Roundup: Tidewater Glaciers, North Cascades, Antarctic Bacterium

Posted by on Aug 10, 2015

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The Culprit for Greenland Ice Sheet Mass Loss

Source: Christine Zenino/Flickr

Greenland Ice Sheet. Source: Christine Zenino/Flickr

“Overall mass loss from the Greenland ice sheet nearly doubled during the early 2000s resulting in an increased contribution to sea-level rise, with this step-change being mainly attributed to the widespread frontal retreat and accompanying dynamic thinning of tidewater glaciers. Changes in glacier calving-front positions are easily derived from remotely sensed imagery and provide a record of dynamic change […] In this study multiple calving-front positions were derived for 199 Greenland marine-terminating outlet glaciers with width greater than 1 km using Landsat imagery for the 11-year period 2000–2010 in order to identify regional seasonal and inter-annual variations. Our results suggest several regions in the south and east of the ice sheet likely share controls on their dynamic changes, but no simple single control is apparent.”

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Area Changes of North Cascades Glaciers

North Cascades Glaciers. Source: Sean Munson/Flickr

North Cascades Glaciers. Source: Sean Munson/Flickr

“We present an exhaustive spatial analysis using the geographic, geometric, and hypsometric characteristics of 742 North Cascades glaciers to evaluate changes in their areal extents over a half-century period. Our results indicate that, contrary to our initial expectations, glacier change throughout the study region cannot be explained readily by correlations in glacier location, size, or shape. Our statistical analyses of the changes observed indicate that geometric data from a large number of glaciers, as well as a surprisingly large amount of spatial change, are required for a credible statistical detection of glacier-length and area changes over a short (multidecadal) period of time.”

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The Small Tough Organisms

Growth of cold-sensitive mutants on Antarctic Bacterial Media containing stressor. Source: D. Sengupta et al (2015).

Growth of cold-sensitive mutants on Antarctic Bacterial Media containing stressor. Source: D. Sengupta et al (2015).

“A population of cold-tolerant Antarctic bacteria was screened for their ability to tolerate other environmental stress factors. Besides low temperature, they were predominantly found to be tolerant to alkali. Attempt was also made to postulate a genetic basis of their multistress-tolerance […] A number of multistress-sensitive mutants were isolated. The mutated gene in one of the mutants sensitive to low temperature, acid and alkali was found to encode citrate synthase. Possible role of citrate synthase in conferring multistress-tolerance was postulated.”

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