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Variations in Atmospheric CO2 Growth Rates Controlled by Tropical Temperature
Weile
Wang, CSUMB&NASA/ARC, weile.wang@gmail.com
(Presenter)
Philippe
Ciais, LSCE, philippe.ciais@lsce.ipsl.fr
Ramakrishna
R.
Nemani, NASA ARC, rama.nemani@nasa.gov
Josep
Canadell, CSIRO, pep.canadell@csiro.au
Shilong
Piao, Peking University, shilong.piao@lsce.ipsl.fr
Stephen
Sitch, University of Exeter, s.a.sitch@exeter.ac.uk
Michael
White, Utah State Univ., mikew@cc.usu.edu
Hirofumi
Hashimoto, CSUMB&NASA/ARC, hirofumi.hashimoto@gmail.com
Cristina
Milesi, CSUMB/NASA ARC, cristina.milesi@gmail.com
Ranga
Babu
Myneni, Boston University, rmyneni2013@gmail.com
Previous studies have highlighted the occurrence and intensity of El Niño-Southern Oscillation (ENSO) as important drivers of the interannual variability of the atmospheric CO2 growth rate, but the underlying biogeophysical mechanisms governing such connections remain unclear. Here we show a strong and persistent coupling (r2≈0.50) between interannual variations of the CO2 growth rate and tropical land-surface air temperature during 1959-2011, with a 1°C tropical temperature anomaly leading to a 3.5±0.6 PgC/yr CO2 growth-rate anomaly on average. Analysis of simulation results from dynamic global vegetation models (DGVMs) suggests that this temperature-CO2 coupling is contributed mainly by the additive responses of heterotrophic respiration (Rh) and net primary production (NPP) to temperature variations in tropical ecosystems. However, we find a weaker and less consistent (r2≈0.25) interannual coupling between CO2 growth rate and tropical land precipitation than diagnosed from the DGVMs, likely resulting from the subtractive responses of tropical Rh and NPP to precipitation anomalies that partly offset each other in the net ecosystem exchange (NEE ≈ Rh-NPP). Other climatic variability or extremes may induce transient reductions in the temperature-CO2 coupling, but the relationship is robust over the past 50 years and shows full recovery within a few years after any major variability event. Therefore, the relationship provides an important diagnostic tool for improved understanding of the contemporary and future global carbon cycle.
Presentation Type: Poster
Session: Poster Session 2-B
(Wed 4:30 PM)
Associated Project(s):
- Related Activity or Previously Funded TE Activity
Poster Location ID: 82
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