Larvatus Prodeo

My attention has been drawn to a blog piece by Andrew Bolt which purports to show graphical evidence to support the central dogma of the Stupid Cult of Cooling.

The centrepiece of Bolt’s article is a monthly series graph of global average temperatures from the Hadley Centre for Climate Change. On the basis of this graph Bolt claims that:

As you see, since 1998—an unusually warm year thanks to the “El Nino” pool of warmer water in the Pacific—the world’s temperature dropped back to a steady plateau, followed by a few years of cooling.

What Bolt either does not understand, or is not telling his readers, is that monthly series graphs register very short-term (i.e. monthly) fluctuations in global average temperatures. Short-term fluctuations tell us little about long-term trends, which is what the global warming debate is about. I explained this in the LP post linked to above, with reference to year to year trends which are subject to the influence of short-run trends such as movements in the El Nino/La Nina cycle (hereafter referred to as ENSO). What is true with respect to yearly fluctuations holds a fortiori for monthly fluctuations.
Continue reading ‘Rip Van Bolt’s missing months’