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| Titel |
Numerical studies on the Impact of the Last Glacial Cycle on recent borehole temperature profiles: implications for terrestrial energy balance |
| VerfasserIn |
H. Beltrami, G. S. Matharoo, L. Tarasov, V. Rath, J. E. Smerdon |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 10, no. 5 ; Nr. 10, no. 5 (2014-09-10), S.1693-1706 |
| Datensatznummer |
250117049
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| Publikation (Nr.) |
 copernicus.org/cp-10-1693-2014.pdf |
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| Zusammenfassung |
| Reconstructions of
past climatic changes from borehole temperature profiles are important
independent estimates of temperature histories over the last millennium.
There remain, however, multiple uncertainties in the interpretation of these
data as climatic indicators and as estimates of the changes in the heat
content of the continental subsurface due to long-term climatic change. One
of these uncertainties is associated with the often ignored impact of the
last glacial cycle (LGC) on the subsurface energy content, and on the
estimate of the background quasi steady-state signal associated with the
diffusion of accretionary energy from the Earth's interior. Here, we provide
the first estimate of the impact of the development of the Laurentide ice
sheet on the estimates of energy and temperature reconstructions from
measurements of terrestrial borehole temperatures in North America. We use
basal temperature values from the data-calibrated Memorial University of
Newfoundland glacial systems model (MUN-GSM) to quantify the extent of the
perturbation to estimated steady-state temperature profiles, and to derive
spatial maps of the expected impacts on measured profiles over North America.
Furthermore, we present quantitative estimates of the potential effects of
temperature changes during the last glacial cycle on the borehole
reconstructions over the last millennium for North America. The range of
these possible impacts is estimated using synthetic basal temperatures for a
period covering 120 ka to the present day that include the basal temperature
history uncertainties from an ensemble of results from the calibrated
numerical model. For all the locations, we find that within the depth ranges
that are typical for available boreholes (≈600 m), the induced
perturbations to the steady-state temperature profile are on the order of
10 mW m−2, decreasing with greater depths. Results indicate that
site-specific heat content estimates over North America can differ by as much
as 50%, if the energy contribution of the last glacial cycle in those
areas of North America that experienced glaciation is not taken into account
when estimating recent subsurface energy changes from borehole temperature
data. |
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