scholarly journals A multi-proxy perspective on millennium-long climate variability in the Southern Pyrenees

2012 ◽  
Vol 8 (2) ◽  
pp. 683-700 ◽  
Author(s):  
M. Morellón ◽  
A. Pérez-Sanz ◽  
J. P. Corella ◽  
U. Büntgen ◽  
J. Catalán ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Ice Age ◽  
Deciduous Tree ◽  
Last Millennium ◽  
Medieval Climate Anomaly ◽  
Cold Temperatures ◽  
Significant Development ◽  
Arid Conditions ◽  
Rainfall Variations ◽  
Second Period

Abstract. This paper reviews multi-proxy paleoclimatic reconstructions with robust age-control derived from lacustrine, dendrochronological and geomorphological records and characterizes the main environmental changes that occurred in the Southern Pyrenees during the last millennium. Warmer and relatively arid conditions prevailed during the Medieval Climate Anomaly (MCA, ca. 900–1300 AD), with a significant development of xerophytes and Mediterranean vegetation and limited deciduous tree formations (mesophytes). The Little Ice Age (LIA, 1300–1800 AD) was generally colder and moister, with an expansion of deciduous taxa and cold-adapted montane conifers. Two major phases occurred within this period: (i) a transition MCA–LIA, characterized by fluctuating, moist conditions and relatively cold temperatures (ca. 1300 and 1600 AD); and (ii) a second period, characterized by the coldest and most humid conditions, coinciding with maximum (recent) glacier advances (ca. 1600–1800 AD). Glaciers retreated after the LIA when warmer and more arid conditions dominated, interrupted by a short-living cooling episode during the late 19th to early 20th centuries. Some records suggest a response to solar activity with colder and slightly moister conditions during solar minima. Centennial-scale hydrological fluctuations are in phase with reconstructions of NAO variability, which appears to be one of the main climate mechanisms influencing rainfall variations in the region during the last millennium.

scholarly journals A multi-proxy perspective on millennium-long climate variability in the Southern Pyrenees

2011 ◽  
Vol 7 (5) ◽  
pp. 3049-3089 ◽  
Author(s):  
M. Morellón ◽  
A. Pérez-Sanz ◽  
J. P. Corella ◽  
U. Büntgen ◽  
J. Catalán ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Environmental Changes ◽  
Ice Age ◽  
Deciduous Tree ◽  
Last Millennium ◽  
Medieval Climate Anomaly ◽  
Cold Temperatures ◽  
Significant Development ◽  
Arid Conditions ◽  
Second Period

Abstract. A review of selected, well-dated, multiproxy paleoclimatic records (lacustrine, dendrochronological, geomorphological) characterizes the main environmental changes occurred in the Southern Pyrenees during the last millennium. Warmer and relatively arid conditions prevailed during the Medieval Climate Anomaly (MCA, <1300 AD), with a significant development of xerophytes and Mediterranean vegetation and limited deciduous tree formations (mesophytes). The Little Ice Age (LIA, 1300–1800 AD) was generally colder and moister, with an expansion of deciduous taxa and cold-adapted mountainous conifers. Two major phases occurred within this period: (i) a transition MCA-LIA, characterized by fluctuating, moist conditions and relatively cold temperatures (ca. 1300 and 1600 AD); – (ii) a second period, characterized by coldest conditions and higher humidity, coinciding with maximum (recent) glacier advances (ca. 1600–1850 AD). After the LIA a warming and more arid phase started coinciding with glacier retreat, and interrupted by a short-living cooling episode during the late 19th to early 20th centuries. Some records suggest a response to solar activity with colder and slightly moister conditions during solar minima. Centennial-scale hydrological fluctuations are in phase with reconstructions of NAO variability, which appears to be the main forcing for humidity in the region during the last millennium.

Vegetation shifts, human impact and peat bog development in Bassa Nera pond (Central Pyrenees) during the last millennium

The Holocene ◽  
2016 ◽  
Vol 27 (4) ◽  
pp. 553-565 ◽  
Author(s):  
Sandra Garcés-Pastor ◽  
Núria Cañellas-Boltà ◽  
Albert Clavaguera ◽  
Miguel Angel Calero ◽  
Teresa Vegas-Vilarrúbia
Keyword(s):  
Environmental Changes ◽  
Ice Age ◽  
Peat Bog ◽  
High Mountain ◽  
Last Millennium ◽  
Medieval Climate Anomaly ◽  
Human Pressure ◽  
Climate Anomaly ◽  
Vegetation Shifts ◽  
Central Pyrenees

High-mountain lakes are suitable ecosystems for studying local environmental shifts driven by large-scale climate changes, with potential applications to predict future scenarios. The precise features in the response of species assemblages are not fully understood, and human pressure may often hide climatic signals. To investigate the origin and impact of past environmental changes in high-mountain ecosystems and apply this palaeoecological knowledge to anticipate future changes, we performed a multi-proxy study of a sediment core from Bassa Nera, a pond located close to montane–subalpine ecotone in the southern central Pyrenees. Combining pollen and diatom analysis at multidecadal resolution, we inferred vegetation shifts and peat bog development during the past millennium. We introduced a montane pollen ratio as a new palaeoecological indicator of altitudinal shifts in vegetation. Our results emphasize the sensitivity of the montane ratio to detect upward migrations of deciduous forest and the presence of the montane belt close to Bassa Nera pond during the Medieval Climate Anomaly. Changes in aquatic taxa allowed to date the onset of the surrounding peat bog which appeared and infilled the coring site around AD 1565. Overall, our results suggest a low-intensity human pressure and changes in management of natural resources during the last millennium, where farming was the main activity from the Medieval Climate Anomaly until AD 1500. Afterwards, people turned to highland livestock raising coinciding with the ‘Little Ice Age’.

scholarly journals South Atlantic Surface Boundary Current System during the Last Millennium in the CESM-LME: The Medieval Climate Anomaly and Little Ice Age

Geosciences ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 299
Author(s):  
Fernanda Marcello ◽  
Ilana Wainer ◽  
Peter R. Gent ◽  
Bette L. Otto-Bliesner ◽  
Esther C. Brady
Keyword(s):  
Little Ice Age ◽  
South Atlantic ◽  
Subtropical Gyre ◽  
Ice Age ◽  
Surface Boundary ◽  
South American ◽  
Last Millennium ◽  
Medieval Climate Anomaly ◽  
The South ◽  
Gyre Circulation

Interocean waters that are carried northward through South Atlantic surface boundary currents get meridionally split between two large-scale systems when meeting the South American coast at the western subtropical portion of the basin. This distribution of the zonal flow along the coast is investigated during the Last Millennium, when natural forcing was key to establish climate variability. Of particular interest are the changes between the contrasting periods of the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA). The investigation is conducted with the simulation results from the Community Earth System Model Last Millennium Ensemble (CESM-LME). It is found that the subtropical South Atlantic circulation pattern differs substantially between these natural climatic extremes, especially at the northern boundary of the subtropical gyre, where the westward-flowing southern branch of the South Equatorial Current (sSEC) bifurcates off the South American coast, originating the equatorward-flowing North Brazil Undercurrent (NBUC) and the poleward Brazil Current (BC). It is shown that during the MCA, a weaker anti-cyclonic subtropical gyre circulation took place (inferred from decreased southern sSEC and BC transports), while the equatorward transport of the Meridional Overturning Circulation return flow was increased (intensified northern sSEC and NBUC). The opposite scenario occurs during the LIA: a more vigorous subtropical gyre circulation with decreased northward transport.

scholarly journals Vegetation and geochemical responses to Holocene rapid climate change in Sierra Nevada (SE Iberia): The Laguna Hondera record

2018 ◽  
Author(s):  
Jose Manuel Mesa-Fernández ◽  
Gonzalo Jiménez-Moreno ◽  
Marta Rodrigo-Gámiz ◽  
Antonio García-Alix ◽  
Francisco J. Jiménez-Espejo ◽  
...  
Keyword(s):  
Climate Variability ◽  
High Altitude ◽  
Sierra Nevada ◽  
Environmental Changes ◽  
Regional Scale ◽  
Saharan Dust ◽  
Ice Age ◽  
Mountain Lake ◽  
High Mountain ◽  
Arid Conditions

Abstract. High-altitude peat bogs and lacustrine records are very sensitive to climate changes and atmospheric pollution. Recent studies show a close relationship between regional climate aridity and enhanced eolian input to lake sediments. However, changes in regional-scale dust fluxes due to climate variability at short-scales and how alpine environments were impacted by climatic- and human-induced environmental changes are not completely understood. Here we present a multi-proxy lake sediment record of climate variability in the Sierra Nevada (SE Iberian Peninsula) over the Holocene. Palynological, geochemical and magnetic susceptibility (MS) proxies obtained from the high mountain lake record of Laguna Hondera (LH) evidence humid conditions during the Early Holocene, while a trend towards more arid conditions is recognized since ~ 7000 cal yr BP, with enhanced Saharan eolian dust deposition until Present. This trend towards enhanced arid conditions was modulated by millennial-scale climate variability. Relative humid conditions occurred during the Iberian Roman Humid Period (2600–1450 cal yr BP) and predominantly arid conditions occurred during the Dark Ages and the Medieval Climate Anomaly (1450–650 cal yr BP). The Little Ice Age (650–150 cal yr BP) is characterized in the LH record by an increase in runoff and a minimum in eolian input. In addition, human impact in the area is noticed through the record of Olea cultivation, Pinus reforestation and Pb pollution during the Industrial Period (150 cal yr BP-present). Furthermore, a unique feature preserved at LH is the correlation between Zr and Ca, two important elements of Saharan dust source in Sierra Nevada lake records. This supports that present day biochemical observations, pointing to eolian input as main inorganic nutrient source for oligotrophic mountain lakes, are comparable to the past record of eolian supply to these high-altitude lakes.

scholarly journals Environmental changes in the northern Altai during the last millennium documented in Lake Teletskoye pollen record

2007 ◽  
Vol 67 (3) ◽  
pp. 394-399 ◽  
Author(s):  
Andrei A. Andreev ◽  
Roberto Pierau ◽  
Ivan A. Kalugin ◽  
Andrei V. Daryin ◽  
Lyubov G. Smolyaninova ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Vegetation History ◽  
Climatic Conditions ◽  
Ice Age ◽  
Pollen Record ◽  
Last Millennium ◽  
Climate Conditions ◽  
Lake Teletskoye ◽  
Pollen Concentrations ◽  
Siberian Pine

AbstractA high-resolution pollen record from Lake Teletskoye documents the climate-related vegetation history of the northern Altai Mountain region during the last millennium. Siberian pine taiga with Scots pine, fir, spruce, and birch dominated the vegetation between ca. AD 1050 and 1100. The climate was similar to modern. In the beginning of the 12th century, birch and shrub alder increased. Lowered pollen concentrations and simultaneous peaks in herbs (especially Artemisia and Poaceae), ferns, and charcoal fragments point to colder and more arid climate conditions than before, with frequent fire events. Around AD 1200, regional climate became warmer and more humid than present, as revealed by an increase of Siberian pine and decreases of dry herb taxa and charcoal contents. Climatic conditions were rather stable until ca. AD 1410. An increase of Artemisia pollen may reflect slightly drier climate conditions between AD 1410 and 1560. Increases in Alnus, Betula, Artemisia, and Chenopodiaceae pollen and in charcoal particle contents may reflect further deterioration of climate conditions between AD 1560 and 1810, consistent with the Little Ice Age. After AD 1850 the vegetation gradually approached the modern one, in conjunction with ongoing climate warming.

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

2014 ◽  
Vol 26 (5) ◽  
pp. 585-598 ◽  
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.

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

2016 ◽  
Vol 12 (7) ◽  
pp. 1459-1472 ◽  
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.

scholarly journals The Medieval Climate Anomaly and the Little Ice Age in the eastern Ecuadorian Andes

2013 ◽  
Vol 9 (1) ◽  
pp. 307-321 ◽  
Author(s):  
M.-P. Ledru ◽  
V. Jomelli ◽  
P. Samaniego ◽  
M. Vuille ◽  
S. Hidalgo ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Water Storage ◽  
Ice Age ◽  
Last Millennium ◽  
Medieval Climate Anomaly ◽  
Climate Anomaly ◽  
Abrupt Decrease ◽  
Enso Variability ◽  
P Index ◽  
Poaceae Pollen

Abstract. To better characterize the climate variability of the last millennium in the high Andes, we analyzed the pollen content of a 1150-yr-old sediment core collected in a bog located at 3800 m a.s.l. in the páramo in the eastern Cordillera in Ecuador. An upslope convective index based on the ratio between cloud transported pollen from the Andean forest to the bog (T) and Poaceae pollen frequencies, related to the edaphic moisture of the páramo (P), was defined. This index was used to distinguish changes in the atmospheric moisture from the soil moisture content of the páramo and their associated patterns of interdecadal El Niño–Southern Oscillation (ENSO) variability and South American summer monsoon (SASM) activity. Results show that between 850 and 1250 AD, the Medieval Climate Anomaly interval was warm and moist with a high transported pollen/Poaceae pollen (T/P) index linked to high ENSO variability and weak SASM activity. Between 1250 and 1550 AD, a dry climate prevailed, characterized by an abrupt decrease in the T/P index and therefore no upslope cloud convection, related to lower ENSO variability and with significant impact on the floristic composition of the páramo. During the Little Ice Age, two phases were observed: first, a wet phase between 1550 and 1750 AD linked to low ENSO variability in the Pacific and warm south equatorial Atlantic sea surface temperatures (SSTs) favored the return of a wet páramo, and then a cold and dry phase between 1750 and 1800 AD associated with low ENSO variability and weak SASM activity resulted in drying of the páramo. The current warm period marks the beginning of a climate characterized by high convective activity – the highest in the last millennium – and weaker SASM activity modifying the water storage of the páramo. Our results show that the páramo is progressively losing its capacity for water storage and that the interdecadal variability of both tropical Pacific and Atlantic SSTs matter for Andean climate patterns, although many teleconnection mechanisms are still poorly understood.

scholarly journals Vegetation and geochemical responses to Holocene rapid climate change in the Sierra Nevada (southeastern Iberia): the Laguna Hondera record

2018 ◽  
Vol 14 (11) ◽  
pp. 1687-1706 ◽  
Author(s):  
Jose M. Mesa-Fernández ◽  
Gonzalo Jiménez-Moreno ◽  
Marta Rodrigo-Gámiz ◽  
Antonio García-Alix ◽  
Francisco J. Jiménez-Espejo ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Climate Variability ◽  
High Altitude ◽  
Sierra Nevada ◽  
Environmental Changes ◽  
Regional Scale ◽  
Saharan Dust ◽  
Ice Age ◽  
High Mountain ◽  
Arid Conditions

Abstract. High-altitude peat bogs and lacustrine records are very sensitive to climate changes and atmospheric dust input. Recent studies have shown a close relationship between regional climate aridity and enhanced eolian input to lake sediments. However, changes in regional-scale dust fluxes due to climate variability at short scales and how alpine environments were impacted by climatic- and human-induced environmental changes are not completely understood. Here we present a multi-proxy (palynological, geochemical and magnetic susceptibility) lake sediment record of climate variability in the Sierra Nevada (southeastern Iberian Peninsula) over the Holocene. Magnetic susceptibility and geochemical proxies obtained from the high mountain lake record of Laguna Hondera evidence humid conditions during the early Holocene, while a trend towards more arid conditions is recognized since ∼7000 cal yr BP, with enhanced Saharan eolian dust deposition until the present. This trend towards enhanced arid conditions was modulated by millennial-scale climate variability. Relative humid conditions occurred during the Iberian Roman Humid Period (2600–1450 cal yr BP) and predominantly arid conditions occurred during the Dark Ages and the Medieval Climate Anomaly (1450–650 cal yr BP). The Little Ice Age (650–150 cal yr BP) is characterized in the Laguna Hondera record by an increase in runoff and a minimum in eolian input. In addition, we further suggest that human impact in the area is noticed through the record of Olea cultivation, Pinus reforestation and Pb pollution during the Industrial Period (150 cal yr BP–present). Furthermore, we estimated that the correlation between Zr and Ca concentrations stands for Saharan dust input to the Sierra Nevada lake records. These assumptions support that present-day biochemical observations, pointing to eolian input as the main inorganic nutrient source for oligotrophic mountain lakes, are comparable to the past record of eolian supply to these high-altitude lakes.

Sign in / Sign up

Export Citation Format

Share Document