(Part of the How to Talk to a Global Warming Skeptic guide)
Objection: Some stations, in the U.S. for example, show cooling trends. If there were really global warming, it would be warming everywhere.
Answer: Global warming is the long-term increase in globally and seasonally averaged surface temperatures. It is not the case, nor is it expected, that all regions on the planet, let alone all weather stations, will show the same changes in temperature or rainfall patterns. Many stations have shown cooling, and some small regions have shown modest cooling as well. This does not invalidate global warming theory; it is merely the result of regional variation, and an example of how varied and complex the climate system is.
The contrarian website CO2 Science makes this fallacious argument part of its homepage by featuring a “Station of the Week” that’s exhibited trends significantly different from the global one. Given the effort and technical content behind that website, and the fact that they prominently display this intellectual sleight of hand, I think it is safe to say they are simply being dishonest.
All of the various global temperature trend analyses show significant warming in the average temperature:
These analyses agree with the expectations of climate theory, as well as all the other lines of evidence.