Document Type



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. © Author(s) 2011.

Publication Title


Publication Date






First Page


Last Page







atmosphere-biosphere interaction, atmospheric transport, biogeochemistry, bottom-up approach, carbon dioxide, carbon flux, climate change, data set, drought, eddy covariance, El Nino-Southern Oscillation, fire behavior, flux measurement, global climate, global perspective, land cover, net ecosystem exchange, source-sink dynamics, terrestrial environment

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Included in

Geography Commons



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.