October 13, 1997
from AmericanAlmanac Website
Before the completion of the glacial
retreat, there were no Great Lakes, for example. None of the many
lakes, large and small, that dot the northern tier of the United
States existed. Other lakes - such as the 20,000-square mile Lake
Bonneville that once covered much of Utah - dried up, leaving behind
only a few relatively smaller remnants, like the Great Salt Lake.
The lower Ohio drained into a now nonexistent
river, which geologists have named the Teays.
Another Name For Population Reduction
The primary purpose behind the global warming scare, is to convince you to accept the necessity of population reduction. There is no scientific evidence behind global warming, as the following article by Laurence Hecht, the first in an occasional series in the New Federalist, will show.
This report, which first appeared in
21st Century Science & Technology magazine, Winter 1993-1994, was
written shortly before Hecht, an associate editor of 21st Century
magazine, began serving a 33-year sentence as a political prisoner
in the state of Virginia, along with five other associates of Lyndon LaRouche.
We can look to the efforts of a leading Malthusian activist, Dame Margaret Mead, for the answer. Mead chaired a conference in November 1975 on "The Atmosphere: Endangered or Endangering.''
Scientists who attended that conference warning
about a coming Ice Age, such as Stephen Schneider, left the
conference promoting global warming.
Mead went on to say, that the point is to draw from people their capacity for "sacrifice.''
In other words, scientists should create artificial but plausible stories that will sufficiently scare people, that they will give up their standard of living and modern industrial society - and in the process kill off half or more of the world's population. We are now in an ice age and have been for about the past 2 million years.
Over the past 800,000 or so years, the Earth's climate has gone through eight distinct cycles of roughly 100,000-year durations.
These cycles are driven by regular periodicities in the eccentricity, tilt, and precession of the Earth's orbit. In each of the past eight cycles, a period of glacial buildup lasting about 80,000 years has ended with a melt, followed by a roughly 10,000-year period - known as an interglacial - in which relatively warm climates prevail over previously ice-covered northern latitudes.
The present interglacial has already lasted beyond the 10,000-year average. One may thus suspect that a new period of glacial advance, a new "ice age,'' is in the making. Whether it will take a few thousand years or a few hundred, or whether the process of glacial advance is already under way is difficult to say.
Of one thing we are sure: The present
hysteria over global warming - with its apocalyptic forecast of
melting of the polar ice caps, flooding of the coastal cities, and
desertification of the world's breadbaskets - is not helping
citizens to understand the real and complex forces that shape the
Rather, let us take a sober look at the long-term picture of Earth's climate that has been put together over centuries of careful work in the fascinating and challenging multidiscipline science known as paleoclimatology.
Louis Agassiz, the Swiss paleontologist
and associate of the famous Humboldt brothers, waged the fight to
convince the scientific community of the truth of this hypothesis,
beginning at a conference of the Swiss Society of Natural Sciences
at Neuchatel in 1837.
Within our present Quaternary period, there are two further subdivisions known as epochs.
Currently, the greatest area of glaciation is the continental ice
sheet of Antarctica (about 5.0 million square miles), which began
its expansion about 5 million years ago. The largest Northern
Hemisphere glacier is the Greenland ice sheet (about 0.8 million
square miles). As the glaciation expands, most of the additional
growth takes place in the Northern Hemisphere.
Driven by well-defined cycles in the Earth's orbital
orientation to the Sun, periods of roughly 100,000 years of
generally advancing glaciation have been followed by short periods,
of roughly 10,000 years' duration, in which the glaciers retreat.
These two periods or subdivisions of the ice age are known as
glacials and interglacials.
The maximum extent of glaciation, the glacial climax of the last 100,000-year ice age, occurred just 18,000 years ago, at a time when human societies were already well established on the Earth. At that time, a huge continental glacier covered North America down through the northeastern states of the United States, reaching across the midwestern plains and up into Canada (2).
This most recent
of the great continental glaciations is known in North America as
the Wisconsin (in Europe as the Weichselian). Its southernmost limit
extended across the middle of Long Island, through northern New
Jersey, lower New York State, western Pennsylvania, Ohio, Indiana,
Illinois, Iowa, then up diagonally through the northeast corner of
Nebraska, into the Dakotas, and across the southern tier of the
A separate portion extended outward from the Alps and another
one from the Caucasus Mountains in Asia Minor.
But hunting was apparently good along the fringes of the continental glaciers, and man survived in these regions in a fairly primitive state, wearing animal furs for warmth and seeking shelter in caves.
The global climate has been generally cooling over the past 6,000 to 8,000 years, and is now about 1 degree Fahrenheit cooler than at the time of the postglacial climatic optimum. One might cite evidence such as the advance of the Greenland ice sheet and the southward movement of the line of citrus growing in the southeast United States over the past 40 years to suggest that the expected cooling is even now under way.
However, because these astronomically driven cyclical trends are of long duration (10,000 years being the shortest cooling cycle), it is not possible to attribute a climatic trend on a time span so short as a few decades or even a few centuries to a single cause.
One must take a broader view.
Following a number of short-term oscillations beginning about 12,000 B.C., a rise in temperature that set in about 8300 B.C. led to sustained warm climates in the northern European lands formerly covered by ice. The maximum summer temperatures experienced in Europe, over the last 10,000 years, occurred in about 6000 B.C. Over North America, where the process of glacial retreat lagged somewhat, the maximum was reached by about 4000 B.C.
That period is known as the
Postglacial Climatic Optimum (or the altithermal period), when mean
temperatures were about 1 degree Fahrenheit warmer than today.
Europe the most marked change appears from 1200 B.C. to 700 B.C.,
coinciding with the Dark Age period that Homeric scholarship
suggests occurred in Greek-speaking lands. In some places (Alaska,
Chile, China) there is evidence that the cooling and re-advance of
the glaciers began as early as 1500 B.C. [fn2]
Known as the Medieval (or Little) Climatic Optimum, temperatures in this period became, briefly, nearly as warm as in the postglacial climatic optimum.
As Lamb describes it:
This warming period, which ended as early as 1100 in parts of North America and later in Europe, was followed by a roughly 500-year period of severe cooling known as the Little Ice Age - the Klima-Verschleterung, or climate-worsening in the German literature. The low point of the cooling occurred from about 1550 to 1750, but extreme cold weather began earlier and ended considerably later in many parts.
The Greenland colony, for example, died out not long after the year 1400. And in England, tent cities were set up, and Frost Fairs celebrated on the frozen river Thames as late as the winter of 1813-14.
Some of the symptoms of the cooling as described by Lamb were:
There are two basic requirements for an ice age:
Although the causes that give rise to these two conditions are complex and far from perfectly understood, the recognition of their importance and of some of the basic mechanisms governing their genesis, dates to no later than the early part of this century.
Subsequent advances in nearly all the physical
sciences and the work of thousands of researchers in the many fields
related to historical climatology have greatly enhanced our
understanding and documentation of the climate record. But the big
challenge, to understand climate well enough to be able to predict
its future course, is still out of reach.
The St. Petersburg-born meteorologist came from a
German family that had settled in Russia during the reign of
Catherine II. He began his study of natural sciences in Heidelberg
in 1866 and received his doctorate in 1870 with a paper, published
in Moscow, on the effects of heat on plant growth. After a brief
period of work at the Central Observatory in St. Petersburg, Köppen
came to the German Marine Observatory in Hamburg where he stayed for
44 years, becoming first the head of the weather service and then
meteorologist of the observatory.
Wegener's now-famous theory was initially rejected by the science establishment, and became widely accepted only in the 1960s and 1970s, well after his tragic death on the Greenland glacier in 1930.
It is recorded in a charming letter to his wife:
The idea itself was not new; it had been
noted in Alexander von Humboldt's famous Cosmos, among other
One prominent attempt at an explanation was the hypothesis that land bridges had once existed, for example, connecting South Africa with southern South America, North Africa with Florida and the Caribbean, and so forth. Twenty years before Wegener, the great Viennese geologist Eduard Suess had proposed that the continents may have been linked together in one supercontinent, which he called Gondwanaland.
The similarity in geological
development of the continents of the Southern Hemisphere (including
the Indian subcontinent), and their marked difference from those of
the north, had already suggested some such link. But Suess was not
sufficiently versed in these fields to recognize the paleobiological
and climatological significance of his hypothesis.
The sial, which corresponds most
closely to granite, has a specific gravity (a measure of its weight
in comparison to an equivalent volume of water) of 2.7, while the
sima, which is like basalt, is somewhat heavier at 3.0. Thus the
lighter rock making up the continental crust could be thought of as
giant blocks, floating somewhat like icebergs above the denser sima.
The first book-length account, Die Enstehung der Kontinente und Ozeane (The Origin of the Continents and Oceans), appeared in 1915. Here and in his other early papers, Wegener was somewhat at a loss to explain by what mechanism the drifting apart of these blocks would occur. In 1929, he tentatively proposed the means by which the drift is today understood to occur, referring to the possibility of convection currents in the magma - the layer of molten rock on which the Earth's crust is thought to float.
The high mountain ranges
found near the edge of continents - the Alps, Himalayas, and the
Cordilleras, which range from Alaska to southern Chile - were seen as
produced by the crumpling up of layers of rock on the leading edge
of the drifting continents, produced by forces similar to that of a
bow wave. [fn4]
According to the modern reconstruction of the theory of drifting continents, only in the Permian period (250 million years ago), and the present Quaternary, does the placement of the continental land masses in the higher latitudes, allow for the buildup of the great glacial ice sheets.
Through their extensive fieldwork in Alpine regions, Penck and Brückner had been able to distinguish four separate cycles of glacial advance and retreat over the ages, and they produced a climatic curve for the ice age. Köppen conceived the idea of essentially overlaying on this curve the time-scale produced by examining the changes in solar radiation caused by regular cycles in the Earth's orbital relationship to the Sun.
Köppen's hope was that
the cycles of glacial advance and retreat could be dated by
correlating them to the astronomical cycles.
His hypothesis was taken up and elaborated first by the French mathematician J.F. Adhémar in 1842, and then, by the self-taught Scottish climatologist James Croll, beginning in 1860, who added into his calculations the cycle of change of the eccentricity of the orbit. However, at the end of the 19th Century, the exact periodicity and extent of this cyclical variable had not been precisely calculated.
Croll was also hampered by his incorrect
supposition that periods of ice buildup would coincide with the
From 1911 until his first contact with Köppen in 1920, Milankovitch carried out painstaking calculations of the long curve of the variability of solar insolation (the amount of sunlight) at northern latitudes, in hopes of demonstrating its forcing effect on the ice age cycles.
He published a few small papers on his work and then, in
1920, a book in the French language, The Mathematical Theory of Heat
Phenomena Produced by Solar Radiation, which came to the attention
A postcard from Köppen initiated an extended correspondence between the two men.
Milankovitch, who hoped
to use his calculations to produce a curve of past climates, was
troubled by the question of which season and which latitude was most
critical to the advance of glaciation. One of the important fruits
of the exchange was Köppen's conclusion that it is the diminution of
summer heat - not the increase of winter coldness, as Croll had
thought - that is most important to the ice buildup.
Nevertheless, a number of paleoclimatologists in
America and Europe took it up and carried out pioneering work from
the 1930s onward, which tended to corroborate the Milankovitch
cycles. Much of this was in the field of paleobiology, examining
core samples from various marine basins under the microscope, using
innovative means of dating the biota and determining sea levels and
temperature levels coinciding with the time of their formation.
Deep-sea core samples taken in the 1970s showed the Milankovitch 20,000, 40,000, and 100,000-year periodicities going back for 1.7 million years. The new work was reported in Science magazine in 1976 in a paper written by a team of researchers at Columbia University's Lamont-Doherty Geological Laboratory. [fn6]
Somewhat ironically, the geology department at that university had
been one of the staunchest holdouts against Wegener's theory of
(Milankovitch had expected that the 40,000-year cycle
of the angle of obliquity would be the dominant one; it was for the
periods before about 800,000 years ago. But since that time, for
reasons not yet fully understood, the 100,000-year periodicity
The Solar Cycles
Johannes Kepler's discovery in the early 17th
Century, that the planets move in ellipses about the Sun, with the
Sun at one focus, and his elaboration of the laws of this motion are
the basis of all astronomical hypothesis concerning climate. (Nor
can it be accidental that Wegener had studied classical astronomy
and wrote his dissertation at the University of Berlin on the
subject "The Alphonsine Tables for the Use of a Modern
Calculator,'' a recalculation of the old tables used to ascertain
the positions of the Sun, Moon, and the five then-known planets.
Looking down upon the North Pole of the Earth, the orbital motion is counter-clockwise from P to Q'A, to A to Q and back to P again. We have exaggerated the ellipse in order to simplify visualization of the processes described. As the Sun sits at one focus of the ellipse, the distance from Earth to Sun is least when the Earth is at P, the position known as perihelion, and greatest at A, the aphelion.
Let us examine the change in the amount of solar radiation that will
be felt as the Earth moves from aphelion to perihelion.
Now, the Earth is not simply a moving point, but a solid body of more or less spherical shape. It rotates about an axis that is inclined to the plane of the ellipse by a certain angle known as the angle of obliquity.
It is this inclination of the Earth's axis, which is now about 23.5 degrees, that causes the main difference in temperature between polar and equatorial regions. The Sun's rays striking the Earth obliquely are forced to pass through a much greater thickness of atmosphere, thus dissipating their warming effect, than those rays that strike in a more perpendicular direction and are thus required to penetrate a lesser amount of the atmosphere.
Even without that obliquity there would be some
variation in temperature between pole and equator, because of the
changing angle at which the parallel rays of the Sun will strike the
circular arc that represents the Earth's surface (4). An
increase in the angle of obliquity tends to exacerbate this effect.
However, in one annual revolution around the Sun, the axis will take up all orientations with respect to the line perpendicular to the plane of the ellipse and passing through the center of the Sun, which is known as the pole of the ecliptic. When the Earth's spin axis is pointed 180 degrees away from the pole of the ecliptic (looking down on the ellipse from the direction of the North Pole), the Northern Hemisphere experiences its shortest day, known as the winter solstice.
On the same day, the Southern Hemisphere experiences its
longest day, the summer solstice. The opposite situation would arise
at the position 180 degrees around the ellipse.
Another consequence, which was noted by the ancient
astronomers, was the long-period change in that constellation in
which they observed the Sun rising on the day of the vernal (spring)
equinox. Later comparison of the physical dynamics of this
phenomenon to the precession of a spinning top (the wobbling as it
winds down) led to the name precession of the equinox for the
The result is that the complete cycle of return to the position where Northern Hemisphere winter occurs at P takes approximately 21,000, not 26,000, years (8).
Recalling that the most important astronomical requirement for glacial advance is a string of mild summers in which the winter snow buildup is not completely erased by melt, we are now in a position to examine how the orientations of the orbit might contribute to meeting this need.
Astronomy and Climate
It might at first appear that the occurrence of
Northern Hemisphere summer at A, combined with a relatively high
eccentricity, would produce the most favorable conditions.
If winter solstice occurs at P, climatologists call the two smaller quadrants caloric winter and the two larger ones caloric summer.
One sees then that another way of describing the condition described above is to say that the summer is longer and milder (at least with respect to solar insolation) than winter. The difference in length between caloric summer and winter can be as great as 33 days. At the present time, the difference is 7 days.
This will vary with the
eccentricity, which, as we have mentioned, has a cycle of about
The greatest excess in the
number of days of caloric summer over winter will then be
experienced, and consequently the lowest flux density of the summer insolation. Assuming the proper meteorological dynamics, this should
be an ideal position for the rapid advance of glaciation.
eccentricity will have lessened by only about one-fifth of its
greatest value in this position (its cycle of change is not
perfectly linear), the Earth will now experience a most intense
daily flux of solar radiation during the relatively brief caloric
summer, creating ideal conditions for glacial melt. The winter,
however, will be longer and colder than normal insofar as the solar
flux affects it. The outcome is perhaps a toss-up. Half a precessional cycle later, winter solstice occurs again at
P and the
eccentricity is still relatively great. Conditions for glacial
advance are again good.
When these added considerations are taken into account, a curve can be derived of the sort illustrated for various latitudes in (9).
The close relationship between the variations of average daily insolation and the estimated variation in average temperature during the last 100,000-year-plus ice age cycle is seen.