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| Titel |
Abrupt rise in atmospheric CO2 at the onset of the Bølling/Allerød: in-situ ice core data versus true atmospheric signals |
| VerfasserIn |
P. Köhler, G. Knorr, D. Buiron, A. Lourantou, J. Chappellaz |
| 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 ; 7, no. 2 ; Nr. 7, no. 2 (2011-05-04), S.473-486 |
| Datensatznummer |
250004511
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| Publikation (Nr.) |
 copernicus.org/cp-7-473-2011.pdf |
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| Zusammenfassung |
| During the last glacial/interglacial transition the Earth's climate underwent abrupt changes
around 14.6 kyr ago. Temperature proxies from ice cores revealed the onset of the
Bølling/Allerød (B/A) warm period in the north and the start of the Antarctic Cold
Reversal in the south. Furthermore, the B/A was accompanied by a rapid sea level rise of
about 20 m during meltwater pulse (MWP) 1A, whose exact timing is a matter of current
debate. In-situ measured CO2 in the EPICA Dome C (EDC) ice core also revealed
a remarkable jump of 10 ± 1 ppmv in 230 yr at the same time. Allowing for the modelled age
distribution of CO2 in firn, we show that atmospheric CO2 could have jumped
by 20–35 ppmv in less than 200 yr, which is a factor of 2–3.5 greater than the
CO2 signal recorded in-situ in EDC.
This rate of change in atmospheric CO2 corresponds to 29–50% of
the anthropogenic signal during the last 50 yr and is connected with a
radiative forcing of 0.59–0.75 W m−2.
Using a model-based airborne fraction
of 0.17 of atmospheric CO2, we infer that 125 Pg of carbon need to be released into the
atmosphere to produce such a peak. If the abrupt rise in CO2 at the
onset of the B/A is unique with respect to other Dansgaard/Oeschger (D/O)
events of the last 60 kyr (which seems plausible if not unequivocal based on
current observations), then the mechanism responsible for it may also have
been unique. Available δ13CO2 data are neutral, whether the
source of the carbon is of marine or terrestrial origin. We therefore
hypothesise that most of the carbon might have been activated as a
consequence of continental shelf flooding during MWP-1A. This potential impact of rapid sea level
rise on atmospheric CO2 might define the point of no return during the last
deglaciation. |
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