| 1. |
- Das, Indrani, et al.
(författare)
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21st-century increase in glacier mass loss in the Wrangell Mountains, Alaska, USA, from airborne laser altimetry and satellite stereo imagery
- 2014
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Ingår i: Journal of Glaciology. - 0022-1430 .- 1727-5652. ; 60:220, s. 283-293
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Tidskriftsartikel (refereegranskat)abstract
- Alaskan glaciers are among the largest regional contributors to sea-level rise in the latter half of the 20th century. Earlier studies have documented extensive and accelerated ice wastage in most regions of Alaska. Here we study five decades of mass loss on high-elevation, land-terminating glaciers of the Wrangell Mountains (similar to 4900 km(2)) in central Alaska based on airborne center-line laser altimetry data from 2000 and 2007, a digital elevation model (DEM) from ASTER and SPOT5, and US Geological Survey topographic maps from 1957. The regional mass-balance estimates derived from center-line laser altimetry profiles using two regional extrapolation techniques agree well with that from DEM differencing. Repeat altimetry measurements reveal accelerated mass loss over the Wrangell Mountains, with the regional mass-balance rate evolving from -0.07 +/- 0.19 m w.e. a(-1) during 1957-2000 to -0.24 +/- 0.16 m w.e. a(-1) during 2000-07. Nabesna, the largest glacier in this region (similar to 1056 km(2)), lost mass four times faster during 2000-07 than during 1957-2000. Although accelerated, the mass change over this region is slower than in other glacierized regions of Alaska, particularly those with tidewater glaciers. Together, our laser altimetry and satellite DEM analyses demonstrate increased wastage of these glaciers during the last 50 years.
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| 2. |
- Deschamps-Berger, Cesar, et al.
(författare)
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Closing the mass budget of a tidewater glacier : the example of Kronebreen, Svalbard
- 2019
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Ingår i: Journal of Glaciology. - : Cambridge University Press (CUP). - 0022-1430 .- 1727-5652. ; 65:249, s. 136-148
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we combine remote sensing, in situ and model-derived datasets from 1966 to 2014 to calculate the mass-balance components of Kronebreen, a fast-flowing tidewater glacier in Svalbard. For the well-surveyed period 2009-2014, we are able to close the glacier mass budget within the prescribed errors. During these 5 years, the glacier geodetic mass balance was -0.69 +/- 0.12 m w.e. a(-1), while the mass budget method led to a total mass balance of -0.92 +/- 0.16 m w.e. a(-1), as a consequence of a strong frontal ablation (-0.78 +/- 0.11 m w.e. a(-1) ), and a slightly negative climatic mass balance (-0.14 +/- 0.11 m w.e. a(-1) ). The trend towards more negative climatic mass balance between 1966-1990 (+0.20 +/- 0.05 m w.e. a(-1) ) and 2009-2014 is not reflected in the geodetic mass balance trend. Therefore, we suspect a reduction in ice-discharge in the most recent period. Yet, these multidecadal changes in ice-discharge cannot be measured from the available observations and thus are only estimated with relatively large errors as a residual of the mass continuity equation. Our study presents the multidecadal evolution of the dynamics and mass balance of a tidewater glacier and illustrates the errors introduced by inferring one unmeasured mass-balance component from the others.
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| 3. |
- Gardner, Alex S., et al.
(författare)
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A Reconciled Estimate of Glacier Contributions to Sea Level Rise : 2003 to 2009
- 2013
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 340:6134, s. 852-857
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Tidskriftsartikel (refereegranskat)abstract
- Glaciers distinct from the Greenland and Antarctic Ice Sheets are losing large amounts of water to the world's oceans. However, estimates of their contribution to sea level rise disagree. We provide a consensus estimate by standardizing existing, and creating new, mass-budget estimates from satellite gravimetry and altimetry and from local glaciological records. In many regions, local measurements are more negative than satellite-based estimates. All regions lost mass during 2003-2009, with the largest losses from Arctic Canada, Alaska, coastal Greenland, the southern Andes, and high-mountain Asia, but there was little loss from glaciers in Antarctica. Over this period, the global mass budget was -259 +/- 28 gigatons per year, equivalent to the combined loss from both ice sheets and accounting for 29 +/- 13% of the observed sea level rise.
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| 4. |
- Papasodoro, Charles, et al.
(författare)
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Area, elevation and mass changes of the two southernmost ice caps of the Canadian Arctic Archipelago between 1952 and 2014
- 2015
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Ingår i: The Cryosphere. - : European Geosciences Union (EGU). - 1994-0416 .- 1994-0424. ; 9, s. 1535-1550
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Tidskriftsartikel (refereegranskat)abstract
- Grinnell and Terra Nivea Ice Caps are located onthe southern Baffin Island, Nunavut, in the Canadian Arctic Archipelago. These relatively small ice caps have received little attention compared to the much larger ice masses further north. Their evolution can, however, give valuable information about the impact of the recent Arctic warming at lower latitudes (i.e. ∼62.5◦ N). In this paper, we measure or estimate historical and recent changes of area, elevation and mass of both ice caps using in situ, airborne and spaceborne data sets, including imagery from the Pléiades satellites. The area of Terra Nivea Ice Cap has decreased by 34 % since the late 1950s, while that of Grinnell Ice Cap has decreased by 20 % since 1952. For both ice caps, the areal reduction accelerated at the beginning of the 21st century. The estimated glacier-wide mass balance was−0.37 ± 0.21 m a^−1 water equivalent (w.e.) over Grinnell Ice Cap for the 1952–2014 period, and −0.47 ± 0.16 m a^−1 w.e. over Terra Nivea Ice Cap for the 1958/59–2014 period. Terra Nivea Ice Cap has experienced an accelerated rate of mass loss of −1.77 ± 0.36 m a^−1 w.e. between 2007 and 2014.This rate is 5.9 times as negative when compared to the 1958/59–2007 period (−0.30 ± 0.19 m a^−1 w.e.) and 2 times as negative when compared to the mass balance of other glaciers in the southern parts of Baffin Island over the 2003– 2009 period. A similar acceleration in mass loss is sus-pected for the Grinnell Ice Cap, given the calculated elevation changes and the proximity to Terra Nivea Ice Cap. The recent increase in mass loss rates for these two ice caps is linked to a strong near-surface regional warming and a lengthening of the melt season into the autumn that may beindirectly strengthened by a later freezing of sea ice in the Hudson Strait sector. On a methodological level, our study illustrates the strong potential of Pléiades satellite data to unlock the underexploited archive of old aerial photographs.
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