Subject: Whales & El Nino (fwd)

Mike Williamson (pita@www1.wheelock.edu)
Fri, 5 Dec 1997 14:03:54 -0500 (EST)

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---------- Forwarded message ----------
Date: Fri, 5 Dec 1997 10:12:31 -0700
From: Pieter Folkens <animalbytes@earthlink.net>
Reply-To: Marine Mammals Research and Conservation Discussion
     <MARMAM@UVVM.UVIC.CA>
To: MARMAM@UVVM.UVIC.CA
Subject: Whales & El Nino

To John Goold's question: "If, as some climatologists predict, global
warming causes El Nino to become a more regular event - . . . - what are
the likely implications for large whales which rely on the Antarctic Food
Web?"

I offer this perspective:
Whales have remained pretty much unchanged (morphologically) for at least
the past half million years. During that time the earth's mean temperature
has fluctuated widely between much cooler and much warmer than now. The
large whales will likely survive the present warming just fine (providing
we don't start shooting at them again).

Taking a wide-view, the warming trend which began 14,000 years ago has
added about 135 meters to the mean sea level from then to about 4500 ybp.
Several times during the ensuing 4 millenia the earth has been warmer with
the mean sea level as much as 3.25 meters higher than it is now. Looking at
the most recent 700 years we are presently coming out of a cool period and
headed towards the average temperature of the past 4000 years (as expressed
by mean sea level).

For the really wide view consider that the cetacea evolved out of
Mesonychidae at a time of warm seas with no evidence of ice at the poles.
(The North American southeast was underwater.) Major cooling happened in
the early Oligocene killing off the Archaeoetes and giving a boost to the
Odontocetes and Mysticetes. In the middle Early Miocene earth reached a
thermal maximum with very high sea levels. (California's Central Valley was
under about a thousand feet of water.) During this period the early deep
diving Odontocetes developed along with the early balaenid skim feeders.
Cooling got underway again at the end of the Early Miocene, increasing
markedly in the Late Miocene. It was into this cooling that the archaic
delphinids died off giving way to the first species in many extant
families, including the Balaenopterids (rorquals), [and bipedalism in
Hominids]. Major buildup of Arctic ice and terrestrial glaciation happened
about 2.4 million years ago leading to the modern species assemblage of
Cetaceans, [and brain expansion in Hominids].

For the really narrow view it is interesting to note that the "historical"
Adam and Eve flourished in a particularly warm post-glacial period with sea
levels over 2 meters higher than now. Their "removal" from Eden correlates
with a rapid cooling which put enough water into the polar ice to drop the
mean sea level to 1.5 meters below the present level. This was followed by
a dramatic rapid warming which took the mean sea level to over 3 meters
higher than the present and brought us . . . (you guessed it!) Noah.

It is important to note that 1) the earth is in a definite warming trend,
though intermediate cooling moments are quite possible, if not expected; 2)
the warming was not caused (though possibly and minutely exacerbated) by
human activity; and 3) there's nothing we can do to alter its course. The
recommendation? Don't buy coastal property; and go skiing while we've got
snow.

data sources: Milliman & Emery 1968 Sea levels during the past 35,000
years, in Science 162:1121-1123; Fordyce, RE, LG Barnes. 1994 The
Evolutionary History of Whales and Dolphins

Pieter Folkens
animalbytes@earthlink.net


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