A midge-based late-glacial temperature reconstruction from southwestern Nova Scotia

2005 ◽  
Vol 42 (11) ◽  
pp. 2051-2057 ◽  
Author(s):  
Bronwen S Whitney ◽  
Jessie H Vincent ◽  
Les C Cwynar
Keyword(s):  
Nova Scotia ◽  
Younger Dryas ◽  
Temperature Reconstruction ◽  
Late Glacial ◽  
Organic Content ◽  
Eastern North America ◽  
Quantitative Reconstruction ◽  
Late Glacial Period ◽  
Maritime Canada ◽  
Glacial Climate

We present a quantitative reconstruction of the thermal regime spanning the late-glacial period of Nova Scotia (14 700 to 11 600 BP) as inferred by analyzing fossil midges from a small lake (Lac à Magie) in southwestern Nova Scotia. The GS-1 event (equivalent to the Younger Dryas, dating from 12 700 to 11 600 BP in Maritime Canada) was marked by a 5 °C decline in inferred mean July surface-water temperatures and a 15% drop in organic content. Previous pollen and plant macrofossil analyses of this site demonstrate a response of vegetation to GS-1 cooling. These data, coupled with a midge-inferred temperature reconstruction from a nearby site, suggest that late-glacial climate change was less pronounced in southern Nova Scotia than in other sites in Maritime Canada and adjacent eastern North America.

Allerød–Younger Dryas Coleoptera from western Cape Breton Island, Nova Scotia, Canada

1996 ◽  
Vol 33 (1) ◽  
pp. 33-41 ◽  
Author(s):  
Randall F. Miller
Keyword(s):  
Nova Scotia ◽  
Younger Dryas ◽  
Late Glacial ◽  
Cold Climate ◽  
Western Cape ◽  
Cape Breton Island ◽  
Cape Breton ◽  
Beetle Assemblages ◽  
Climate Indicator ◽  
Younger Dryas Event

Studies of Coleoptera remains from two late-glacial sites on Cape Breton Island, Nova Scotia, Canada, present a picture of the paleoenvironment and paleoclimate during the Allerød–Younger Dryas transition in the Maritimes region. They provide evidence for the Younger Dryas event in northeastern North America. Between 11 300 and 10 800 BP, the beetle assemblages at the Campbell site are typical of faunas of the modern middle to northern boreal forest. The West Mabou site contains beetle fossils younger than 10 900 BP, possibly as young as 10 500 BP, extending into the time period of the Younger Dryas, dated from 10 800 to 10 000 BP in the Maritimes. A "cold climate" indicator recognizable in the beetle fauna, Olophrum boreale, occurs in relative abundance and provides an interesting comparison with sites in Europe where the same northern boreo-montane species is evident at the beginning of the Younger Dryas.

A late-glacial – Holocene palaeoecological record from Pye Lake on the eastern shore of Nova Scotia, CanadaGeological Survey of Canada Contribution 20080395.

2009 ◽  
Vol 46 (9) ◽  
pp. 637-650 ◽  
Author(s):  
Robert J. Mott ◽  
Ian R. Walker ◽  
Samantha L. Palmer ◽  
Martin Lavoie
Keyword(s):  
Nova Scotia ◽  
Younger Dryas ◽  
Late Glacial ◽  
Forest Composition ◽  
Eastern Shore ◽  
The North ◽  
Tundra Vegetation ◽  
History Of ◽  
Climatic History ◽  
Recent Sediments

Pollen and chironomid analyses and radiocarbon dating at Pye Lake on the eastern shore of Nova Scotia are used to outline the vegetation and climatic history of the area. The coast was deglaciated prior to ∼12 200 14C BP (14 300 cal BP), and herbaceous tundra vegetation invaded the area. Midge-inferred maximum summer surface-water temperatures in the lake ranged between 9 and 11 °C. Subsequent gradual warming to ∼18 °C by 10 800 14C BP (12 725 cal BP) favoured the migration of a variety of herbaceous and shrub taxa into the region. Rapid cooling to ∼10 °C saw vegetation revert to herbaceous tundra communities. This interval, related to the Younger Dryas cold interval of the North Atlantic and Europe, lasted until ∼10 000 14C BP (11 630 cal BP). The climate then warmed again to conditions similar to those that prevailed immediately before onset of Younger Dryas cooling. Further warming saw successive tree species migrate into the area until, by the mid-Holocene, the forests contained most of the taxa prevalent today. Since ∼3500 years ago, cooling of the climate has favoured conifer species over broad-leaved taxa. Agriculture and logging practices in the last 150 years have altered the forest composition, but pollen analysis of the most recent sediments cannot resolve these changes adequately.

Evidence for high-frequency late Glacial to mid-Holocene (16,800 to 5500 cal yr B.P.) climate variability from oxygen isotope values of Lough Inchiquin, Ireland

2006 ◽  
Vol 65 (1) ◽  
pp. 78-86 ◽  
Author(s):  
Aaron F. Diefendorf ◽  
William P. Patterson ◽  
Henry T. Mullins ◽  
Neil Tibert ◽  
Anna Martini
Keyword(s):  
Climate Variability ◽  
High Frequency ◽  
Younger Dryas ◽  
Late Glacial ◽  
Climate Anomaly ◽  
Climate Conditions ◽  
Late Glacial Period ◽  
High Frequency Variability ◽  
Western Ireland

AbstractA 7.6-m core recovered from Lough Inchiquin, western Ireland provides evidence for rapid and long-term climate change from the Late Glacial period to the Mid-Holocene. We determined percentage of carbonate, total organic matter, mineralogy, and δ18Ocalcite values to provide the first high-resolution record of climate variability for this period in Ireland. Following deglaciation, rapid climate amelioration preceded large increases in GISP2 δ18Oice values by ∼2300 yr. The Oldest Dryas (15,100 to 14,500 cal yr B.P.) Late Glacial event is documented in this record as a decrease in δ18Ocalcite values. Brief warming at ∼12,700 cal yr B.P. was followed by characteristic Younger Dryas cold and dry climate conditions. A rapid increase in δ18Ocalcite values at ∼10,500 cal yr B.P. marked the onset of Boreal warming in western Ireland. The 8200 cal yr B.P. event is represented by a brief cooling in our record. Prior to general warming, a larger and previously undescribed climate anomaly between 7300 and 6700 cal yr B.P. is characterized by low δ18Ocalcite values with high-frequency variability.

Jura glacial lakes: a paleoclimatic and paleoenvironmental evolution since the Late Glacial Period.

2020 ◽  
Author(s):  
Brahimsamba Bomou ◽  
Damien Zappa ◽  
Anne-Marie Rachoud-Schneider ◽  
Jean-Nicolas Haas ◽  
Marina Gärtner ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Lacustrine Sediments ◽  
Younger Dryas ◽  
Late Glacial ◽  
Glacial Period ◽  
Glacial Lakes ◽  
Late Glacial Period ◽  
Paleoenvironmental Evolution ◽  
Multiproxy Approach

<p>During the retreat of a Würm ice sheet, numerous glacial paleolakes took place in the Swiss and French Jura. Two sites were investigated: the Amburnex Valley site (Switzerland), which evolved in well-developed peatland and the Lake Val (France), which is still persisted as a lacustrine system. During the Late Glacial period, both sites were glacial lakes characterized by a significant accumulation of lacustrine sediments.</p><p>Using a multiproxy approach, this project aims to reconstruct the paleoclimatic and the paleoenvironmental evolution recorded in lacustrine sediments and peatbog deposits since the last 13’000 years.</p><p>The Amburnex core (7m) exhibit a basal morainic deposit from the Würm period, overlain by three meters of lacustrine deposits and four meters of peatland deposits. The Lake Val core (4.5m) consists of the same lithological succession.</p><p>A multiproxy approach based on palynological analyses, grain-size analyses, mineralogical analyses (XRD) and geochemical analyses (TOC, Nitrogen, Phosphorus and Mercury contents; major and trace elements; organic carbon isotopes) have been used to characterize the hydrological and climatic fluctuations, the trophic level and the origin of organic matter in order to reconstruct the paleoenvironmental and paleoclimatic evolution of this area.</p><p>In the Amburnex site, the Bølling-Allerød, the Younger Dryas and the beginning of the Preboreal period have been recognized by palynological analyses and confirmed by carbon 14 dating. During the Oldest Dryas, oligotrophic conditions took place as suggested by the very low concentrations in nitrogen and organic matter. Then, during the warmer Bølling period, an enrichment in total organic carbon (TOC) associated with a decrease in phosphorus content are observed, implying the development of eutrophic conditions and maybe phosphorus recycling. Later in the Allerød period, low TOC and phosphorus contents, associated with varved carbonate deposits, indicate a return to more oligotrophic conditions. New organic matter enrichments are observed in the interval corresponding to the colder Younger Dryas period. These trends are quite consistent with those observed in the Lake Val and reflect significant changes in runoff and nutrient inputs at least at regional scale.</p>

Last glacial–interglacial environments in the southern Rocky Mountains, USA and implications for Younger Dryas-age human occupation

2012 ◽  
Vol 77 (1) ◽  
pp. 96-103 ◽  
Author(s):  
Christy E. Briles ◽  
Cathy Whitlock ◽  
David J. Meltzer
Keyword(s):  
Rocky Mountains ◽  
Fire History ◽  
Younger Dryas ◽  
Late Glacial ◽  
Subalpine Forest ◽  
Glacial Period ◽  
Last Glacial ◽  
Southern Rocky Mountains ◽  
Late Glacial Period ◽  
Fire Activity

The last glacial-interglacial transition (LGIT; 19–9 ka) was characterized by rapid climate changes and significant ecosystem reorganizations worldwide. In western Colorado, one of the coldest locations in the continental US today, mountain environments during the late-glacial period are poorly known. Yet, archaeological evidence from the Mountaineer site (2625 m elev.) indicates that Folsom-age Paleoindians were over-wintering in the Gunnison Basin during the Younger Dryas Chronozone (YDC; 12.9–11.7 ka). To determine the vegetation and fire history during the LGIT, and possible explanations for occupation during a period thought to be harsher than today, a 17-ka-old sediment core from Lily Pond (3208 m elev.) was analyzed for pollen and charcoal and compared with other high-resolution records from the southern Rocky Mountains. Widespread tundra and Picea parkland and low fire activity in the cold wet late-glacial period transitioned to open subalpine forest and increased fire activity in the Bølling–Allerød period as conditions became warmer and drier. During the YDC, greater winter snowpack than today and prolonged wet springs likely expanded subalpine forest to lower elevations than today, providing construction material and fuel for the early inhabitants. In the early to middle Holocene, arid conditions resulted in xerophytic vegetation and frequent fire.

Chironomid Evidence for Late-Glacial Climatic Reversals in Maine

1995 ◽  
Vol 43 (3) ◽  
pp. 405-413 ◽  
Author(s):  
Les C. Cwynar ◽  
André J. Levesque
Keyword(s):  
Surface Water ◽  
Younger Dryas ◽  
Late Glacial ◽  
Strongly Correlated ◽  
Maritime Canada ◽  
A Minor

AbstractPreviously published pollen studies from Maine have not identified any late-glacial reversals despite evidence for them from adjacent areas. The distribution and abundance of midge flies are strongly correlated with summer surface-water temperatures. We analyzed fossils of larval midge flies from the sediments of two ponds (Trout and Tilley) from Maine. Each site reveals a major and a minor oscillation during which inferred summer surface-water temperatures fell by 7-13°C and 2.1-2.6°C, respectively. We tentatively correlate these events with the Younger Dryas cooling and Killarney Oscillation reported from adjacent Maritime Canada, where they have been AMS 14C-dated at 10,770-10,000 and 11,160-10,910 yr B.P., respectively. A third oscillation occurs at the northernmost site, Tilley Pond, and may represent the effects of a local ice advance in northern Maine.

scholarly journals Deglaciation of Nova Scotia: Stratigraphy and chronology of lake sediment cores and buried organic sections

2002 ◽  
Vol 52 (1) ◽  
pp. 3-21 ◽  
Author(s):  
Rudolph R. Stea ◽  
Robert J. Mott
Keyword(s):  
Nova Scotia ◽  
Sediment Cores ◽  
Younger Dryas ◽  
Organic Content ◽  
Sediment Flux ◽  
Coarse Grained ◽  
Glacial Lake ◽  
Bay Of Fundy ◽  
Sediment Layer ◽  
Organic Sediment

Abstract The deglaciation of Nova Scotia is reconstructed using the AMS-dated chronology of lake sediments and buried organic sections exposed in the basins of former glacial lakes. Ice cleared out of the Bay of Fundy around 13.5 ka, punctuated by a brief read- vance ca. 13-12.5 ka (Ice Flow Phase 4). Glacial Lake Shubenacadie (1) formed in central Nova Scotia, impounded by a lobe of ice covering the northern Bay of Fundy outlet. Drainage was re-routed to the Atlantic Ocean until the Fundy outlet became ice free after 12 ka. When this lake drained, bogs and fens formed on the lake plain during climatic warming. Organic sediment (gyttja) began to accumulate in lake basins throughout Nova Scotia. Glacierization during the Younger Dryas period (ca. 10.8 ka) resulted in the inundation of lakes and lake plains with mineral sediment. The nature and intensity of this mineral sediment flux or "oscillation" varies from south to northern regions. Southern lakes simply record changes in total organic content whereas northern lakes, where most buried peat sections are found, feature a thick inorganic sediment layer. Glacial ice or permanent snow cover and seasonal melting are essential in the formation of this mineral sediment layer; both to provide the water source for erosion, and to prevent plant re- colonization and landscape stabilization. Some northern lakes do not appear to record the Younger Dryas event, with organic accumulation starting around 10 ka. During the Younger Dryas, fine and coarse-grained deposits were deposited in Glacial Lake Shubenacadie (2) and other lowland areas at elevations similar to former (12 ka) lake levels, impounded by re-invigorated residual ice caps and permanent snow/aufeis.

Late-Glacial climatic changes in Eastern France (Lake Lautrey) from pollen, lake-levels, and chironomids

2005 ◽  
Vol 64 (2) ◽  
pp. 197-211 ◽  
Author(s):  
O. Peyron ◽  
C. Bégeot ◽  
S. Brewer ◽  
O. Heiri ◽  
M. Magny ◽  
...  
Keyword(s):  
Younger Dryas ◽  
Late Glacial ◽  
High Temporal Resolution ◽  
Lake Levels ◽  
Late Glacial Period ◽  
Climate Reconstructions ◽  
Quantitative Estimates ◽  
Abrupt Changes ◽  
Cold Events ◽  
Climate Signals

AbstractHigh-temporal resolution analyses of pollen, chironomid, and lake-level records from Lake Lautrey provide multi-proxy, quantitative estimates of climatic change during the Late-Glacial period in eastern France. Past temperature and moisture parameters were estimated using modern analogues and ‘plant functional types’ transfer-function methods for three pollen records obtained from different localities within the paleolake basin. The comparison of these methods shows that they provide generally similar climate signals, with the exception of the Bölling. Comparison of pollen- and chironomid-based temperature of the warmest month reconstructions generally agree, except during the Bölling. Major abrupt changes associated with the Oldest Dryas/Bölling, Alleröd/Younger Dryas, and the Younger Dryas/Preboreal transitions were quantified as well as other minor fluctuations related to the cold events (e.g., Preboreal oscillation). The temperature of the warmest month increased by ∼5°C at the start of Bölling, and by 1.5°�"3°C at the onset of the Holocene, while it fell by ca. 3° to 4°C at the beginning of Younger Dryas. The comparative analysis of the results based on the three Lautrey cores have highlighted significant differences in the climate reconstructions related to the location of each core, underlining the caution that is needed when studying single cores not taken from deepest part of lake basins.

Constraining past global tropospheric methane budgets with carbon and hydrogen isotope ratios in ice

2007 ◽  
Vol 365 (1856) ◽  
pp. 1793-1828 ◽  
Author(s):  
Michael Whiticar ◽  
Hinrich Schaefer
Keyword(s):  
Younger Dryas ◽  
Late Glacial ◽  
Mixing Ratio ◽  
Mass Balances ◽  
Late Glacial Period ◽  
The Past ◽  
Methane Budget ◽  
Hydrogen Isotope Ratios ◽  
Palaeoenvironmental Conditions ◽  
Carbon And Hydrogen Isotope

Upon closer inspection, the classical view of the synchronous relationship between tropospheric methane mixing ratio and Greenland temperature observed in ice samples reveals clearly discernable variations in the magnitude of this response during the Late Pleistocene (<50 kyr BP). During the Holocene this relationship appears to decouple, indicating that other factors have modulated the methane budget in the past 10 kyr BP. The δ 13 CH 4 and δD-CH 4 of tropospheric methane recorded in ice samples provide a useful constraint on the palaeomethane budget estimations. Anticipated changes in palaeoenvironmental conditions are recorded as changes in the isotope signals of the methane precursors, which are then translated into past global δ 13 CH 4 and δD-CH 4 signatures. We present the first methane budgets for the late glacial period that are constrained by dual stable isotopes. The overall isotope variations indicate that the Younger Dryas (YD) and Preindustrial Holocene have methane that is 13 C- and 2 H-enriched, relative to Modern. The shift is small for δ 13 CH 4 (approx. 1‰) but greater for δD-CH 4 (approx. 9‰). The YD δ 13 CH 4 –δD-CH 4 record shows a remarkable relationship between them from 12.15 to 11.52 kyr BP. The corresponding C- and H-isotope mass balances possibly indicate fluctuating emissions of thermogenic gas. This δ 13 CH 4 –δD-CH 4 relationship breaks down during the YD–Preboreal transition. In both age cases, catastrophic releases of hydrates with Archaeal isotope signatures can be ruled out. Thermogenic clathrate releases are possible during the YD period, but so are conventional natural gas seepages.

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