus major), breeding in deciduous woodland in eastern England to demonstrate a time-lagged linear relationship between the on-set of egg laying and the winter index of the North Atlantic Oscillation such that timing can be predicted from the winter index for the previous year. Thus the timing of bird breeding (and, by inference, the timing of spring events in general) can be predicted one year in advance. We also show that the relationship with the winter index appears to arise through an abiotic time-lag with local spring warmth in our study area. Examining this link between local conditions and larger-scale processes in the longer-term showed that, in the past, significant relationships with the immediately preceding winter index were more common than those with the time-lagged index, and especially so from the late 1930s to the early 1970s. However, from the mid 1970s onwards, the time-lagged relationship has become the most significant, suggesting a recent change in climate patterns. The strength of the current time-lagged relationship suggests that it might have relevance for other temperature-dependent ecological relationships.
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Affiliation(s)
- Shelley A. Hinsley
- Centre for Ecology and Hydrology Monks Wood, Abbots Ripton, Huntingdon, Cambridgeshire, United Kingdom
- * E-mail:
| | - Paul E. Bellamy
- Centre for Ecology and Hydrology Monks Wood, Abbots Ripton, Huntingdon, Cambridgeshire, United Kingdom
| | - Ross A. Hill
- Centre for Ecology and Hydrology Monks Wood, Abbots Ripton, Huntingdon, Cambridgeshire, United Kingdom
| | - Peter N. Ferns
- Cardiff School of Biosciences, BIOSI2, Cardiff University, Cardiff, United Kingdom
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Yang H, Zhao Y, Liu Z, Li Q, He F, Zhang Q. Heat Transport Compensation in Atmosphere and Ocean over the Past 22,000 Years. Sci Rep 2015; 5:16661. [PMID: 26567710 PMCID: PMC4645171 DOI: 10.1038/srep16661] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 10/19/2015] [Indexed: 11/09/2022] Open
Abstract
The Earth’s climate has experienced dramatic changes over the past 22,000 years; however, the total meridional heat transport (MHT) of the climate system remains stable. A 22,000-year-long simulation using an ocean-atmosphere coupled model shows that the changes in atmosphere and ocean MHT are significant but tend to be out of phase in most regions, mitigating the total MHT change, which helps to maintain the stability of the Earth’s overall climate. A simple conceptual model is used to understand the compensation mechanism. The simple model can reproduce qualitatively the evolution and compensation features of the MHT over the past 22,000 years. We find that the global energy conservation requires the compensation changes in the atmosphere and ocean heat transports. The degree of compensation is mainly determined by the local climate feedback between surface temperature and net radiation flux at the top of the atmosphere. This study suggests that an internal mechanism may exist in the climate system, which might have played a role in constraining the global climate change over the past 22,000 years.
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Affiliation(s)
- Haijun Yang
- Laboratory for Climate and Ocean-Atmosphere Studies (LaCOAS) and Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100871, China.,Qingdao Collaborative Innovation Center of Marine Science and Technology, Qingdao 266003, China
| | - Yingying Zhao
- Laboratory for Climate and Ocean-Atmosphere Studies (LaCOAS) and Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100871, China
| | - Zhengyu Liu
- Laboratory for Climate and Ocean-Atmosphere Studies (LaCOAS) and Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100871, China.,Center for Climatic Research, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - Qing Li
- Laboratory for Climate and Ocean-Atmosphere Studies (LaCOAS) and Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100871, China.,Department of Earth, Environmental and Planetary Sciences, Brown University, Rhode Island 02912, USA
| | - Feng He
- Center for Climatic Research, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - Qiong Zhang
- Department of Physical Geography and Bolin Centre for Climate Research, Stockholm University, Stockholm 10691, Sweden
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Regional and global forcing of glacier retreat during the last deglaciation. Nat Commun 2015; 6:8059. [PMID: 26293133 PMCID: PMC4560787 DOI: 10.1038/ncomms9059] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 07/10/2015] [Indexed: 11/13/2022] Open
Abstract
The ongoing retreat of glaciers globally is one of the clearest manifestations of recent global warming associated with rising greenhouse gas concentrations. By comparison, the importance of greenhouse gases in driving glacier retreat during the most recent deglaciation, the last major interval of global warming, is unclear due to uncertainties in the timing of retreat around the world. Here we use recently improved cosmogenic-nuclide production-rate calibrations to recalculate the ages of 1,116 glacial boulders from 195 moraines that provide broad coverage of retreat in mid-to-low-latitude regions. This revised history, in conjunction with transient climate model simulations, suggests that while several regional-scale forcings, including insolation, ice sheets and ocean circulation, modulated glacier responses regionally, they are unable to account for global-scale retreat, which is most likely related to increasing greenhouse gas concentrations. The extent to which greenhouse gases forced glacier retreat during the last deglaciation remains unclear. Here, the authors recalculate cosmogenic nuclide ages for 195 glacier moraines and show that deglacial glacier retreat was broadly globally synchronous with rising levels of atmospheric CO2.
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Regional and global forcing of glacier retreat during the last deglaciation. Nat Commun 2015. [PMID: 26293133 DOI: 10.1038/ncomms9059]] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The ongoing retreat of glaciers globally is one of the clearest manifestations of recent global warming associated with rising greenhouse gas concentrations. By comparison, the importance of greenhouse gases in driving glacier retreat during the most recent deglaciation, the last major interval of global warming, is unclear due to uncertainties in the timing of retreat around the world. Here we use recently improved cosmogenic-nuclide production-rate calibrations to recalculate the ages of 1,116 glacial boulders from 195 moraines that provide broad coverage of retreat in mid-to-low-latitude regions. This revised history, in conjunction with transient climate model simulations, suggests that while several regional-scale forcings, including insolation, ice sheets and ocean circulation, modulated glacier responses regionally, they are unable to account for global-scale retreat, which is most likely related to increasing greenhouse gas concentrations.
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