The conceptualization of “global warming” has become so entrenched in the lexicon that few give much thought to its dubious derivation.
Many assume that “global warming” actually means that all or nearly all of the globe is warming as a consequence of the “well-mixed” greenhouse gases in the atmosphere (i.e., CO2 concentrations have indeed reached right about 400 parts per million from the Arctic to Antarctica, or all across the globe). In reality, however, only parts of the globe have been warming. Large regions of the Earth have seen stable or falling temperatures in recent decades, or even dating back to the mid-20th century, when anthropogenic emissions have been claimed to have caused most climate changes.
The only means by which it could be said that we have had global-scale warming is to presume that only the overall net temperature difference counts – for all the regions of the world added together. The regions of the world where it has not been warming necessarily do not count in the “global warming” conceptualization.
Let’s say that Greenland has warmed by 1.2° C since 1979, but Antarctica has cooled by -0.9° C since 1979. Would it be misleading to add these two regions together and claim that the poles have warmed by tenths of a degree in the last 37 years? Yes, because one pole has not been warming, but cooling – even though both poles are subjected to the same atmospheric CO2 concentrations. But this mischaracterization of temperature trends (effectively claiming that both poles have been warming when only one has) is precisely what is done in framing the “global warming” conceptualization.
As a prototypical example of “global warming” manufacture, consider the recently published Riser et al. (2016) paper entitled, “Fifteen years of ocean observations with the global ARGO array” (below). The 25 authors summarize the temperature changes in the 0-700 m near-surface layer for all the ocean regions combined since 1950. They point out that the Pacific Ocean all the way “from Chile to Alaska” has cooled by -1° C during the last 65 years. Other parts of the oceans have warmed by 1° C to compensate. And when all the cooling and warming regions of the oceans are added together, the warming regions barely win out, scoring a net gain of “nearly 0.2°C” since the mid-20th century. So because the net temperature change has been slightly positive, it can technically (albeit misleadingly) be said that the global oceans have been warming. This way, the large regions of the oceans that have been cooling can be buried and ignored, and the “global warming” conceptualization remains intact.