Does terrestrial drought explain global CO 2 flux anomalies induced by El Niño?

Christopher R Schwalm, C. A. Williams, K. Schaefer, I. Baker, G. J. Collatz, C. Rödenbeck

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

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 CO 2 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 CO 2 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 CO 2 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.

Original languageEnglish (US)
Pages (from-to)2493-2506
Number of pages14
JournalBiogeosciences
Volume8
Issue number9
DOIs
StatePublished - 2011
Externally publishedYes

Fingerprint

net ecosystem exchange
drought
anomaly
climate
eddy covariance
Southern Africa
land cover
bottom-up approach
oscillation
Southern Oscillation
atmospheric transport
uncertainty
weather
carbon cycle
global climate
carbon

ASJC Scopus subject areas

  • Earth-Surface Processes
  • Ecology, Evolution, Behavior and Systematics

Cite this

Schwalm, C. R., Williams, C. A., Schaefer, K., Baker, I., Collatz, G. J., & Rödenbeck, C. (2011). Does terrestrial drought explain global CO 2 flux anomalies induced by El Niño? Biogeosciences, 8(9), 2493-2506. https://doi.org/10.5194/bg-8-2493-2011

Does terrestrial drought explain global CO 2 flux anomalies induced by El Niño? / Schwalm, Christopher R; Williams, C. A.; Schaefer, K.; Baker, I.; Collatz, G. J.; Rödenbeck, C.

In: Biogeosciences, Vol. 8, No. 9, 2011, p. 2493-2506.

Research output: Contribution to journalArticle

Schwalm, CR, Williams, CA, Schaefer, K, Baker, I, Collatz, GJ & Rödenbeck, C 2011, 'Does terrestrial drought explain global CO 2 flux anomalies induced by El Niño?', Biogeosciences, vol. 8, no. 9, pp. 2493-2506. https://doi.org/10.5194/bg-8-2493-2011
Schwalm, Christopher R ; Williams, C. A. ; Schaefer, K. ; Baker, I. ; Collatz, G. J. ; Rödenbeck, C. / Does terrestrial drought explain global CO 2 flux anomalies induced by El Niño?. In: Biogeosciences. 2011 ; Vol. 8, No. 9. pp. 2493-2506.
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