Current published global estimates of CO2 outgassing from inland waters range from 0.75 to 1.2 Pg C/y (Cole et al. 2007; Battin et al. 2009). These estimates largely ignore the tropical freshwaters despite conservative estimates by Richey et al. (2002) that the Amazon alone outgasses 0.5 Pg C/y from surface waters and that waters in all the humid tropics likely outgas 0.9 Pg C/y. Recent field and remote sensing data suggest that the estimates from Richey et al (2002) were underestimated by a factor of 2 or more for the humid tropics. Here we completely re-evaluate global outgassing by all inland waters by latitude bins, based on new data on pCO2 concentrations, gas exchange velocities (k), and the spatial and temporal distribution of continental inundation by inland water types. Our preliminary results suggest that global CO2 outgassing is likely 3 Pg C/y, with nearly 2 Pg C/y from the tropics.
Aufdenkampe, A. K., Mayorga, E., Alin, S R, Raymond, P, Melack, J M, Doney, S C. (2010): Spatially and Temporally Distributed Re-evaluation of Global CO2 Outgassing from Inland Waters: The Tropics Dominate Global Fluxes Abstract B24A-02 . Abstract B24A-02. AGU Fall Meeting, San Francisco, CA, December 13-17..