CCNet DIGEST, 23 July 1999

MODERATOR'S NOTE: I will be on holidays for the next three weeks
(until August 17). If you wish to keep up-to-date with CCNet-related
issues, you may find NEO news and information on the following websites:

Michael Paine's NEO News



With best wishes for a relaxing and uneventful summer.

Benny J Peiser



     The proper name is The Binzel Scale, just like we have The Richter
     Scale, because Richard Binzel conceived it and answered critics
     carefully, patiently for nearly a decade, at meetings at various
     places (Tom Gehrels, 22 July 1999).

     The adoption of Richard Binzel's "Torino Scale" is a great
     development. My only comments are that a Scale 8 incident is
     likely to only be relevant AFTER the event since we are unlikely
     to see the impactor before it hits. My point is that our inability
     to predict a large proportion of these "Scale 8" events should be
     pointed out, otherwise the rest of the system will lose
     credibility if an unpredicted "localized" event occurs.
     (Michael Paine, 22 July 1999).

     One of the field's most vocal skeptics, Dr. Benny J. Peiser, said
     the Torino Scale can't overcome the scientific problems associated
     with uncertainty regarding the risk of asteroids. "Whether (the
     scale) will be beneficial or not has to be seen when applied to
     real cases of potential impactors. The experience of the last
     twelve months, during which three asteroids with a non-zero impact
     risk were discovered, would suggest that the scale might not
     always provide the clarity many now expect." (Robert Roy Britt,
     Explorezone, 22 July 1999)

    BBC Online Network, 22 July 1999

    Andrew Yee <>

    CHANNEL 4 (London)

    Tom Gehrels <tgehrels@LPL.Arizona.EDU>

    Michael Paine <>

    ScienceNOW, 21 July 1999

    THE BOSTON GLOBE, 22 July 1999

    EXPLOREZONE, 22 July 1999

    Jim Benson <>

     Andrew Yee <>


From the BBC Online Network, 22 July 1999

By BBC News Online Science Editor Dr David Whitehouse

The most detailed study of an asteroid shows that it contains precious
metals worth at least $20,000bn. The data were collected last December
by the Near Earth Asteroid Rendezvous (Near) spacecraft which
passed close to the asteroid Eros.

It provided an unprecedented look at one of the mountains of rock that
fly around the solar system. The first conclusions from that encounter
are now published the journal Science.



From Andrew Yee <>

News Services
University of Arizona

James V. Scotti, 520-621-2717
July 22, 1999

Asteroid found by Spacewatch is fastest spinning solar system object

TUCSON, Ariz. -- A unique near-Earth asteroid discovered last year by
Spacewatch at the Univerity of Arizona in Tucson is the
fastest-spinning solar system object yet found, scientists report in
tomorrow's issue (July 23) of Science.

Only 30 meters (100 feet) across, asteroid 1998 KY26 spins once every
10.7 minutes. That's 10 times faster than the spin rate of any other
object and almost 60 times faster than the average of all known
asteroid rotation periods, the scientists say.

Whirling at that speed and given its size, 1998 KY26 has to be a
strong, single chunk of rock that was sent reeling from its parent
asteroid in some space collision, said James V. Scotti , a senior
research specialist at the UA Lunar and Planetary Laboratory (LPL) and
a co-author of the Science paper.

LPL Professor Tom Gehrels, Spacewatch co-founder, discovered asteroid
1998 KY26 on May 28, 1998, using the 0.9 meter (36-inch) Spacewatch
telescope at Kitt Peak, Ariz. Six nights later Scotti, joined at the
Spacewatch telescope by Dan Durda, took 111 images of the asteroid,
measuring its minimum to maximum changes in brightness. Durda of the
Southwest Research Institute in Boulder, Co., was formerly with LPL.

Astronomers at telescopes in the Czech Republic, Hawaii and California
also made the same kind of photometric measurements from June 2 to 8.
This was when the asteroid made its closest swing by Earth at a half
million miles, or twice the distance between the Earth and the moon.
Between June 6 and 8, Steven J. Ostro headed a team from the NASA Jet
Propulsion Laboratory in Pasadena, Calif., that used the Goldstone
X-band radar of NASA's Deep Space Network to track the asteroid. Radar
echoes revealed the asteroid's rapid spin rate. Petr Pravec of Ondrejov
Astronomy Institute in the Czech Republic combined data gathered by the
different optical observing groups and constructed a light curve to
determine the precise rotation rate.

The astronomers discovered the size and shape of 1998 KY26 from the
radar echoes. This asteroid is unusual in that it is almost spherical,
with a bare-rock surface pocked at least in part by meteoroid
bombardment, they report. Their optical and radar observations show
this asteroid is similar to carbonaceous chondritic meteorites, objects
that formed early in solar system history. These meteorites are rich in
primordial complex organic compounds and water.

Asteroids in the 30-meter-diameter range survive between 10 million and
100 million years before being destroyed in space collisions.
Carbonaceous chondrites are weaker meteorites, so this asteroid will be
smashed sooner than later, they add.

Information from recent asteroid flybys suggest that large asteroids
are less dense than the meteorites recovered and measured on Earth.
Scientists theorize that most larger asteroids are porous "rubble
piles" rather than monolithic bodies, Scotti said. Current theory says
that "these rubble piles are conglomerates of debris broken apart by
multiple collisions and held together by their mutual gravity, spinning
slowly enough so that they don't fall apart," he added.

Studying the detailed structure of these asteroids involves more than
just scientific curiosity, Scotti said. There are two practical reasons
for learning more about them: Asteroid minerals can provide raw
materials for future space construction, and knowing how asteroids are
put together provides critical knowledge for deflecting large ones
headed for Earth.

Each month, Spacewatch -- the world's first telescope dedicated to
searching for near-Earth asteroids -- finds an average of two-to-three
asteroids in our vicinity, and another 2,000 new ones in the asteroid
belt. Spacewatch is funded by NASA, the University of Arizona and
private donors.



From CHANNEL 4 (London)

"1500 years ago the earth was rocked by a natural catastrophe. The sky
went black for two years causing massive famine, drought and disease. 
New nations and religions emerged and the old order was swept away.
Following over four years of research and a life-threatening expedition
to Krakatoa, Secrets of the Dead's two-part Catastrophe reveals new
scientific evidence on the birth of the modern world.

In 535AD,  nature literally came to standstill. Winter gripped the
earth for two years.

Startling new evidence shows that trees all over the world - from
Ireland to Siberia, California to Finland - stopped growing during the
mid-sixth century.

Eyewitness accounts describe what we might now call a 'nuclear winter.'
According to the Syrian Bishop, John of  Ephesus "The sun became dark
...Each day it shone for about four hours, and still this light was
only a feeble shadow." An ancient chronicle from Southern China states
that: "Yellow dust rained like snow. It could be scooped up in
handfuls." Famine and plague followed, killing millions and altering
the course of history.

What caused this climatic catastrophe? Did an asteroid or meteorite hit
the earth or was there a massive volcanic eruption? Vital clues lie in
ice core samples from Greenland. These detect changes in the
environment over thousands of years.

Author and historian, DAVID KEYS consulted over 80 experts on drought,
famine, floods, cosmic and ecological disasters, epidemics and ancient
wars during more than four years of research on the project. This
unique story of scientific detection is based on Keys' book
Catastrophe: an investigation into the Origin of the Modern World  
(Century, 16.99),

Part 1, Catastrophe: the Day the Sun Went Out, uncovers the cause of
this global disaster that wiped millions of people from the face of the
Part 2 Catastrophe: How the World Changed examines how the new world order
which emerged from environmental chaos.

"The mid-sixth century catastrophe was the most important date in the
history of the past 2,000 years," says Keys. "It really did lay the
foundations of the world we live in today."


From Tom Gehrels <tgehrels@LPL.Arizona.EDU>
Dear Benny,
The proper name is The Binzel Scale, just like we have The Richter
Scale, because Richard Binzel conceived it and answered critics
carefully, patiently for nearly a decade, at meetings at various
Tom Gehrels


From Michael Paine <>

Dear Benny,

The adoption of Richard Binzel's "Torino Scale" is a great development.
My only comments are that a Scale 8 incident ("A collision capable of
causing localized destruction. Such events occur somewhere on Earth
between once per 50 years and once per 1000 years") is likely to only be
relevant AFTER the event since we are unlikely to see the impactor
before it hits (assuming we are talking about NEOs with a diameter less
than 200m - over a decade the full Spaceguard Survey will detect about
20% of 200m NEAs, 2% of 100m NEAs and 0.5% of 50m NEAs). My point is
that our inability to predict a large proportion of these "Scale 8"
events should be pointed out, otherwise the rest of the system will lose
credibility if an unpredicted "localized" event occurs.

Also it is a pity that the term "once in X years" has been used. It
gives the public the perception that we have X years before the next
impact. It would be better the express the risk as the chance in any one
year or century, or at least say the event "occurs ON AVERAGE once every
X years".
On another matter, I noticed that the Conference held in the UK last
December intended to include the effects of impacts on ice, such as
Antartica. This got me thinking... I understand that some 20,000 years
ago at the peak of the Ice Age about one third of the land surface of
the Earth was covered by glaciers. This might be one of the solutions to
my question "Where have all the craters gone?" (~1km diameter craters
such as Meteor Crater are apparently not evident in the past 50,000
years). Not only would an impact onto a glacier have reduced the
possibility of a crater forming in the underlying land but, I presume,
the advancing glaciers would have scoured away evidence of craters
created between 50,000 and 20,000 years ago. An impact onto a glacier
might also have minimised environmental effects of the impact because
water would have been ejected rather than (vaporised) rock.

Michael Paine
The Planetary Society Australian Volunteers


From ScienceNOW, 21 July 1999
Astronomers have devised a scale to rate the danger posed by asteroids
headed for Earth, comparable to the Richter scale of earthquake fame.
The so-called Torino scale, which ranges from 0 (no collision) to 10
(certain collision causing Earth-wide devastation), was developed by
Richard Binzel of the Massachusetts Institute of Technology and
presented to colleagues during a June workshop in Turin (Torino),
Italy. The International Astronomical Union will endorse it in a
statement tomorrow.
The topic of asteroids is "prone to sensationalism," says Binzel; twice
in recent years a media hype erupted after astronomers discovered a
rock that had a remote possibility of slamming into Earth within 50
years (ScienceNOW, 11 March 1998 and 20 April 1999). "It's very hard to
communicate extremely low probabilities to the general public," says
Binzel. "The new scale gives us a common lexicon."
The scale, which Binzel had been working on since 1994, takes into
account the chances an asteroid will hit as well as the possible
collision's kinetic energy, which is determined by the asteroid's size
and speed relative to Earth. Torino scale values of 8, 9, and 10 refer
to certain collisions, with local, regional, and global consequences
respectively. Just as no Californian would be alarmed by the prospect
of an earthquake registering 1 on the Richter scale, "the average
citizen shouldn't be concerned about an asteroid with a Torino value of
1," says Binzel. The two recently discovered asteroids both would have
been rated 1 after they were first discovered, but subsequent
observations would have placed them firmly in the 0 category.
The scale hasn't been tested with the general public, but Binzel says
he was advised by science writers Kelly Beatty of Sky & Telescope and
David Chandler of The Boston Globe. "In formulating the scale, we tried
to be sociologists as well as scientists," he says.
But will astronomers adopt the new scale? "This will have to sink in a
little bit," says Tom Gehrels of the Lunar and Planetary Laboratory of
the University of Arizona, who heads one of the projects searching for
near-Earth objects. "I think we ought to use it," he adds. Carl Pilcher of
NASA's Office of Space Science calls the Torino Scale "a major advance in
our ability to explain the hazard posed by a particular [object]." In the
end, Binzel hopes that it may also raise public awareness and lead to more
funding for asteroid searches. "Already, we're beyond the giggle factor."
--Govert Schilling

Copyright 1999, AAAS


From THE BOSTON GLOBE, 22 July 1999

By David L. Chandler, Globe Staff, 07/22/99

Remember that asteroid last year that astronomers initially thought had
a slight chance of striking Earth in 40 years? Well, that risk would
have rated a 1 on a new 0-to-10 scale of impact risks being unveiled
today by the International Astronomical Union.

On the 'Torino Scale,' developed by Massachusetts Institute of
Technology astronomer Richard Binzel, that asteroid was found within a
day to have a true risk of zero, and thus would have quickly reverted
to zero on the hazard scale as well.

But Binzel and other astronomers think many people may have been
unduly and unnecessarily alarmed by some of the initial media reports
of the possibility of an impact with that asteroid, called 1997 XF 11,
which was first reported in March last year. The hazard scale is an
attempt to provide perspective on announcements of this kind so
that people will better understand the remote nature of the risk.

The scale was presented last month at an astronomers' meeting on the
risk of impacts from comets or asteroids, held in Torino, Italy.
Astronomers at the meeting endorsed the new system, which then became
known as the Torino Scale.

While Binzel and others like to compare the new scale to the well-known
Richter scale used for measuring the intensity of earthquakes, or to
similar scales used for the force of hurricanes and tornadoes, the
Torino scale is actually quite different. Unlike those scales, which
measure intensity, the Torino scale attempts to combine both the
severity of an impact and the probability of its occurrence.

For example, if an object is ever discovered that is found to be on a
definite collision course with Earth, its rating on the scale would
then depend solely on its size, and thus the severity of the expected

An object so small that it would simply shatter in the atmosphere and
never strike the ground - something about the size of a house or
smaller - would be rated zero, even if it were certain to strike,
because it would have no discernible effect. But an object heading
toward Earth that was a bit bigger, between 60 and 300 feet across,
would have a rating of 8, because such an impact could be devastating
to a city-size region. Objects from 300 feet to about 3,000 feet across
would be rated 9, meaning they could devastate a large region of the 
planet, and objects larger than that - ones big enough to threaten the
entire planet - would get the highest rating of 10.

"What I hope the scale will accomplish is to put in perspective whether
an object merits concern," Binzel said.

All asteroids discovered so far fall safely within the "zero" part of
the scale. But when a new asteroid is discovered there can
be a brief period during which the uncertainties about its orbit make a
future collision possible, and thus push the number - temporarily at
least - up into the "1" range or beyond.

Last year's report about asteroid 1997 XF 11, for example, included the
possibility that there could be an impact in a few decades. Brian
Marsden, the astronomer who runs the international clearinghouse in
Cambridge where all newly discovered asteroids and comets are first
reported, calculated that based on what was known at the time of the
initial report, the likelihood of an impact was about 1 in 100,000 or

This estimate would have placed the object somewhere between categories
"1" and "2" on the scale - described as "events meriting concern." But
thanks to the widespread interest generated by that report, within a
day old photographs had been found that proved that the chance of
impact was nil.

Similarly, another asteroid discovered early this year, 1999 AN 10, was
first reported to have a possibility of impacting Earth in 2044, and 
over a few weeks that probability kept increasing as new observations
were made - enough to raise it to a category 1 - "events meriting
careful monitoring." But then old pictures were found that, once again,
proved that the chance of impact - at least for the next 70 years or so
- was nil.

Benny Peiser, an anthropologist at Liverpool John Moores University in
England who circulates a daily newsletter of information about the
hazards from asteroids and comets, said in an interview yesterday he
thinks every tool helps to explain a fairly complex problem, and so
was glad to see the new scale offered to help convey some information.

Nevertheless, he said, "as we've seen in the last 12 months, things
change so rapidly and so unexpectedly that we might see some
limitations of the scale."

In the case of 1999 AN 10, he pointed out, the calculated probability
of impact changed, over a period of a few weeks, from one
in a billion to about 1 in 100,000, before suddenly going to zero.
Tracking those rapidly changing numbers might not have been any easier
with the scale than without it, except perhaps by reassuring people
that even with the increases the object was never more than a "1."

This story ran on page A12 of the Boston Globe on 07/22/99.

Copyright 1999 Globe Newspaper Company.


From EXPLOREZONE, 22 July 1999

By Robert Roy Britt,  07.22.99

Earthquakes have their Richter Scale. Tornadoes have the Fujita Scale,
and hurricanes fall into neat little categories. Now asteroids have a
measurement system all their own, one that estimates the threat of

In an attempt to help scientists, the media and the public assess the
potential danger of asteroids and comets, an MIT professor created a
scale, which runs from zero to 10, to gauge the risk of a collision
with Earth.

The Torino Scale, as it is called, was adopted earlier this year at a
conference in Turin, Italy. It is supported by the International
Astronomical Union and will be announced today.
Though the scale will likely raise public interest in asteroids, at
least initially, its creator -- Richard P. Binzel, professor of Earth,
atmospheric and planetary sciences at MIT -- hopes the risk labeling
system will ultimately assuage concerns about potential impacts. Binzel
likened the system to an advance form of Richter Scale monitoring.

"If you tell a Californian that an earthquake registering one on the
Richter scale was going to hit tomorrow, he would say, 'So what?'"
Binzel said. "If you were talking about a six, that would be different."

Many asteroid researchers applauded the new system, but one skeptic
said the scale will have to prove itself useful by overcoming the
uncertainties of science.

"The Torino scale is a major advance in our ability to explain the
hazard posed by a particular NEO," said Carl Pilcher, science director
for solar system exploration in the NASA Office of Space Science in
Washington, D.C. "If we ever find an object with a greater value than
one, the scale will be an effective way to communicate the resulting

The risk of impact

Asteroids and comets orbit the Sun in varying shaped loops that can
take anywhere from a few years to several hundred years to complete.
Their paths sometimes cross the orbital path of Earth, and in some
instances a close brush on one orbit can alter the object's trajectory
and set it on a possible future collision course with our home planet
-- at speeds up to 100,000 mph.

Collectively, these objects that are close to us at some point during
their orbit are known as Near-Earth Objects, or NEOs. Researchers
estimate that only a handful of all NEOs have been found, and efforts
are underway in several countries to increase the pace of discovery.

Though firm estimates are not possible, researchers expect there may be
as many as 2,000 NEOs that are a half-mile wide or bigger, which is
large enough to possibly cause a global catastrophe on impact. Objects
this size are thought to strike Earth only every once every 100,000 or
1 million years. Smaller objects, capable of destroying whole cities,
hit more frequently. Even tinier chunks of rock and metal, capable of
localized damage, crash down as frequently as every 50 years or so.

There may be hundreds of thousands of these smaller asteroids out
there, researchers estimate, though most will never threaten Earth.

Questioning the scale's capabilities

One of the field's most vocal skeptics, Dr. Benny J. Peiser, said the
Torino Scale can't overcome the scientific problems associated with
uncertainty regarding the risk of asteroids. Peiser's research at
Liverpool John Moores University focuses on neo-catastrophism, and he
runs an electronic newsletter than serves as a clearinghouse for
information and opinions about all things related to impact hazards.

"Whether (the scale) will be beneficial or not has to be seen when
applied to real cases of potential impactors," Peiser told "The experience of the last twelve months, during
which three asteroids with a non-zero impact risk were discovered,
would suggest that the scale might not always provide the clarity many
now expect."

How it works

To assign risk, the Torino Scale takes into account an object's path
and speed, and the likelihood that it will hit Earth on any of its
future passes through the inner solar system. The scale uses colors and
numbers to assign risk. Zero or one means virtually no chance of
impact or damage; 10 means certain catastrophe. [See the scale]

There are currently no asteroids listed in that final category. In
fact, researchers say, none identified to date has a scale value
greater than one, in which the "chance of collision is extremely
unlikely" but the object "merits careful monitoring."

The Torino Scale -- the name is a popular, international derivation of
the Italian town Turin -- has been in the works since 1995, when an
earlier version was presented at a United Nations conference. A revised
version was layed out at the June 1999 international conference on
Near-Earth Objects in Turin, where scientists voted to adopt it.

The International Astronomical Union, which oversees much of the data
on NEOs, will announce today official endorsement of the Torino Scale
at a United Nations conference on the exploration and peaceful uses of
outer space, held in Vienna, Austria. ez

Copyright 1999, Explorezone


From Jim Benson <>
July 20, 1999 (Poway, California) - SpaceDev, Inc. (OTC-BB:  SPDV) has
made its first commercial sale of a payload ride to deep space on its
planned Near Earth Asteroid Prospector (NEAP) spacecraft.  The company
has signed a contract with Dojin Limited in Tyler, Texas, to deliver a
package from Earth to near-Earth asteroid Nereus.

The NEAP mission is one of a series of missions SpaceDev is defining as
part of its long-range strategy of conducting commercial deep-space
missions.  NEAP is planned to be injected on a trajectory to the
near-Earth asteroid Nereus in January 2002 and should rendezvous with
the small, 1-km diameter body approximately four months later to
conduct a variety of characterizations and observations using remote
sensing instruments and ejectable surface instrument packages.

Dojin announced this week its Cosmic Voyage 2000 (CV2K) program, which
makes it possible for people to become "digital passengers" aboard the
NEAP vehicle by integrating their digital presence -- image, identity,
personal messages, etc. - on a CD-ROM to be launched and preserved in
space.  Dojin states that a portion of the proceeds from the CV2K
program will be donated to charity or help promote the
commercialization of space, as directed by each paying customer.

"SpaceDev offers package delivery rides from our commercial price list
which defines a variety of services for NEAP, and we are pleased to
have this concept validated. NASA delivered astronauts to the moon
thirty years ago, and now commercial companies can deliver packages to
other planetary bodies," said Jim Benson, Chairman and CEO of SpaceDev.

The $200,000 contract calls for SpaceDev to integrate the
Dojin-supplied CD-ROM package into the NEAP vehicle and to successfully
launch it into space.  Dojin and SpaceDev are considering augmenting
this contract with additional low-mass payloads.

"This contract validates one of the several revenue producing
approaches we are offering on the NEAP project," said Benson.

NEAP will be the first mission to deliver payloads - not necessarily
science payloads - beyond Earth orbit using ordinary commercial
business practices.  In addition to rides for payloads attached to
NEAP, SpaceDev also offers to deliver ejectable instruments or
technology test packages to the surface of Nereus. SpaceDev also
intends to deliver complete science-quality data sets generated by
SpaceDev-supplied instruments back to investigators and researchers on
Earth.  SpaceDev previously announced a letter of intent with the
University of Arizona to provide two such instruments onboard NEAP - a
multi-band camera and a neutron spectrometer.

"We at Dojin Limited ( are extremely excited
about this unique opportunity and feel very fortunate to be the first
commercial participant in SpaceDev's historic deep space science
mission," said Rick Barrett, Dojin spokesperson.

SpaceDev (, a two-year-old, 70-person company based in
Poway, in northern San Diego County, is the world's first commercial
space exploration and development company.  Co-located in new Poway
facilities are SpaceDev's corporate offices, its wholly owned
subsidiary Integrated Space Systems ( and the firm's
Space Missions Division. The company's other wholly owned subsidiary,
Space Innovations, Limited (, is in Newbury, England.

The Space Missions Division recently completed a study of low-cost Mars
micromissions for JPL, which are estimated to cost NASA less than $50
million.  SIL is under contract to build an Earth orbiting
microsatellite for Australia, and sells a variety of low-cost,
small-satellite subsystems and ground-tracking equipment.

For more information, contact:

SpaceDev:  Jim Benson, Chairman and CEO - (858) 375-2020

Dojin:  Rick Barrett, - 214-752-5281


From Andrew Yee <>

Office of Public Relations
University of Colorado-Boulder
354 Willard Administrative Center
Campus Box 9
Boulder, Colorado 80309-0009
(303) 492-6431

Don Barber, (303)-492-7641
John Andrews, (303) 492-5183
Jim Scott (303) 492-3114

July 21, 1999


The catastrophic draining of two gigantic glacial lakes in Canada's
Hudson Bay region some 8,200 years ago appears to have caused the most
abrupt, widespread cold spell on Earth during the last 10,000 years,
according to a group of scientists.

Don Barber, a geological sciences doctoral student at the University of
Colorado at Boulder, said the lakes, Agassiz and Ojibway, contained
more water than all of the Great Lakes combined. Barber and his
colleagues estimated that when an ice dam from a remnant of the
Laurentide Ice Sheet collapsed, the flow of lake water rushing through
the Hudson Strait and into the Labrador Sea was about 15 times greater
than the present discharge of the Amazon River.

The fresh water probably gushed into the Labrador Sea in the North
Atlantic for about a year, reducing sea-surface salinity and altering
ocean circulation patterns at the time, said Barber, also a researcher
at CU-Boulder's Institute of Arctic and Alpine Research. Ocean
circulation models suggest massive influxes of freshwater can disrupt
heat transport in currents flowing from the tropics to temperate

Ice core data taken by scientists in Greenland show temperatures
dropped by as much as 15 degrees Fahrenheit in central Greenland and by
nearly 6 degrees F in Western Europe following the catastrophic lake
drainage. "This was the coldest climate event in the last 10,000
years," Barber said.

A paper on the subject by Barber, published in the July 22 issue of
Nature, was co-authored by INSTAAR's John Andrews, Anne Jennings, Mike
Kerwin and Mark Morehead. Other co-authors include John Southon of the
Lawrence Livermore National Lab in Livermore, Calif., Art Dyke and
Roger McNeely of the Geological Survey of Canada, Claude
Hillaire-Marcel and Guy Bilodeau of the University of Quebec and
Jean-Marc Gagnon of the Canadian Museum of Nature.

The surface currents of the Atlantic act much like conveyor belts,
carrying salty, warm water from the tropics to the temperate regions.
The water cools in the temperate North Atlantic, then becomes dense
enough to sink and send heat into the atmosphere, said Barber.

Under normal conditions, winds blowing from the west across the
Atlantic send air warmed by the sea toward Western Europe, said Barber.
About one-third of the heat that warms Western Europe is delivered by
the ocean, while the other two-thirds comes from the sun, he said.

Although southern Greenland and northern Canada are at about the same
latitude as Sweden and Norway, Greenland is almost uninhabitable
because of its colder temperatures and lack of viable agricultural land
for crops and livestock.

But if an enormous amount of freshwater is suddenly infused into the
temperate Atlantic waters as it apparently was 8,200 years ago, Western
Europeans could suffer severely. The Laurentide lakes drainage seems to
have halted the sinking of surface waters in the Labrador Sea,
temporarily crippling the water conveyor belt and causing the Western
European cold snap to last for about 200 to 400 years, according to
ice-core data.

"If the scenarios of extreme global warming in the future come true, it
could lead to significant melting of the Greenland Ice Sheet and create
more precipitation at high latitudes," said CU-Boulder geological
sciences Professor John Andrews. "Adding very large amounts of
freshwater to large rivers could conceivably close down the vertical
circulation system in the North Atlantic, leading to another extreme
cooling event."

Evidence for the catastrophic Laurentide lakes drainage comes from "red
bed" sediments underlying the ancient glacial lakes that were carried
some 800 miles through the Hudson Strait by the massive freshwater
plume, said Barber. In addition, fossil clams from the Labrador seabed
corresponding to the freshwater flood were radiocarbon-dated to about
8,200 years ago.

In addition, oxygen isotopes from the shells of tiny, plankton-like
organisms from the same age of sediments showed the creatures lived in
less salty water about 8,200 years ago, indicating the Laurentide lake
drainage made the Labrador Sea significantly fresher.

At its peak about 20,000 years ago, the Laurentide Ice Sheet that
covered much of North America dipped down south as far as Ohio, and the
ice is estimated to have been a mile deep at present-day Detroit, said
Barber. At the time of glacial lake draining, the Laurentide Ice Sheet
probably had retreated by about 80 percent.

The CCNet is a scholarly electronic network. To subscribe/unsubscribe,
please contact the moderator Benny J Peiser < >.
Information circulated on this network is for scholarly and
educational use only. The attached information may not be copied or
reproduced for any other purposes without prior permission of the
copyright holders. The fully indexed archive of the CCNet, from
February 1997 on, can be found at

CCCMENU CCC for 1999