Geothermal heat flux and its influence on the oceanic abyssal circulation and radiocarbon distribution

Geothermal heating of abyssal waters is rarely regarded as a significant driver of the large-scale oceanic circulation. Numerical experiments with the Ocean General Circulation Model POTSMOM-1.0 suggest, however, that the impact of geothermal heat flux on deep ocean circulation is not negligible. Geothermal heating contributes to an overall warming of bottom waters by about 0.4 degrees C, decreasing the stability of the water column and enhancing the formation rates of North Atlantic Deep Water and Antarctic Bottom Water by 1.5 Sv (10%) and 3 Sv (33%), respectively. Increased influx of Antarctic Bottom Water leads to a radiocarbon enrichment of Pacific Ocean waters, increasing Delta C-14 values in the deep North Pacific from -269 parts per thousand when geothermal heating is ignored in the model, to -242 parts per thousand when geothermal heating is included. A stronger and deeper Atlantic meridional overturning cell causes warming of the North Atlantic deep western boundary current by up to 1.5 degrees C. Citation: Hofmann, M., and M. A. Morales Maqueda (2009), Geothermal heat flux and its influence on the oceanic abyssal circulation and radiocarbon distribution, Geophys. Res. Lett., 36, L03603, doi: 10.1029/2008GL036078.