No increase in global temperature variability despite changing regional patterns

Evidence from Greenland ice cores shows that year-to-year temperature
variability was probably higher in some past cold periods, but
there is considerable interest in determining whether global warming
is increasing climate variability at present. This interest is
motivated by an understanding that increased variability and
resulting extreme weather conditions may be more difficult for
society to adapt to than altered mean conditions. So far, however,
in spite of suggestions of increased variability, there is considerable
uncertainty as to whether it is occurring.
Regionally, greater year-to-year changes recently occurred
in much of North America and Europe. Many climate models predict
that total variability will ultimately decrease under high greenhouse
gas concentrations, possibly associated with reductions in sea-ice
cover. Our findings contradict the view that a warming world will
automatically be one of more overall climatic variation.