PLEASE NOTE:
*
CCNet, 1 November 1999
-----------------------
(1) MYSTERIOUS FIREBALL EXPLAINED
Ron Baalke <baalke@ssd.jpl.nasa.gov>
(2) HALIFAX FIREBALL 28 OCTOBER 1999
Heather Preston <hlp@alum.mit.edu>
(3) WILL THERE BE A METEOR SHOWER FROM COMET C/1999 J3 THIS YEAR?
Peter Jenniskens <pjenniskens@mail.arc.nasa.gov>
(4) SCIENTISTS SPECULATE ABOUT SUDDEN END OF ICE AGE
Andrew Yee <ayee@nova.astro.utoronto.ca>
(5) STUDY HINTS AT EXTREME CLIMATE CHANGE
CNN Online, 28 October 1999
(6) SCIENTISTS SEE EVIDENCE OF RAPID CLIMATE CHANGE
MSNBC Online, 28 October 1999
(7) SCIENCE AND SCIENCE-FICTION ON CCNET: ONLINE SCIENCE DATA
& ITS
PROBLEMS
Andrew Glikson <geospectral@spirit.com.au>
(8) COMETS, ASTEROIDS & COSMIC DUST
Bas Van Geel <vangeel@bio.uva.nl>
(9) LAND-BASED LIFE ONE BILLION YEARS OLDER THAN THOUGHT?
Andrew Yee <ayee@nova.astro.utoronto.ca>
============
(1) MYSTERIOUS FIREBALL EXPLAINED
From Ron Baalke <baalke@ssd.jpl.nasa.gov>
Mysterious fireballs explained
By ART CHAMBERLAIN -- Executive Producer, CNEWS
October 28, 1999
It's highly unlikely any trace will be found of the meteorite
that lit up
the Maritimes last night, an expert says.
Hundreds of people witnessed huge balls of fire crossing the sky
about 9:30
p.m., flooding RCMP detachments and the Rescue Co-ordination
Centre in
Halifax with calls.
What they saw was probably a chunk of rock that was part of an
asteroid,
says John Rucklidge, geology professor at the University of
Toronto and an
expert on fireballs and meteorites.
"Eyewitness reports are notoriously unreliable because it
always appears
that the meteorite crashed just behind the trees on the
horizon,'' Rucklidge
said in an interview with CANOE.
"You need witnesses on both sides of the track to even begin
to locate it,''
he said. ''Even when it hits the ground, unless it's in a
populated area,
it's virtually impossible to find."
Full story here:
http://www.canoe.ca/TopStories/fireballs_oct28.html
===============
(2) HALIFAX FIREBALL 28 OCTOBER 1999
From Heather Preston <hlp@alum.mit.edu>
From the Fireball story by Barry Dorey:
> Astronomer David Lane, a professor at Saint Mary's
University,
> said witnesses probably felt the shock wave of explosions
when the
> meteor began fragmenting, rather than the rattle of impact.
> But he said a similar show over Montreal two years ago
littered
> small fragments east of the city.
> Wednesday's display was not part of a scheduled or expected
meteor
> shower, he said.
The Orionids meteor shower extends from October 15 to 29, with a
maximum occurring around October 21/22. The maximum number of
meteors
to expect are around 20 per hour and the meteors are described as
fast.
There is also a new long-period comet discovered by LINEAR which
is
expected to possibly yield a meteor shower next week.
Somebody tell the readers?
Clear Skies,
Heather Preston
===============
(3) WILL THERE BE A METEOR SHOWER FROM COMET C/1999 J3 THIS YEAR?
From Peter Jenniskens <pjenniskens@mail.arc.nasa.gov>
There has been some excitement about the possible meteor outburst
activity of long period comet C/1999J3. The comet is expected to
pass
fairly close to Earth's orbit, at 0.0115 AU outside of the
Earth's
orbit, and at a location that we will pass on November 11.82 UT.
This is a long-period comet, with a period of some 63,000 years
long.
This type of comets cause "far-comet" type outbursts,
i.e. outbursts
that do not correlate with the return of the comet to perihelion.
Instead, the planets cause a dust trail in the comet orbit to
move in
the Earth's path once in a while. Typically once or twice every
sixty
years. The showers are brief (less than 1-2 hours) and they occur
close
to the node of the comet orbit.
The reason why the showers do not correlate with the return of
the
comet is because the long period orbit causes large differences
in
orbital period for individual grains that are ejected with a
range of
ejection velocities. Hence, the dust spreads rapidly along the
comet
orbit during even a single orbit, and quickly dillutes so much as
to be
hardly detectable.
A shower from this comet may have occurred in the past, which
should
have been much at the same solar longitude as the decending node
of the
comet orbit. The maximum effect of planetary perturbations is
needed to
move the trail by 0.0115 AU. Hence, the years when the planets
Jupiter and Saturn lined up in the right direction will have had
best chance.
Hence, it is unlikely that there will be activity from comet
C/1999J3
this year, unless the planets happen to favor a position of the
dust
trail that is right in Earth's path. That is unlikely.
Nevertheless, keep an eye out for the unexpected! Also, this type
of
"far-comet" outbursts must occur relatively frequently
all throughout
the year, many showers of which remain to be discovered.
Peter Jenniskens
==============
(4) SCIENTISTS SPECULATE ABOUT SUDDEN END OF ICE AGE
From Andrew Yee <ayee@nova.astro.utoronto.ca>
Scripps Institution of Oceanography
University of California-San Diego
Media Contacts:
Janet Howard or Cindy Clark, (619) 534-3624
E-mail:jehoward@ucsd.edu;
cclark@ucsd.edu
SCIENTISTS DETERMINE TRIGGER OF END OF ICE AGE
Using a new technique to analyze air trapped in ancient ice
cores,
scientists at Scripps Institution of Oceanography at the
University
of California, San Diego and Washington State University have
determined that the end of the last ice age was triggered by an
abrupt period of warming that began in the North Atlantic rather
than
in the tropics. Scientists have debated for years which region of
the
globe is responsible for triggering periods of rapid warming.
The researchers report in the Oct. 29 issue of Science that
Greenland
temperatures rose by 16 degrees Fahrenheit in less than several
decades, bringing the last ice age to a close about 15,000 years
ago.
They were surprised to learn, however, that the dramatic period
of
warming appears to have been triggered by changes in circulation
in
the North Atlantic rather than in the tropics, commonly believed
to
be the region that drives global climate change because it is
central
to the Earth's heat and water vapor budgets.
"There has been a lot of interest lately in the role the
tropics
might play in climate change -- everything from causing El Ninos
to
speculation that the abrupt warmings during the last ice age were
caused by changes in the tropics," said Jeffrey
Severinghaus, an
assistant professor in the Scripps Geosciences Research Division
who
is the paper's lead author. "These findings sort of go
against that
grain because they suggest that the North Atlantic climate
changed
first."
Using a new technique based on analysis of nitrogen and argon
isotopes in air trapped in Greenland ice, Severinghaus and Edward
Brook of Washington State University determined that the
Greenland
Summit warmed some 16 degrees Fahrenheit over a period of several
decades beginning 14,672 years ago. Analysis of methane
concentrations trapped in the ice -- an indicator of tropical
climate
-- showed, however, that temperatures in the tropics began to
climb
20 to 80 years after the onset of the abrupt Greenland warming.
"Our data clearly shows that tropical climate lags the
Greenland
climate by at least 20 years, so that means the tropics could not
have triggered the event," Severinghaus said. "Our work
doesn't,
however, rule out that the tropics could play a role in
amplifying
warming once it begins."
Determining what may trigger rapid periods of warming is of key
interest to scientists who are trying to predict what effect
adding
carbon dioxide to the atmosphere from the burning of fossil fuels
may
have on future climate.
"We know that over the next 100 years the Earth will
probably warm
because of the greenhouse effect and there is a remote
possibility
that we might trigger one of these abrupt climate events,"
Severinghaus said. "So, it is very important that we
understand the
underlying mechanisms behind them."
In order to trace how Greenland temperatures changed over time,
Severinghaus analyzed tiny air bubbles trapped within the layers
of
snow-turned-to-ice deposited in Greenland over the past hundreds
of
thousands of years. Similar to the way in which sediments are
laid
down at the bottom of the ocean, the ice cores are made up of
compacted snow layers that become older with depth. Severinghaus
focused his efforts on analyzing samples of ice taken from the
Greenland Ice Sheet Project Two (GISP 2) core covering a period
from
15,000 to 10,000 years ago.
Current methods of analyzing ice cores are plagued by the problem
that air trapped in bubbles within the ice is younger than that
of
the surrounding matrix, making the air sample difficult to
accurately
date. The problem stems from the fact that air is only trapped
within
the consolidated snow at a depth of several hundred feet below
the
surface at which point the ice may be thousands of years old.
Because
of this, it has been difficult for scientists to relate the
precise
timing of rapid warming events with concurrent changes in
atmospheric
gases.
To overcome this dilemma, Severinghaus developed a new technique
based on thermal diffusion in which he used changes in the
isotopic
ratios of argon and nitrogen in the GISP 2 core to develop a
gas-based temperature record for Greenland near the end of the
last
ice age. Brook then analyzed methane concentrations within the
same
ice samples in order to track changes in tropical climate over
the
same period.
Because the period of rapid warming was seen first at high
northern
latitudes, the two scientists propose that the end of the last
ice
age was triggered by changes in circulation of the North Atlantic
that caused heat to be transported from the equator towards
Europe
and the poles.
==============
(5) STUDY HINTS AT EXTREME CLIMATE CHANGE
From CNN Online, 28 October 1999
http://www.cnn.com/NATURE/9910/28/climate.change.enn/index.html
Study hints at extreme climate change
By Environmental News Network staff
Abrupt climate change could be in the future for the Earth if
a
recently discovered pattern repeats itself. After analyzing
sediment
from the subtropical Atlantic Ocean deposited during the last ice
age, scientists discovered extreme temperature fluctuations
occurred
during and at the end of the period.
The scientists found that even during an ice age, warm oceans can
heat up.
"What is new here is clear evidence that the warm Atlantic,
like the
polar Atlantic, was undergoing very large and very rapid
temperature
changes during the last glacial period," said Scott Lehman,
a
research associate at the University of Colorado Institute of
Arctic
and Alpine Research.
Discovering changes in the warm Atlantic is important because
warm
oceans increase the temperature of the Earth. The vast surface
area
of Earth's warm oceans creates much more water vapor than cold
oceans, increasing atmospheric heat trapping.
"The temperature of the warm ocean realm regulates the water
vapor
content of the atmosphere and its greenhouse capacity," said
Lehman.
Past temperature records and climate models suggest ocean
circulation
changes, like those in the last glacial period, can be triggered
by
human activity, showing that "the impact of possible future
circulation changes may be more dramatic and widespread than
suspected," he said.
Lehman and Julian Sachs, a former CU-Boulder researcher at
INSTAAR
now at Columbia University's Barnard College wrote a paper on the
study that appeared in the Oct. 22 issue of Science.
Lehman and Sachs' study revealed temperature changes in the
Sargasso
Sea between the West Indies and the Azores fluctuated repeatedly
by
up to 9 degrees Fahrenheit from 60,000 to 30,000 years ago. The
last ice age happened between 110,000 and 10,000 years ago, said
Lehman.
"The records reveal a large, two to five degrees Celsius
temperature
change in the subtropical Atlantic Ocean," said Lehman.
"That's
comparable to the total change between the ice age and the
present
day at the same location."
Lehman and Sachs reached their conclusions after studying 50
meters
of sediment cores hauled up from several miles deep in the
Sargasso
Sea near Bermuda by French scientists as part of an international
project. They analyzed the saturation state of organic molecules
from
planktonic algae over the past 100,000 years, revealing
sea-surface
temperatures during that period.
"The warming at the end of the last ice age, about 10,000
years ago,
was supported by the disappearance of enormous ice sheets, a
one-third increase in atmospheric carbon dioxide levels and
changes
in the seasonal distribution of the sun's energy," said
Lehman. "But
the abrupt changes we documented during the last ice age seem to
be
almost entirely ocean driven."
Melting glaciers send fresh water into the Earth's oceans and
scientists believe this cycle triggers abrupt and long-lasting
cooling events, including ice ages, by interfering with the
conveyor
belt of water carrying heat from the tropics to temperate
regions.
"Numerical modeling studies show that similar changes can be
triggered by warming associated with human emissions as
well," said
Lehman.
"Trapping more heat in the atmosphere has the potential to
kill major
parts of ocean circulation, with the effects reverberating
throughout
the world," he said.
The scientists next hope to determine if similar changes occurred
in
the much larger Pacific Ocean, said Lehman. "If so, any
human-induced
changes to the ocean's plumbing are likely to affect everyone on
Earth, not just Greenlanders and northern Europeans."
Copyright 1999, Environmental News Network, All Rights Reserved
===============
(6) SCIENTISTS SEE EVIDENCE OF RAPID CLIMATE CHANGE
From MSNBC Online, 28 October 1999
http://www.msnbc.com/news/328749.asp
Could climate do a quick change? Scientists see evidence of
ancient
rapid warming
ASSOCIATED PRESS
WASHINGTON, Oct. 28 — In a study that may sound a
warning about global
warming, researchers have found evidence that the world’s
climate can
change suddenly, almost like a thermostat that clicks from cold
to hot.
A NEW TECHNIQUE for analyzing gases trapped in Greenland glaciers
shows
that an ice age that gripped the Earth for thousands of years
ended
abruptly 15,000 years ago when the average air temperatures
soared.
"There was a 16-degree abrupt warming at the end of the last
ice age,”
said Jeffrey P. Severinghaus of the Scripps Institution of
Oceanography, lead author of a study to be published Friday in
the
journal Science. “It happened within just a couple of
decades. The old
idea was that the temperature would change over a thousand years.
But
we found it was much faster.”
CHANGE IN WATER TEMPERATURE
Severinghaus said the rapid rise in air temperature in Greenland
may
have been touched off by a surge in warm currents in the Atlantic
Ocean
that brought a melting trend to the vast ice sheet that covered
the
Northern Hemisphere. It still took hundreds of years for the ice
to
recede, but the start of the great thaw was much more sudden than
scientists had once thought.
This suggests, Severinghaus said, that the Earth’s climate
is “tippy” —
prone to be stable for long periods, but then suddenly change
when the
conditions are right. This raises a red flag of caution for the
effect
of greenhouse gases on global warming.
“We know that over the next 100 years the Earth will
probably warm
because of the greenhouse effect and there is a remote
possibility that
we might trigger one of these abrupt climate changes,” he
said.
Many experts have predicted that global warming, caused by an
increase
in greenhouse gases such as carbon dioxide, will be gradual, with
temperatures smoothly rising over many decades.
But Severinghaus said the Greenland ice core study suggests that
changes in the Earth’s climate may not be smooth, but
sudden.
“We can’t really say how much carbon dioxide (a
greenhouse gas) is OK
or not OK,” he said.. “We might do well to expect
surprises.”
The greenhouse effect is global warming caused by the build up in
the
atmosphere of man-made carbon dioxide and other gases that trap
the
sun’s heat. The carbon dioxide rise is thought to be from
increased
burning of fossil fuels, such as gasoline and coal, and the
rising
concentration of certain gases, such as methane, that are linked
to the
industrial age.
© 1999 Associated Press. All rights reserved.
=============
(7) SCIENCE AND SCIENCE-FICTION ON CCNET: ONLINE SCIENCE DATA
& ITS
PROBLEMS
From Andrew Glikson <geospectral@spirit.com.au>
Dear Benny
I agree with the concern expressed by Kelley Beatty (Sky and
Telescope)(CCNet 29.10.99) regarding the danger of bogus news and
pseudoscience creeping into Internet bulletins.
Since CCNet defines itself as a "a scholarly electronic
network" - ways
need to be explored whereas readers can distinguish between
science and science fiction, actual observations and pure theory,
as well as identify plegiarism. Self-correcting procedures can
only rarely work as most active scientists are simply too busy to
have the time to respond to every problem on the web. Sadly this
may result in a trend from quality to quantity and the
deterioration of scientific bulletins to tabloid standard - a
forum for self-promoters and the reinventors of wheels.
I empathise with the dilemma this poses for the moderator. To
maintain and protect standards I suggest a very simple procedure
should be required from contributors, namely, CONTRIBUTIONS NEED
TO BE ACCOMPANIED BY A SHORT LIST OF RELEVANT REFERENCES,
ALLOWING READERS TO ASCERTAIN THE VALIDITY OF OBSERVATIONS AND
ASSERTIONS.
Andrew Glikson
Research School of Earth Science
Institute of Advanced Studies
Australian National University
Canberra ACT 0200 Australia
andrew.glikson@anu.edu.au
<mailto:andrew.glikson@anu.edu.au>
----------
WHAT CHANGES TO THE FORMAT DO YOU WISH?
From Benny J Peiser <b.j.peiser@livjm.ac.uk>
Dear Andrew
Thank you for your comments and suggestions which are much
appreciated. May I kindly ask you to clarify some of your
suggestions
and how you believe they could work best.
What workable changes are you actually proposing? How, for
instance,
should I deal with press releases circulated by thousands of
universities and research institutions? What about science news
stories from the WWW which feature widely on CCNet? What about
abstracts? It would be impossible to ask peers to review all
scientific press releases, news stories or papers that are posted
on
the WWW or circulated by e-mail. How should I deal with comments
such
as your's or Kelly's? Should these be reviewed before posted or
should I ask contributors to add some references to their private
opinion?
I can see that there are genuine problems that need to be
addressed.
But a network such as the CCNet also needs to be organised in a
practical and managable way. After all, I am an academic with a
full
time job.
I don't wish to sound boastful, but compared to most of the
*professional* science networks on the WWW, CCNet is generally
appreciated for its high scientific standards. Your reference to
"science fiction" on the CCNet seems rather harsh - or
are you saying
CCNet should not post comments by individuals that are
controversial?
I would very much appreciate a clearer idea of what you are
suggesting.
You need to keep in mind that a moderated network is quite
different
from the traditional methods of communication and that some time
is
required to find the best possible format which will satisfy the
wishes of the vast majority of CCNet subscribers (700+). So
please
try to clarify your proposal.
Best wishes, Benny
------------
CLARIFICATIONS & SUGGESTIONS
From Andrew Glikson <geospectral@spirit.com.au>
Dear Benny,
Indeed I empathize with your position as moderator, and believe
that
- to your credit - you are succeeding in maintaining
excellent
standards to date. The danger is always there for serious
deterioration and misrepresentation, but although there have been
examples of misinformed and misleading communications, I do not
think
many of us would like to assume the thankless task of pointing
them
out. In response to your invitation for specific suggestions, the
following could be considered:
1. News releases/communications cited from the print media,
conference abstracts etc. are O.K., as long as the source/s are
identified on CCNet.
2. New hitherto-unpublished communications by individuals or
groups
need to contain the relevant scientific references on which they
are
based or to which they refer.
3. Communications which reflect personal - but
scientifically
non-specific and unreferenced - views may need to be kept short.
The
volume problem is very real - examples abound of (other) Internet
bulletins where significant news items are drowned in an ocean of
non-specific material.
4. Limited editing may thus be needed, not of contents but of
presentation. In some instances one or more relevant references
may
be required. I realize this potentially places more work on the
moderator - hopefully a realistic balance can be achieved.
Best Wishes
Andrew Glikson
29.10.99
==============
(8) COMETS, ASTEROIDS & COSMIC DUST
From Bas Van Geel <vangeel@bio.uva.nl>
EUROPEAN GEOPHYSICAL SOCIETY XXV GENERAL ASSEMBLY: MILLENNIUM
CONFERENCE ON EARTH, PLANETARY & SOLAR SYSTEM SCIENCES
NICE, France 25-29 April 2000
The conference includes sessions on COMETS, ASTEROIDS,
METEORITES,
COSMIC DUST
For further information see
http://www.copernicus.org/EGS/egsga/nice00/nice00.htm
=============
(9) LAND-BASED LIFE ONE BILLION YEARS OLDER THAN THOUGHT?
From Andrew Yee <ayee@nova.astro.utoronto.ca>
Pennsylvania State University
Contacts:
A'ndrea Elyse Messer, (814) 865-9481 (o), aem1@psu.edu
Vicki Fong, (814) 865-9481 (o), vyf1@psu.edu
Ancient Iron-Rich Rocks Point to Early Occurrence of Land-Based
Life
Denver, Colo. -- Iron-rich rock formations dating to 2.3 billion
years ago suggest that the Earth's land masses were covered with
living things at least a billion years earlier than previously
thought, according to a Penn State geologist.
"Until now, the earliest accepted date for land-based life
was 1.2
billion years ago, but now we can push that back at least another
billion years," says Dr. Hiroshi Ohmoto, professor of
geosciences and
director of the Penn State Astrobiology Research Center. "Of
course,
terrestrial life back then was more in the nature of bacterial
mats
than oak trees and mammals."
Ohmoto, in collaboration with Nick Beukes of Rand Afrikaans
University, Johannesburg, South Africa, investigated laterites,
iron-rich deposits that form when organic acids -- those acids
created when living things decay -- leach iron from upper layers
of
rock and then deposit them as oxides in layers below. The normal
make-up of a laterite is three bands -- an iron-deficient layer
covered by an iron-rich layer that is covered by an
iron-deficient
layer. Modern laterites form in the tropics where large amounts
of
organic material rapidly decay.
"In order for laterites to form, there must be organic
material and
atmospheric oxygen," Ohmoto told attendees at the annual
meeting of
the Geological Society of America today (Oct.26) in Denver.
"Since we
have now traced these laterites to 2.3 billion years ago, there
must
have been atmospheric oxygen and terrestrial life at that
time."
Ohmoto originally looked at formations in Waterval Onder, South
Africa, an area near Pretoria. However, in this area, the
iron-rich
layer and upper iron-poor layer have eroded away. To get the big
picture, the researchers looked at core samples drilled by miners
who
typically drill through these layers looking for gold and uranium
ores buried much farther down.
"We looked at two cores in South Africa and one in Botswana
that
showed the complete series of rocks," says Ohmoto. "It
appears that
this laterite formation covers a rather large area."
There are several places further west where the formation is
actually
exposed, but these locations had previously been dated as much
younger rock. The researchers have now identified these laterite
formations as part of the same, much older formation, because it
sits
directly on the Hekpoort basalt, an extensive basalt formation
that
was extruded 2.3 to 2.4 billion years ago.
"Because we can trace the basalt all the way across, even to
a depth
of 2,600 feet, we know that the laterite deposits directly above
are
only slightly younger than the basalts," says Ohmoto.
Geologists currently are involved in a debate as to when
significant
amounts of oxygen appeared in the Earth's atmosphere. These
laterites
suggest that oxygen was plentiful 2.3 billion years ago, both for
the
generation of land-based biota and to convert iron to iron
oxides.
EDITORS: Dr. Ohmoto is at (814) 863-8761 or ohmoto@geosc.psu.edu by
email.
----------------------------------------
THE CAMBRIDGE-CONFERENCE NETWORK (CCNet)
----------------------------------------
The CCNet is a scholarly electronic network. To
subscribe/unsubscribe,
please contact the moderator Benny J Peiser <b.j.peiser@livjm.ac.uk>.
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 http://abob.libs.uga.edu/bobk/cccmenu.html