SETI public: COSMIC DRIVER OF TERRESTRIAL CLIMATE CHANGE?

(1) COSMIC DRIVER OF TERRESTRIAL CLIMATE CHANGE?

Eurekalert, 28 June 2003

http://www.eurekalert.org/pub_releases/2003-06/gsoa-gr0062703.php

Celestial Driver of Phanerozoic Climate?

Nir J. Shaviv, Racah Institute of Physics, Hebrew University of
Jerusalem, Jerusalem, 91904, Israel, and Ján Veizer, Institut für
Geologie, Mineralogie und Geophysik, Ruhr Universität, 44780 Bochum,
Germany, and Ottawa-Carleton Geoscience Centre, University of Ottawa,
Ottawa, ON K1N 6N5, Canada.

Is there a link between the climate on planet Earth and celestial
processes associated with solar activity, supernovas ands spiral
galaxies? In a uniquely cross-disciplinary approach to this problem, Nir
Shaviv, an astrophysicist at Racah Institute of Physics (Hebrew
University, Israel) and Jan Veizer a geochemist at the University of
Ottawa (Canada) and Ruhr University (Germany), have collaborated to
address this question from the perspective of astrophysics and geology.
In this paper, the authors examined the periodicity in the Earth's
climate over the past 600 m.y. that is apparent from the analysis of
isotopes of oxygen in fossil material. This was compared to the
periodicity predicted in the variation in the flux of cosmic rays (CRF)
reaching the Earth (and observed in the CRF recorded in iron meteorites)
as a function of the periodic passage of our solar system through the
spiral arms of the Milky Way. Cosmic rays are interpreted to influence
cloud formation on our planet and hence affect the planetary albedo. The
authors demonstrate a tantalizing correlation between celestial and
geological processes and add to the proposition that celestial processes
may be an important, perhaps even dominant influence, on climate change.
If this is the case, then the role of carbon dioxide becomes even more
critical to understand as it may well amplify the signals forced by
celestial processes. This is one of a number of new studies that are
shaking up our traditional understanding of the link between climate and
atmospheric gases.

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(2) CELESTIAL DRIVER OF PHANEROZOIC CLIMATE?

GSA Today, 1 July 2003

ftp://rock.geosociety.org/pub/GSAToday/gt0307.pdf

Celestial driver of Phanerozoic climate?

Nir J.Shaviv, Racah Institute of Physics,Hebrew University of
Jerusalem,Jerusalem, 91904, Israel
Ján Veizer, Institut für Geologie,Mineralogie und Geophysik,Ruhr
Universität, 44780 Bochum, Germany, and Ottawa-Carleton Geoscience
Centre, University of Ottawa, Ottawa,Ontario K1N 6N5,Canada

Abstract
Atmospheric levels of CO2 are commonly assumed to be a main driver of
global climate. Independent empirical evidence suggests that the
galactic cosmic ray flux (CRF) is linked to climate variability. Both
drivers are presently discussed in the context of daily to millennial
variations, although they should also operate over geological time
scales. Here we analyze the reconstructed seawater paleotemperature
record for the Phanerozoic (past 545 m.y.), and compare it with the
variable CRF reaching Earth and with the reconstructed partial pressure
of atmospheric CO2 (pCO2 ). We find that at least 66% of the variance in
the paleotemperature trend could be attributed to CRF variations likely
due to solar system passages through the spiral arms of the galaxy.
Assuming that the entire residual variance in temperature is due solely
to the CO2 greenhouse effect, we propose a tentative upper limit to the
long-term "equilibrium" warming effect of CO2, one which is potentially
lower than that based on general circulation models.

FULL PAPER at ftp://rock.geosociety.org/pub/GSAToday/gt0307.pdf

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(9) AND FINALLY: DESPERATE DOOM-MONGERS START PLAYING THE MASS
     EXTINCTION CARD

The Guardian, 1 July 2003

http://www.guardian.co.uk/comment/story/0,3604,988380,00.html

Shadow of extinction: Only six degrees separate our world from the
cataclysmic end of an ancient era

George Monbiot

It is old news, I admit. Two hundred and fifty-one million years old, to
be precise. But the story of what happened then, which has now been told
for the first time, demands our urgent attention. Its implications are
more profound than anything taking place in Iraq, or Washington, or even
(and I am sorry to burst your bubble) Wimbledon. Unless we understand
what happened, and act upon that intelligence, prehistory may very soon
repeat itself, not as tragedy, but as catastrophe.

The events that brought the Permian period (between 286m and 251m years
ago) to an end could not be clearly determined until the mapping of the
key geological sequences had been completed. Until recently,
palaeontologists had assumed that the changes that took place then were
gradual and piecemeal. But three years ago a precise date for the end of
the period was established, which enabled geologists to draw direct
comparisons between the rocks laid down at that time in different parts
of the world.

Having done so, they made a shattering discovery. In China, South
Africa, Australia, Greenland, Russia and Svalbard, the rocks record an
almost identical sequence of events, taking place not gradually, but
relatively instantaneously. They show that a cataclysm caused by natural
processes almost brought life on earth to an end. They also suggest that
a set of human activities that threatens to replicate those processes
could exert the same effect, within the lifetimes of some of those who
are on earth today.

As the professor of palaeontology Michael Benton records in his new
book, When Life Nearly Died, the marine sediments deposited at the end
of the Permian period record two sudden changes. The first is that the
red or green or grey rock laid down in the presence of oxygen is
suddenly replaced by black muds of the kind deposited when oxygen is
absent. At the same time, an instant shift in the ratio of the isotopes
(alternative forms) of carbon within the rocks suggests a spectacular
change in the concentration of atmospheric gases.

On land, another dramatic transition has been dated to precisely the
same time. In Russia and South Africa, gently deposited mudstones and
limestones suddenly give way to massive dumps of pebbles and boulders.
But the geological changes are minor in comparison with what happened to
the animals and plants.

The Permian was one of the most biologically diverse periods in the
earth's history. Herbivorous reptiles the size of rhinos were hunted
through forests of tree ferns and flowering trees by sabre-toothed
predators. At sea, massive coral reefs accumulated, among which lived
great sharks, fish of all kinds and hundreds of species of shell
creatures.

Then suddenly there is almost nothing. The fossil record very nearly
stops dead. The reefs die instantly, and do not reappear on earth for 10
million years. All the large and medium-sized sharks disappear, most of
the shell species, and even the great majority of the toughest and most
numerous organisms in the sea, the plankton. Among many classes of
marine animals, the only survivors were those adapted to the
near-absence of oxygen.

On land, the shift was even more severe. Plant life was almost
eliminated from the earth's surface. The four-footed animals, the
category to which humans belong, were nearly exterminated: so far only
two fossil reptile species have been found anywhere on earth that
survived the end of the Permian. The world's surface came to be
dominated by just one of these, an animal a bit like a pig. It became
ubiquitous because nothing else was left to compete with it or to prey
upon it.

Altogether, Benton shows, some 90% of the earth's species appear to have
been wiped out: this represents by far the gravest of the mass
extinctions. The world's "productivity" (the total mass of biological
matter) collapsed.

Ecosystems recovered very slowly. No coral reefs have been found
anywhere on earth in the rocks laid down over the following 10 million
years. One hundred and fifty million years elapsed before the world once
again became as biodiverse as in the Permian.

So what happened? Some scientists have argued that the mass extinction
was caused by a meteorite. But the evidence they put forward has been
undermined by further studies. There is a more persuasive case for a
different explanation. For many years, geologists have been aware that
at some point during or after the Permian there was a series of gigantic
volcanic eruptions in Siberia. The lava was dated properly for the first
time in the early 1990s. We now know that the principal explosions took
place 251 million years ago, precisely at the point at which life was
almost extinguished.

The volcanoes produced two gases: sulphur dioxide and carbon dioxide.
The sulphur and other effusions caused acid rain, but would have bled
from the atmosphere quite quickly. The carbon dioxide, on the other
hand, would have persisted. By enhancing the greenhouse effect, it
appears to have warmed the world sufficiently to have destabilised the
superconcentrated frozen gas called methane hydrate, locked in sediments
around the polar seas. The release of methane into the atmosphere
explains the sudden shift in carbon isotopes.

Methane is an even more powerful greenhouse gas than carbon dioxide. The
result of its release was runaway global warming: a rise in temperature
led to changes that raised the temperature further, and so on. The
warming appears, alongside the acid rain, to have killed the plants.
Starvation then killed the animals.

Global warming also seems to explain the geological changes. If the
temperature of the surface waters near the poles increases, the
circulation of marine currents slows down, which means that the ocean
floor is deprived of oxygen. As the plants on land died, their roots
would cease to hold together the soil and loose rock, with the result
that erosion rates would have greatly increased.

So how much warming took place? A sharp change in the ratio of the
isotopes of oxygen permits us to reply with some precision: 6C. Benton
does not make the obvious point, but another author, the climate change
specialist Mark Lynas, does. Six degrees is the upper estimate produced
by the UN's scientific body, the intergovernmental panel on climate
change (IPCC), for global warming by 2100. A conference of some of the
world's leading atmospheric scientists in Berlin last month concluded
that the IPCC's model may have underestimated the problem: the upper
limit, they now suggest, should range between 7 and 10 degrees. Neither
model takes into account the possibility of a partial melting of the
methane hydrate still present in vast quantities around the fringes of
the polar seas.

Suddenly, the events of a quarter of a billion years ago begin to look
very topical indeed. One of the possible endings of the human story has
already been told. Our principal political effort must now be to ensure
that it does not become set in stone.

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