The sum of these upward directed fluxes

Although insignificant regarding the anthropogenic heat flux of all individual sources, increased ground surface temperatures (GST) are the most dominant contributor of anthropogenic heat flow in Cologne, with values of 0.4 ± 0.1 PJ/a due to the spatial extent of the affected areas. In Karlsruhe, fluxes from increased GST generate a heat flow of 0.3 ± 0.1 PJ/a, which represents the second largest source of anthropogenic heat flow in the groundwater.