Predictable variations of the carbon sinks and atmospheric CO2 growth in
a multi-model framework
Abstract
Inter-annual to decadal variability in the strength of the land and
ocean carbon sinks impede accurate predictions of year-to-year
atmospheric carbon dioxide (CO2) growth rate. Such information is
crucial to verify the effectiveness of fossil fuel emissions reduction
measures. Using a multi-model framework comprising prediction systems
based on Earth system models, we find a predictive skill for the global
ocean carbon sink of up to 6 years. Longer regional predictability
horizons and robust spatial patterns are found across single models. On
land, a predictive skill of up to 2 years is primarily maintained in the
tropics and extra-tropics enabled by the initialization of the physical
climate variables towards observations. We further show that anomalies
of atmospheric CO2 growth rate inferred from natural variations of the
land and ocean carbon sinks are predictable at lead time of 2 years and
the skill is limited by the land carbon sink predictability horizon.