Interannual variability in the global uptake of CO 2

A major uncertainty are the causes for interannual variability of the global ocean uptake of CO 2 . Existing estimates, based on atmospheric CO 2 data, indicate that peak‐to‐peak interannual variability in ocean uptake of CO 2 is up to 2–4 Pg C year −1 (Pg = 10 15 g), while those estimates based on ocean observations and models suggest that year‐to‐year variability is much smaller (∼0.4–0.8 Pg C year −1 ). Here, it is shown that these differences can be partly reconciled if global air‐sea CO 2 flux estimates include the CO 2 flux associated with tropical cyclones (TC), extra‐tropical cyclones (ETC), and new air‐sea CO 2 gas exchange relationships. The impact of storm events on air‐sea CO 2 flux is influenced by climate variability such as the El Niño/Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO), contributing to an interannual peak‐to‐peak variability in global ocean uptake of CO 2 of up to ∼1.8 Pg C year −1 .