نتایج جستجو برای: glacial
تعداد نتایج: 11388 فیلتر نتایج به سال:
A generic procedure for semantics-oriented landform classification using object-based image analysis
In most landform classification studies – either per cell or object-based – the authors have ignored modeling the semantics of landforms explicitly. Thus, landform classification schemes rely on individual knowledge, and are too much tailored to specific areas and/or scales. Integration of structured knowledge models in the classification process has been proposed to overcome the limitations in...
Microrefugia at high altitudes or high latitudes are thought to play an important role in the post-glacial colonization of species. However, how populations in such microrefugia have responded to climate changes in alternating cold glacial and warm interglacial stages remain unclear. Here we present evidence to indicate the Rongbuk Valley of the Mt. Qomolangma (Mt. Everest) area, the highest re...
A new physical mechanism involving the Antarctic ice-sheet extent is able to link climatic and CO2 glacial–interglacial changes. It is furthermore able to explain many features of the glacial cycles, like the 100 kyr oscillations or the peculiarities of stage 11 (about 400 kyr BP). Indeed, from recent results, the glacial ocean bottom waters were possibly much more saline and consequently, may ...
[1] Mineral aerosol impacts on climate through radiative forcing by natural dust sources are examined in the current, last glacial maximum, pre-industrial and doubled-carbon dioxide climate. Modeled globally averaged dust loadings change by +88%, +31% and 60% in the last glacial maximum, pre-industrial and future climates, respectively, relative to the current climate. Model results show global...
A comprehensive glacier–glacial lake inventory was developed for the Bhutan Himalayas based on satellite observations between 1987–1990 and 2006–2011. In total, 733 lakes (covering 82.6 km2) were delineated between 4000 and 6000 m a.s.l. and their relationships to associated glaciers were documented. Using this new inventory, the scale and potential for glacial lake outburst flooding (GLOF) bas...
The characteristics of glacial oscillations changed drastically 0:8Ma ago, at the ‘‘mid-Pleistocene transition’’. During the past 0.8Ma the 100kyr glacial–interglacial oscillations were strongly asymmetric (i.e., long glacial intervals of growth followed by rapid intervals of deglaciation). The 40 kyr oscillations prior to the mid-Pleistocene transition were of a smaller amplitude and lessasymm...
Today, Antarctica exhibits some of the harshest environmental conditions for life on Earth. During the last glacial period, Antarctic terrestrial and marine life was challenged by even more extreme environmental conditions. During the present interglacial period, polar life in the Southern Ocean is sustained mainly by large-scale primary production. We argue that during the last glacial period,...
Glacial lakes in the Nepal Himalaya can threaten downstream communities and have large socio-economic consequences if an outburst flood occurs. This study identified 131 glacial lakes in Nepal in 2015 that are greater than 0.1 km2 and performed a first-pass hazard and risk assessment for each lake. The hazard assessment included mass entering the lake, the moraine stability, and how lake expans...
Ice sheets play a fundamental role within Earth’s climate system and in shaping landscapes. Despite extensive research, the maximum extent and basal dynamics of the Laurentide Ice Sheet (LIS) during the last glacial cycle remain elusive and debated in many areas. Recently, cosmogenic nuclides (e.g., 36Cl, 26Al, 10Be) have played an important role in improving our understanding of LIS extent and...
We present here continuous records of 8180 and t~13C in benthic foraminifera, extending well into the last ice age, in two piston cores from the Andaman Sea (sill depth ~ 1.3 km) and the Bay of Bengal (3 km). These show that, contrary to the previous reports, the glacial to interglacial shift in 613C at mid-depths in the Northeast Indian Ocean was indistinguishable from the mean oceanic 313C ch...
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