The purpose of this paper is to examine changes in the spatial varianc
e of mean monthly and daily temperatures that may have occurred during
the period of historical records. The northern hemispheric lower-trop
ospheric satellite-based temperature records from 1979 to 1996 and the
near-surface air temperature records from either 1947 to 1996 or 1897
to 1996 show relatively consistent temporal patterns with respect to
spatial variance. Overall, the spatial variance in temperature anomali
es has declined during the period of historical records; the interannu
al spatial variance levels in temperature anomalies are negatively rel
ated to mean hemispheric temperature. Both of these fundamental findin
gs are consistent with model simulations for increasing atmospheric co
ncentrations of greenhouse gases. It is further argued that these find
ings from the historical temperature records are consistent with a gro
wing body of literature on reductions in cyclone activity in the North
ern Hemisphere.