Abstract
ABSTRACTAccelerated discharge through marine-terminating outlet glaciers has been a key component of the rapid mass loss from Arctic glaciers since the 1990s. However, glacier retreat and its climatic controls have not been assessed at the pan-Arctic scale. Consequently, the spatial and temporal variability in the magnitude of retreat, and the possible drivers are uncertain. Here we use remotely sensed data acquired over 273 outlet glaciers, located across the entire Atlantic Arctic (i.e. areas potentially influenced by North Atlantic climate and/or ocean conditions, specifically: Greenland, Novaya Zemlya, Franz Josef Land and Svalbard), to demonstrate high-magnitude, accelerating and near-ubiquitous retreat between 1992 and 2010. Overall, mean retreat rates increased by a factor of 3.5 between 1992 and 2000 (−30.5 m a−1) and 2000–10 (−105.8 m a−1), with 97% of the study glaciers retreating during the latter period. The Retreat was greatest in northern, western and south-eastern Greenland and also increased substantially on the Barents Sea coast of Novaya Zemlya. Glacier retreat showed no significant or consistent relationship with summer air temperatures at decadal timescales. The rate of frontal position change showed a significant, but weak, correlation with changes in sea-ice concentrations. We highlight large variations in retreat rates within regions and suggest that fjord topography plays an important role. We conclude that marine-terminating Arctic outlet glaciers show a common response of rapid and accelerating retreat at decadal timescales.
Highlights
Atmospheric warming in the Arctic is forecast to far exceed the global average, reaching 2.2–8.3°C by 2100 (IPCC, 2013)
Following the approach employed in previous studies (e.g. Moon and Joughin, 2008; Carr and others, 2014), marineterminating outlet glacier frontal positions were obtained from a combination of Synthetic Aperture Radar (SAR) Image Mode Precision data (ERS-1, ERS-2 and Envisat), provided by the European Space Agency (ESA), and visible Landsat imagery, provided by the USGS Global Visualisation Viewer
Our results demonstrated that there was a widespread retreat of marine-terminating outlet glaciers between 1992 and 2010, and there was a marked increase in the rate of retreat from −30.5 m a−1 in 1992–2000 to −105.8 m a−1 for 2000–10 (Table 1; Fig. 1)
Summary
Atmospheric warming in the Arctic is forecast to far exceed the global average, reaching 2.2–8.3°C by 2100 (IPCC, 2013). Following changes in the south-east, glacier retreat began in the north-west from the mid-2000s (McFadden and others, 2011; Carr and others, 2013b; Murray, 2015), with almost 100% of glaciers in the region showing net retreat between 2000 and 2010 (Howat and Eddy, 2011). This was accompanied by substantial glacier acceleration (Moon and others, 2012) and ice loss (Khan and others, 2010). Glacier retreat and thinning has been observed across Svalbard since the early 20th century and has accelerated in recent years (e.g. Nuth and others, 2007; Blaszczyk and others, 2009; Moholdt and others, 2010; Nuth and others, 2010)
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