13 June 2018 (University of Waterloo) – A new study from the University of Waterloo discovered that rising sea levels could be accelerated by vulnerable ice shelves in the Antarctic.

The study, by an international team of polar scientists led by Canada Research Chair Christine Dow of Waterloo’s Faculty of Environment, discovered that the process of warmer ocean water destabilizing ice shelves from below is also cracking them apart from above, increasing the chance they’ll break off.

“We are learning that ice shelves are more vulnerable to rising ocean and air temperatures than we thought,” said Dow. “There are dual processes going on here. One that is destabilizing from below, and another from above. This information could have an impact on our projected timelines for ice shelf collapse and resulting sea level rise due to climate change.”

The study, which was conducted over two years, applied methods similar to forensic science on ice shelves which had already calved. Using radar surveys and Landsat imagery, Dow reports direct evidence that a major 2016 calving event at Nansen Ice Shelf in the Ross Sea was the result of fracture driven by channels melted into the bottom of the ice shelf. The surveys also demonstrated that similar basal channel-driven transverse fractures occur elsewhere in Greenland and Antarctica.

Videos from the Korea Polar Research Institute, and photos from ENV researcher Christine Dow, show that as warmer salt water erodes channels into the ice that attaches the ice shelves to stable land, it also generates massive vertical fractures splitting glaciers from above and below. Surface water melting on top of the ice shelves then pours into these cracks, accelerating the problem further. Photo: Korea Polar Research Institute / University of Waterloo

As warmer salt water erodes channels into the ice that attaches glaciers to stable land, it also generates massive vertical fractures splitting glaciers from above and below. Surface water melting on top of the ice shelves then pours into these cracks, accelerating the problem further.

“This study is more evidence that the warming effects of climate change are impacting our planet in ways that are often more dangerous than we perhaps had thought,” said Dow. “There are many more vulnerable ice shelves in the Antarctic that, if they break up, will accelerate the processes of sea level rise.”

The study, titled “Basal channels drive active surface hydrology and transverse ice-shelf fracture”, was recently published in AAAS Science Advances.

Contact

Ryon Jones
University of Waterloo
519-888-4567 ext. 30031
www.uwaterloo.ca/news
@UWaterlooNews

Climate change accelerating rising sea levels


Transverse fractures related to ice shelf channels on Antarctic and Greenland ice shelves. In all images, transverse fractures are shown in black, basal channels are shown in blue, and black arrows indicate general ice-flow direction. Graphic: Dow, et al., 2018 / Science Advances

ABSTRACT: Ice shelves control sea-level rise through frictional resistance, which slows the seaward flow of grounded glacial ice. Evidence from around Antarctica indicates that ice shelves are thinning and weakening, primarily driven by warm ocean water entering into the shelf cavities. We have identified a mechanism for ice shelf destabilization where basal channels underneath the shelves cause ice thinning that drives fracture perpendicular to flow. These channels also result in ice surface deformation, which diverts supraglacial rivers into the transverse fractures. We report direct evidence that a major 2016 calving event at Nansen Ice Shelf in the Ross Sea was the result of fracture driven by such channelized thinning and demonstrate that similar basal channel–driven transverse fractures occur elsewhere in Greenland and Antarctica. In the event of increased basal and surface melt resulting from rising ocean and air temperatures, ice shelves will become increasingly vulnerable to these tandem effects of basal channel destabilization.

Basal channels drive active surface hydrology and transverse ice shelf fracture

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