Interannual variability in the global uptake of CO2

A major uncertainty are the causes for interannual variability of the global ocean uptake of CO2. Existing estimates, based on atmospheric CO2 data, indicate that peak-to-peak interannual variability in ocean uptake of CO2 is up to 2–4 Pg C year?1 (Pg = 1015 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 CO2 flux estimates include the CO2 flux associated with tropical cyclones (TC), extra-tropical cyclones (ETC), and new air-sea CO2 gas exchange relationships. The impact of storm events on air-sea CO2 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 CO2 of up to ?1.8 Pg C year?1