Here's a letter I sent to the editor of The Economist:
Last winter, we were told by scientists that it was `stupid' to
take the cold weather as evidence against global warming. Yet this
winter you are quite happy to speculate, entirely against the
consensus view, that the cold weather is evidence for global
warming (`A Cold Warming', Dec 4th). In
support of this fancy, you cite `some' evidence that summer heat
`may' induce shifts in atmospheric circulation that `might'
encourage seasonal patterns that would `probably' mean more cold
winters in Britain. Spare us the astrology, please.
The article contains the following paragraph:
Europe's cold winters and the warmth of the
planet as a whole might even be linked. There is some evidence that
the summer heat stored in the newly ice-free seas north of Siberia
may induce shifts in the atmosphere's circulation, when the heat is
given up to the air in subsequent autumns and winters. Those shifts
might in turn encourage seasonal patterns in which the Arctic is
warm and the continents below it cold, as in early 2010. Since the
sea-ice area looks likely to go on shrinking, such a link, if
indeed it exists, would probably mean more cold winters in Britain
and much of Europe.
There is a more serious point at issue here. Without man-made
global warming Britain experienced terrible winters like that of
1947 and 1963. If the Economist is right and it can still
experience such winters despite (or even because of) global
warming, then where exactly is the problem? How are we to
distinguish the effect of climate from weather?
Observe the following chart, from Willis Eschenbach, showing the temperature
record in Armagh, Northern Ireland. The dark blue line is climate
change (with a healthy helping urban heat island effect). The pale
blue fuzz is weather.