12 April, 2010: The railway debris flow of South Tyrol

12. April 2010 South Tyrol: 9 confirmed victims, 23 people injured; this was the headline about a rail crash between the towns of Latsch and Kastelbell reported by the news almost worldwide.
The modern railway between the two localities follows the orographic right bank of the main river Etsch, the accident occurred at a segment inside a gorge eroded by the river in Holocene sediments (manly a large alluvial fan coming from south with unconsolidated debris-flow deposits).
At 9.02 in the morning, just when the train approached, a debris flow of 400 cubic meters - with a width of 10 to 15 meters and a thickness of 2m - bursted off 50m above the railway line and hit the first wagon, knocking it from the railway.

Fig.1. The derailed train during the difficult rescue efforts (SüdtirolNews).

To clarify possible causes of the landslide soon after geological investigations were initiated. Eye witnesses reported large quantities of water running down the slope after the accident. A preliminary site investigation by the authorities concluded that the leakage of an irrigation system above the location (the area is used for agriculture) saturated the soil and underlying sediments with water, causing a mudslide just in the moment the train passed. The irrigation system was in use since the previous week and at least for the last days or hour's large quantities of water infiltrated in the underlying slope and saturated the debris. It is possible that the vibrations of the approaching train triggered finally the fatal slide that initiated the debris flow.

Today, one year after the deadly debris flow, a memorial stone was inaugurated to remember the nine victims of the disaster.

In search of Lemuria

"Yet if hope has flown away
In a night, or in a day,
In a vision, or in none,
Is it therefore the less gone?
All that we see or seem
Is but a dream within a dream."
"A Dream Within A Dream" by Edgar Allan Poe (1809-1849)

With the census of life forms in the 19th century naturalists realized that many similar animal species were distributed on different continents or remote islands. For short distances this was explainable by (voluntary or involuntarily) migration on water, on islands or in the air, but many distances were too great to overcome by large animals, especially by mammals.
The English lawyer and zoologist Philip Lutley Sclater (1829-1913) noted the particular distribution pattern of a particular group of primates - the Lemurs. Sclater however included in his Lemuridae more species than modern systematic - the Lemurs, the Indri and the Aye-aye (found on Madagascar), the Galagos (found in Africa), the Loris (found in Asia) and the Tarsiers (found in Indonesia). He observed that "while 30 different species of Lemurs are found in Madagascar alone, all of Africa contains some 11 or 12, while the Indian region has only 3." In a short essay of 1864 titled "The Mammals of Madagascar", published in the brand new "The Quarterly Journal of Science", he addressed the possible answer - Madagascar with it's rich diversity of species was the homeland of lemurs which spread all over Asia and Africa by a land bridge connecting once these continents. He named this supposed continent appropriately "Lemuria" and because of similarities with of the lemurs of Madagascar to new world monkeys he speculated even with a connection to America:

"The anomalies of the Mammal fauna of Madagascar can best be explained by supposing that anterior to the existence of Africa in its present shape, a large continent occupied parts of the Atlantic and Indian Oceans stretching out towards (what is now) America to the west, and to India and its islands on the east; that this continent was broken up into islands, of which some have became amalgamated with the present continent of Africa, and some, possibly, with what is now Asia; and that in Madagascar and the Mascarene Islands we have existing relics of this great continent, for which as the original focus of the "Stirps Lemurum," I should propose the name Lemuria!"

In later works he was more cautious:

"This fact would seem to show that the ancient "Lemuria", as the hypothetical continent which was originally the home of the Lemurs has been termed, must have extended across the Indian Ocean and the Indian Peninsula to the further side of the Bay of Bengal and over the great islands of the Indian Archipelago."
Page 236-237, SCLATER & SCLATER (1899): "The Geography of Mammals."

Sclater was not the first to promote ancient land bridges or even a sunken continent in the Indian Ocean, the idea of oceans as drown landmasses was a plausible geological theory at the time. Marine fossils found on land demonstrated that sea level changed over time, land became sea and even if the exact mechanism was unknown, it was not impossible to image that also land would become sea.
The French geologist Etienne Geoffrey Saint-Hilaire had speculated about a connection between Madagascar and India in 1840, the English geologist Searles V. Wood (1830-1884) hypothesized the existence of a giant southern continent during the "secondary era" (modern Mesozoic). Alfred R. Wallace (1823-1913), biogeographer of South America and Indonesia, proposed in 1859 a sunken continent to explain the fauna found on Celebes, but became later one of the most eloquent critic of the theory.
The theory of Lemuria was interesting speculation but even Sclater mention it only as idea and never promoted it too much.

In 1868 the German biologist Ernst Haeckel published his German edition of "Natürliche Schöpfungsgeschichte"(The history of Creation), addressed to a general public where he promoted his view of evolution of life and humans. Haeckel considered the earliest humans descending from Asian primates and placed the cradle of humanity in Asia or in alternative Africa and very cautiously on the hypothetical continent between these landmasses. Lemuria played a major role as possible migration route of humans into Africa and Indonesia (Natürliche Schöpfungsgeschichte, page 515).
In later editions and the English version of the book, translated by Ray Lankester in 1876, the supposed continent is even emphasised and labelled in the map as "Paradise" and displayed as cradle of humanity.

"The primeval home, or the "Centre of Creation", of the Malays must be looked for in the south-eastern part of the Asiatic continent, or possibly in the more extensive continent which existed at the time when further India was directly connected with the Sunda Archipelago and eastern Lemuria."
Page 329, HAECKEL (1876): "The history of Creation."

Fig.2. and 3. Ernst Haeckel, "A hypothetical sketch of the monophyletic origin and extension of the twelve races of Man from Lemuria over Earth." From Haeckel, Natürliche Schöpfungsgeschichte, Plate XV. Note the differences in the German version (1868) without Lemuria and the English version (1876) with Lemuria, after 1870 Haeckel adopted and promoted the idea of a sunken continent in the Indian Ocean.

"The probable primeval home or "Paradise" is here assumed to be Lemuria, a tropical continent at present lying below the level of the Indian Ocean, the former existence of which in the tertiary period seems very probable from numerous facts in animal and vegetable geography. But it is also very possible that the hypothetical "cradle of the human race" lay further to the east (in Hindostan or Further India), or further to the west (in eastern Africa)."
HAECKEL in 1870.

Haeckels work, as vague at is was, however spread the idea of sunken continents to a larger public, still in 1919 the English author Herbert George Wells wrote:

"We do not know yet the region in which the ancestors of the brownish Neolithic peoples worked their way up from the Palaeolithic stage of human development. Probably it was somewhere about south-western Asia, or in some region now submerged beneath the Mediterranean Sea or the Indian Ocean, that, while the Neanderthal men still lived their hard lives in the bleak climate of a glaciated Europe, the ancestors, of the white men developed the rude arts of their Later Palaeolithic period."
WELLS (1919): "Outline of History."

The idea of Lemura as lost cradle of humankind proposed (however not too actively supported) by serious scientists was to fascinating for pseudoscientific and esoteric groups and authors not to be incorporated in their worldview.
In 1888 the Russian esoteric author Elena Petrovna Blavatskaja (1831-1891), strongly influenced by Asian philosophy, published her "The secret doctrine" in which she proposes Lemuria as the cradle of one of the seven root races of humanity. These beings supposedly possessed four arms and eyes and were egg-laying hermaphrodites and shared the continent Lemuria with dinosaurs. The never existed continent of Lemuria became part of popular culture.

Bibliography:

RAMASWAMY, S. (2004): The lost land of Lemuria - Fabulous geographies, catastrophic histories. University of California Press: 334

Online Resources:

FREISTETTER, F. (04.04.2011): Lemuria: wenn Wissenschaft zu Esoterik wird. (Accessed on 07.04.2011)

6 April, 2009: L'Aquila Earthquake

At 3:32 in the morning a 20 seconds lasting earthquake with magnitude 6,9 (followed quite until midday by weaker aftershocks) occurred 7km near the city of Aquila, the capital of Abruzzo, within a depth of 8,8km.

Fig.1. Intensity map of Central Italy Earthquake 2009-04-06 (L'Aquila) from the USGS.

More than 45 towns were affected, 308 people killed, 1.600 injured and more then 65.000 inhabitants were forced to leave their houses.

Italy has a long and tragic history of earthquakes. The setting between to larger continental plates (the European and African) and various micro plates results in a highly active tectonics all over the peninsula.
The first map of seismicity of the Mediterranean area and an extensive research on earthquakes in Italy was published in 1857 by the Irish engineer - and self educated geologist - Robert Mallet under the title "Great Neapolitan Earthquake- The First Principles of Observational Seismology". Mallet got interested in earthquakes in 1830 by a drawing in a natural science book displaying two columns twisted by an earthquake in Calabria. He decided to study the forces able to do this to human constructions. In his work he noted that damages on constructions were distributed in distinct areas, setting out from a point of heaviest havoc. These points, the epicentre of an earthquake, were not randomly distributed, but found in "seismic belts" following the Apennines.

Earthquakes mark the history of the region surrounding L'Aquila and the province of Abruzzo, historic events or swarms of trembles are recorded from 1315, 1349, 1452, 1461, 1498, 1501, 1646, 1703, 1706, 1791, 1809, 1848 and 1887, one of the most important on the 2, February of 1703 which caused devastation across much of central Italy and largely destroyed the city of L'Aquila and killed 5.000 people.

The destruction caused by the earthquake of 2009 surprised experts and generated discussions about the antiseismic building standards adopted in Italy. While most of the medieval structures in rural areas collapsed or were heavily damaged, in L'Aquila most concern arouse the observation that the modern buildings suffered the greatest damage and that the death toll included mostly young people. L'Aquila was a university town and cheaper accommodations which suffered severe damage were inhabited by students, also many students died when a dormitory at the University of L'Aquila collapsed. Even some buildings that were believed to be "earthquake-proof" were damaged, like parts of the new hospital and various buildings of the government.
In rural areas the "core" of most of the historic houses consisted of local material, like stone, superimposed by cement constructions or supplementary storeys of modern age. It was this mismatch that caused the collapse of many buildings. In L'Aquila the earthquake of 1703 destroyed most of the ancient buildings, during reconstruction work first antiseismic regulations were introduced - the rebuild houses possessed thicker walls, improved joints between floors and the allowed height of the building was limited. Most "modern" buildings in contrast were build previously of 1984, before modern antiseismic buildings standards were introduced in Italy.
However there was and still is a widespread disregard of building standards and the ignorance by people and (in part corrupt) authorities of the seismic hazards. Many concrete elements of the collapsed buildings (like the hospital) "seemed to have been made poorly, possibly with sand" a common tactic to build fast and cheap by building enterprises controlled by criminal organisations.
The earthquake of L'Aquila was therefore only in part a natural disaster and the manmade catastrophe was strongly misused by Italian politics and economy and many promises are still unrealized today.

Fig.2. The local prefecture (a government office) damaged by the earthquake, emblem of the situation in Italy, from Wikipedia.



However most alarming were the legal repercussions of the earthquake on science. Based on a general lack of understanding of science by the public and authorities various persons were accused to have ignored "premonitory signs" of the earthquake and early warnings- pseudoscientific "premonitory signs" of dubious veracity and warnings mostly published by individuals in internet.

To cite what the geographer Grove Karl Gilbert (who studied intensively the earthquake in San Francisco of 1906) resumed during a meeting of the American Association of Geographers (AAG) in 1909 about the predictability of earthquakes:

"Common people would be satisfied to know if we reached the point where a scientific predictability for an imminent earthquake is possible."

But Gilbert criticised the simple belief that earthquakes automatically occur in cycles or after long periods of quiescence and that an extrapolation based only on historical records is possible.

"Considering the complexity of conditions and the chaotic interrelationships between underground tensions, it can not be assumed that the particular conditions of every epoch will repeat always at the same manner."

Gilbert concluded that we should not try to predict specific events, but to prepare for the general hazard:

"[seismologists should not]…try to enforce control on the course of nature, but with the support of science, predict the imminent changes, so to enable the people to be warned and to be prepared…[]. The determination of the instant of seismic hazard belongs to an indefinite future. It is still a realm of try and hope."

Bibliography:

TERTULLIANI, A. (2011): Il segni del terremoto sul tessuto urbano. DARWIN No. 42 Marzo/Aprile: 80-83
WALKER, B. (1982): Earthquake. Planet Earth. Time Life Books: 154

Earthquake and nuclear disaster hoaxes

The earthquake and the catastrophic tsunami in Japan unfortunately were, are and will be misused by cranks to promote their personal political or pseudoscientific worldview.
Especially the Fukushima nuclear disaster and the chaotic situation in the last weeks at the plant have raised concern about use of nuclear energy in Europe - an objective discussion could be a good thing, unfortunately most people base their subjective opinion on false premises.
For real information about the earthquake and nuclear situation in Japan I advise to visit impartial sites like reliably news or science magazines or neutral blogs - for example:

Scientific American
The excellent series by Evelyn and Mark L. Mervine at the Georneys Blog

I will try to collect internet hoaxes about the earthquake I came aware in this post:

The following map, posted by some blogs some days after the earthquake and apparently showing the distribution of radioactive fallout particles is an internet hoax - the cited Australian company (recognizable by the logo in the corner) denied to have produced it and declined every responsibility. Note also the incorrect use of an obselete unite like "rad (radiation absorbed dose)":

Fig.1. HOAX !!

A newspaper from April 6. reported a fraud to exploit the fear of the local population: several men sold forged medicine to prevent "radiation disease" to more than 1.000 people, earning in total 24 million Yen.

The presumed predictability of earthquakes based on the position of stars and the moon was addressed already here.
Most concerning are the quotes of religious fanatics like for example the Tokyo Governor Shintaro Ishihara, the American Glenn Beck or Roberto De Mattei, vice-president of the Italian National Research Council (!), in his religious broadcast "radici cristiane (Christian roots)" on the radio station "Radio Maria" 20. March 2011.
Other cranks claim that the erathquake was caused, or could be foreseen, by the American HAARP-project (anyway - the power used to run the facility is less than for a common radio station).
Other pseudoscientific claims are the supposed trigger of earthquakes by other large earthquakes; this issue is addresses by Chris Rowan, who also points out the general problem how to report natural hazards risk in the media.

The eruption of the Shinmoedake volcano in the south-western end of Japan was reported in some journals and attributed to the aftermath effects of the earthquake, however the volcano was active already since January and Jessica Ball explains why earthquakes and eruptions are rarely linked and the long term effects of tectonics on volcanoes.

A month after the earthquake news begun to misinterpret the results of various paleoseismic studies with headlines like "The Man Who Predicted the Tsunami" or "The new Cassandra from Japan", referring to an online text published in 2010. Claiming that a geologic study to interfere the probability in time of past tsunamis enables us to predict a future tsunami (implying exact time and extant of a catastrophe) is an incorrect media statement.

On the tracks of ancient mammals

The hill of Osoppo, after the small town of Osoppo in the Italian province of Udine, is a 120m high local "mountain" dominating the large fluvial plain of the river Tagliamento.

During the Pleistocene the entire area was covered by the Tagliamento glacier, eroding older rocks and depositing glacial sediments. So it is no wonder that the Osoppo hill is composed mainly of sandstone and conglomerate of the Quaternary epoch, however by the particular topography in the shadow of larger mountains the glacier in this spot was not able to erode all of the older rocks - on the steep flanks and the hilltop of Osoppo rocks dating back to the Pliocene and Miocene can be found.
The stratigraphic succession is clearly visible along a street leading to the fortress of the First World War on top of the hill. The base of the hill is composed of siltstone interpreted by the presence of limnic ostracods as sediments of a brackish lake deposited during or immediately after the Messinian Salinity Crisis five million years ago. The fine grained sediments are covered by a 110 m thick coarse grained sandstone and conglomerate succession of the Osoppo conglomerate dated to the Miocene to Pliocene. In the apparently homogenous succession of alternating layers of sandstone and conglomerates there is a change in the inclination of the layers. These clastic sediments were deposited in a large fluvial delta entering the sea or a large lake, however the observed changes in the inclination of the foreset beds demonstrate that the river changed over time flow direction and deposited various intersecting overlying sediment units. To the hilltop the foreset beds are truncated by the topset beds of a large river plain.

Fig.2. Osoppo conglomerates of the delta complex, the bending of the single layers (the foreset beds of the delta) is observable.Fig.3. Oversimplified sketch of composed delta geometry, by change of the river flow also the progradation (red arrows) of the delta changes.

The hill of Osoppo is not only peculiar by the preservation of such an old delta, more remarkably the coarse grain sediments contain fossils - more precise trace fossils. During work to preserve the crumbling walls of the fortress a surface of the fossil river plain was uncovered, showing various impressions - trackways attributed to various large mammals.

Fig.4. and 5. Photography of the Pliocene trackways site in Osoppo in 1994 and map of the exposed surface with reconstructed trackways and geology: signatures 1) conglomerate of former river island 2) sandstone of former channels 3) mud cracks 4) ripple marks. Trackways signatures - Blue: rhinoceros; Red: equid; Green: bovid, after DALLA VECCHIA & RUSTIONI 1996 and Geositi del Friuli-Venezia-Giulia.

During the Miocene the modern peninsula of Italy was an archipelago of larger and smaller islands, fossils of land vertebrates are therefore rare findings and the exact identification of the makers of the five trackways is difficult.

- The first track-morphotype is stubby and very large (15 to 30 cm long) with three toes, these characteristics suggest a large perissodactyl like a tapir or more likely a small rhinoceros.

- The second track-morphotype also shows three toes, a central 8 cm large and two smaller lateral toes, preserved only when the central digit pushed deep in the moist sediment - the medial hoof of a three digit horse similar in appearance to the genus Hipparion.

- The third and last recognized track-morphotype is 15 to 20 cm long with two elongated parallel hoof-imprints, attributed to an artiodactyl it is probably produced by a large bovid, cervids appeared only later in the European geological record.

Fig.6. to 8. Overview and detail of the weathered ichnofossil of equid (Hipparion ?), length of pen ca. 14cm.

The five trackways are preserved on an ancient island of coarse grained conglomerate surrounded by sandy layers of the river channels. All the animals walked mostly parallel to the direction of the ancient channels, the horses were the first to venture on the river plain, as demonstrated by the deep tracks left in the yet wet sediments, followed by the bovid and rhinoceros, the last trampling on the tracks of the bovid.

Mammal trackways are not too frequent, but trackways of Hipparion are even rarer, other known examples for example include the site of Laetoli in Africa. It is this rarity that makes the site of Osoppo special.
However the actual situation and conservation at the fossil site is not optimal. The local authorities provided only a small board (with incorrect footprints similar to a felid species) to advertise the importance of the discovery and after a first excavation campaigns years ago the surface with the tracks was exposed without protection, many of the already poorly preserved tracks were heavily eroded and damaged. Finally the site was covered by a plastic sheet, which however provides only a small shelter and hides the fossil to interested visitors.

Bibliography:

DALLA VECCHIA F.M. & RUSTONI M. (1996): Mammalian trackways in the Conglomerato di Osoppo (Udine, NE Italy) and their contribution to its age determination. Mem. Sc. Geol. 48: 221-232
DALLA VECCHIA, F.M. (2008): Vertebrati fossili del Friuli - 450 milioni di anni di evoluzione. Pubblicazion N.50 Museo Friuliano di Storia Naturale, Udine: 303

Is Eoanthropus dawsoni a valid species?

"It's better to ask some questions than to know all the answers."

James Thurber, American writer and illustrator (1894-1961)

At the beginning of the twentieth century the search for our ancestors - the supposed "missing links" between man and the animal kingdom was a crucial point in the new emerging field of human palaeontology. First results came from Germany with the discovery in 1907 of a jaw with mixed characteristics between apes and humans - a good start, but scientists wanted something even better.

Only a year later some workers discovered strange bones in a gravel pit near the village of Piltdown in southern Sussex and consigned them to the lawyer, antiquarian and amateur geologist Charles Dawson.
Dawson initiated with the help of Arthur Smith Woodward, keeper of the geological department at the British Museum, a private prospection campaign in the gravel pit. Dawson already had experience in digging up fossils, many of which he donated to the museum, and was a respected fellow of the Geological Society.
Between June and September of 1912 several fragments of a human skull, along with bones of Pleistocene animals like elephant, teeth of mastodon and beaver and finally during a "warm summer evening" (so Woodward) the half of a jaw, that fit with the human skull, were unearthed.

Fig.1. A photograph by John Frisby of Uckfield, showing excavations at the Piltdown gravels in 1912. Standing centre left in the picture is the white-bearded figure of Arthur Smith Woodward and working in the trench on the right is Charles Dawson, the local solicitor who had "discovered" the skull of "Piltdown Man" (by Sussex PhotoHistory Home Page).

Woodward begun secretly with the reconstruction of the entire skull, it resembled that of modern man, except for the part where the skull is attached to the spinal cord and the cranial volume, with an estimated brain volume of 1070ccm (about two-third of modern humans). The jaw was indistinguishable from that of a modern, young chimpanzee, except by the presence of two molars identical to human ones.

On December 18, 1912 Woodward presented the complete reconstruction in front of a large audience and suggested that the fossil represent an evolutionary missing link between ape and man, since the combination of a large cranial capacity with the jaw of a monkey seemed to support the notion that the main characteristic of human evolution was the early development of the brain. The reconstruction was harshly criticized, especially by anthropologists and archaeologists from the continent.
Many of these experts noted that the fragments didn't fit or even necessarily belong together; the anatomist Arthur Keith at the Royal College of Surgeons produced a reconstruction quite identical to a modern man (Homo piltdownensis), Marcellin Boule, a French archaeologist affirmed in 1921 that the remains belong to two different species - if it was not entirely a hoax. This conclusion was supported by the American zoologist Gerrit Smith Miller, who however attributed the jaw to a still undescribed species of chimpanzee, informally named Pan vetus. The German anthropologist Franz Weidenreich examined the remains and reasserted that the presumed fossil was simply a modern human skull and an orang-utan jaw with manipulated teeth.
But finally there were no conclusive evidence to assert that the entire story was a fake and the British scientific community accepted the new species as Eoanthropus dawsoni.
Over the years further discoveries were made at Piltdown: bones of animals, an object that resembled a cricket bat (!) and supposedly two more skulls. It was in 1915 that Dawson claimed to have found fragments of a second skull (called Piltdown II) in a not specified site about two to three miles away from the first site, however Woodward himself seems never to have visited this site. Dawson died in August 1916, leaving Woodward with the heredity of Piltdown, who in 1917 continued to present material to support the alleged Piltdown Man.

However in the next three decades discoveries on the African continent seemed to contradict the hypothesis based on the genus Eoanthropus, ancient biped hominids were found only in Africa and the cranial capacity did not differ significantly from chimpanzees.

In October 1948 the geologist Kenneth Oakley decided to apply a new dating method and analyzed the fluorine concentration in the bones of the Pleistocene animals and compared the results with the remains of the Piltdown man. While the bones contain up to 3% fluorine, Piltdown showed just 0,2%, it was not possible that both the bones as the skull lay underground side by side for thousand of years.

This seemed the end of the Piltdown man, but recent discoveries now again cast new light on the evolution of humans. The fossil bones of Homo floresiensis of Indonesia, the genetic analysis of the human remains of Denisova in Siberia and controversial early H. sapiens teeth discovered in Israel have shown that the model of a unique migration out from Africa was too simple. It is possible that diverse migration waves occurred and that single populations of hominids evolved separately in various forms - this could possibly explain also the repeated sightings of large biped apelike creatures all around the world in recent times.
For Eoanthropus this means that it is possibly a younger descendant of a common ancestor to modern humans, as supported by the relative young age inferred by the low concentration of fluorine, with evolved characteristics, like the large brain, and atavistic characteristics, like the orang-utan jaw. The preliminary results of the new hypothesis and the official (re)recognition of the species Eoanthropus dawsoni will occur in London on 29, April 2011, as a tribute and wedding present to the British Crown.

Bibliography:

HERSHKOVITZ, I.; SMITH, P.; SARIG, R.; QUAM, R. RODRIGUEZ, L.; GARCIA, R.; ARSUAGA, J.L.; BARKAI, R. & GOPHER, A. (2010): Middle pleistocene dental remains from Qesem Cave (Israel). American Journal of Physical Anthropology. Vol. 144(4): 575-592
KRAUSE et al. (2010): The complete mitochondrial DNA genome of an unknown hominin from southern Siberia. Nature online publication 24 March 2010: doi:10.1038/nature08976
REICH. D. GREEN, R.E.; KIRCHER, M.; KRAUSE, J.; PATTERSON, N. et al. (2010): Genetic history of an archaic hominin group from Denisova Cave in Siberia. Nature 468: 1053-1060

Online resources:

Anonymous (): Welcome To the Piltdown Plot! (Accessed 01.04.2011)
Bournemouth University (2010): Piltdown Man. (Accessed 01.04.2011)
REITH, A. (1970): Faked Fossils of Primitive Man. (Accessed 01.04.2011)

Blue Marble: 22.000 years of changing earth

"Within a few millennia our ice may be gone, but if we shall have paid a fearful price for its going. Ice at its maximum extent is disastrous, but no ice is worse. The best stage is the halfway one, where we are this blessed moment, but like others it too unstable and will not stay put. We know where we are and which way we are going, but which way we shall be going a little later we do not know."
William Jackson Humphreys (1862-1949), meteorological Physicist.

The project Blue Marble 3000 is a simulation by Adrian Meyer and Karl Rege from the Zurich University of Applied Sciences of the environment changes experienced by earth from the last Ice Age some 21.000 years ago in the past to the Anthropocene some 1.000 years in the future. The simulation is based mostly on freely accessible data of temperature, vegetation, satellite photos and topography:

10.000 to 8.000 years ago the melting ice caps frees huge amounts of water and a dramatic rise of the global sea level follows, in Europe the northern plains of the Mammoth tundra became inundated and the British islands are separated from the European mainland.
6.000 years ago nearly all of the continents of Europe and North America became free of the ice.
By changing atmospheric current patterns more moisture arrives to North Africa, the Sahara is a vast savannah with periodic large lakes until 4.000 years ago, then again a shift in the currents transform this rich environment in one of the largest deserts on earth today.
These environments remains stable for nearly further 4.000 years, then an acceleration of the retreat of the ice caps is visible. The temporal scale changes now from 500 years steps to 50 years steps to emphasize a new epoch - the Anthropocene has begun.