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  • 1
    Online Resource
    Online Resource
    Interglacial instability of North Atlantic Deep Water ventilation
    American Association for the Advancement of Science (AAAS) ; 2020
    In:  Science Vol. 367, No. 6485 ( 2020-03-27), p. 1485-1489
    Details
    In: Science, American Association for the Advancement of Science (AAAS), Vol. 367, No. 6485 ( 2020-03-27), p. 1485-1489
    Abstract: Disrupting North Atlantic Deep Water (NADW) ventilation is a key concern in climate projections. We use (sub)centennially resolved bottom water δ 13 C records that span the interglacials of the last 0.5 million years to assess the frequency of and the climatic backgrounds capable of triggering large NADW reductions. Episodes of reduced NADW in the deep Atlantic, similar in magnitude to glacial events, have been relatively common and occasionally long-lasting features of interglacials. NADW reductions were triggered across the range of recent interglacial climate backgrounds, which demonstrates that catastrophic freshwater outburst floods were not a prerequisite for large perturbations. Our results argue that large NADW disruptions are more easily achieved than previously appreciated and that they occurred in past climate conditions similar to those we may soon face.
    Type of Medium: Online Resource
    ISSN: 0036-8075 , 1095-9203
    URL: Article
    DOI: 10.1126/science.aay6381
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 2020
    detail.hit.zdb_id: 128410-1
    detail.hit.zdb_id: 2066996-3
    detail.hit.zdb_id: 2060783-0
    SSG: 11
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    A low climate threshold for south Greenland Ice Sheet demise during the Late Pleistocene
    Proceedings of the National Academy of Sciences ; 2020
    In:  Proceedings of the National Academy of Sciences Vol. 117, No. 1 ( 2020-01-07), p. 190-195
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 117, No. 1 ( 2020-01-07), p. 190-195
    Abstract: The Greenland Ice Sheet (GIS) has been losing mass at an accelerating rate over the recent decades. Models suggest a possible temperature threshold between 0.8 and 3.2 °C, beyond which GIS decline becomes irreversible. The duration of warmth above a given threshold is also a critical determinant for GIS survival, underlining the role of ocean warming, as its inertia prolongs warmth and triggers longer-term feedbacks. The exact point at which these feedbacks are triggered remains equivocal. Late Pleistocene interglacials provide potential case examples for constraining the past response of the GIS to a range of climate states, including conditions warmer than present. However, little is known about the magnitude and duration of warming near Greenland during these periods. Using high-resolution multiproxy surface ocean climate records off southern Greenland, we show that the previous 4 interglacials over the last ∼450 ka all reached warmer than present climate conditions and exceeded the modeled temperature threshold for GIS collapse but by different magnitudes and durations. Complete deglaciation of the southern GIS in Marine Isotope Stage 11c (MIS 11c; 394.7 to 424.2 ka) occurred under climates only slightly warmer than present (∼0.5 ± 1.6 °C), placing the temperature threshold for major GIS retreat in the lower end of model estimates and within projections for this century.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1911902116
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2020
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    Millennial-Scale Instability of the Antarctic Ice Sheet During the Last Glaciation
    American Association for the Advancement of Science (AAAS) ; 2000
    In:  Science Vol. 288, No. 5472 ( 2000-06-09), p. 1815-1819
    Details
    In: Science, American Association for the Advancement of Science (AAAS), Vol. 288, No. 5472 ( 2000-06-09), p. 1815-1819
    Abstract: Records of ice-rafted detritus (IRD) concentration in deep-sea cores from the southeast Atlantic Ocean reveal millennial-scale pulses of IRD delivery between 20,000 and 74,000 years ago. Prominent IRD layers correlate across the Polar Frontal Zone, suggesting episodes of Antarctic Ice Sheet instability. Carbon isotopes (δ 13 C) of benthic foraminifers, a proxy of deepwater circulation, reveal that South Atlantic IRD events coincided with strong increases in North Atlantic Deep Water (NADW) production and inferred warming (interstadials) in the high-latitude North Atlantic. Sea level rise or increased NADW production associated with strong interstadials may have resulted in destabilization of grounded ice shelves and possible surging in the Weddell Sea region of West Antarctica.
    Type of Medium: Online Resource
    ISSN: 0036-8075 , 1095-9203
    URL: Article
    DOI: 10.1126/science.288.5472.1815
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 2000
    detail.hit.zdb_id: 128410-1
    detail.hit.zdb_id: 2066996-3
    detail.hit.zdb_id: 2060783-0
    SSG: 11
    Location Call Number Limitation Availability
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  • 4
    Online Resource
    Online Resource
    Reduced North Atlantic Deep Water Coeval with the Glacial Lake Agassiz Freshwater Outburst
    American Association for the Advancement of Science (AAAS) ; 2008
    In:  Science Vol. 319, No. 5859 ( 2008-01-04), p. 60-64
    Details
    In: Science, American Association for the Advancement of Science (AAAS), Vol. 319, No. 5859 ( 2008-01-04), p. 60-64
    Abstract: An outstanding climate anomaly 8200 years before the present (B.P.) in the North Atlantic is commonly postulated to be the result of weakened overturning circulation triggered by a freshwater outburst. New stable isotopic and sedimentological records from a northwest Atlantic sediment core reveal that the most prominent Holocene anomaly in bottom-water chemistry and flow speed in the deep limb of the Atlantic overturning circulation begins at ∼8.38 thousand years B.P., coeval with the catastrophic drainage of Lake Agassiz. The influence of Lower North Atlantic Deep Water was strongly reduced at our site for ∼100 years after the outburst, confirming the ocean's sensitivity to freshwater forcing. The similarities between the timing and duration of the pronounced deep circulation changes and regional climate anomalies support a causal link.
    Type of Medium: Online Resource
    ISSN: 0036-8075 , 1095-9203
    URL: Article
    DOI: 10.1126/science.1148924
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 2008
    detail.hit.zdb_id: 128410-1
    detail.hit.zdb_id: 2066996-3
    detail.hit.zdb_id: 2060783-0
    SSG: 11
    Location Call Number Limitation Availability
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  • 5
    Online Resource
    Online Resource
    Rapid Reductions in North Atlantic Deep Water During the Peak of the Last Interglacial Period
    American Association for the Advancement of Science (AAAS) ; 2014
    In:  Science Vol. 343, No. 6175 ( 2014-03-07), p. 1129-1132
    Details
    In: Science, American Association for the Advancement of Science (AAAS), Vol. 343, No. 6175 ( 2014-03-07), p. 1129-1132
    Abstract: Deep ocean circulation has been considered relatively stable during interglacial periods, yet little is known about its behavior on submillennial time scales. Using a subcentennially resolved epibenthic foraminiferal δ 13 C record, we show that the influence of North Atlantic Deep Water (NADW) was strong at the onset of the last interglacial period and was then interrupted by several prominent centennial-scale reductions. These NADW transients occurred during periods of increased ice rafting and southward expansions of polar water influence, suggesting that a buoyancy threshold for convective instability was triggered by freshwater and circum-Arctic cryosphere changes. The deep Atlantic chemical changes were similar in magnitude to those associated with glaciations, implying that the canonical view of a relatively stable interglacial circulation may not hold for conditions warmer and fresher than at present.
    Type of Medium: Online Resource
    ISSN: 0036-8075 , 1095-9203
    URL: Article
    DOI: 10.1126/science.1248667
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 2014
    detail.hit.zdb_id: 128410-1
    detail.hit.zdb_id: 2066996-3
    detail.hit.zdb_id: 2060783-0
    SSG: 11
    Location Call Number Limitation Availability
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