From Harvard University Science: Scientists find signs of ‘snowball Earth’
Research suggests global glaciation 716.5 million years ago
Steve Bradt
Harvard Staff Writer
Geologists have found evidence that sea ice extended to the equator 716.5 million years ago, bringing new precision to a “snowball Earth” event long suspected of occurring around that time.
Led by scientists at Harvard, the team reports on its work in the latest edition of the journal Science . The new findings — based on an analysis of ancient tropical rocks in remote northwestern Canada — bolster the theory that the planet has, at times in the past, been covered with ice at all latitudes.
“This is the first time that the Sturtian glaciation [the name for that ice age] has been shown to have occurred at tropical latitudes, providing direct evidence that this particular glaciation was a ‘snowball Earth’ event,” said lead author Francis A. Macdonald, an assistant professor in Harvard’s Department of Earth and Planetary Sciences. “Our data also suggests that the Sturtian glaciation lasted a minimum of 5 million years.”
The survival of eukaryotic life — organisms composed of one or more cells, each with a nucleus enclosed by a membrane — throughout this period indicates that sunlight and surface water remained available somewhere on the surface of Earth. The earliest animals arose at roughly the same time, following a major proliferation of eukaryotes.
Even on a snowball Earth, Macdonald said, there would be temperature gradients, and it is likely that ice would be dynamic: flowing, thinning, and forming local patches of open water, providing refuge for life.
“The fossil record suggests that all of the major eukaryotic groups, with the possible exception of animals, existed before the Sturtian glaciation,” Macdonald said. “The questions that arise from this are: If a snowball Earth existed, how did these eukaryotes survive? Moreover, did the Sturtian snowball Earth stimulate evolution and the origin of animals?”
“From an evolutionary perspective,” he added, “it’s not always a bad thing for life on Earth to face severe stress.”
The rocks that Macdonald and his colleagues analyzed in Canada’s Yukon Territory showed glacial deposits and other signs of glaciation, such as striated clasts, ice-rafted debris, and deformation of soft sediments. The scientists were able to determine, based on the magnetism and composition of these rocks, that 716.5 million years ago they were located at sea level in the tropics, at about 10 degrees latitude.
“Because of the high albedo [light reflection] of ice, climate modeling has long predicted that if sea ice were ever to develop within 30 degrees latitude of the equator, the whole ocean would rapidly freeze over,” Macdonald said. “So our result implies quite strongly that ice would have been found at all latitudes during the Sturtian glaciation.”
Scientists don’t know exactly what caused this glaciation or what ended it, but Macdonald says its age of 716.5 million years closely matches the age of a large igneous province stretching more than 930 miles from Alaska to Ellesmere Island in far northeastern Canada. This coincidence could mean the glaciation was either precipitated or terminated by volcanic activity.
Macdonald’s co-authors on the Science paper are research assistant Phoebe A. Cohen; David T. Johnston, assistant professor of earth and planetary sciences; and Daniel P. Schrag, Sturgis Hooper Professor of Geology and Professor of Environmental Science and Engineering, all of Harvard. Other co-authors are Mark D. Schmitz and James L. Crowley of Boise State University; Charles F. Roots of the Geological Survey of Canada; David S. Jones of Washington University in St. Louis; Adam C. Maloof of Princeton University; and Justin V. Strauss.
The work was supported by the Polar Continental Shelf Project and the National Science Foundation’s Geobiology and Environmental Geochemistry Program.
There are many things that strike me as missing in the current theory. I can accept the general outline of an unknown event causing a gradual glaciation through albedo change. I can also accept that once water vapour disappeared, nights would become much colder (i.e. just like a desert night) – what I find is glossed over is how long this lasted.
Let’s face it – after even a couple of thousand years of no precipitation, and constant vulcanism, the top layer of ice would be indistinguishable from dirty black. And although desert nights are tremdously cool, desert days are blisteringly hot. With no open water to evaporate to form clouds, there would be no shielding from this. Open water would form, albedo would change once more and the earth would return to normal quite quickly.
What seems more likely to me, is that some event stripped away part of the atmosphere, such that the adiabatic lapse rate became a distant memory. It was only the planet outgassing, and gradually building up air pressure again that caused the ice to melt. It was the air pressure – the fact the was a lot of CO2 in it was just co-incidental.
Five million years would be about right for that – we do have a lot of atmosphere.
Wow, another ‘theory’ based upon that nasty gas CO2 – as if it is the ONLY gas around – The Universal gas!
Are these Scientist really that moronic – they continue to embarrass themselves.
Not only does CO2 cause heat (NOT) but it also causes cold (NOT) and for good measure it also feeds plants – which we need to survive.
The morons at the EPA have really stepped in it again – first their moron director outlawed DDT and caused 60 million to die.
Now they are trying to starve us to death – time for all of these twits to the gallows – or maybe? no!
Phillep Harding (13:39:06) :
The near side of the moon has more craters than the far side. Why? Best guess is that the earth’s gravity attracts asteroids, bending their path so that they more likely to collide with the moon, on the side facing the earth. Gravitic lensing, sort of.
I sort of have a problem with that as the speed of meteors would impact before gravity can pull the trajectory. Going past may bend it slightly but it would have to be grazing the moon.
The moon at one time was also a rotational body slowing by the friction of our atmosphere, gravity (and a biggie) magnetic field.
While I’m not exactly sure of the time lines involved, isn’t it possible that the continents were in different locations 716 million years ago.
Also there is the effect of the Moon: it’s currently moving away from the Earth at about 1-1/2 inches per year. Has any one extrapolated what the position of the Moon was 716 million years ago, and any effect it may have had on Earth’s climate?
As to the magnetic similarities of distant locals, isn’t it a fact that the Earth’s magnetic field has shifted numerous time over that 716 million years?
One thing I’ve learned from reading articles on this, and even some “alarmist” websites is that the more we learn, the more we realize how much we don’t know. I think that it would be safe to say that that portion of “the science is settled”.
All of the hypotheses regarding a Snowball Earth are based upon the locations of the continents being appropriate for the time period being investigated. So, yes, the Snowball hypothese include plate tectonics.
Yes, and not only was there a greater lunar tidal effect upon the Earth, the Lunar orbital period was different and the Earth’s diurnal perod was much shorter, making the days and nights much shorter.
Yes, the Earth’s paleomagnetic pole has been shifting, which has been one of the problems with interpreting paleomagnetic data supporting the various Snowball Earth hypotheses. Some critics have even suggested natural events which could have caused the paleomagnetic data to be reset, and one has suggested ways in which the Earth’s magnetic pole could have been a West Pole. There is at least one geological formation in Australia, however, which is claimed to have been free of the circumstances in which the paleomagnetic data could have been naturally reset or set in the wrong direction. So, the hypotheses have survived at least that challenge, so far.
Tenuc (16:18:06) :
No mention of the GOE….
Scientists don’t know exactly what caused this glaciation or what ended it…
So how come there is a graphic above it from a published textbook (Pearson Publishing?), I presume, that shows exactly what these scientists don’t know? Wasn’t there a Supreme Court case involving the young-Earthers and science that got science like that thrown out of the school system? You know the kind you put in textbooks even though there is no evidence? Addison-Wesley, you should be ashamed. Of course, given the ‘humanities’ textbook I just suffered through published by the parent company, Pearson, I can only display a profound lack of shock.
Apologies ctm, I did not see the other posts relating to the young-earth subject, my point was really more about unsubstantiated science in textbooks rather than some religious point or conversation.
Tenuc (16:18:06) :
Just remember to distinguish between the well proven elements and evidence of the various Snowball Earth and ice age hypotheses versus those elements which are not well proven or supportive at all. In other words, don’t throw the baby out with the bathwater.
The computer modeling and the possible overstatement of carbon dioxide as an agent of change may or may not be part of the bathwater which needs to be thrown out?
The cause could have been many things; it’s possible that the sun went through a cold cycle. But i think what’s more interesting than the cause of iceball earth was it’s end – once the earth is frozen over, given the high albedo ever and the lack of moisture in the air (too cold), how does it end? What mechanism could cause the earth to warm up enough again to melt all of that? Since in our experience volcanic activity seems to have a cooling effect, not a warming one, I don’t think that’s a viable mechanism.
I’m curious for scientific ideas you all may have – was was this system not at equilibrium? Why was it unstable?
I betcha, on a snowball earth, it would get cold enough to snow out all the CO2, at least at the poles. Then when it warms up all that CO2 releases at once and the overdose finally ends up as carbonate rock layers.
What an utter load of crap.
If the idea of a totally frozen Snowball Earth seems unlikely, then consider the example of Europa – one of the Snowball Moons of Jupiter.
Points of interest:-
Europa has an extremely tenuous atmosphere consisting of almost 100% oxygen gas.
Europa is covered with young ice, 50 million years old on average, with a high albedo (whiteness) and low number of asteroid impact craters.
This young age implies either an ice rafting surface repair process or a free water surface (albeit briefly) at a geological time equivalent to the Eocene Epoch on Earth.
(For Europe read Europa in this Google Translated link from the original Spanish text http://singularidad.wordpress.com/2007/02/20/proximo-destino-europa/ )
Ref – Anu (15:25:44) :
http://earthobservatory.nasa.gov/Features/GlobalWarming/global_warming_update4.php
“The above example is climate modeling of the Mt. Pinatubo eruption in 1991 in the Phillipines. The global circulation model closely matched the observed cooling of about four years duration.”
_______________________
(Half serious)
It seems fairly obvious from your example that, should Global Warming (and/or over-population) ever become be real problem and not just a way for Gore & Co., Inc., to make a bundle, we only have to detonate the Yellowstone Super Volcano to cool things off for another 5-10 million years.
(Serious)
I guess my bigest problem with Fat Albert and his friends is Fat Albert and his friends.
tty (10:23:08) : Thank you, Just couldn’t come up with what oil-in-process would be.
D. Patterson (01:40:08)
You mention the Ordovician-Silurian ice age, which was severe if not necessarily a snowball-earth. Your posting helpfully puts in long term perspective the fluctuating global CO2 level.
Some interesting features of this glaciation relate to the CO2-AGW debate:
1. CO2 levels were 8-20 times higher than at present during the Ordovician
2. Instead of causing runaway global warming, the Ordovician era ended with the severe (Andean-Saharan) ice age.
3. What about high CO2 being the cause of ocean acidification and death of corals? The exact opposite happened – corals evolved during the Ordovician.
http://www.palaeos.com/Paleozoic/Ordovician/Ordovician.htm
These facts destroy the idea of CO2 rising from present very low levels causing catastrophic warming (plus coral-killing). But the “scientific” community is able to blissfully and serenely ignore them.
A recent thread referred to a paper by Dana Royer using palaeoclimate to examine CO2-temperature climate sensitivity.
http://wattsupwiththat.com/2010/02/15/paleo-tagging-past-climate-sensitivity/
CO2-AGW was the unquestioned orthodoxy and paradigm of the paper. The author was obviously in terror of questioning this orthodoxy. Somehow these inconvenient details of the Ordovician, CO2 corals, ice age etc. were ignored. CO2-AGW sailed on unscathed.
Wonderful thing this peer-reviewed scientific literature.
Arrived late, enjoyed this post and the comments. Glad to see so many others took up my thought: it’s the volcanic ash and soot that darkened the ice, reduced albedo, absorbed solar heat and melted the ice. CO2 has nothing to do with it.
So, what caused the volcanoes? Probably the stress on the earth’s crust where thick ice sheets build up. A self-regulating system.
phlogiston (06:23:08) :
The Ordovician/Silurian ice age which lasted from 460 Mya to about 420 Mya and then the Carboniferous ice age which lasted from about 350 Mya to 300 Mya is understood with this map of the continental drift of Gondwana from the NCDC (keeping in mind large parts of the continent were below sea level for parts of the overall period and consequently glaciers could not build up – just sea ice).
http://www.ncdc.noaa.gov/paleo/ctl/images/figure05_10.jpg
I have trouble getting past the question of where additional atmospheric CO2 came from when the planet was totally enveloped in ice. Are there any proxies from which to quantify atmospheric CO2 at that time? If the CO2 level was constant, what were the heat sources that melted the snowball?
D. Patterson (16:08:05) :
WWF – World Wrestling Foundation or World Wildlife Fund?
Rascal (11:14:27) :
Women Wrestling Fans?….nah.
It was large parts of Laurentia (North American plate), Siberia, and Baltica which had a majority of their areas covered by epi-continental seas, because much of the continents were below sea level during the highstand of the oceans during the Early and Middle Ordovician Epochs. Laurentia was at this time astride the equator and enjoying arid, tropical, and warm temperate climates. There certainly were no glacial ice caps in Laurentia or neighboring Baltica or Siberia during the Ordovician and Silurian Periods.
There was, however, a major glacial ice cap across the southernmost regions of Gondwana astride the South Pole during the Middle Ordovician Epoch, Late Ordivician Epoch, and early epochs/s of the Silurian Period.
During the Early Ordovician epoch, the Gondwana supercontinent was in movement from one side of the Southern Hemisphere to the other side while passing nearby the South Pole. Marginal areas of the South American and African plates comprising part of Gondwana actually crossed the South Pole. During the Early Ordivician Epoch these areas of the South American and African plates of Gondwana had some epi-continental seas and seaways as a consequence of the highstand of the oceans during this warm period and nearby convergent subduction zones. Gondwana’s area of epi-continental seas within the Antarctic Circle were a very minor part of Gondwana and the South American and African plates in this region. The very large regions of Gondwana which were flooded with major epi-continental seas and seaways were astride the temperate mid-latitudes and tropical equatorial latitudes. The climate of Gondwana’s South American and African plates located within the high latitude areas of the Antarctic Circle were experiencing a cool temperate climate with no glacial icecaps to worry about. At this time there was no ice age and no glacial ice caps at the South Pole or anywhere else in the world.
The Saharan-Andean Ice Age developed during the Middle and Late Ordovician Epochs. At this time Gondwana had a small part of its continental shoreline astride the South Pole. The epi-continental sea was very narrow and small. As the cold climate of the ice age developed, the former highstand of the ocean sea levels receded to a very lowstand. The declines in sea levels reduced and in some cases extinguished many of the world’s epi-continental seas. There was only a very trivial fraction of Gondwana’s landmass located in the high latitudes which remained flooded by epi-continental seas and seaways. The icecap had nearly all of the landmass of the world’s largest supercontinent of the period upon which to form and grow. Since the South Pole was located just inshore of Gondwana’s seacoast, The glacial icecap extended its ice sheets over the sea adjacent to Gondwana’s coastline. However, these ice sheets extended from the above sea level terrain within the high latitudws of a supercontinent that otherwise extended overall from the equator on one side of the world and across the South Polar region to the equator on the opposite side of the world.
During the early epochs of the Silurian Period, the ice age waned and ended altogether. The icecap first retreated to a fraction of its former extent it had during the Late Ordovician Epoch. The edge of the icesheet and icecap closest to Gondwana’s seacoast retreated to a point where it half-covered a large epi-continental sea created by Gondwana’s slight movement northwards as the vast bulk of the Supercontinent continued its movement to the other side of the world while passing nearby the South Pole. Two arms of the shoreline nearly enclosed the epi-continental sea on the north side. The edge of the icecap crossed the middle of this sea. The South Pole was located just inshore on the southern edge of this sea. Just as Greenland is a chain of islands and portions of the Antarctic continent of today is also below sea level, the icecap a mile thick or more flowed from shore into these basins, displacing the shallow epicontinental seas until the icecaps melted.
The icecap of the Saharan-Andean Ice Age had most of the above sea level terrain of a supercontinent on which to form, grow, and persist. Saying “glaciers could not build up – just sea ice” is simply and utterly wrong.
Could some one recommend a good basic primer on earths geological and climate history for the non scientist reader? I am interested in planetary formation, continental formation, glaciation, volcanoes, etc… For example I seen references to 6 periods of glaciation as well as to 16? What gives? Creationists please don’t respond. Thanks
jim (14:59:52) :
The approximately six ice ages are subdivided into glacial periods, inter-glacial periods, and other types of periods. The glacial periods are themselves divided into lesser periods.
The Earth is estimated to be about 4.6 billion or 4600 million years old. The Earth’s atmosphere started out with a composition of about 80 percent carbon dioxide. This overwhelming predominance of carbon dioxide in the Earth’s original atmsophere has undergone a dramtic decrease to far less than 1 percent of the atmosphere.
Earth’s original atmosphere did not have any significant oxygen. At the time of the first great ice age, the Huronian Ice Age about 2.4 billion or 2400 million years ago, the composition of the Earth’s atmosphere was still 0 percent. It wasn’t until 2 billion or 2000 million years ago that oxygen became a non-trivial percentage of the Earth’s atmosphere, rising to the present approximately 20 percent levels.
Hypotheses concerning the origins of the Huronian, Stuartian-Varangian, and Saharan-Andean Ice Ages often consider the roles of oxygen, carbon dioxide, and aerobic lifeforms as agents in causing the ice ages. The weathering of terrestrial landscapes and the evolution of aerobic lifeforms are often considered as the reason for the development of an oxygen rich atmosphere and massive declines in atmospheric carbon dioxide, which in turn are considered for their roles in causing the Huronian Ica Age. Likewise, the invasion of plant life upon the terrestrial landscape and proliferation of early trees in the Devonian are considered for their possible roles in radically changing atmospheric chemistry in oxygen, carbon dioxide, and nitrogen, thereby playing some role in triggering the Saharan-Andean Ice Ages.
In other words, geochemical processes and biological processes are deemed to be responsible for the radical chemical evolution of the earth’s atmosphere.