On the Heat Stored trends in the oceanic mixing layer and the Climate Change

The main components of the Climate system are the atmosphere and the ocean. The part of the ocean interacting with the atmosphere at annual time scale is the deepest mixed layer of the year. Within the mixed layer, temperature is almost constant with depth, so its average value can be approximated by the sea surface temperature. The heat capacity of the whole system is almost completely provided by the mixed layer of the upper ocean that interacts thermally with the atmosphere. The heat stored, calculated from this temperature and the maximum annual depth of the mixed layer, was integrated for zonal and meridional bands, for both hemispheres and globally. It was detected a global positive trend of this heat stored during 1903-1994, which is almost entirely due to a Southern Hemisphere warming, while the Northern Hemisphere did not show any trend. This different hemispheric behavior is also the outcome of models that include both aerosols and greenhouse gases forcing and therefore can be considered a fingerprint of the anthropogenic global warming. The pronounced cooling trend of the Northern Hemisphere from late 1950s to mid 1970s is not apparent in the Southern Hemisphere where a steady cooling trend is observed, and a subsequent warning.