Abstract
AbstractIce shelves play a vital role in regulating loss of grounded ice and in supplying freshwater to coastal seas. However, melt variability within ice shelves is poorly constrained and may be instrumental in driving ice shelf imbalance and collapse. High‐resolution altimetry measurements from 2010 to 2016 show that Dotson Ice Shelf (DIS), West Antarctica, thins in response to basal melting focused along a single 5 km‐wide and 60 km‐long channel extending from the ice shelf's grounding zone to its calving front. If focused thinning continues at present rates, the channel will melt through, and the ice shelf collapse, within 40–50 years, almost two centuries before collapse is projected from the average thinning rate. Our findings provide evidence of basal melt‐driven sub‐ice shelf channel formation and its potential for accelerating the weakening of ice shelves.
Highlights
The majority of meteoric ice that forms in West Antarctica leaves the ice sheet through floating ice shelves, many of which have been thinning substantially over the last 25 years (Holland et al, 2015; Paolo et al, 2015; Pritchard et al, 2012; Shepherd et al, 2003)
Termed the Dotson Ice Shelf (DIS) Channel (DISC), the mean rate of elevation change is À0.76 ± 0.03 m yrÀ1, which accounts for 30% of the total elevation change of DIS
While much of the recent thinning of DIS has clearly been concentrated along the DISC, it is unknown for how long this process has formed a major component of the ice shelf’s loss
Summary
The majority of meteoric ice that forms in West Antarctica leaves the ice sheet through floating ice shelves, many of which have been thinning substantially over the last 25 years (Holland et al, 2015; Paolo et al, 2015; Pritchard et al, 2012; Shepherd et al, 2003). Under some ice shelves, concentrated melting leads to the formation of inverted channels (Alley et al, 2016; Berger et al, 2017; Fricker et al, 2009; Le Brocq et al, 2013; Marsh et al, 2016; Rignot & Steffen, 2008; Sergienko, 2013). These channels guide buoyant melt-laden outflow, which can lead to localized melting of the sea ice cover (Mankoff et al, 2012). It is important that we observe spatial patterns, as well as magnitudes, of ice shelf thinning, in order to improve understanding of the ocean drivers of thinning and of their impacts on ice shelf stability
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