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  • 1
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    PANGAEA
    In:  Supplement to: Lecavalier, Benoit; Fisher, David A; Milne, Glenn A; Vinther, Bo Møllesøe; Tarasov, Lev; Huybrechts, Philippe; Lacelle, Denis; Main, Bill; Zheng, James; Bourgeois, Jocelyne; Dyke, Arthur (2017): High Arctic Holocene temperature record from the Agassiz ice cap and Greenland ice sheet evolution. Proceedings of the National Academy of Sciences, 114(23), 5952-5957, https://doi.org/10.1073/pnas.1616287114
    Publication Date: 2023-01-30
    Description: We present a revised and extended high Arctic air temperature reconstruction from a single proxy that spans the past ∼12,000 y (up to 2009 CE). Our reconstruction from the Agassiz ice cap (Ellesmere Island, Canada) indicates an earlier and warmer Holocene thermal maximum with early Holocene temperatures that are 4-5 °C warmer compared with a previous reconstruction, and regularly exceed contemporary values for a period of ∼3,000 y. Our results show that air temperatures in this region are now at their warmest in the past 6,800-7,800 y, and that the recent rate of temperature change is unprecedented over the entire Holocene. The warmer early Holocene inferred from the Agassiz ice core leads to an estimated ∼1 km of ice thinning in northwest Greenland during the early Holocene using the Camp Century ice core. Ice modeling results show that this large thinning is consistent with our air temperature reconstruction. The modeling results also demonstrate the broader significance of the enhanced warming, with a retreat of the northern ice margin behind its present position in the mid Holocene and a ∼25% increase in total Greenland ice sheet mass loss (∼1.4 m sea-level equivalent) during the last deglaciation, both of which have implications for interpreting geodetic measurements of land uplift and gravity changes in northern Greenland.
    Keywords: Agassiz ice cap; Canadian Arctic; Greenland ice sheet; Holocene climate; Ice core; temperature reconstruction
    Type: Dataset
    Format: application/zip, 3 datasets
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  • 2
    Publication Date: 2023-01-30
    Keywords: Agassiz_IceCap; Agassiz ice cap; AGE; Canadian Arctic; Ellesmere Island, Canadian Arctic Archipelago; Greenland ice sheet; Holocene climate; Ice core; ICEM; Ice measurement; Temperature, air, annual mean; temperature reconstruction; δ18O, water
    Type: Dataset
    Format: text/tab-separated-values, 3848 data points
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  • 3
    Publication Date: 2023-01-30
    Keywords: Agassiz ice cap; AGE; Camp_Century; Canadian Arctic; Greenland; Greenland ice sheet; Holocene climate; Ice core; MULT; Multiple investigations; Surface elevation change; temperature reconstruction
    Type: Dataset
    Format: text/tab-separated-values, 1752 data points
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  • 4
    Publication Date: 2023-02-12
    Keywords: Agassiz_IceCap; Agassiz ice cap; AGE; Canadian Arctic; Ellesmere Island, Canadian Arctic Archipelago; Greenland ice sheet; Holocene climate; Ice core; ICEM; Ice measurement; Melt fraction; Temperature, summer; temperature reconstruction
    Type: Dataset
    Format: text/tab-separated-values, 2730 data points
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  • 5
    Publication Date: 2024-04-20
    Description: We provide a global 0.5-degree grid of vertical land motion (in mm/a) of the LM17.3 glacial isostatic adjustment (GIA) model. The radially varying earth model part is profile VM5a (Peltier et al. 2015). The ice load is different to any other GIA model and combines regional ice loads without taking care of balancing the global sea-level equivalent of all ice sheets and glaciers with that expected from paleo-sea-level indicators. The regional models are: * GLAC-1D for North America (Tarasov et al. 2012), * HUY3 for Greenland (Lecavalier et al. 2014), * GLAC #71340 for Fennoscandia/Barents Sea (Tarasov et al., 2014), * ANU-ICE for Iceland, High Mountain Areas, Siberian Mountains and Tibet (Lambeck et al. 2014), * IJ04_Patagonia for Patagonia (updated from Ivins & James 2004), * ICE-6G_C for New Zealand (Argus et al. 2014, Peltier et al. 2015), * GLAC-1D for Antarctica (Briggs et al. 2014). Additional models (W12, Whitehouse et al. 2012, and IJ05_R2, Ivins et al. 2013, for Antarctica; ANU-ICE, Lambeck et al. 2017, and NAIce, Gowan et al. 2016, for North America) were tested in the development of the model but not used in the end. Little ice age is not included nor any ice mass change during the last 100 years. The eustatic sea-level equivalent at last glacial maximum amounts to 113.8 m for all ice sheets and glaciers together. Because we use an ice model that has not been tuned to fit global constraints, it may highlight areas which cannot match commonly used GIA observations. However, we note that the earth model used in our calculations is different to the earth model used in the development of some regional ice models, e.g. HUY3, ANU-ICE, IJ04_Patagonia (see respective references), thus some differences can be related to this. The LM17.3 model was introduced in Jäggi et al. (2019), and its DDK5-filtered geoid and water heights can be found in the EGSIEM plotter (http://plot.egsiem.eu/index.php?p=timeseries). The GIA model uses material compressibility and includes time-dependent coastlines and rotational feedback. The vertical land motion can be used/tested in sea-level investigations and projections. Work towards a model that incorporates 3D earth structure, and an updated ice model, is ongoing.
    Keywords: EGSIEM; European Gravity Service for Improved Emergency Management; glacial isostatic adjustment; sea level
    Type: Dataset
    Format: application/zip, 1.9 MBytes
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  • 6
    Publication Date: 2020-08-03
    Description: The Antarctic Ice Sheet is an important indicator of climate change and driver of sea-level rise. Here we combine satellite observations of its changing volume, flow and gravitational attraction with modelling of its surface mass balance to show that it lost 2,720 ± 1,390 billion tonnes of ice between 1992 and 2017, which corresponds to an increase in mean sea level of 7.6 ± 3.9 millimetres (errors are one standard deviation). Over this period, ocean-driven melting has caused rates of ice loss from West Antarctica to increase from 53 ± 29 billion to 159 ± 26 billion tonnes per year; ice-shelf collapse has increased the rate of ice loss from the Antarctic Peninsula from 7 ± 13 billion to 33 ± 16 billion tonnes per year. We find large variations in and among model estimates of surface mass balance and glacial isostatic adjustment for East Antarctica, with its average rate of mass gain over the period 1992–2017 (5 ± 46 billion tonnes per year) being the least certain.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 7
    Publication Date: 2020-08-03
    Description: The Greenland Ice Sheet has been a major contributor to global sea-level rise in recent decades1,2, and it is expected to continue to be so3. Although increases in glacier flow4–6 and surface melting7–9 have been driven by oceanic10–12 and atmospheric13,14 warming, the magnitude and trajectory of the ice sheet’s mass imbalance remain uncertain. Here we compare and combine 26 individual satellite measurements of changes in the ice sheet’s volume, flow and gravitational potential to produce a reconciled estimate of its mass balance. The ice sheet was close to a state of balance in the 1990s, but annual losses have risen since then, peaking at 345 ± 66 billion tonnes per year in 2011. In all, Greenland lost 3,902 ± 342 billion tonnes of ice between 1992 and 2018, causing the mean sea level to rise by 10.8 ± 0.9 millimetres. Using three regional climate models, we show that the reduced surface mass balance has driven 1,964 ± 565 billion tonnes (50.3 per cent) of the ice loss owing to increased meltwater runoff. The remaining 1,938 ± 541 billion tonnes (49.7 per cent) of ice loss was due to increased glacier dynamical imbalance, which rose from 46 ± 37 billion tonnes per year in the 1990s to 87 ± 25 billion tonnes per year since then. The total rate of ice loss slowed to 222 ± 30 billion tonnes per year between 2013 and 2017, on average, as atmospheric circulation favoured cooler conditions15 and ocean temperatures fell at the terminus of Jakobshavn Isbræ16. Cumulative ice losses from Greenland as a whole have been close to the rates predicted by the Intergovernmental Panel on Climate Change for their high-end climate warming scenario17, which forecast an additional 70 to 130 millimetres of global sea-level rise by 2100 compared with their central estimate.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 8
    Publication Date: 2019-01-25
    Description: Analysis | Published: 13 June 2018 Mass balance of the Antarctic Ice Sheet from 1992 to 2017 The IMBIE team Naturevolume 558, pages219–222 (2018) | Download Citation Abstract The Antarctic Ice Sheet is an important indicator of climate change and driver of sea-level rise. Here we combine satellite observations of its changing volume, flow and gravitational attraction with modelling of its surface mass balance to show that it lost 2,720 ± 1,390 billion tonnes of ice between 1992 and 2017, which corresponds to an increase in mean sea level of 7.6 ± 3.9 millimetres (errors are one standard deviation). Over this period, ocean-driven melting has caused rates of ice loss from West Antarctica to increase from 53 ± 29 billion to 159 ± 26 billion tonnes per year; ice-shelf collapse has increased the rate of ice loss from the Antarctic Peninsula from 7 ± 13 billion to 33 ± 16 billion tonnes per year. We find large variations in and among model estimates of surface mass balance and glacial isostatic adjustment for East Antarctica, with its average rate of mass gain over the period 1992–2017 (5 ± 46 billion tonnes per year) being the least certain.
    Description: Published
    Description: 219-222
    Description: 5A. Paleoclima e ricerche polari
    Description: JCR Journal
    Keywords: Antarctica ; Ice sheet mass balance ; 02.02. Glaciers ; 04.03. Geodesy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
    Publication Date: 2023-04-26
    Description: Ice losses from the Greenland and Antarctic ice sheets have accelerated since the 1990s, accounting for a significant increase in the global mean sea level. Here, we present a new 29-year record of ice sheet mass balance from 1992 to 2020 from the Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE). We compare and combine 50 independent estimates of ice sheet mass balance derived from satellite observations of temporal changes in ice sheet flow, in ice sheet volume, and in Earth's gravity field. Between 1992 and 2020, the ice sheets contributed 21.0±1.9 mm to global mean sea level, with the rate of mass loss rising from 105 Gt yr−1 between 1992 and 1996 to 372 Gt yr−1 between 2016 and 2020. In Greenland, the rate of mass loss is 169±9 Gt yr−1 between 1992 and 2020, but there are large inter-annual variations in mass balance, with mass loss ranging from 86 Gt yr−1 in 2017 to 444 Gt yr−1 in 2019 due to large variability in surface mass balance. In Antarctica, ice losses continue to be dominated by mass loss from West Antarctica (82±9 Gt yr−1) and, to a lesser extent, from the Antarctic Peninsula (13±5 Gt yr−1). East Antarctica remains close to a state of balance, with a small gain of 3±15 Gt yr−1, but is the most uncertain component of Antarctica's mass balance. The dataset is publicly available at https://doi.org/10.5285/77B64C55-7166-4A06-9DEF-2E400398E452 (IMBIE Team, 2021).
    Description: Published
    Description: 1597–1616
    Description: 5A. Ricerche polari e paleoclima
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 10
    Publication Date: 2024-01-18
    Description: The Greenland Ice Sheet has been a major contributor to global sea-level rise in recent decades, and it is expected to continue to be so. Although increases in glacier flow and surface melting have been driven by oceanic and atmospheric warming, the magnitude and trajectory of the ice sheet’s mass imbalance remain uncertain. Here we compare and combine 26 individual satellite measurements of changes in the ice sheet’s volume, flow and gravitational potential to produce a reconciled estimate of its mass balance. The ice sheet was close to a state of balance in the 1990s, but annual losses have risen since then, peaking at 345 ± 66 billion tonnes per year in 2011. In all, Greenland lost 3,902 ± 342 billion tonnes of ice between 1992 and 2018, causing the mean sea level to rise by 10.8 ± 0.9 millimetres. Using three regional climate models, we show that the reduced surface mass balance has driven 1,964 ± 565 billion tonnes (50.3 per cent) of the ice loss owing to increased meltwater runoff. The remaining 1,938 ± 541 billion tonnes (49.7 per cent) of ice loss was due to increased glacier dynamical imbalance, which rose from 46 ± 37 billion tonnes per year in the 1990s to 87 ± 25 billion tonnes per year since then. The total rate of ice loss slowed to 222 ± 30 billion tonnes per year between 2013 and 2017, on average, as atmospheric circulation favoured cooler conditions and ocean temperatures fell at the terminus of Jakobshavn Isbræ. Cumulative ice losses from Greenland as a whole have been close to the rates predicted by the Intergovernmental Panel on Climate Change for their high-end climate warming scenario, which forecast an additional 70 to 130 millimetres of global sea-level rise by 2100 compared with their central estimate.
    Description: Published
    Description: 233–239
    Description: 4A. Oceanografia e clima
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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