The Last Interglacial in the Labrador Sea: a sedimentary ancient DNA investigation 

2021 ◽  
Author(s):  
Danielle Grant ◽  
Kristine Steinsland ◽  
Sigrid Mugu ◽  
Katrine Sandnes Skaar ◽  
Umer Z. Ijaz ◽  
...  
Keyword(s):  
Ancient Dna ◽  
Late Quaternary ◽  
Greenland Ice Sheet ◽  
Small Subunit ◽  
Labrador Sea ◽  
Time Interval ◽  
Climate Projections ◽  
Last Interglacial ◽  
Climate Conditions ◽  
Spin Column

<p>The Last Interglacial (LIG, ~128–116ka) was characterized by a warmer climate, increased sea level, and a reduced Greenland ice sheet compared to today. Climate projections suggest our future climate may resemble LIG conditions if anthropogenic climate change progresses unabated. Previous studies have identified key shifts in the Labrador Sea oceanography and climate before, during, and after the LIG, making this time interval an exciting target for exploring high-latitude marine ecological dynamics. In recent years, the application of sedimentary ancient DNA (sedaDNA) has provided new glimpses into past ocean and climate conditions. Here, we have explored sedaDNA alongside other, traditional, paleoceanography proxies, to better understand the changing Labrador Sea biome across climate transitions and in a globally warmer world. We have generated a sedaDNA record from a giant piston core at the Eirik Drift (Labrador Sea). Our sedaDNA record, dating back to ~135 ka, was sampled at 4 cm depth intervals and covers the glacial-interglacial transition, as well as the LIG. SedaDNA was purified using a commercial spin column kit and analysed using a metabarcoding approach targeting the V7 hypervariable region of the eukaryote small subunit RNA. Illumina MiSeq analysis of metabarcoding libraries revealed PCR-amplifiable eukaryotic DNA throughout the investigated downcore section. Shifts in relative taxon abundance and alpha- and beta-diversity metrics paralleled shifts in foraminifer isotope records (δ<sup>18</sup>Ο), palynological assemblages, and biomarkers suggesting that the molecular genetic signal preserved in downcore sediments shows promise for identifying ecological shifts across the LIG. We are currently investigating the potential utility of specific taxa identified in the sedaDNA record to act as indicators of the glacial-interglacial transition. This study strengthens the growing potential of marine sedaDNA as a supplemental proxy for climate reconstructions in the Late Quaternary.</p>

A sedimentary ancient DNA approach to elucidate the Labrador Sea paleoceanography over the last ~130,000 years

2020 ◽  
Author(s):  
Stijn De Schepper ◽  
Jessica Louise Ray ◽  
Lisa Griem ◽  
Nicolas Van Nieuwenhove ◽  
Danielle Magann Grant ◽  
...  
Keyword(s):  
Ancient Dna ◽  
Hypervariable Region ◽  
Small Subunit ◽  
Marine Isotope Stage ◽  
Labrador Sea ◽  
Time Interval ◽  
Rrna Gene ◽  
Heinrich Events ◽  
Marine Isotope Stage 5 ◽  
Eukaryotic Organisms

<p>Long sedimentary ancient DNA (<em>sed</em>aDNA) records from the marine environment are at present a curiosity and their utility in paleoceanographic research is not yet fully explored. Nevertheless, a few studies indicate that this ecogenetic repository represents an untapped source of new information with which paleoclimatic and paleoceanographic variability can be more deeply explored. We have generated a <em>sed</em>aDNA record from a 19.6 m-long sediment core in the Labrador Sea (Eirik Drift, south of Greenland). The record extends from the early Holocene to Marine Isotope Stage 5 (ca. 130,000 years ago), and we characterized several important climatic transitions in this time interval using stable isotope stratigraphy, ice-rafted detritus counts, and dinoflagellate cyst census counts. The primary goal of this investigation was to query the <em>sed</em>aDNA record for a biological indication of the last and penultimate deglaciation, as well as Heinrich events identified between 65,000 and 25,000 years ago. Our metabarcoding strategy targeted a broad diversity of eukaryotic organisms through amplification of the V7 hypervariable region of the small subunit ribosomal RNA (SSU rRNA) gene. The preliminary <em>sed</em>aDNA results indicate that eukaryote ancient DNA is present in all samples investigated, including those dating back to Marine Isotope Stage 5. Furthermore, we identified abundance shifts in Protaspidae (cercozoa), diatoms, dinoflagellates, and marine stramenopiles (amongst others) that may be linked to changes in paleoceanography during the last two deglaciations as well as Heinrich events (HE3, HE4).</p>

scholarly journals Paleoclimate in continental northwestern Europe during the Eemian and early Weichselian (125–97 ka): insights from a Belgian speleothem

2016 ◽  
Vol 12 (7) ◽  
pp. 1445-1458 ◽  
Author(s):  
Stef Vansteenberge ◽  
Sophie Verheyden ◽  
Hai Cheng ◽  
R. Lawrence Edwards ◽  
Eddy Keppens ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Regional Climate ◽  
Time Interval ◽  
Last Interglacial ◽  
High Resolution Data ◽  
Climate Conditions ◽  
Spatial Coverage ◽  
Stable Conditions ◽  
Mis 5E ◽  
Δ13c And Δ18o

Abstract. The last interglacial serves as an excellent time interval for studying climate dynamics during past warm periods. Speleothems have been successfully used for reconstructing the paleoclimate of last interglacial continental Europe. However, all previously investigated speleothems are restricted to southern Europe or the Alps, leaving large parts of northwestern Europe undocumented. To better understand regional climate changes over the past, a larger spatial coverage of European last interglacial continental records is essential, and speleothems, because of their ability to obtain excellent chronologies, can provide a major contribution. Here, we present new, high-resolution data from a stalagmite (Han-9) obtained from the Han-sur-Lesse Cave in Belgium. Han-9 formed between 125.3 and  ∼  97 ka, with interruptions of growth occurring at 117.3–112.9 and 106.6–103.6 ka. The speleothem was investigated for its growth, morphology and stable isotope (δ13C and δ18O) composition. The speleothem started growing relatively late within the last interglacial, at 125.3 ka, as other European continental archives suggest that Eemian optimum conditions were already present during that time. It appears that the initiation of Han-9 growth is caused by an increase in moisture availability, linked to wetter conditions around 125.3 ka. The δ13C and δ18O proxies indicate a period of relatively stable conditions after 125.3 ka; however, at 120 ka the speleothem δ18O registered the first signs of regionally changing climate conditions, being a modification of ocean source δ18O linked to an increase in ice volume towards the Marine Isotope Stage (MIS) 5e–5d transition. At 117.5 ka, drastic vegetation changes are recorded by Han-9 δ13C immediately followed by a cessation of speleothem growth at 117.3 ka, suggesting a transition to significantly dryer conditions. The Han-9 record covering the early Weichselian displays larger amplitudes in both isotope proxies and changes in stalagmite morphology, evidencing increased variability compared to the Eemian. Stadials that appear to be analogous to those in Greenland are recognized in Han-9, and the chronology is consistent with other European (speleothem) records. Greenland Stadial 25 is reflected as a cold/dry period within Han-9 stable isotope proxies, and the second interruption in speleothem growth occurs simultaneously with Greenland Stadial 24.

scholarly journals A technique for generating consistent ice sheet initial conditions for coupled ice-sheet/climate models

2013 ◽  
Vol 6 (2) ◽  
pp. 2491-2516 ◽  
Author(s):  
J. G. Fyke ◽  
W. J. Sacks ◽  
W. H. Lipscomb
Keyword(s):  
Climate Models ◽  
Initial Conditions ◽  
Model Simulation ◽  
Ice Core ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Climate Projections ◽  
Past Climate ◽  
Surface Mass ◽  
Climate Conditions

Abstract. A new technique for generating ice sheet preindustrial 1850 initial conditions for coupled ice-sheet/climate models is developed and demonstrated over the Greenland Ice Sheet using the Community Earth System Model (CESM). Paleoclimate end-member simulations and ice core data are used to derive continuous surface mass balance fields which are used to force a long transient ice sheet model simulation. The procedure accounts for the evolution of climate through the last glacial period and converges to a simulated preindustrial 1850 ice sheet that is geometrically and thermodynamically consistent with the 1850 preindustrial simulated CESM state, yet contains a transient memory of past climate that compares well to observations and independent model studies. This allows future coupled ice-sheet/climate projections of climate change that include ice sheets to integrate the effect of past climate conditions on the state of the Greenland Ice Sheet, while maintaining system-wide continuity between past and future climate simulations.

scholarly journals Paleoclimate in continental northwestern Europe during the Eemian and Early-Weichselian (125–97 ka): insights from a Belgian speleothem

2016 ◽  
Author(s):  
Stef Vansteenberge ◽  
Sophie Verheyden ◽  
Hai Cheng ◽  
Lawrence R. Edwards ◽  
Eddy Keppens ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Regional Climate ◽  
Time Interval ◽  
Last Interglacial ◽  
High Resolution Data ◽  
Climate Conditions ◽  
Spatial Coverage ◽  
Stable Conditions ◽  
Mis 5E ◽  
Δ13c And Δ18o

Abstract. The Last Interglacial serves as an excellent time interval for studying climate dynamics during past warm periods. Speleothems have been successfully used for reconstructing the paleoclimate of Last Interglacial continental Europe. However, all previously investigated speleothems are restricted to southern Europe or the Alpine region, leaving large parts of northwestern Europe undocumented. To better understand regional climate changes over the past, a larger spatial coverage of European Last Interglacial speleothems is essential. Here, we present new, high-resolution data from a stalagmite (Han-9) obtained from the Han-sur-Lesse cave in Belgium. The Han-9 formed between 125.3 and ~97 ka, with interruptions of growth occurring at 117.3–112.9 ka and 106.6–103.6 ka. The speleothem was investigated for its growth, morphology and stable isotope (δ13C and δ18O) content. Speleothem formation within the Last Interglacial started relatively late in Belgium, as this is the oldest sample of that time period found so far, dated at 125.3 ka. Other European continental archives suggest that Eemian optimum conditions were already present during that time, therefore it appears that the initiation of the Han-9 growth is caused by an increase in moisture availability, linked to wetter conditions around 125.3 ka. The δ13C and δ18O proxies indicate a period of relatively stable conditions after 125.3 ka, however at 120 ka the speleothem δ18O registered the first signs of regionally changing climate conditions, being a modification of ocean source δ18O linked to an increase in ice volume towards the MIS 5e-5d transition. The end of the Eemian is marked by drastic vegetation changes recorded in the speleothem δ13C at 117.5 ka, immediately followed by a stop in speleothem growth at 117.3 ka, suggesting that climate became significantly dryer. The Han-9 record covering the Early-Weichselian displays larger amplitudes in both the isotope proxies and the stalagmite morphology, evidencing increased variability compared to the Eemian. Greenland Stadials are recognized in the Han-9 and the chronology is consistent with other European (speleothem) records. Greenland Stadial 25 is reflected as a cold/dry period within the stable isotope proxies and the second interruption in speleothem growth occurs simultaneously with Greenland Stadial 24.

The Methow Beaver Project: the Challenges of an Ecosystem Services Experiment

2019 ◽  
Vol 3 (1) ◽  
pp. 1-14
Author(s):  
Philip Brick ◽  
Kent Woodruff
Keyword(s):  
Ecosystem Services ◽  
Climate Adaptation ◽  
Castor Canadensis ◽  
Water Storage ◽  
Climate Projections ◽  
High Mountain ◽  
Natural Resource Policy ◽  
Watershed Scale ◽  
Positive Role ◽  
Climate Conditions

This case explores the Methow Beaver Project (MBP), an ambitious experiment to restore beaver (Castor canadensis) to a high mountain watershed in Washington State, USA. The Pacific Northwest is already experiencing weather regimes consistent with longer term climate projections, which predict longer and drier summers and stronger and wetter winter storms. Ironically, this combination makes imperative more water storage in one of the most heavily dammed regions in the nation. Although the positive role that beaver can play in watershed enhancement has been well known for decades, no project has previously attempted to re-introduce beaver on a watershed scale with a rigorous monitoring protocol designed to document improved water storage and temperature conditions needed for human uses and aquatic species. While the MBP has demonstrated that beaver can be re-introduced on a watershed scale, it has been much more difficult to scientifically demonstrate positive changes in water retention and stream temperature, given hydrologic complexity, unprecedented fire and floods, and the fact that beaver are highly mobile. This case study can help environmental studies students and natural resource policy professionals think about the broader challenges of diffuse, ecosystem services approaches to climate adaptation. Beaver-produced watershed improvements will remain difficult to quantify and verify, and thus will likely remain less attractive to water planners than conventional storage dams. But as climate conditions put additional pressure on such infrastructure, it is worth considering how beaver might be employed to augment watershed storage capacity, even if this capacity is likely to remain at least in part inscrutable.

scholarly journals Late Quaternary Landscape Dynamics at the La Spezia Gulf (NW Italy): A Multi-Proxy Approach Reveals Environmental Variability within a Rocky Embayment

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 427
Author(s):  
Veronica Rossi ◽  
Alessandro Amorosi ◽  
Marco Marchesini ◽  
Silvia Marvelli ◽  
Andrea Cocchianella ◽  
...  
Keyword(s):  
Sea Level ◽  
Environmental Variability ◽  
Late Quaternary ◽  
Landscape Dynamics ◽  
Last Interglacial ◽  
Core Depth ◽  
Coastal Bay ◽  
Nw Italy ◽  
Global Sea Level ◽  
Geomorphological Features

The Gulf of La Spezia (GLS) in Northwest Italy is a rocky embayment with low fluvial influence facing the Mediterranean Sea. Past landscape dynamics were investigated through a multi-proxy, facies-based analysis down to a core depth of 30 m. The integration of quantitative ostracod, foraminifera, and pollen analyses, supported by radiocarbon ages, proved to be a powerful tool to unravel the late Quaternary palaeoenvironmental evolution and its forcing factors. The complex interplay between relative sea-level (RSL), climatic changes, and geomorphological features of the embayment drove four main evolution phases. A barrier–lagoon system developed in response to the rising RSL of the Late Pleistocene (likely the Last Interglacial). The establishment of glacial conditions then promoted the development of an alluvial environment, with generalised erosion of the underlying succession and subsequent accumulation of fluvial strata. The Holocene transgression (dated ca. 9000 cal year BP) caused GLS inundation and the formation of a low-confined lagoon basin, which rapidly turned into a coastal bay from ca. 8000 cal year BP onwards. This latter environmental change occurred in response to the last Holocene stage of global sea-level acceleration, which submerged a morphological relief currently forming a drowned barrier-island complex in the embayment.

Structural safety and design under climate change

2019 ◽  
Author(s):  
Pietro Croce ◽  
Paolo Formichi ◽  
Filippo Landi
Keyword(s):  
Climate Change ◽  
Greenhouse Gas ◽  
Structural Reliability ◽  
Greenhouse Gas Emission ◽  
Extreme Value ◽  
Structural Safety ◽  
Climate Projections ◽  
Climate Conditions ◽  
Impact Of Climate Change ◽  
The Impact

<p>The impact of climate change on climatic actions could significantly affect, in the mid-term future, the design of new structures as well as the reliability of existing ones designed in accordance to the provisions of present and past codes. Indeed, current climatic loads are defined under the assumption of stationary climate conditions but climate is not stationary and the current accelerated rate of changes imposes to consider its effects.</p><p>Increase of greenhouse gas emissions generally induces a global increase of the average temperature, but at local scale, the consequences of this phenomenon could be much more complex and even apparently not coherent with the global trend of main climatic parameters, like for example, temperature, rainfalls, snowfalls and wind velocity.</p><p>In the paper, a general methodology is presented, aiming to evaluate the impact of climate change on structural design, as the result of variations of characteristic values of the most relevant climatic actions over time. The proposed procedure is based on the analysis of an ensemble of climate projections provided according a medium and a high greenhouse gas emission scenario. Factor of change for extreme value distribution’s parameters and return values are thus estimated in subsequent time windows providing guidance for adaptation of the current definition of structural loads.</p><p>The methodology is illustrated together with the outcomes obtained for snow, wind and thermal actions in Italy. Finally, starting from the estimated changes in extreme value parameters, the influence on the long-term structural reliability can be investigated comparing the resulting time dependent reliability with the reference reliability levels adopted in modern Structural codes.</p>

scholarly journals How warm was Greenland during the last interglacial period?

2016 ◽  
Vol 12 (9) ◽  
pp. 1933-1948 ◽  
Author(s):  
Amaelle Landais ◽  
Valérie Masson-Delmotte ◽  
Emilie Capron ◽  
Petra M. Langebroek ◽  
Pepijn Bakker ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Ice Core ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Water Isotopes ◽  
Interglacial Period ◽  
Last Interglacial ◽  
Last Interglacial Period ◽  
Ice Sheet Topography ◽  
North Greenland

Abstract. The last interglacial period (LIG, ∼ 129–116 thousand years ago) provides the most recent case study of multimillennial polar warming above the preindustrial level and a response of the Greenland and Antarctic ice sheets to this warming, as well as a test bed for climate and ice sheet models. Past changes in Greenland ice sheet thickness and surface temperature during this period were recently derived from the North Greenland Eemian Ice Drilling (NEEM) ice core records, northwest Greenland. The NEEM paradox has emerged from an estimated large local warming above the preindustrial level (7.5 ± 1.8 °C at the deposition site 126 kyr ago without correction for any overall ice sheet altitude changes between the LIG and the preindustrial period) based on water isotopes, together with limited local ice thinning, suggesting more resilience of the real Greenland ice sheet than shown in some ice sheet models. Here, we provide an independent assessment of the average LIG Greenland surface warming using ice core air isotopic composition (δ15N) and relationships between accumulation rate and temperature. The LIG surface temperature at the upstream NEEM deposition site without ice sheet altitude correction is estimated to be warmer by +8.5 ± 2.5 °C compared to the preindustrial period. This temperature estimate is consistent with the 7.5 ± 1.8 °C warming initially determined from NEEM water isotopes but at the upper end of the preindustrial period to LIG temperature difference of +5.2 ± 2.3 °C obtained at the NGRIP (North Greenland Ice Core Project) site by the same method. Climate simulations performed with present-day ice sheet topography lead in general to a warming smaller than reconstructed, but sensitivity tests show that larger amplitudes (up to 5 °C) are produced in response to prescribed changes in sea ice extent and ice sheet topography.

scholarly journals Last Interglacial climate and sea-level evolution from a coupled ice sheet–climate model

2016 ◽  
Vol 12 (12) ◽  
pp. 2195-2213 ◽  
Author(s):  
Heiko Goelzer ◽  
Philippe Huybrechts ◽  
Marie-France Loutre ◽  
Thierry Fichefet
Keyword(s):  
Surface Temperature ◽  
Sea Level ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Last Interglacial ◽  
A Minor ◽  
The Antarctic ◽  
The Impact ◽  
And Sea Level

Abstract. As the most recent warm period in Earth's history with a sea-level stand higher than present, the Last Interglacial (LIG,  ∼  130 to 115 kyr BP) is often considered a prime example to study the impact of a warmer climate on the two polar ice sheets remaining today. Here we simulate the Last Interglacial climate, ice sheet, and sea-level evolution with the Earth system model of intermediate complexity LOVECLIM v.1.3, which includes dynamic and fully coupled components representing the atmosphere, the ocean and sea ice, the terrestrial biosphere, and the Greenland and Antarctic ice sheets. In this setup, sea-level evolution and climate–ice sheet interactions are modelled in a consistent framework.Surface mass balance change governed by changes in surface meltwater runoff is the dominant forcing for the Greenland ice sheet, which shows a peak sea-level contribution of 1.4 m at 123 kyr BP in the reference experiment. Our results indicate that ice sheet–climate feedbacks play an important role to amplify climate and sea-level changes in the Northern Hemisphere. The sensitivity of the Greenland ice sheet to surface temperature changes considerably increases when interactive albedo changes are considered. Southern Hemisphere polar and sub-polar ocean warming is limited throughout the Last Interglacial, and surface and sub-shelf melting exerts only a minor control on the Antarctic sea-level contribution with a peak of 4.4 m at 125 kyr BP. Retreat of the Antarctic ice sheet at the onset of the LIG is mainly forced by rising sea level and to a lesser extent by reduced ice shelf viscosity as the surface temperature increases. Global sea level shows a peak of 5.3 m at 124.5 kyr BP, which includes a minor contribution of 0.35 m from oceanic thermal expansion. Neither the individual contributions nor the total modelled sea-level stand show fast multi-millennial timescale variations as indicated by some reconstructions.

scholarly journals Greenland ice sheet contribution to sea level rise during the last interglacial period: a modelling study driven and constrained by ice core data

2013 ◽  
Vol 9 (1) ◽  
pp. 353-366 ◽  
Author(s):  
A. Quiquet ◽  
C. Ritz ◽  
H. J. Punge ◽  
D. Salas y Mélia
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ice Core ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Interglacial Period ◽  
Last Interglacial ◽  
Intergovernmental Panel ◽  
Orbital Configuration ◽  
Global Sea Level

Abstract. As pointed out by the forth assessment report of the Intergovernmental Panel on Climate Change, IPCC-AR4 (Meehl et al., 2007), the contribution of the two major ice sheets, Antarctica and Greenland, to global sea level rise, is a subject of key importance for the scientific community. By the end of the next century, a 3–5 °C warming is expected in Greenland. Similar temperatures in this region were reached during the last interglacial (LIG) period, 130–115 ka BP, due to a change in orbital configuration rather than to an anthropogenic forcing. Ice core evidence suggests that the Greenland ice sheet (GIS) survived this warm period, but great uncertainties remain about the total Greenland ice reduction during the LIG. Here we perform long-term simulations of the GIS using an improved ice sheet model. Both the methodologies chosen to reconstruct palaeoclimate and to calibrate the model are strongly based on proxy data. We suggest a relatively low contribution to LIG sea level rise from Greenland melting, ranging from 0.7 to 1.5 m of sea level equivalent, contrasting with previous studies. Our results suggest an important contribution of the Antarctic ice sheet to the LIG highstand.

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