The effects of interannual climate variability on the moraine record

Valley glacier moraines are commonly used to infer past mean annual precipitation and mean melt-season temperature. However, recent research has demonstrated that, even in steady climates, multi-decadal, kilometer-scale fluctuations in glacier length occur in response to stochastic, year-to-year var...

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Bibliographic Details
Published in:Geology (Boulder) 2014-01, Vol.42 (1), p.55-58
Main Authors: Anderson, Leif S, Roe, Gerard H, Anderson, Robert S
Format: Article
Language:English
Subjects:
annual variations
Cenozoic
Climate change
Colorado
Effects
end moraines
Front Range
glacial extent
glacial features
glacial geology
glaciation
Glaciers
last glacial maximum
mathematical models
moraines
paleoclimatology
paleohydrology
Precipitation
Quaternary
Quaternary geology
Temperature
terminal moraines
United States
upper Quaternary
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Summary:Valley glacier moraines are commonly used to infer past mean annual precipitation and mean melt-season temperature. However, recent research has demonstrated that, even in steady climates, multi-decadal, kilometer-scale fluctuations in glacier length occur in response to stochastic, year-to-year variability in mass balance. When interpreting moraine sequences it is important to include the effect of interannual weather variability on glacier length; moraines record advances that are forced either by interannual variability or by a combination of climate change and interannual variability. We address this issue for the Last Glacial Maximum (LGM) glaciers of the Colorado Front Range, United States. Using a linear glacier model that allows thorough exploration of parameter uncertainties, supplemented by a shallow-ice flowline model, our analyses suggest that (1) glacial standstills longer than 50 years were unlikely; (2) mean glacier lengths are ∼10%-15% up-valley from maximum glacier lengths; and (3) individual LGM terminal moraines were formed by a combination of a climate change and interannual variability-forced advances.
ISSN:0091-7613
1943-2682
DOI:10.1130/G34791.1