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| Titel |
Fall season atypically warm weather event leads to substantial CH4 loss in Arctic ecosystems? |
| VerfasserIn |
Donatella Zona, Virginie Moreaux, Anna Liljedahl, Salvatore Losacco, Patrick Murphy, Walter Oechel |
| 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 |
250087282
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| Publikation (Nr.) |
 EGU/EGU2014-1314.pdf |
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| Zusammenfassung |
| In the last century (during 1875-2008) high-latitudes are warming at a rate of 1.360C
century-1, almost 2 times faster than the Northern Hemisphere trend (Bekryaev et al., 2010).
This warming has been more intense outside of the summer season, with anomalies of 1.09,
1.59, 1.730C in the fall, winter, and spring season respectively (Bekryaev et al., 2010). This
substantial temperature anomalies have the potential to increase the emission of greenhouse
gas (CO2 and CH4) fluxes from arctic tundra ecosystems. In particular, CH4 emissions,
which are primarily controlled by temperature (in addition to water table), can steeply
increase with warming. Despite the potential relevance of CH4 emissions, very few
measurements have been performed outside of the growing season across the entire Arctic,
due to logistic constrains. Importantly, no flux measurements achieved a temporal and spatial
data coverage sufficient to estimate with confidence an annual CH4 emissions from
tundra ecosystem in Alaska, and its sensitivity to warming. Fall 2013 was unusually
warm in central and northern Alaska. Following a relatively warm summer with
dramatically above-average rainfall, the October mean monthly temperatures was the 4th
and top warmest in Barrow (1949-2013) and Ivotuk (1998-2013), respectively.
As we just upgraded several eddy covariance towers to measure CO2 and CH4
fluxes year-round, the atypical weather conditions of fall 2013 represented a unique
chance for testing the sensitivity of CH4 loss to these atypically warm temperatures.
All our sites across a latitudinal gradient (from the northern site, Barrow, to the
southern site, Ivotuk), presented substantial CH4 loss in the fall. Importantly, in two
of these sites (Barrow, Ivotuk) where the fall weather was substantially warmer
than the long term trend, fall CH4 emission represented between 44-63% of the
June-November cumulative emission. Surprisingly, in the southernmost site (Ivotuk), when
the temperature anomaly was the highest, cumulative fall CH4 emission outpaced
even the summer emission. This shows the sensitivity of CH4 loss to abnormal
conditions, and the importance of fall periods for the annual CH4 budget in these Arctic
ecosystems.
Bekryaev, R. V., I. V. Polyakov, and V. A. Alexeev. 2010. Role of polar amplification in
long-term surface air temperature variations and modern Arctic warming. Journal of Climate
23(14):3888–3906. |
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