Climate driven declines in terrestrial input over the middle and late Holocene of perched boreal lakes in northeast Ontario (Canada) and teleconnections to the North Atlantic

2021 ◽  
Vol 265 ◽  
pp. 107056
Author(s):  
Cale A.C. Gushulak ◽  
Eduard G. Reinhardt ◽  
Brian F. Cumming
Keyword(s):  
North Atlantic ◽  
Late Holocene ◽  
Boreal Lakes ◽  
The North ◽  
Terrestrial Input ◽  
The North Atlantic ◽  
Middle And Late Holocene

scholarly journals Late Holocene climate variability in the southwestern Mediterranean region: an integrated marine and terrestrial geochemical approach

2010 ◽  
Vol 6 (6) ◽  
pp. 807-816 ◽  
Author(s):  
C. Martín-Puertas ◽  
F. Jiménez-Espejo ◽  
F. Martínez-Ruiz ◽  
V. Nieto-Moreno ◽  
M. Rodrigo ◽  
...  
Keyword(s):  
Climate Variability ◽  
North Atlantic ◽  
Mediterranean Region ◽  
Late Holocene ◽  
Western Mediterranean ◽  
Medieval Climate Anomaly ◽  
Holocene Climate ◽  
Climate Anomaly ◽  
The North ◽  
The North Atlantic

Abstract. A combination of marine (Alboran Sea cores, ODP 976 and TTR 300 G) and terrestrial (Zoñar Lake, Andalucia, Spain) geochemical proxies provides a high-resolution reconstruction of climate variability and human influence in the southwestern Mediterranean region for the last 4000 years at inter-centennial resolution. Proxies respond to changes in precipitation rather than temperature alone. Our combined terrestrial and marine archive documents a succession of dry and wet periods coherent with the North Atlantic climate signal. A dry period occurred prior to 2.7 cal ka BP – synchronously to the global aridity crisis of the third-millennium BC – and during the Medieval Climate Anomaly (1.4–0.7 cal ka BP). Wetter conditions prevailed from 2.7 to 1.4 cal ka BP. Hydrological signatures during the Little Ice Age are highly variable but consistent with more humidity than the Medieval Climate Anomaly. Additionally, Pb anomalies in sediments at the end of the Bronze Age suggest anthropogenic pollution earlier than the Roman Empire development in the Iberian Peninsula. The Late Holocene climate evolution of the in the study area confirms the see-saw pattern between the eastern and western Mediterranean regions and the higher influence of the North Atlantic dynamics in the western Mediterranean.

scholarly journals Late Holocene climate variability in the southwestern Mediterranean region: an integrated marine and terrestrial geochemical approach

2010 ◽  
Vol 6 (5) ◽  
pp. 1655-1683 ◽  
Author(s):  
C. Martín-Puertas ◽  
F. Jiménez-Espejo ◽  
F. Martínez-Ruiz ◽  
V. Nieto-Moreno ◽  
M. Rodrigo ◽  
...  
Keyword(s):  
Climate Variability ◽  
North Atlantic ◽  
Little Ice Age ◽  
Mediterranean Region ◽  
Late Holocene ◽  
Western Mediterranean ◽  
Warm Period ◽  
Ice Age ◽  
The North ◽  
The North Atlantic

Abstract. A combination of marine (Alboran Sea cores, ODP 976 and TTR 300 G) and terrestrial (Zoñar Lake, Andalucia, Spain) paleoclimate information using geochemical proxies provides a high resolution reconstruction of climate variability and human influence in southwestern Mediterranean region for the last 4000 years at inter-centennial resolution. Proxies respond to changes in precipitation rather than temperature alone. Our archive documents a succession of dry and wet periods coherent with the North Atlantic climate signal. Drier stages occurred prior to 2.7 cal ka BP, well-correlated with the global aridity crisis of the third-millennium BC, and during the Medieval Warm Period (1.4–0.7 cal ka BP). Wetter conditions prevailed from 2.7 to 1.4 cal ka BP and after the Medieval Warm Period and the onset of the Little Ice Age. Hydrological signatures during the Little Ice Age are highly variable but consistent with more humidity that the period before. Additionally, Pb anomalies in sediments at the end of Bronze Age suggest anthropogenic pollution earlier than the Roman Empire development in the Iberian Peninsula. The evolution of the climate in the study area during the Late Holocene confirms the see-saw pattern previously shown between eastern and western Mediterranean regions and suggests a higher influence of the North Atlantic dynamics in the western Mediterranean.

scholarly journals Reconstructing Late Holocene North Atlantic atmospheric circulation changes using functional paleoclimate networks

2017 ◽  
Vol 13 (11) ◽  
pp. 1593-1608 ◽  
Author(s):  
Jasper G. Franke ◽  
Johannes P. Werner ◽  
Reik V. Donner
Keyword(s):  
Atmospheric Circulation ◽  
North Atlantic ◽  
Late Holocene ◽  
Dominant Mode ◽  
The North ◽  
The North Atlantic ◽  
Earth’S Climate ◽  
The North Atlantic Oscillation ◽  
Circulation Changes

Abstract. Obtaining reliable reconstructions of long-term atmospheric circulation changes in the North Atlantic region presents a persistent challenge to contemporary paleoclimate research, which has been addressed by a multitude of recent studies. In order to contribute a novel methodological aspect to this active field, we apply here evolving functional network analysis, a recently developed tool for studying temporal changes of the spatial co-variability structure of the Earth's climate system, to a set of Late Holocene paleoclimate proxy records covering the last two millennia. The emerging patterns obtained by our analysis are related to long-term changes in the dominant mode of atmospheric circulation in the region, the North Atlantic Oscillation (NAO). By comparing the time-dependent inter-regional linkage structures of the obtained functional paleoclimate network representations to a recent multi-centennial NAO reconstruction, we identify co-variability between southern Greenland, Svalbard, and Fennoscandia as being indicative of a positive NAO phase, while connections from Greenland and Fennoscandia to central Europe are more pronounced during negative NAO phases. By drawing upon this correspondence, we use some key parameters of the evolving network structure to obtain a qualitative reconstruction of the NAO long-term variability over the entire Common Era (last 2000 years) using a linear regression model trained upon the existing shorter reconstruction.

Tracing the North Atlantic decadal-scale climate variability in a late Holocene pollen record from southern Siberia

2015 ◽  
Vol 426 ◽  
pp. 75-84 ◽  
Author(s):  
Steffi Hildebrandt ◽  
Stefanie Müller ◽  
Ivan A. Kalugin ◽  
Andrei V. Dar'in ◽  
Mayke Wagner ◽  
...  
Keyword(s):  
Climate Variability ◽  
North Atlantic ◽  
Late Holocene ◽  
Pollen Record ◽  
Southern Siberia ◽  
The North ◽  
Decadal Scale ◽  
The North Atlantic

scholarly journals Mid to late-Holocene sea-surface temperature variability off north-eastern Newfoundland and its linkage to the North Atlantic Oscillation

The Holocene ◽  
2020 ◽  
Vol 31 (1) ◽  
pp. 3-15 ◽  
Author(s):  
Lisa C Orme ◽  
Arto Miettinen ◽  
Marit-Solveig Seidenkrantz ◽  
Kirsi Tuominen ◽  
Christof Pearce ◽  
...  
Keyword(s):  
Surface Temperature ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Late Holocene ◽  
Sea Surface ◽  
Labrador Sea ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

In recent decades the surface water temperature and salinity in the Labrador Sea have been influenced by atmospheric circulation patterns, such as the North Atlantic Oscillation (NAO), as well as a trend to increasingly warm atmospheric temperatures in recent years. These changes are concerning, given the important role that temperature and salinity have on deep convection in the Labrador Sea. Yet, due to the shortness of available records, the long-term patterns of climate variability in the region are not clear. Here, a diatom-based reconstruction of summer sea-surface temperature (SST) developed from Trinity Bay, Newfoundland, provides insight into variations of SST since 7.2 cal ka BP in the southwestern Labrador Sea. The results show that the Holocene Thermal Maximum (HTM) lasted until c. 5.2 cal ka BP, which was followed by a gradual cooling trend overprinted by centennial temperature fluctuations of 1–2°C. Long-term cooling was likely the result of declining Northern Hemisphere orbital summer insolation, potentially amplified by long-term changes in surface and bottom water salinity, which led to a gradual reduction in the stratification of the water column. Centennial fluctuations in temperature vary in-phase with reconstructed variations in the NAO, supporting a consistent relationship between atmospheric circulation and SST over centennial-millennial timescales. Other factors influencing the SST variability may have been solar forcing during the mid-Holocene and variations in the strength of the subpolar gyre during the late-Holocene. The most prolonged cool period at 5.2–4.1 cal ka BP coincides with sharply reduced salinity in the Labrador Sea and a weakening of deep ventilation in the northeast Atlantic, highlighting a period with altered ocean surface conditions and circulation across the northern North Atlantic.

Mid-Holocene emergence of a low-frequency millennial oscillation in western Mediterranean climate: Implications for past dynamics of the North Atlantic atmospheric westerlies

The Holocene ◽  
2012 ◽  
Vol 23 (2) ◽  
pp. 153-166 ◽  
Author(s):  
William J Fletcher ◽  
Maxime Debret ◽  
Maria Fernanda Sanchez Goñi
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
Late Holocene ◽  
Mediterranean Climate ◽  
Zonal Flow ◽  
Western Mediterranean ◽  
Early Holocene ◽  
Internal Oscillation ◽  
The North ◽  
The North Atlantic

The nature and tempo of Holocene climate variability is examined in the record of forest vegetation from western Mediterranean marine core MD95-2043. Episodes of forest decline occurred at 10.1, 9.2, 8.3, 7.4, 5.4–4.5 and 3.7–2.9 cal. ka BP, and between 1.9 cal. ka BP and the top of the record (1.3 cal. ka BP). Wavelet analysis confirms a ~900 yr periodicity prior to and during the early Holocene and the dominance of a ~1750 yr periodicity after 6 cal. ka BP. The ~900 yr periodicity has counterparts in numerous North Atlantic and Northern Hemisphere palaeoclimate records, and in solar irradiance proxies (Δ14C and 10Be), and may relate to a Sun–climate connection during the early Holocene. Comparisons between the MD95-2043 forest record and strategically located records from Morocco, Iceland, Norway and Israel suggest that the ~1750 yr mid- to late-Holocene oscillation reflects shifts between a prevailing strong and weak state of the zonal flow, with impacts similar to the positive and negative modes of the present-day North Atlantic Oscillation (NAO). The mid- to late-Holocene millennial oscillation in zonal flow appears closely coupled to North Atlantic surface ocean circulation dynamics, and may have been driven by an internal oscillation in deep-water convection strength. The findings suggest that the mid-Holocene transition in western Mediterranean climate was accompanied by a shift in the fundamental tempo of millennial-scale variability, reflecting contrasting sensitivity of the North Atlantic climate system to different forcing factors (solar versus oceanic) under deglacial and fully interglacial conditions.

scholarly journals Environmental changes, climate and anthropogenic impact in southern-eastern Tunisia during the last 8 kyr

2016 ◽  
Author(s):  
Sahbi Jaouadi ◽  
Vincent Lebreton ◽  
Viviane Bout-Roumazeilles ◽  
Giuseppe Siani ◽  
Rached Lakhdar ◽  
...  
Keyword(s):  
North Atlantic ◽  
Late Holocene ◽  
Environmental Changes ◽  
Climatic Variability ◽  
Classical Antiquity ◽  
Human Populations ◽  
Desert Ecosystems ◽  
The North ◽  
The North Atlantic ◽  
The Mediterranean

Abstract. Pollen and clay mineralogical analyses of a Holocene sequence from Sebkha Boujmel (southern Tunisia) traces the climatic and environmental dynamics in the lower arid bioclimatic zone over the last 8000 years. During the Mid- to Late Holocene transition, between 8 and 3 ka, a succession of five wet/dry oscillations is recorded. An intense arid event occurs between 5.7 and 4.6 ka. This episode marks the onset of a long-term aridification trend with a progressive retreat of Mediterranean woody xerophytic vegetation and of grass steppes. It ends with the establishment of pre-desert ecosystems around 3 ka. The millennial-scale climate change recorded in the data from Sebkha Boujmel is consistent with records from the south and east Mediterranean, as well as with climatic records from the desert region for the end of the African Humid Period (AHP). Eight centennial climatic events are recorded at Sebkha Boujmel and these are contemporary with those recorded in the Mediterranean and in the Sahara. They indicate a clear coupling between the southern Mediterranean and the Sahara before 3 ka. The event at 4.2 ka is not evidenced and the link between events recorded in Sebkha Boujmel and the North Atlantic Cooling events is clearer from 3 ka onwards. These variations indicate the importance of climatic determinism in the structuring of landscapes, with the establishment of the arid climatic conditions of the Late Holocene. It is only from 3 ka onwards that the dynamic of plant associations is modified by both human activity and climatic variability. The climatic episodes identified during the historic period indicate strong regionalisation related to the differential impact of the North Atlantic Oscillation (NAO) and the Mediterranean Oscillation (MO) on the Mediterranean basin. The local human impact on regional ecosystems is recorded in the form of episodes of intensification of pastoral and/or agricultural activities. The development of olive production and of several taxa associated with agriculture attest to increasing sedentism among human populations during Classical Antiquity. The significant increase in Artemisia (wormwood) between 1.1 and 0.8 ka (850–1150 AD) is linked to intensive pastoral activity, associated with heightened interannual and/or seasonal climatic instability. A complete re-shaping of the landscape is recorded during the 20th century. The remarkable expansion of the olive tree, and the deterioration of regional ecosystems with the spread of desert species, is linked to recent local socio-economic changes in Tunisia.

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