Evidências Geomorfológicas de Mudanças Ambientais na Baía Esperança, Península Antártica

A geomorphological interpretation of the glacial geomorphology of the proglacial environments of the Buenos Aires, Kenney and Flora glaciers in Hope Bay, Antarctica, between the coordinates 63° 23'S and 63° 26'S latitude and 56° 8'W and 57° 4'W longitude. Sedimentary, granulometric and morphological analyzes were carried out on 15 samples collected in 2017 for the identification of depositional geomorphological features and subsequent geomorphological mapping. The glacier fronts were delineated from Sentinel-2 and Quickbird images of 1988, 2008 and 2017 using the ArcGIS® software to identify the landforms chronology of the shapes. The higher number of coarse grains, low selection, and high values of C40 in all samples indicate modification by erosive processes in supraglacial environment and/or transport distance after substrate quarrying process and grain fracturing by post-depositional physical weathering. The reconstruction of the Hope Bay’s Holocene landscape of indicates glaciers with tens of meters of advance compared to the current front during the Little Ice Age (LIA). The geomorphological mapping and sedimentary analyzes showed recent environmental changes in the proglacial system, with formation of hummocky moraines indicating the retreat/stabilization of the glaciers in the LIA. Furthermore, they set evidences of recent recession moraines, which prevail in the Buenos Aires Glacier predominate in the 2008-2017 phase, on the Flora Glacier in 1988-2008 period and the Kenney Glacier in the 2008-2017 period.

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Recent, rapid and profound changes to glacier morphology and dynamics, Juneau Icefield, Alaska

10.5194/egusphere-egu21-1539 ◽

2021 ◽

Author(s):

Bethan Davies ◽

Jacob Bendle ◽

Robert McNabb ◽

Jonathan Carrivick ◽

Christopher McNeil ◽

...

Keyword(s):

Little Ice Age ◽

Ice Age ◽

Aerial Photographs ◽

Equilibrium Line Altitude ◽

Regional Warming ◽

Geomorphological Mapping ◽

Glacier Recession ◽

Digital Elevation ◽

High Resolution Satellite Imagery ◽

Global Sea Level

The Alaskan region (comprising glaciers in Alaska, British Columbia and Yukon) contains the third largest ice volume outside of the Greenland and Antarctic ice sheets, and contributes more to global sea level rise than any other glacierised region defined by the Randolph Glacier Inventory. However, ice loss in this area is not linear, but in part controlled by glacier hypsometry as valley and outlet glaciers are at risk of becoming detached from their accumulation areas during thinning. Plateau icefields, such as Juneau Icefield in Alaska, are very sensitive to changes in Equilibrium Line Altitude (ELA) as this can result in rapidly shrinking accumulation areas. Here, we present detailed geomorphological mapping around Juneau Icefield and use this data to reconstruct the icefield during the &#8220;Little Ice Age&#8221;. We use topographic maps, archival aerial photographs, high-resolution satellite imagery and digital elevation models to map glacier lake and glacier area and volume change from the Little Ice Age to the present day (1770, 1948, 1979, 1990, 2005, 2015 and 2019 AD). Structural glaciological mapping (1979 and 2019) highlights structural and topographic controls on non-linear glacier recession.&#160; Our data shows pronounced glacier thinning and recession in response to widespread detachment of outlet glaciers from their plateau accumulation areas. Glacier detachments became common after 2005, and occurred with increasing frequency since then. Total summed rates of area change increased eightfold from 1770-1948 (-6.14 km2 a-1) to 2015-2019 (-45.23 km2 a-1). Total rates of recession were consistent from 1770 to 1990 AD, and grew increasingly rapid after 2005, in line with regional warming.

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Hydrological change and human activity during Yuan–Ming Dynasties in the Loulan area, northwestern China

The Holocene ◽

10.1177/0959683618771495 ◽

2018 ◽

Vol 28 (8) ◽

pp. 1266-1275 ◽

Cited By ~ 3

Author(s):

Kangkang Li ◽

Xiaoguang Qin ◽

Lei Zhang ◽

Zhaoyan Gu ◽

Bing Xu ◽

...

Keyword(s):

Human Activity ◽

Little Ice Age ◽

Environmental Changes ◽

Ice Age ◽

Flood Events ◽

Lop Nur ◽

Plant Remains ◽

Ancient Silk Road ◽

Climate Transition ◽

Changes Over Time

Human activity on arid lands has been related to oases evolution. The ancient Loulan, an important transportation hub of the ancient Silk Road, developed on an ancient oasis on the west bank of the lake Lop Nur in Xinjiang, China. Previous studies and historical documents suggest that the region has experienced dramatic natural environmental and human activity–related changes over time, transitioning from a particularly prosperous oasis to a depopulated zone with harsh environment after about 1500 a BP (before present, where present = AD 1950). Based on systematic radiocarbon (14C) dating for natural plant remains and archeological sites in the Loulan area, it was revealed that the region re-experienced oasis environment from 1260 to 1450 cal. AD, corresponding to the Yuan–Ming Dynasties, which is the climate transition stage from the ‘Medieval Warm Period’ to the ‘Little Ice Age’, encompassing a series of pulse-like flood events which cannot be identified from lacustrine deposition due to the limits of sampling resolution and dating. It was found that humans re-occupied the Loulan area and built canals to irrigate farmlands during the period. The more habitable hydrological conditions that resulted from these environmental changes present one major reason for the re-emergence of human activities in the Loulan area.

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Vegetation changes in the Hotyn Upland over the last 2000 years (based on pollen data)

Journal of Geology Geography and Geoecology ◽

10.15421/111906 ◽

2019 ◽

Vol 28 (1) ◽

pp. 51-58 ◽

Cited By ~ 1

Author(s):

N. Gerasimenko ◽

T. Yurchenko ◽

Ye. Rohozin

Keyword(s):

Little Ice Age ◽

Environmental Changes ◽

Medieval Warm Period ◽

Warm Period ◽

Ice Age ◽

Humid Climate ◽

Cool Period ◽

Surface Samples ◽

Pollen Surface ◽

Short Period

Pollen study of two soil sections, located in two different relief positions (the gully bottom at Sadgora 1 and the upper part of a slope at Ridkivtsi I) enables us to show vegetational and climatic changes in the Bukovyna area (the Chernivtsi region) during the last 2000 years (the end of the Early Subatlantic, the Middle and Late Subatlantic). The reconstructions of past vegetation are based on the analyses of pollen surface samples, taken from the soils of different ecotops in the sites’ vicinity. The reconstructed short-period phases of environmental change correspond well with those established in other areas. These are the end of the “Roman warm period” (before the 14C date of 1.74 ka BP), with the humid climate; the relatively dry “Dark Ages cool period” (before the 14C date of 1.19 ka BP); the wet “Medieval warm period”; the cool “Little Ice Age” (with its wetter beginning and drier ending) and the modern warm phase (the last 150 years).Centennial environmental changes − the cooling within the Medieval Warming (XI cent.) and the warming within the “Little Ice Age” (XV cent.) – have been detected. Human impact on the vegetation can be demonstrated – forest clearance (with the presence of particles of microscopic charcoal and pollen of pyrophitic plants), the introduction of thermophilous walnut during warm periods, and the appearance of pasture lands in the place of former fern patches and woods during the “Little Ice Age”, and the last warm phase (with the presence of pollen of pastoral synanthropic plants). In the last 2000 years, broad-leaved woodland, dominated by hornbeam, grew extensively near Sadgora and Ridkivtsi only during the “Medieval Warm Period”.

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The Little Ice Age: evidence from a sediment record in Gullmar Fjord, Swedish west coast

Biogeosciences ◽

10.5194/bg-10-1275-2013 ◽

2013 ◽

Vol 10 (3) ◽

pp. 1275-1290 ◽

Cited By ~ 14

Author(s):

I. Polovodova Asteman ◽

K. Nordberg ◽

H. L. Filipsson

Keyword(s):

Little Ice Age ◽

Stable Carbon Isotopes ◽

Environmental Changes ◽

Cold Water ◽

Land Use Changes ◽

Ice Age ◽

Sediment Geochemistry ◽

Sediment Record ◽

Terrestrial Organic Matter ◽

Swedish West Coast

Abstract. We discuss the climatic and environmental changes during the last millennium in NE Europe based on a ca. 8-m long high-resolved and well-dated marine sediment record from the deepest basin of Gullmar Fjord (SW Sweden). According to the 210Pb- and 14C-datings, the record includes the period of the late Holocene characterised by anomalously cold summers and well-known as the Little Ice Age (LIA). Using benthic foraminiferal stratigraphy, lithology, bulk sediment geochemistry and stable carbon isotopes we reconstruct various phases of the cold period, identify its timing in the study area and discuss the land–sea interactions occurring during that time. The onset of the LIA is indicated by an increase in cold-water foraminiferal species Adercotryma glomerata at ~ 1350 AD The first phase of the LIA was characterised by a stormy climate and higher productivity, which is indicated by a foraminiferal unit of Nonionella iridea and Cassidulina laevigata. Maximum abundances of N. iridea probably mirror a short and abrupt warming event at ~ 1600 AD. It is likely that due to land use changes in the second part of the LIA there was an increased input of terrestrial organic matter to the fjord, which is indicated by lighter δ13C values and an increase of detritivorous and omnivorous species such as Textularia earlandi and Eggerelloides scaber. The climate deterioration during the climax of the LIA (1675–1704 AD), as suggested by the increase of agglutinated species, presence of Hyalinea balthica, and a decline of N. iridea may have driven the decline in primary productivity during this time period.

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Geological, Paleoclimatological, and Archaeological History of the Baltic Sea Region Since the Last Glaciation

Oxford Research Encyclopedia of Climate Science ◽

10.1093/acrefore/9780190228620.013.621 ◽

2020 ◽

Author(s):

Jan Harff ◽

Hauke Jöns ◽

Alar Rosentau

Keyword(s):

Baltic Sea ◽

Sea Level Rise ◽

Sea Level ◽

Little Ice Age ◽

Environmental Changes ◽

Ice Age ◽

The Baltic Sea ◽

The Holocene ◽

Socioeconomic System ◽

The Baltic

The correlation of climate variability; the change environment, in particular the change of coastlines; and the development of human societies during the last millennia can be studied exemplarily in the Baltic area. The retreat of the Scandinavian ice-sheet vertical crustal movement (glacio-isostatic adjustment), together with climatically controlled sea-level rise and a continuously warming atmosphere, determine a dramatic competition between different forcings of the environment that advancing humans are occupying step by step after the glaciation. These spatially and temporally changing life conditions require a stepwise adjustment of survival strategies. Changes in the natural environment can be reconstructed from sedimentary, biological proxy data and archaeological information. According to these reconstructions, the main shift in the Baltic area’s environment happened about 8,500 years before present (BP) when the Baltic Sea became permanently connected to the Atlantic Ocean via the Danish straits and the Sound, and changed the environment from lacustrine to brackish-marine conditions. Human reaction to environmental changes in prehistoric times is mainly reconstructed from remains of ancient settlements—onshore in the uplifting North and underwater in the South dominated by sea-level rise. According to the available data, the human response to environmental change was mainly passive before the successful establishment of agriculture. But it became increasingly active after people settled down and the socioeconomic system changed from hunter-gatherer to farming communities. This change, mainly triggered by the climatic change from the Holocene cool phase to the warming period, is clearly visible in Baltic basin sediment cores as a regime shift 6,000 years (BP). But the archaeological findings prove that the relatively abrupt environmental shift is reflected in the socioeconomic system by a period of transition when hunter-gatherer and farming societies lived in parallel for several centuries. After the Holocene warming, the permanent regression in the Northern Baltic Sea and the transgression in the South did affect the socioeconomic response of the Baltic coastal societies, who migrated downslope at the regressive coast and upslope at the transgressive coast. The following cooling phases, in particular the Late Antique Little Ice Age (LALIA) and the Little Ice Age (LIA), are directly connected with migration and severe changes of the socioeconomic system. After millennia of passive reaction to climate and environmental changes, the Industrial Revolution finally enabled humans to influence and protect actively the environment, and in particular the Baltic Sea shore, by coastal constructions. On the other hand, this ability also affected climate and environment negatively because of the disturbance of the natural balance between climate, geosystem, and ecosystem.

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The Animal in Late Medieval Britain

10.1093/oxfordhb/9780198744719.013.65 ◽

2018 ◽

Author(s):

Louisa Gidney

Keyword(s):

Sex Ratio ◽

Little Ice Age ◽

Environmental Changes ◽

Companion Animals ◽

Warm Period ◽

Ice Age ◽

Selection Pressures ◽

Late Medieval ◽

Causative Effect ◽

The Impact

Evidence is considered here for the utilization of domestic farm and companion animals for products other than meat, for example goat horns and calf and cat skins. Selection pressures driving changes in the stature of cattle are suggested to reflect environmental changes from the Medieval Warm Period to the Little Ice Age. An example of catastrophic cattle mortality is examined with regard to the difficulty of establishing the causative effect, the sex ratio of the bodies, and the impact on the manorial farm. Routine disposal of inedible carrion is discussed with regard to urban disposal of horse bones. Constraints on livestock husbandry and the survival of faunal evidence in the uplands of Wales, northern England, and Scotland are used to demonstrate the effect of legal and commercial considerations on the Scottish data.

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Development of Polar Inughuit Culture in the Smith Sound Region

10.1093/oxfordhb/9780199766956.013.43 ◽

2016 ◽

Author(s):

Genevieve LeMoine ◽

Christyann Darwent

Keyword(s):

Indigenous People ◽

General Public ◽

Little Ice Age ◽

Environmental Changes ◽

Ice Age ◽

Archaeological Record ◽

Archaeological Remains ◽

Historic Period ◽

Far North ◽

The World

The Inughuit of northwestern Greenland are the most northerly indigenous people in the world. They have long been of interest to scholars and the general public due to their evident isolation when first contacted by Europeans in 1818, their loss of key hunting technologies such as kayaks and bows and arrows before contact, their extensive use of meteoric iron, and their important role in exploration of the far north. This chapter summarizes the archaeological record from the thirteenth century, when Thule migrants first arrived in the region, through the historic period. The key period of emerging Inughuit culture, between the sixteenth and nineteenth centuries, has left few archaeological remains. Work by the Inglefield Land Archaeology Project and studies in ethnohistory and paleoclimatology suggest that many factors, including epidemics and environmental changes associated with the Little Ice Age, led to the distinctive Inughuit culture described by explorers in the nineteenth century.

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Absence of a Medieval Climate Anomaly, Little Ice Age and twentieth century warming in Skarvsnes, Lützow Holm Bay, East Antarctica

Antarctic Science ◽

10.1017/s0954102014000029 ◽

2014 ◽

Vol 26 (5) ◽

pp. 585-598 ◽

Cited By ~ 11

Author(s):

Ines Tavernier ◽

Elie Verleyen ◽

Dominic A. Hodgson ◽

Katrien Heirman ◽

Stephen J. Roberts ◽

...

Keyword(s):

Twentieth Century ◽

Southern Hemisphere ◽

Northern Hemisphere ◽

Little Ice Age ◽

Environmental Changes ◽

Open Water ◽

Ice Age ◽

Medieval Climate Anomaly ◽

Climate Anomaly ◽

The Past

AbstractPalaeoclimate changes, such as the Medieval Climate Anomaly and the Little Ice Age, are well-defined in the Northern Hemisphere during the past 2000 years. In contrast, these anomalies appear to be either absent, or less well-defined, in high-latitude regions of the Southern Hemisphere. Here, we inferred environmental changes during the past two millennia from proxies in a sediment core from Mago Ike, an East Antarctic lake in Skarvsnes (Lützow Holm Bay). Variations in lake primary production were inferred from fossil pigments, sedimentological and geochemical proxies and combined with absolute diatom counts to infer past diatom productivity and community changes. Three distinct stratigraphic zones were recognized, resulting from a shift from marine to lacustrine conditions with a clear transition zone in between. The presence of open-water marine diatoms indicates a coastal zone seasonally free of sea ice between c. 2120–1500 cal yr bp. Subsequently, the lake became isolated from the ocean due to isostatic uplift. Freshwater conditions were established from c. 1120 cal yr bp onwards after which the proxies are considered highly sensitive to temperature changes. There is no evidence for a Medieval Climate Anomaly, Little Ice Age or twentieth century warming in our lake sediment record suggesting that studies that have imposed Northern Hemisphere climate anomalies onto Southern Hemisphere palaeoclimate records should be treated with caution.

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The Little Ice Age: evidence from a sediment record in Gullmar Fjord, Swedish west coast

Biogeosciences Discussions ◽

10.5194/bgd-9-14053-2012 ◽

2012 ◽

Vol 9 (10) ◽

pp. 14053-14089 ◽

Cited By ~ 1

Author(s):

I. Polovodova Asteman ◽

K. Nordberg ◽

H. L. Filipsson

Keyword(s):

Little Ice Age ◽

Stable Carbon Isotopes ◽

Environmental Changes ◽

Cold Water ◽

Land Use Changes ◽

Ice Age ◽

Sediment Geochemistry ◽

Sediment Record ◽

Terrestrial Organic Matter ◽

Swedish West Coast

Abstract. We discuss the climatic and environmental changes during the last millennium in NE Europe based on a ca. 8-m long high-resolved and well-dated marine sediment record from the deepest basin of Gullmar Fjord (SW Sweden). According to the 210Pb- and 14C-datings, the record includes the period of the late Holocene characterised by anomalously cold summers and well known as the Little Ice Age (LIA). Using benthic foraminiferal stratigraphy, lithology, bulk sediment geochemistry and stable carbon isotopes we reconstruct various phases of this cold period, identify its timing in the study area and discuss the land-sea interactions occurring during that time. The onset of the LIA is indicated by an increase in cold-water foraminiferal species Adercotryma glomerata at ~ 1350 AD. The first phase of the LIA was characterised by a stormy but milder climate, which is indicated by a presence of Nonionella iridea. Maximum abundances of this species are likely to mirror a short and abrupt warming event at ~ 1600 AD. It is likely that due to land use changes in the second part of the LIA there was an increased input of terrestrial organic matter to the fjord, which is indicated by lighter δ13C values and an increase of detritivorous and omnivorous species as Textularia earlandi and Eggerelloides scaber. The climate deterioration during the climax of the LIA (1675–1704 AD), as suggested by the agglutinated species, caused some carbonate dissolution, variations in primary productivity and a decline of N. iridea dependant on fresh phytodetritus. It is also assumed that an increase of Hyalinea balthica could be indicative of climate warming trends at 1600–1743 and 1813–1940 AD.

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Palaeoceanographic changes in Hornsund Fjord (Spitsbergen, Svalbard) over the last millennium: new insights from ancient DNA

Climate of the Past ◽

10.5194/cp-12-1459-2016 ◽

2016 ◽

Vol 12 (7) ◽

pp. 1459-1472 ◽

Cited By ~ 13

Author(s):

Joanna Pawłowska ◽

Marek Zajączkowski ◽

Magdalena Łącka ◽

Franck Lejzerowicz ◽

Philippe Esling ◽

...

Keyword(s):

Ancient Dna ◽

Environmental Conditions ◽

Little Ice Age ◽

Environmental Changes ◽

Water Masses ◽

Ice Age ◽

Last Millennium ◽

Climatic Fluctuations ◽

High Sedimentation ◽

Calving Rate

Abstract. This paper presents a reconstruction of climate-driven environmental changes over the last millennium in Hornsund Fjord (Svalbard), based on sedimentological and micropalaeontological records. Our palaeo-investigation was supported by an analysis of foraminiferal ancient DNA (aDNA), focusing on the non-fossilized monothalamous species. The main climatic fluctuations during the last millennium were the Medieval Warm Period (MWP, AD 1000–1600), the Little Ice Age (LIA, AD 1600–1900) and the modern warming (MW, AD 1900 to present). Our study indicates that the environmental conditions in Hornsund during the MWP and the early LIA (before ∼ AD 1800) were relatively stable. The beginning of the LIA (∼ AD 1600) was poorly evidenced by the micropalaeontological record but was well marked in the aDNA data by an increased proportion of monothalamous foraminifera, especially Bathysiphon sp. The early LIA (∼ 1600 to ∼ AD 1800) was marked by an increase in the abundance of sequences of Hippocrepinella hirudinea and Cedhagenia saltatus. In the late LIA (after ∼ AD 1800), the conditions in the fjord became glacier-proximal and were characterized by increased meltwater outflows, high sedimentation and a high calving rate. This coincided with an increase in the percentages of sequences of Micrometula sp. and Vellaria pellucidus. During the MW, the major glacier fronts retreated rapidly to the inner bays, which limited the iceberg discharge to the fjord's centre and caused a shift in the foraminiferal community that was reflected in both the fossil and aDNA records. The palaeoceanographic changes in the Hornsund fjord over the last millennium were driven mainly by the inflow of shelf-originated water masses and glacial activity. However, the environmental changes were poorly evidenced in the micropalaeontological record, but they were well documented in our aDNA data. We considerably increased the number of potential proxy species by including monothalamous foraminifera in the palaeoecological studies.

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