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| Titel |
Does terrestrial drought explain global CO2 flux anomalies induced by El Niño? |
| VerfasserIn |
C. R. Schwalm, C. A. Williams, K. Schaefer, I. Baker, G. J. Collatz, C. Rödenbeck |
| 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 ; 8, no. 9 ; Nr. 8, no. 9 (2011-09-09), S.2493-2506 |
| Datensatznummer |
250006115
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| Publikation (Nr.) |
 copernicus.org/bg-8-2493-2011.pdf |
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| Zusammenfassung |
| The El Niño Southern Oscillation is the dominant year-to-year mode of
global climate variability. El Niño effects on terrestrial carbon
cycling are mediated by associated climate anomalies, primarily drought,
influencing fire emissions and biotic net ecosystem exchange (NEE). Here we
evaluate whether El Niño produces a consistent response from the global
carbon cycle. We apply a novel bottom-up approach to estimating global NEE
anomalies based on FLUXNET data using land cover maps and weather
reanalysis. We analyze 13 years (1997–2009) of globally gridded
observational NEE anomalies derived from eddy covariance flux data,
remotely-sensed fire emissions at the monthly time step, and NEE estimated
from an atmospheric transport inversion. We evaluate the overall consistency
of biospheric response to El Niño and, more generally, the link between
global CO2 flux anomalies and El Niño-induced drought. Our
findings, which are robust relative to uncertainty in both methods and
time-lags in response, indicate that each event has a different spatial
signature with only limited spatial coherence in Amazônia, Australia and
southern Africa. For most regions, the sign of response changed across El
Niño events. Biotic NEE anomalies, across 5 El Niño events, ranged
from –1.34 to +0.98 Pg C yr−1, whereas fire emissions anomalies were
generally smaller in magnitude (ranging from –0.49 to +0.53 Pg C yr−1). Overall drought does not appear to impose consistent terrestrial
CO2 flux anomalies during El Niños, finding large variation in
globally integrated responses from –1.15 to +0.49 Pg C yr−1. Despite
the significant correlation between the CO2 flux and El Niño
indices, we find that El Niño events have, when globally integrated,
both enhanced and weakened terrestrial sink strength, with no consistent
response across events. |
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