نتایج جستجو برای: glaciers
تعداد نتایج: 4288 فیلتر نتایج به سال:
We present a new record of ice thickness change, reconstructed at nearly 100,000 sites on the Greenland Ice Sheet (GrIS) from laser altimetry measurements spanning the period 1993-2012, partitioned into changes due to surface mass balance (SMB) and ice dynamics. We estimate a mean annual GrIS mass loss of 243 ± 18 Gt ⋅ y(-1), equivalent to 0.68 mm ⋅ y(-1) sea level rise (SLR) for 2003-2009. Dyn...
By matching of repeat optical satellite images it is now possible to investigate glacier dynamics within large regions of the world and also between regions to improve knowledge about glacier dynamics in space and time. In this study we investigate whether the negative glacier mass balance seen over large parts of the world has caused the glaciers to change their speeds. The studied regions are...
Viable microbes have been detected beneath several geographically distant glaciers underlain by different lithologies, but comparisons of their microbial communities have not previously been made. This study compared the microbial community compositions of samples from two glaciers overlying differing bedrock. Bulk meltwater chemistry indicates that sulfide oxidation and carbonate dissolution a...
The Greenland Ice Sheet's (GIS) contribution to sea level rise more than doubled in the last seven years due to a surprisingly rapid (and unpredicted) mass loss. The loss was not so much a result of increased surface melt but, rather, of ice loss due to the widespread and nearly-simultaneous acceleration of several outlet glaciers in Greenland’s western and southeastern sectors [Rignot and Kana...
The degree to which debris-covered glaciers record past environmental conditions is debated. Here we describe a novel palaeoclimate archive derived from the surface morphology and internal debris within cold-based debris-covered glaciers in Antarctica. Results show that subtle changes in mass balance impart major changes in the concentration of englacial debris and corresponding surface topogra...
We describe volumetric changes in three benchmark glaciers in the Nepal Himalayas on which observations have been made since the 1970s. Compared with the global mean of glacier mass balance, the Himalayan glaciers showed rapid wastage in the 1970s-1990s, but similar wastage in the last decade. In the last decade, a glacier in an arid climate showed negative but suppressed mass balance compared ...
overshoot may go undetected – increasing the ecological deficit and reducing nature's capacity to meet society's needs. " The Ecological Footprint is a resource accounting tool used to address underlying sustainability questions " , the researchers say. It measures the extent to which humans are using nature's resources faster than they can regenerate. It can illustrate who uses how much of whi...
Most glaciers in China lie in high mountainous environments and have relatively large surface slopes. Common analyses consider glaciers’ projected areas (2D Area) in a two-dimensional plane, which are much smaller than glacier’s topographic surface extents (3D Area). The areal difference between 2D planar areas and 3D surface extents exceeds −5% when the glacier’s surface slope is larger than 1...
We calculate thinning rates ( ) at the 5800 km2 Stikine Icefield of southeast dt Alaska from stacked digital elevation models (DEMs) acquired between 2000 and 2013/2014, and glacier velocities between 1985 and 2014 from feature tracking on optical image pairs. We find a mass change rate of −3.3 ± 1.1 Gt yr−1 between 2000 and 2014, equivalent to an area-averaged elevation change rate of −0.57 ± ...
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