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| Titel |
δ¹³Catm and [CO2] measurements in Antarctic ice cores, 160 kyrBP - present |
| VerfasserIn |
Sarah Eggleston, Jochen Schmitt, Robert Schneider, Fortunat Joos, Hubertus Fischer |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250091446
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| Publikation (Nr.) |
 EGU/EGU2014-5740.pdf |
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| Zusammenfassung |
| Measurements from Antarctic ice cores allow us to reconstruct atmospheric concentrations of
climatically important gases including CO2 over the past 800 kyr. Such measurements show
that [CO2] has varied in parallel with Antarctic temperatures on glacial-interglacial
timescales. Knowledge of the variations of the stable carbon isotope of CO2, δ13Catm, can
help us better understand the processes involved in these fluctuations. Here, we
present a first complete δ13Catmrecord extending from 160 kyrBP to the present
accompanied by δ15N2 measurements during Marine Isotope Stage 3 (MIS 3, 57 - 29
kyrBP).
The present record, measured primarily on ice from the EPICA Dome C and Talos Dome
ice cores, has an average resolution of 500 yr, focused mainly on the Last Glacial Maximum
and termination (180 yr; Schmitt et al., 2012), MIS 3 (660 yr), and Termination II through
MIS 5.4 (590 yr; Schneider et al., 2013). Throughout the record, δ13Catm varies between
approximately -6.8 and -6.4oá¸ollowing a period of relatively constant δ13Catm at the end of
MIS 6 (around -6.8), the boundaries of MIS 5 correspond roughly with the beginning and end
of a gradual enrichment in this isotope. In comparison, the more recent record depicts
three more abrupt excursions to lighter values around 63 - 59, 46, and 17 kyrBP,
in each case followed by a slower return (0.4oover the course of 5 - 15 kyr) to
more enriched isotopic values. These coincide with Heinrich events 6, 5, and 1,
respectively.
No direct correlation is observed between the concentration and carbon isotope of CO2
over the last 160 kyr. The data indicate rather that numerous processes, such as uptake and
release of atmospheric CO2 by the ocean and land biosphere, perhaps influenced by
regions of growing permafrost during MIS 3 and 4, acting on a variety of timescales
must be considered in explaining the evolution of δ13Catm on glacial-interglacial
timescales.
References:
Schmitt, J. et al. Science 336, 711-714 (2012)
Schneider, R. et al. Clim. Past, 9, 2507-2523 (2013) |
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