Comment on “Catastrophic ice shelf breakup as the source of Heinrich event icebergs” by C. L. Hulbe et al.

Alley, Richard B.; Andrews, John T.; Barber, Donald C.; Clark, Peter U.

doi:10.1029/2004pa001086

Cited by 32 publications

(28 citation statements)

References 29 publications

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“…Ice streams draining the LIS into the North Atlantic have also been identified as a source of ice rafted debris (IRD) found in the ocean sedimentary record (Bond et al, 1992). These layers of IRD on the ocean floor have been interpreted to document periods of significant dynamic mass loss from the Pleistocene ice sheets of the Northern Hemisphere (Heinrich events;Heinrich, 1988;Andrews, 1998), particularly, but not exclusively, in the vicinity of the Hudson Strait Ice Stream (MacAyeal, 1993;Andrews and MacLean, 2003;Hemming, 2004;Alley et al, 2005).…”

Section: Introductionmentioning

confidence: 98%

Ice streams in the Laurentide Ice Sheet: Identification, characteristics and comparison to modern ice sheets

Margold

Stokes

Clark

2015

Earth-Science Reviews

223

222

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This paper presents a comprehensive review and synthesis of ice streams in the Laurentide Ice Sheet (LIS) based on a new mapping inventory that includes previously hypothesised ice streams and includes a concerted effort to search for others from across the entire ice sheet bed. The inventory includes 117 ice streams, which have been identified based on a variety of evidence including their bedform imprint, large-scale geomorphology/ topography, till properties, and ice rafted debris in ocean sediment records. Despite uncertainty in identifying ice streams in hard bedrock areas, it is unlikely that any major ice streams have been missed. During the Last Glacial Maximum, Laurentide ice streams formed a drainage pattern that bears close resemblance to the present day velocity patterns in modern ice sheets. Large ice streams had extensive onset zones and were fed by multiple tributaries and, where ice drained through regions of high relief, the spacing of ice streams shows a degree of spatial self-organisation which has hitherto not been recognised. Topography exerted a primary control on the location of ice streams, but there were large areas along the western and southern margin of the ice sheet where the bed was composed of weaker sedimentary bedrock, and where networks of ice streams switched direction repeatedly and probably over short time scales. As the ice sheet retreated onto its low relief interior, several ice streams show no correspondence with topography or underlying geology, perhaps facilitated by localised build-up of pressurised subglacial meltwater. They differed from most other ice stream tracks in having much lower length-to-width ratios and have no modern analogues. There have been very few attempts to date the initiation and cessation of ice streams, but it is clear that ice streams switched on and off during deglaciation, rather than maintaining the same trajectory as the ice margin retreated. We provide a first order estimate of changes in ice stream activity during deglaciation and show that around 30% of the margin was drained by ice streams at the LGM (similar to that for present day Antarctic ice sheets), but this decreases to 15% and 12% at 12 cal ka BP and 10 cal ka BP, respectively. The extent to which these changes in the ice stream drainage network represent a simple and predictable readjustment to a changing mass balance driven by climate, or internal ice dynamical feedbacks unrelated to climate (or both) is largely unknown and represents a key area for future work to address.

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Section: Introductionmentioning

confidence: 98%

Ice streams in the Laurentide Ice Sheet: Identification, characteristics and comparison to modern ice sheets

Margold

Stokes

Clark

2015

Earth-Science Reviews

223

222

View full text Add to dashboard Cite

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“…The provenance of iceberg rafted debris (IRD) associated with Heinrich layers has been directly linked to a source region around Hudson Strait Andrews and Tedesco, 1992) where there is persuasive evidence for a large ice stream occupying the marine trough (Laymon, 1992;Andrews and MacLean, 2003). Although several mechanisms have been proposed as the cause of Heinrich events, it is most likely that ice streaming in Hudson Strait played a key role in the supply of IRD Andrews and MacLean, 2003;Hulbe et al, 2004;Alley et al, 2005).…”

Section: Introductionmentioning

confidence: 98%

Late Pleistocene ice export events into the Arctic Ocean from the M'Clure Strait Ice Stream, Canadian Arctic Archipelago

Stokes

Clark

Darby

et al. 2005

Global and Planetary Change

110

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“…While relevant to impact and climate policies assessment (see IPCC 2007b; Alley et al 2005), it is not possible to predict catastrophic change with any certainty as it is thought to revolve around major thresholds or tipping points where a small change in one or a combination of climate variables may result in a large change in other parts of the Earth's bio-geophysical system (e.g. in ocean currents or in ice sheet dynamics) (e.g., Hansen 2007).…”

Section: Overview Impacts At the City Scalementioning

confidence: 99%

The economics of climate change impacts and policy benefits at city scale: a conceptual framework

2010

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International audienceCities are particularly vulnerable to climate change and climate extremes in part because they concentrate many activities, people and wealth in limited areas. As a result they represent an important scale for assessment and understanding of climate change impacts. This paper provides a conceptual and methodological framework for urban economic impact assessment of climate change. The focus of the paper is on model-based analysis of future scenarios, including a framing of uncertainty for these projections, as one valuable input into the decision-making process. The paper highlights the main assessment difficulties, methods and tools, and selected examples across these areas. A number of challenges are unique to climate change impact assessment and others are unique to the problem of working at local scales. The paper also identifies the need for additional research, including the need for more integrated and systemic approaches to address climate change as a part of the urban development challenge as well as the need to assess the economic impacts of climate change and response policy at local scale

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Comment on “Catastrophic ice shelf breakup as the source of Heinrich event icebergs” by C. L. Hulbe et al.

Cited by 32 publications

References 29 publications

Ice streams in the Laurentide Ice Sheet: Identification, characteristics and comparison to modern ice sheets

Ice streams in the Laurentide Ice Sheet: Identification, characteristics and comparison to modern ice sheets

Late Pleistocene ice export events into the Arctic Ocean from the M'Clure Strait Ice Stream, Canadian Arctic Archipelago

The economics of climate change impacts and policy benefits at city scale: a conceptual framework

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