Logic Goes Extinct
As Press Overplays Overpeck
Federal climatologist Jonathan
Overpeck is in danger of replacing NASAs James Hansen as the 1998 Apocalyst Poster
Child. Overpeck recently released a spate of papers and conference presentations about
past and future climate.
In the Bulletin of the American
Meteorological Society, for example, he argued that, with or without human-induced
global warming, were headed for some tremendous droughts next century. And, of
course, the greenhouse effect will make things even worse!
And in an earlier presentation at the
December meeting of the American Geophysical Union, Overpeck asserted the so-called
Medieval Warm Period was local, not global. Well concentrate on that one here.
His bombshell concept is that the
Medieval warming was so substantial that it allowed the Vikings to sail westward without
freezing to death, colonizing Greenland and North America, but it was not created by a
general planetary warming. This theory implies that the Little Ice Age, the cooling that
later decolonized that area, was similarly nonglobal; otherwise the Warm Period would have
shown up as, well, global warming, compared with succeeding centuries.
Overpecks speech prompted
handsprings of joy from our greener friends. Now, instead of saying that the 1990s (and,
in particular, 1998) are the warmest in 600 years (which goes back to the beginning of the
putative Warm Period), they can say theyre the warmest in 1,200 years.
"Obviously," they can remark, "the Warm Terror is here and we need to raise
taxes pronto to stop the burning of fossil fuels."
Others might say, "Sure am glad
I havent spent a lick on heating oil and its almost Christmas. Think Ill
go and buy some stuff for the missus."
Still others, somewhat more penurious
and even-headed, realize that Overpeck has created the apocalysts biggest nightmare.
If hes right, then regional climate naturally varies tremendously, whether or
not the globe warms. Climate changes so dramatic that they promoted Viking exploration are
simply the way of things. And ditto for their flipsidelarge regional coolings such
as the Little Ice Age, an event that sent the Rhone Glacier in the Alps some 5,000 feet
farther downslope than it is today.
Poignant testimony to the social
consequences of this regional swing can be found in Kalaallit Nunaat (Thats
politically correctese for Greenland these days), where masonry churches, once built in
pastures, are now encased in ice. While K.Ns climate clearly changed in ways that
were tremendously important to society in Viking times, this apparently had nothing to do
with global warming or cooling.
Instead, Overpeck says, these changes
occurred as pure internal oscillations of the climate system, with no external global
If we accept the notion that large
regional changes in climate are independent of the global temperature, what does it really
mean? Forecast climate changes of the magnitude that is driving the current hysteria will
occur whether or not the planet warms. Further, those who would seek to impose
costs on society now must demonstrate that warming the planet will make these changes
more, not less, likely.
We recently explored this notion in
the refereed literature. Relying upon data (and explicitly ignoring computer models of
climate because of their patent unreality), we found that temperature variability between
seasons and between years has significantly declined in the second half of this century.
And there have been a few warm years in that period, too.
So, when we looked at the variability
as a function of the planets annual temperature, we found that the cool years were
more variable and the warmer ones less so, as our figure shows. Conclusion? Warming the
planet decreases variability on a year-to-year scale. Cooling the planet makes
things more variable.
Figure 1. Our
recent look into the relationship between global temperatures and temperature variability
showed that higher temperatures are associated with less temperature variability
and lower temperatures.
We think thats pretty good
evidence that what human beings are doing to the climate makes things more predictable and
equable than before.
Want more evidence? When the
atmospheres carbon dioxide concentration was at its highest level since animals
first appeared, the largest animals in history roamed the earth: dinosaurs. These beasts
required a tremendous amount of vegetation to reach their enormous size. Carnivores such
as T. rex were in turn supported by the massive herbivores. How many tons of vegetation
were ultimately required to feed him, considering it had to pass through huge lunks like
Apatosaurus? (Thats Brontosaurus to you intellectual dinosaurs.) The earth had to
have been greened beyond recognition.
Whats more, when the dinos were
around, the climate was so stable that they were cold-blooded! Theyd probably still
be here today if they hadnt gone extinct when the earth got clobbered by a small
asteroid. Said asteroid raised a huge cloud of dust and killed them with global cooling,
which made the climate more variable, resulting in an undependable food supply.
We think our greener friends might go
extinct too if they tout Overpecks findings as good news for their side.
1998, How unprecedented is recent Arctic warming: A look back to the medieval Warm Period.
Presented to the Fall Meeting of the American Geophysical Union, San Francisco, Calif.
Michaels, P.J., et
al., 1998, Analysis of trends in the variability of daily and monthly historical
temperature measurements. Climate Research, 10, 2733.
The long-awaited drop in global
temperatures following the breakdown of last years massive El Niņo has finally
appeared in the observations.
The global temperature departures, as
measured by satellites, show a large decline from October to Novembermore than a
quarter of a degree Celsius. We had previously hypothesized (WCR,
Vol. 4, No. 3)
that this decline would occur as the Northern Hemisphere transitioned from a summerlike
regime to a winterlike one.
It looks as if this switch took place
last month (see Earth Track Focus) for more detail.
That 1998s extremely warm
temperatures were largely confined to one calendar year makes the annual record high
temperature 1998 has established quite a difficult one to break.
If we were of a betting sort (and
there are some nasty rumors going around that we are), we would be willing to wager that
the 10-year period beginning in January 1998 and extending through December 2007 will show
a statistically significant downward trend in the monthly satellite record of global
Surely such a wager should sound
interesting to those who think the planetary temperature will increase several tenths of a
degree during that period.
No reasonable offers refused...