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Climate: From 'hot' to 'extremely hot'
January 31, 2012
This is the second in a series of posts by
Frederik Lichtenberg, PSR’s climate intern.
days, global warming makes spring come earlier and fall
later and the period in between to be hotter; summer-like conditions are
protracted. For this reason, in his recent article, “Perceptions of Climate
Change: The New Climate Dice,” global warming expert James Hansen focuses on
changes in summer temperatures.
and his co-authors point out that it is not only the quantity of “hot” events
that has risen but also the quality, which is indicated by a new category
referred to as “extremely hot.” This category, which refers to weather events more
than three standard deviations warmer than climatology would have predicted, did
not exist in the period from 1951-1980. Yet it is quite frequent to find
“extremely hot” weather events in the years 1981-2010.
emergence of this new “extremely hot” category shows that in order to describe
the climate of 1981-2010, then-existing categories were inadequate since such
extreme temperatures so infrequent during 1950-1981. The land areas affected by
these temperatures only covered a “few tenths of one percent” back then. The
current figure for the occurrence of such anomalies is 10%, a drastic increase
which shows very well just how intensely our climate has shifted towards warmer
temperatures in a very short period of time.
frequent temperatures of this magnitude suggest that well-remembered anomalies
such as the summer heat in the Moscow area in 2010 or Texas in 2011 were a
consequence of both global warming and specific local weather patterns at the
this trend – the climate dice loaded towards extreme heat – is expected to