Rapid reorganization in ocean biogeochemistry off Peru towards the end of the Little Ice Age

Abstract. Climate and ocean ecosystem variability has been well recognized during the twentieth century but it is unclear if modern ocean biogeochemistry is susceptible to the large, abrupt shifts that characterized the Late Quaternary. Time series from marine sediments off Peru show an abrupt centennial-scale biogeochemical regime shift in the early nineteenth century, of much greater magnitude and duration than present day multi-decadal variability. A rapid expansion of the subsurface nutrient-rich, oxygen-depleted waters resulted in higher biological productivity, including pelagic fish. The shift was likely driven by a northward migration of the Intertropical Convergence Zone and the South Pacific Subtropical High to their present day locations, coupled with a strengthening of Walker circulation, towards the end of the Little Ice Age. These findings reveal the potential for large reorganizations in tropical Pacific climate with immediate effects on ocean biogeochemical cycling and ecosystem structure.

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Rapid reorganization in ocean biogeochemistry off Peru towards the end of the Little Ice Age

Biogeosciences ◽

10.5194/bg-6-835-2009 ◽

2009 ◽

Vol 6 (5) ◽

pp. 835-848 ◽

Cited By ~ 86

Author(s):

D. Gutiérrez ◽

A. Sifeddine ◽

D. B. Field ◽

L. Ortlieb ◽

G. Vargas ◽

...

Keyword(s):

Little Ice Age ◽

Decadal Variability ◽

Late Quaternary ◽

Walker Circulation ◽

Rapid Expansion ◽

Ice Age ◽

Ecosystem Structure ◽

Ocean Biogeochemistry ◽

Ocean Ecosystem ◽

Abrupt Shifts

Abstract. Climate and ocean ecosystem variability has been well recognized during the twentieth century but it is unclear if modern ocean biogeochemistry is susceptible to the large, abrupt shifts that characterized the Late Quaternary. Time series from marine sediments off Peru show an abrupt centennial-scale biogeochemical regime shift in the early nineteenth century, of much greater magnitude and duration than present day multi-decadal variability. A rapid expansion of the subsurface nutrient-rich, oxygen-depleted waters resulted in the present-day higher biological productivity, including pelagic fish. The shift was likely driven by a northward migration of the Intertropical Convergence Zone and the South Pacific Subtropical High to their present day locations, coupled with a strengthening of Walker circulation, towards the end of the Little Ice Age. These findings reveal the potential for large reorganizations in tropical Pacific climate with immediate effects on ocean biogeochemical cycling and ecosystem structure.

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The ENSO teleconnections to the Indian summer monsoon climate through the Last Millennium as simulated by the PMIP3

10.5194/cp-2018-7 ◽

2018 ◽

Cited By ~ 1

Author(s):

Charan Teja Tejavath ◽

Karumuri Ashok ◽

Supriyo Chakraborty ◽

Rengaswamy Ramesh

Keyword(s):

Summer Monsoon ◽

Indian Summer Monsoon ◽

Little Ice Age ◽

Walker Circulation ◽

Summer Monsoon Rainfall ◽

Ice Age ◽

Boreal Summer ◽

Last Millennium ◽

Enso Teleconnections ◽

The Mean

Abstract. Using seven model simulations from the PMIP3, we study the mean summer (June–September) climate and its variability in India during the Last Millennium (LM; CE 850–1849) with emphasis on the Medieval Warm Period (MWP) and Little Ice Age (LIA), after validation of the simulated current day climate and trends. We find that the above (below) LM-mean summer global temperatures during the MWP (LIA) are associated with relatively higher (lower) number of concurrent El Niños as compared to La Niñas. The models simulate higher (lower) Indian summer monsoon rainfall (ISMR) during the MWP (LIA). This is notwithstanding a strong simulated negative correlation between the timeseries of NINO3.4 index and that of the area-averaged ISMR, Interestingly, the percentage of strong El Niños (La Niñas) causing negative (positive) ISMR anomalies is higher in the LIA (MWP), a non-linearity that apparently is important for causing higher ISMR in the MWP. Distribution of simulated boreal summer velocity potential at 850 hPa during MWP in models, in general, shows a zone of anomalous convergence in the central tropical Pacific flanked by two zones of divergence, suggesting a westward shift in the Walker circulation as compared to the simulations for LM as well as and a majority of historical simulations, and current day observed signal. The anomalous divergence centre in the west also extends into the equatorial eastern Indian Ocean, resulting in an anomalous convergence zone over India and therefore excess rainfall during the MWP as compared to the LM; the results are qualitative, given the inter-model spread.

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A importância da acção do frio do Quaternário final em Portugal e suas implicações nas morfodinâmicas de vertente.

Revista Brasileira de Geografia Física ◽

10.26848/rbgf.v5i2.232748 ◽

2012 ◽

Vol 5 (2) ◽

pp. 421

Author(s):

António Sousa Pedrosa

Keyword(s):

Little Ice Age ◽

Late Quaternary ◽

Climatic Conditions ◽

Ice Age ◽

Glacial Deposits ◽

Central Portugal

Resumo De entre os factores que tiveram maior influência na evolução do relevo de Portugal no decurso final do Quaternário é incontestável que o frio e os processos que lhe estão associados tiveram um papel muito importante na modelação das formas de relevo. Neste trabalho procuraremos fazer uma síntese dos principais aspectos da evolução das vertentes relacionados com os frio, inferir através dos vestígios que chegaram até ao nossos dias quais as condições morfo-climáticas em que ocorreram e quais os processos que lhes estavam encontravam associados. Realçamos assim o papel da acção dos glaciares nas áreas onde ocorreram assim como a importância dos processos periglaciares na evolução das vertentes. O período tardiglaciar também se mostrou marcante na dinâmica de vertentes tendo mobilizado e remobilizado muito material nas vertentes através de solifluxões generalizadas levando muitas delas à sua regularização. O período conhecido como a pequena idade do gelo também deixou as suas marcas na dinâmica das vertentes às quais se associam as escombreiras de gravidade. Por fim enfatizamos um pouco o papel do frio na actual morfodinâmica de vertentes no Norte de Centro de Portugal. Palavras-chave: Norte de Portugal; Montanhas, depósitos glaciares, depósitos periglaciares, dinâmica de vertentes Summary Among the factors that most influenced the evolution of the relief of Portugal during the late Quaternary is incontestable that the cold and the processes associated with it had a very important role in modeling the forms of relief. In this paper, we will try to summarize the importance that the cold had on the evolution of slopes, inferred through the vestiges that have come down to our day, which morpho-climatic conditions in which they occur, and also what processes if they were associated with. Thus enhancing the role of action in areas where glaciers have occurred and the importance of periglacial processes in the evolution of the slopes. In tardiglaciar the dynamics of slopes was very active and mobilized a lot of material through the process of solifluction regularized many of them. The period known as the Little Ice Age has also left its mark on the dynamic slopes which relate to tailings heaps of gravity. Finally we emphasize the role of cold in the current slopes of morphodynamics in north and central Portugal. Keywords: North of Portugal; mountains, glacial deposits, periglacial deposits, morphodynamics of slopes

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Late Quaternary geomorphology and geoarchaeology in the rivers of the Holy Cross Mountains region, central Europe

Quaternary Research ◽

10.1017/qua.2018.55 ◽

2018 ◽

Vol 91 (2) ◽

pp. 584-599 ◽

Cited By ~ 2

Author(s):

Tomasz Kalicki ◽

Marcin Frączek ◽

Paweł Przepióra ◽

Piotr Kusztal ◽

Edyta Kłusakiewicz ◽

...

Keyword(s):

Middle Ages ◽

Little Ice Age ◽

Water Retention ◽

Late Quaternary ◽

Ice Age ◽

Small Scale ◽

Natural Processes ◽

Retention System ◽

Artificial Ponds ◽

Quaternary Geomorphology

AbstractLate Quaternary terraces and sediments in the Holy Cross Mountain region of Poland, emplaced within an environment that had evolved following multiple Pleistocene glaciations, provide evidence of increasing anthropogenic influence on landscape development since the Middle Ages, as revealed by research in the Kamionka, Kamienna, Czarna Konecka, and Nida valleys. The development of the “anthropogenic small-scale water retention system” (ASWRS), including numerous artificial ponds, channels, and forges and mills along the watercourses, resulted in changes in river patterns, with additional anthropogenic channels, which in turn reduced the maximum flood-stage levels during the Little Ice Age. With the collapse of the industries and the disappearance of the ASWRS, several major flood events took place. Unknown in the earlier Holocene, and caused by hydrotechnical failures, the geomorphic effects of these catastrophic flash floods significantly exceeded those of natural processes.

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Was the Little Ice Age the coolest Holocene climatic period in the Italian central Alps?

Progress in Physical Geography Earth and Environment ◽

10.1177/0309133319881105 ◽

2019 ◽

Vol 44 (4) ◽

pp. 495-513 ◽

Cited By ~ 1

Author(s):

Andrea Zerboni ◽

Guido S Mariani ◽

Lanfredo Castelletti ◽

Elena S Ferrari ◽

Marco Tremari ◽

...

Keyword(s):

Iron Age ◽

Little Ice Age ◽

Late Quaternary ◽

Climatic Conditions ◽

Ice Age ◽

Central Alps ◽

Temperature Changes ◽

Medium Resolution ◽

Climatic Period ◽

Pedogenetic Processes

The Estimation of the relative intensity of different cold periods occurring during the Late Quaternary is a difficult task, particularly in non-glaciated mountain landscapes and where high- to medium-resolution archives for proxy data are lacking. In this paper, we study a Holocene polycyclic soil sequence in the central Alps (Val Cavargna, Northern Italy) to estimate climatic parameters (specifically Temperature) changes in non-glaciated, high altitude environments. We investigate this key site through palaeopedological and micromorphological analyses in order to understand phases of soil development and detect hidden evidence of cold conditions during its formation. Three phases of pedogenesis can be recognized and attributed in time to different periods during the Holocene. Pedogenetic phases were separated by two truncation and deposition episodes related to the reactivation of slope processes under cold conditions at the onset of the Neoglacial and the Iron Age Cold Epoch, respectively. Micromorphological evidence of frost action in the soil can instead relate to pedogenetic processes acting in the Little Ice Age. The different expression of these three cold periods corresponds to changes in climatic conditions, pointing to the Little Ice Age as a cooler/drier period in comparison to the preceding ones.

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Late Quaternary stratigraphy and geochronology of the western Killpecker Dunes, Wyoming, USA

Quaternary Research ◽

10.1016/j.yqres.2003.10.003 ◽

2004 ◽

Vol 61 (1) ◽

pp. 72-84 ◽

Cited By ~ 27

Author(s):

James H. Mayer ◽

Shannon A. Mahan

Keyword(s):

Late Pleistocene ◽

Great Plains ◽

Little Ice Age ◽

Late Quaternary ◽

Soil Formation ◽

Ice Age ◽

Dune Field ◽

Eolian Sand ◽

Quaternary Stratigraphy ◽

Precise Understanding

New stratigraphic and geochronologic data from the Killpecker Dunes in southwestern Wyoming facilitate a more precise understanding of the dune field’s history. Prior investigations suggested that evidence for late Pleistocene eolian activity in the dune field was lacking. However, luminescence ages from eolian sand of ∼15,000 yr, as well as Folsom (12,950–11,950 cal yr B.P.) and Agate Basin (12,600–10,700 cal yr) artifacts overlying eolian sand, indicate the dune field existed at least during the latest Pleistocene, with initial eolian sedimentation probably occurring under a dry periglacial climate. The period between ∼13,000 and 8900 cal yr B.P. was characterized by relatively slow eolian sedimentation concomitant with soil formation. Erosion occurred between ∼8182 and 6600 cal yr B.P. on the upwind region of the dune field, followed by relative stability and soil formation between ∼5900 and 2700 cal yr B.P. The first of at least two latest Holocene episodes of eolian sedimentation occurred between ∼2000 and 1500 yr, followed by a brief (∼500 yr) episode of soil formation; a second episode of sedimentation, occurring by at least ∼700 yr, may coincide with a hypothesized Medieval warm period. Recent stabilization of the western Killpecker Dunes likely occurred during the Little Ice Age (∼350–100 yr B.P.). The eolian chronology of the western Killpecker Dunes correlates reasonably well with those of other major dune fields in the Wyoming Basin, suggesting that dune field reactivation resulted primarily due to departures toward aridity during the late Quaternary. Similar to dune fields on the central Great Plains, dune fields in the Wyoming Basin have been active under a periglacial climate during the late Pleistocene, as well as under near-modern conditions during the latest Holocene.

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Greenhouses, hot water bottles, cycles and the future of New Zealand climate

Proceedings of the New Zealand Grassland Association ◽

10.33584/jnzg.2009.71.2772 ◽

2009 ◽

pp. 61-67

Author(s):

W.P. De Lange

Keyword(s):

New Zealand ◽

Thermal Energy ◽

Infrared Radiation ◽

Little Ice Age ◽

Hot Water ◽

Ice Age ◽

The Sun ◽

Weather Patterns ◽

Time Periods ◽

Almost All

The Greenhouse Effect acts to slow the escape of infrared radiation to space, and hence warms the atmosphere. The oceans derive almost all of their thermal energy from the sun, and none from infrared radiation in the atmosphere. The thermal energy stored by the oceans is transported globally and released after a range of different time periods. The release of thermal energy from the oceans modifies the behaviour of atmospheric circulation, and hence varies climate. Based on ocean behaviour, New Zealand can expect weather patterns similar to those from 1890-1922 and another Little Ice Age may develop this century.

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