William H. Calvin, A Brain for All Seasons: Human Evolution and Abrupt Climate Change (University of Chicago Press, 2002). See also http://WilliamCalvin.com/BrainForAllSeasons/AMS2.htm.
ISBN 0-226-09201-1 (cloth) GN21.xxx0
Available from amazon.com or University of Chicago Press.
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William H. Calvin
University of Washington
civilizations began building immediately after the last great
continental ice sheets melted about 10,000 years ago, thanks to
agricultural success. Our present warm
period has been relatively mellow for the last 8,000 years, with fewer
fluctuations than any other similar period in the climate record.
The “Little Ice Age,” a cooling of less than one degree
that lasted from the early Renaissance to the middle of the nineteenth
century, was small stuff in comparison to the ice ages or the abrupt
But the Little Ice Age has a human scale.
You can recognize it by extrapolations from bad storms and
droughts in 20th century newsreels and television. “The Little Ice
Age,” the archaeologist Brian Fagan writes, “reminds us that
climate change is inevitable, unpredictable, and sometimes vicious.”
So it is worth a few pages on the Little Ice Age and
contemporary crop failures, just to give you an emotional base, one
from which you might conceivably manage to further extrapolate to
abrupt climate flips lasting centuries with tenfold greater
temperature excursions and far more widespread disruption of
Little Ice Age as a term is a little vague.
Its first recorded use in 1939 was a very informal analogy, not
a serious attempt at naming, and it covered the last 4,000 years!
The term probably caught on as a description of 1300-1850
because our images of those times came from paintings of ice skaters
on the rivers of Europe and tales of
people walking across the frozen Baltic between Denmark and Sweden.
Books on the subject feature the detailed wintertime scenes
painted by Peter Breughel the Elder during the first great winters of
the Little Ice Age about 1565. An exaggerated winter seems to be what we carry away from the
subject, what remains after we have forgotten the details.
Even historians are unhelpful.
You can read an excellent history of the last five centuries,
such as Jacques Barzun’s From Dawn to Decadence, without
finding the Little Ice Age mentioned even once.
And the average temperature changes of the Little Ice Age seem
small – what’s a degree or so, anyway?
None of us are used to dealing in yearly average temperatures,
and the annual mean temperature hides the combination of a cold winter
and a hot summer. Because
the means are never reported, we have no sense of how much a warm year
differs from a cooler year. We
have the same problem in judging how much difference several degrees
of global warming will make to our lives.
By focusing on temperature per se, we conveniently ignore the
more important aspects of climate change:
floods, droughts, high winds, dust storms, and unseasonable
weather that ruins harvests and sets up famines.
Unsettled extremes are also what the Little Ice Age was all
about. They are what cause people to starve, not what the
The most obvious causes of droughts are
changes in the winds, what happens with almost any climate change
scenario. Afternoon heating of inland regions causes air to rise,
attracting in moist air from offshore which, upon warming and rising
itself, dumps its moisture. Such
monsoon winds often fail for years.
Millions of people in India died in the monsoon failures of the
late 19th century, and relief efforts in earlier such famines were
hampered by the lack of transportation infrastructure.
In the 1930s, there were particularly
strong westerly winds in the U.S.
This extended the rain shadow of the Rocky Mountains farther
eastward and reduced the monsoons from the Gulf of Mexico, resulting
in the Dust Bowl conditions.
Lack of winds can also block rains: a persistent high pressure system, not an uncommon
occurrence, blocked weather systems that might have brought rain to
the American Midwest and East in the summer of 1988.
Searing heat caused at least half of the grain crops to be lost
in the northern Great Plains states.
Long stretches of the Mississippi River became so shallow that
barges were stranded on mud banks for weeks.
Huge forest fires burned major sections of Yellowstone National
Park that year.
When this much damage can be done in a single year, just
remember that serious droughts endure for decades. When people are
told to stop watering their lawns because of a water shortage, they
escalate (in the manner of sports hyperbole)
to use the same word, drought, as is used for far more
serious conditions, on a far vaster scale and lasting many years –
such as the 1930s Dust Bowl or those three Little Ice Age droughts
amidst good times in East Africa, lasting 30, 65, and 80 years.
Besides lack of rain, famines can occur from other climatic
causes, thanks to our reliance on agriculture to support a thousand
times greater population than before agriculture.
Too much rain at the wrong time can flatten wheat fields, one
of the reasons why the Irish shifted from a reliance on grains to less
chancy potatoes. Potatoes
were a huge success and the Irish population grew.
But the over reliance on potatoes left Ireland vulnerable to a
potato blight that crossed the Atlantic Ocean in the 1840s, causing
(together with the ineptitude and unfettered trade ideology of the
British government) the deaths of over a million Irish.
Far greater famines occurred in the twentieth century
exacerbated by politics, such as the Volga famine of 1921 and the
Ukrainian famine of 1932-33.
In addition to the miseries from famine and its associated
diseases, people created their own miseries, driven by a frantic urge
to “do something.” Scapegoating
surged as people blamed other people for their misfortunes.
Americans tend to look with suspicion on the Puritans because
of the Salem witch trials without realizing that this type of
scapegoating was endemic earlier all across Europe and not peculiar to
the Puritans. It
coincided with the demoralization produced by the worst years of
European climate change.
Fagan notes that “As scientists began to seek natural explanations for climatic phenomena, witchcraft receded slowly into the background.” While I hope it stays there, remember that most people still believe in horoscopes – and that most Americans have only rudimentary science literacy. The rational aspects of civilization are a thin veneer and scapegoating, perhaps escalating to genocide, could still happen in future climatic crises.
followed famine bringing epidemics in their train; bread riots and
general disorder brought fear and distrust.
Witchcraft accusations soared, as people accused their
neighbors of fabricating bad weather…. Sixty-three women were burned
to death as witches in the small town of Wisensteig in Germany in 1563
at a time of intense debate over the authority of God over the weather.
. . . Between 1580 and 1620, more than 1,000 people were burned to
death for witchcraft in the Bern region alone.
Witchcraft accusations reached a height in England and France in
the severe weather years of 1587 and 1588.
Almost invariably, a frenzy of prosecutions coincided with the
coldest and most difficult years of the Little Ice Age, when people
demanded the eradication of the witches they held responsible for their
Little Ice Age, 2000
is more terrible than to see ignorance in action.
Johann Wolfgang von Goethe
is an attempt, largely successful, to understand the
world, to get a grip on things, to get hold of ourselves, to steer a
safe course. Microbiology and meteorology now explain what only
a few centuries ago was considered sufficient cause to burn women to
Carl Sagan, 1996
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All of my books are on the web.
The six out-of-print books
are again available via Authors Guild reprint editions,