FW: [Odonata-l] Range changes

[John Acorn]

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From: "John Acorn" <janature@compusmart.ab.ca>
To: Richard Rowe <Richard.Rowe@jcu.edu.au>
Subject: Re: [Odonata-l] Range changes
Date: Mon, Nov 5, 2001, 5:00 PM


Odesters,

Richard Rowe mentioned the Norse colonists of Greenland, and how climate
change destroyed their once-lovely home.  I thought you folks might be
interested in an alternative, entomological explanation-- the moth that ate
Greenland.  The nocutuid moth Eurois occulta (L.), probably played a major
role here.  I read about it in Louis Hanfield's book "Les Guide des
Papillons du Qu=C8bec."  (Version scientifique.  Broquet Inc., Ottawa.  p.
756).  In short, he argues that the Vikings accidentally introduced the
moth, and that the caterpillars became super abundant and ate every green
leaf in sight.  In support of this, there are reports of caterpillars so
thick on the rocks by the sea that kayaks could not be landed due to the
slipperiness of their collective squished bodies.  As well, there are layer=
s
in Greenland peat bogs made up of almost nothing but the remains of Eurois
pupae.  Interesting, no?

When I was a student, I had the good fortune to take a course in Quaternary
environments.  I think that was in 1985.  Back then, no one had heard of
global warming.  I was taught that the first half of the 20th century was
the warmest period in the last 1000 years, and that the climate was cooling
at the time I took the course.  I was also taught that the "little ice age"
and the "hypsithermal" warm period were both slippery concepts, and that th=
e
evidence from one site rarely corresponded with that from another.  The tak=
e
home message seemed to be that climates change a LOT, and that there is no
such thing as normal.  When the global warming debate started up, I got the
impression that climatologists broke into two camps-- those who looked at
evidence from the past and tried to correlate it with predictive models
(such as the Milankovitch curves [hope I spelled that correctly]) and those
who used computer models and recent weather data to predict the future.
Whether these two groups have come together to share their perspectives in
the last 15 years, I have no idea, but surely there is much here that we
should understand before trusting claims about odonate ranges and global
warming.

John Acorn
Edmonton, Canada