«The figures below indicate a the number of stations with record length at least N years as a function of N, b the number of reporting stations as a function of time, c the percent of
hemispheric area located within 1200 km of a reporting station.»
Kobashi et al., 2007 http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.462.9271&rep=rep1&type=pdf «A large number of paleoclimatic records over
a hemispheric area show a large and abrupt climate change around 8200 years BP.
Not exact matches
«Our estimate for the mean soot effect on spectrally integrated albedos in the Arctic (1.5 %) and Northern Hemisphere land
areas (3 %) yields a Northern Hemisphere forcing of 0.3 W m2 or an effective
hemispheric forcing of 0.6 W m2.»
In the global or
hemispheric mean, the differences were imperceptible (since the US is only a small fraction of the global
area).
Using WBGT as a measure of environmental conditions conducive to heat stress, we show that anthropogenic influence has very substantially increased the likelihood of extreme high summer mean WBGT in northern
hemispheric land
areas relative to the climate that would have prevailed in the absence of anthropogenic forcing.
There is a large annual variation due to differences in
hemispheric land
areas.
For either choice of base period, the
hemispheric land
area with extremely hot temperature anomaly (> +3 σ) is more than a factor of 10 larger in recent years than in the 1930s
That would lead to a
hemispheric wide breakdown in the affected
areas infrastructure, governmental control and it's ability to direct recovery and total failures in the modern electrical / communication dependent food supply and food transport and water distribution networks leaving billions without the sophisticated infrastructure that underlies all of today's city centric society ability's to exist and survive.
In the GISTEMP index, the tables of zonal, global,
hemispheric means are computed by combining the 100 subbox series for each box of the equal
area grid, then combining those to get 8 zonal mean series, finally from those we get the Northern (23.6 - 90ºN), Southern and tropical means, always using the same method.
Year - to - year variability is so large for an
area the size of the United States that it is not essential to find an external mechanism for the deviation from the
hemispheric mean.