نتایج جستجو برای: glacial cirques

تعداد نتایج: 11417  

Journal: :Scientific American 1907

2017
Nicholas J. Roberts René W. Barendregt John J. Clague

The extent and behaviour of glaciers during the mid-Piacenzian warm period illustrate the sensitivity of the cryosphere to atmospheric CO2 concentrations above pre-industrial levels. Knowledge of glaciation during this period is restricted to globally or regionally averaged records from marine sediments and to sparse terrestrial glacial deposits in mid-to-high latitudes. Here we expand the Plio...

2011
Clemens Eisank Lucian Drăguţ Thomas Blaschke

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...

2014
Lu Xu Hao Wang Qiong La Fan Lu Kun Sun Yang Fang Mei Yang Yang Zhong Qianhong Wu Jiakuan Chen H. John B. Birks Wenju Zhang

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...

2004
Didier Paillard Frédéric Parrenin

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 ...

2006
Natalie M. Mahowald Masaru Yoshioka William D. Collins Andrew J. Conley David W. Fillmore Danielle B. Coleman

[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...

2017
Hiroto Nagai Jinro Ukita Chiyuki Narama Koji Fujita Akiko Sakai Takeo Tadono Tsutomu Yamanokuchi Nobuhiro Tomiyama

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...

2004
Yosef Ashkenazy Eli Tziperman

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...

2008
SVEN THATJE

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,...

Journal: :Remote Sensing 2017
David R. Rounce C. Scott Watson Daene C. McKinney

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...

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