The wilderness article states that drinking a liter of warm liquid will raise your core body temp 0.3 degrees. A cold liquid will lower it by the same amount. A very hot liquid may raise your temp even more. This 0.6 to 1.0 degree difference in core temp is very very significant. Why they think this is insignificant is beyond me. It is so important that the joint commision for hospitals is requiring the collection and reporting of data on mild hypothermia postoperatively for surgical patients and extra efforts are being used to prevent even mild hypothermia in the operating room. Even a couple of degrees makes a huge difference in bloods ability to clot in a trauma situation. Also the "fact" is that surface area is not the common denominator for heat loss. Due to differences in radiation, insulation, conduction, convection, blood supply and autoregulation your head loses a lot more heat under almost all circumstances than your fat ass.