[meteorite-list] IMPACT & ICE AGES [WAS: Abstract: EL3 Chondrite (not Aubrite)NorthwestAfrica 2828]

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Thu, 29 Mar 2007 17:52:04 -0500
Message-ID: <00c901c77254$df919d70$0e2f4842_at_ATARIENGINE>

Hi, list, and E.P.

    who said:
> The "present ice age" is not going to return... [due to]
> a massive impact at the end of the last ice age [which
> altered currents]...

    The problem with this theory is that the current mild
spell (which is NOT the "end" of the ice age) is mediated
by warm midlevel currents (which do not seem to need
an extraordinary explanation). Full glaciation is the
result of the absence of these currents. If impacts are
involved in any way (and they may be), they would produce
coolings (and help ice ages) rather than preventing or
ending them (or, more correctly, making them milder).

    The planet has long eons during which natural ice
does not accumulate or persist more than momentarily
anywhere on the planet at any time of the year. Ever.
Often this "greenhouse" age lasts for many 10's or even
100's of millions of years. During these times, the ocean
bottom is anaerobic because the oceans do not circulate,
because their bottom layers are the warmest level of the
oceans, being highly saline. The temperature differential
from equator to pole is much less than we are accustomed
to, and the planet as a whole is much warmer than the
maddest dreams of "global warmists."

    In an "Ice Age," the oceans circulate in short time
scales (<1000 years), the bottom waters are the coldest
layers of the ocean, the sediments are aerobic. The
temperature differential from equator to pole is, well,
pack an extra sweater if you visit Antarctica. There are
substantial portions of the planet where ice can be found
at any time of the year. If this sounds oddly familiar,
this is because this is the familiar world which we
presently live in. This (look around you) is what an
ice age is. This is an Ice Age, nor are we "out" of it.

    How'd it get that way?

    About 15 mya (million years ago), a serious cooling
trend began. East Antarctica acquired the beginnings of
its ice sheet 14 mya, the first ice in Antarctica in many ten's
of millions of years. The earliest glaciers in Alaska show
up 9 mya. West Antarctica started its ice sheet 6.5 mya.
The first South American glaciers appear 5.5 mya. Due to
the uptake of water by ice, sealevels declined during
this time.

    At 3.25 mya, cyclical glaciation world-wide (what most
folks call "ice-ages") began. Sealevels dropped sharply,
and cooling became more intense. At 2.4 to 2.2 mya, the
cooling trend steepened again. Another outcome of
The Ice is global declines in the water content of the
atmosphere (the cold trap), and world-wide droughts
result after about 2.0 to 1.8 mya.

    About 800,000 years ago (Australasian "tektite"
impact?), the cooling trend steepened more drastically.
By 700,000 years ago, the North Polar Sea Ice persisted
through the summer, thus becoming "permanent" (as if
there were such a thing).

    We can see more "detail" in the last 128,000 years,
of course, and it presents a fascinating picture:
    128,000 to 115,000 ya (years ago) was a long
"interglacial" or warm spell like today, one of the
longest warm spells. It was very slightly warmer
that it is today, which is the horrible state all the
global warmists all fear, 2 to 4 degrees warmer than
today. However, it was still a full blown ice age with
all the ice age markers present: ice caps, glaciers,
year-round sea ice, and so forth.
    At 115,000 ya, there was a "false ice age." There's
another "false" ice age at 95,000 ya. A "false" ice age
is a sudden sharp drop into extreme glacial conditions
that doesn't last, but "fails" after a few (2? 4? 6?) thousand
years instead of persisting for ten's of thousands of years
like a "real" ice age.
    Because it can be shown that "false" ice ages go to
full glaciation conditions in less than a century, perhaps
less than a decade, most likely they are the result of
impacts. These impacts cannot be identified with any
impact structures, so the suspects are: oceanic impact,
shower of cometary objects, passage through an
interstellar dust cloud, or anything else that would
obscure radiant input.
    But at 73,000 ya, there's a very severe and sharp drop
in temperatures, followed by a long ice age with short,
weak warm spells; it's easier to just point out them in
the record.
    Ice starts at 72,000 ya.
    Ice maximum at 62,000 ya
    Very short warm spell at 58,000 ya, with weak warm
spells at 52,000 to 47,000 ya. Short mild spells between
40,000 ya and 30,000 ya, all with more glaciation between
them.
    Then, at 28,000 ya another very severe and sharp drop
like the one in 73,000. This is the ice age that just "ended"
10,600 years ago. It didn't "end," of course. We're just
having another interglacial. Again. Nice, but they don't last.

    "Ended" is a total misnomer. Do you see any natural ice
anywhere on this planet? If the answer is "yes," then it's an
ICE AGE. 18,000 ya, the French Riviera was permafrost tundra
and the dominant fauna there were reindeer. This peak glaciation
ended as they all do: repeated weak warm spells that fail,
with re-cooling, until the warmth finally successfully switches
on the midlevel currents that perpetuate the mild warming
of an interglacial episode. The present warm midlevel currents
self-limiting.They warm the poles enough to cause melt
whose cold fresh water influx blocks and then shuts off the
warming currents, and everything gets back to "normal" if
the orbital timing is right. Interglacials are episodes; they
never last.

    It's still an "ice age." It's been an "ice age" for 14 my, or
5-6 my, or 3.25 my or 2.2 my, depending on your prejudices.
One thing is certain: it's an on-going condition. Mountain glaciers,
continental glaciers, permanent sea ice, ice caps miles thick:
they have merely shrunk --- they're still there. There's still
permafrost and reindeers; they're just not located in the
vicinity of the French Riviera right now. Don't sell your
beachfront property yet. Just wait a while.

    We are a young species, whose entire evolution has
been conducted during this same ice age; we regard these
conditions as "normal." We are also accustomed to this brief
pause in the usual severity, during which we crafted the
entire mechanism of human "civilization," which has quadrupled
our lifespan, and increased our population by a factor of
one thousand, and given men the appearance of magical
powers of flight, communication, and wizardly devices.
(We are so evolved that there are even humans stupid
enough to weep at the thought that a few more degrees of
warming would cause the permanent loss of even one inch
of Our Beloved Ice. It's almost enough to cause one to wish
that they were right. Intriguingly, these disastrously sharp
coolings at 73,000 ya and 28,000 ya that precede long and
bitter glaciations seem to have been themselves immediately
preceded by a much shorter but very intense warming episode.)

    Yes, we humans are Hot Stuff, obviously destined to
"conquer" the solar system and this local short arm of the
galaxy at the very least. If so, we had better get up off our
bottoms and do it while we can. When (I didn't say "if") The
Ice returns, all bets are off. The Ice is not an enemy we can beat.
We are no more prepared to deal with it than our paleolithic
ancestors were, and we will fare no better unless we happen
to widely and comfortably inhabit the entire solar system
and can simply use the Earth as an exotic winter resort and
deep-ice history museum.

    That little fantasy is, of course, an optimistic vision based on
the notion that humans are intelligent, foresightful and purposed.
The Smart Money is on chewing reindeer hides to soften them
for clothing, eating way too much red meat, hoping your teeth
don't fall out before the first spring green edible appears, trying
to maintain the art of the alphabet even though our kids think
it's stupid and useless, and waiting for the Aliens to show up.

    OK, OK, both are fantasies. Reality will depend on dozens of
factors we can only guess at: the rate of changes, the duration
of events, the depth of a future glaciation, how cold? We could
possibly adapt to a gradual enough shift, assuming we're willing
to give up the use of a portion of the planet, double or triple or
more our population density, limp along from year to year,
provided we're not pushed too hard. I suppose it all depends
on how lucky we are.

    Like big impacts, continued glaciation is a long-term certain
and short-term negligible risk (unless, of course, runaway
Global Warming is our salvation in disguise). In the immortal
words of Clint Eastwood's Dirty Harry, "Do you feel lucky,
punk? Well, do ya?"


Sterling K. Webb
--------------------------------------------------------------------------------
----- Original Message -----
From: "E.P. Grondine" <epgrondine at yahoo.com>
To: <meteorite-list at meteoritecentral.com>
Sent: Thursday, March 29, 2007 9:55 AM
Subject: Re: [meteorite-list] Abstract: EL3 Chondrite (not
Aubrite)NorthwestAfrica 2828


Hello Sterling -

The "present ice age" is not going to return. The
currents of the Pacific Ocean were altered by a
massive impact at the end of the last ice age, and
most likely that impact was what ended it.

The important point here is how long NWA meteorites
have been accumulating, and as you point out it has
been a relatively short period.

Ed
E.P. Grondine
Man and Impact in the Americas
$34.95 at amazon, or contact me off list
Received on Thu 29 Mar 2007 06:52:04 PM PDT