Although climate change and variability involves all aspects of the climate system, the assessment of anthropogenically-forced climate change has focused on surface temperature as the primary metric. Our contribution only addresses this very specific (and limited) metric of the climate system. The term global warming has been used to describe the observed surface air temperature increase in the 20th century. However, this concept of global warming requires assessments of units of heat (that is, Joules). Temperature, by itself, is an incomplete characterization of surface air heat content. Pielke <2003> used the concept of heat changes in the ocean, for example, to diagnose the radiative imbalance of the Earth's climate system. The oceans, of course, are the component of the climate system in which the vast majority of actual global warming or cooling occurs. In this contribution, we use the more limited application of the term global warming to refer to surface air changes.