Predictability Horizons in the Global Carbon Cycle Inferred From a Perfect‐Model Framework
Aaron Spring, Tatiana Ilyina
Abstract
Abstract On interannual timescales the growth rate of atmospheric CO 2 is largely controlled by the response of the land and ocean carbon sinks to climate variability. Yet, it is unknown to what extent this variability limits the predictability of atmospheric CO 2 variations. Using perfect‐model Earth System Model simulations, we show that variations in atmospheric CO 2 are potentially predictable for 3 years. We find a 2‐year predictability horizon for global oceanic CO 2 flux with longer regional predictability of up to 7 years. The 2‐year predictability horizon of terrestrial CO 2 flux originates in the tropics and midlatitudes. With the predictability of the isolated effects of land and ocean carbon sink on atmospheric CO 2 of 5 and 12 years respectively, land dampens the overall predictability of atmospheric CO 2 variations. Our research shows the potential of Earth System Model‐based predictions to forecast multiyear variations in atmospheric CO 2 .