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Carr et al., 2013 (Basics (Joughin et al, van de Broke are two main…
Carr et al., 2013
Basics
Until recently, it was assumed that Arctic ice masses responded to climatic/oceanic forcing over millennia however observations made over the past two decades have proved this incorrect.
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The paper reviews the progress made over the past few decades into understanding MTOGs behaviour in response to ocean-climate systems.
Looked at Alaska, Greenland (Helhein, Kangerdlugssuaq, Jakobshavn Isbrae), Svalbard, Canadian Arctic and Russian High Arctic
Arctic warming is expected to far exceed the global average and is forecast to reach up to 7 degrees by 2100 (IPCC, 2007)
Assessing the potential response of Arctic ice masses to climate change is there- fore crucial for the accurate prediction of near-future sea level rise (IPCC, 2007)
MTOG defined as a channel of fast-moving ice that drains an ice cap or ice sheet and terminates in the ocean, at either a floating or grounded margin (Benn and Evans, 2010)
Joughin et al, van de Broke are two main contributors in this past decade in helping advance our knowledge and understanding that glaciers have rapidly lost mass since the 90s.
Joughin et al., 2010 showed that mass loss is concentrated to the coastal markings, predominantly MTOGs
Figures from the Antarctic back up MTOGs playing a large role in the loss of mass from ice sheets (Pine Island Glacier)
Recent mass deficits have been attributed to both increased marine-terminating outlet glacier discharge and to a more negative surface mass balance (SMB), primarily resulting from increased surface melting relative to accumula- tion (Rignot et al., 2008, 2011; van den Broeke et al., 2009; Zwally et al., 2011)
Sea ice concentrations
The increasing focus on oceanic forcing has led to further consideration of the influence of sea ice on marine-terminating Arctic outlet gla- cier behaviour
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Sea ice may significantly impact upon SMB (Bamber et al.,2004)
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In both northern and southern Greenland sea ice concentrations at Jakobshavn Isbrae appear to influence the timing and nature of calving events, but this occurs on seasonal, as opposed to decadal, timescales (Joughin et al., 2008)
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Ocean forcing
oceanic forcing has been recently recognized as a key control on marine-terminating outlet glacier dynamics.
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Oceanic forcing may be of particular concern in the near future, as model predictions suggest that ocean temperatures around the GIS may warm by 1.7–2C by 2100 (Yin et al., 2012)
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Conclusions
Results from the GIS have highlighted the substantial variation in marine-terminating outlet glacier response to climatic/oceanic forcing
Numerical modelling results have improved our understanding of marine-terminating outlet glacier behaviour, but remain a key area for future development.
Arctic ice masses have rapidly lost mass since the mid-1990s due to a combination of negative SMB and accelerated discharge from marine- terminating glaciers (van den Broeke et al., 2009).
The response of marine- terminating Arctic outlet glaciers to climatic/ oceanic forcing remains a key area for future research and is crucial for accurate prediction of near-future sea level rise and Arctic ice mass response to climate warming.
Air temperature
Arctic air temp has raised substantially since the 90s (Hanna et al., 2004)
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Increased surface melt reaches the bed through crevasses and moulins, causing enhanced basal sliding so there is dynamic thinning of the glacier and increased longitudinal stresses causing more crevasses. The equilibrium line migrates inland creating a bigger ablation zone.
