Decadal Variability in the Terrestrial Carbon Budget Caused by the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation

Abstract

The terrestrial carbon dioxide (CO2) budget interacts with the Earth's climate system on diurnal to centennial and longer time scales, making it critical for climatic prediction and stabilization. Atmospheric observations and global syntheses of CO2 data indicate that the terrestrial biosphere is one the major sources of interannual variability, but the underlying mechanisms operating on different time-scales and the potential impacts of this on future projections remain unclear. Here it is shown that the El Nino and Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and Atlantic Multidecadal Oscillation (AMO) regime affect temporal variability in the terrestrial carbon budget with different time scales. The terrestrial carbon budget, estimated using a process-based model (VISIT) for the period 1910–2005, was correlated with the indices of PDO, AMO, and ENSO with various smoothing periods and lag lengths. ENSO showed the highest short-term correlation, corresponding to interannual terrestrial variability, whereas PDO and AMO had higher correlations at the decadal time scale. Such correlations with the meteorological regimes occurred heterogeneously over the land surface. This study suggests that long-term monitoring is needed to elucidate the temporal variability, and that decadal predictability of climate and terrestrial models should be improved further.