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| Titel |
Impact of an abrupt cooling event on interglacial methane emissions in northern peatlands |
| VerfasserIn |
S. Zürcher, R. Spahni, F. Joos, M. Steinacher, H. Fischer |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 3 ; Nr. 10, no. 3 (2013-03-20), S.1963-1981 |
| Datensatznummer |
250018166
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| Publikation (Nr.) |
 copernicus.org/bg-10-1963-2013.pdf |
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| Zusammenfassung |
| Rapid changes in atmospheric methane (CH4), temperature and
precipitation are documented by Greenland ice core data both for
glacial times (the so called Dansgaard-Oeschger (D-O) events) as well
as for a cooling event in the early Holocene (the 8.2 kyr
event). The onsets of D-O warm events are paralleled by abrupt
increases in CH4 by up to 250 ppb in a few
decades. Vice versa, the 8.2 kyr event is accompanied by an
intermittent decrease in CH4 of about 80 ppb over
150 yr. The abrupt CH4 changes are thought to mainly
originate from source emission variations in tropical and boreal wet
ecosystems, but complex process oriented bottom-up model estimates
of the changes in these ecosystems during rapid climate changes are
still missing. Here we present simulations of CH4 emissions
from northern peatlands with the LPJ-Bern dynamic global vegetation
model. The model represents CH4 production and oxidation in
soils and transport by ebullition, through plant aerenchyma, and by
diffusion. Parameters are tuned to represent site emission data as
well as inversion-based estimates of northern wetland emissions. The
model is forced with climate input data from freshwater hosing
experiments using the NCAR CSM1.4 climate model to simulate an
abrupt cooling event. A concentration reduction of ~10 ppb
is simulated per degree K change of mean northern hemispheric surface
temperature in peatlands. Peatland emissions are equally sensitive to both
changes in temperature and in precipitation.
If simulated changes are taken as an analogy to the 8.2 kyr event, boreal
peatland emissions alone could only explain 23% of the 80 ppb
decline in atmospheric methane concentration. This points
to a significant contribution to source changes from low latitude and tropical wetlands
to this event. |
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