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.
If this snowball earth ever occurred the result would be an extreme lack of water vapor available for the creation of a hothouse earth. CO2 by itself would not be sufficient enough to raise the air temperature above freezing. Whatever water vapor was vented by volcanoes would quickly fall as snow either on the land or the frozen oceans. To see how little effect a volcano has on a glacier take a look at the glacier on Mt. Saint Helens that got its start in the late 1980’s and still exists today despite dome building eruptions between 2004-2006. I have read somewhere that even if the atmosphere was 100% carbon-dioxide it would not retain enough heat to reverse a snowball earth without significant water vapor.
What about slowly accumulating ash and pumice on top of the ice? NASA’s recent paper said soot is ten times stronger than GHG’s in melting ice.
Oh, and Anon, it’s also well known that greenhouses don’t work by blocking infrared radiation. They work by stopping convection.
“Scientists don’t know exactly what caused this glaciation or what ended it…”
And…….. back to Snowball Earth and Venus.
How much did that cost?
gary (20:35:20) :
There are glacial rocks of this age in the tropics, in Australia and Oman for example.
The continents however, have all moved many times since then.
Tim (20:54:42) :
Deposits from high mountains and plateaus are rapidly eroded. There are none preserved that are nearly that old.
Dear anon: you attribute magical properties to CO2, as though it is the only thing that could possibly affect climate. Given the well documented past swings between Ice Age conditions and quasi-tropical conditions, all of which predate human existence, what exactly is the evidence that CO2 is anything more than a bit player in this opera? In my experience, attempting to explain the behavior of a highly complex system in terms of a single variable is an exercise in futility and self-delusion. I will, however, grant that if the sun either goes out or explodes we might have a problem on our hands.
You are laboring under a series of false assumptions, false conclusions, and false beliefs of your own, which can only result in your having false perceptions. For example…
You talk about “taking carbon that was sequestered over tens of millions of years and releasing it in what is essentially an almost instantaneous geological time period.” Most diamonds are made of carbon, and most diamonds were sequestered in the Earth billions of years ago, not only some mere tens of millions of years ago. You are obviously implying that the age of the fossil fuels and their usage in mass quantities by humans in only the very recent Industrial age is supposed to somehow mean there is an overwhelmingly disproportionate release of carbon dioxide and other gases from these fossil fuels into the atmosphere as a consequence. As any decent geologist can tell you, nothing could be further from the truth and reality.
The amount of carbon dioxide released by human consumption of fossil fuels is relatively miniscule and insignificant in absolute quantities and in physical effect upon the planetary environment. Nature is the vastly overwhelming factor in all exchanges of carbon dioxide between the planet’s various environments. If it were somehow possible to invoke magic and make it possible for humans to consume all of the remaining reserves of fossilfuels in only one year or one lifetime, the amount of carbon dioxide available in such quantities is utterly incapable of increasing atmospheric levels to those which have existed for the most recent 500 million years. To reach those levels would require the instant vaporization of significant fractions of the Earth’s carbonaceous continental plates by multiple major asteroidal strikes. Human efforts are absurdly puny by contrast. This is why geologists are typically dismissive of AGW claims that absurdly exagerrate the extent to which humans can extract enough hydrocarbons from the Earth to significantly change the atmospheric chemistry.
You also talk about a “greenhouse effect” in a manner which clearly indicates you do not understand what it is supposed to be or how it is supposed to work. Increasing atmospheric levels of carbon dioxide has a diminishing effect because it cannot have an effect upon energy which has already been removed by other molecules before reaching the additional molecules of carbon dioxide.
What can be considered normal, meaning average over time, levels of atmospheric carbon dioxide is somewhere around 1200ppm to perhaps 2500ppm. Plant life is presently in a state of carbon dioxide deprivation as a consequence of our experiencing an ice age and the present inter-glacial period of the ice age. If humans were to become extinct tomorrow, the Earth would still naturally come out of the present Quaternary Ice Age some millions of years in the future, and the atmospheric carbon dioxide would naturally return to 1200ppm and greater levels of carbon dioxide in the atmosphere as there was before the Quaternary Ice Age had begun.
Given all of the varous factors which can and may affect the onset and end of planetary glaciations, the fixation of some investigators on carbon dioxide as the one and only primary causitive agent is instantly suspect. While atmospheric carbon dioxide may ultimately prove to have a key role in such glaciations, failures to relate the other factors as well gives more experienced and knowledgeable readers reason to suspect the authors are knowingly or unknowingly pandering to the current AGW hoax and CO2 mania for whatever reasons having to do with grants, funding, prestige, or whatever else may be motivations.
As for the so-called risk levels, mammals thrived in atmospheric carbon dioxide levels of 600ppm, 1200ppm, and greater over a period of some thirty million years; so it is up to the people who wish to create an alarm to demonstrate scientifically why mammals generally and humans in particular should be so worried about keping warm and feeding the plant life we all need for survival on this planet.
Volcanos, schmolcanos. If you read the book, The Chilling Stars by Svensmark & Calder, you’ll see they note that the “snowball Earth” episodes within reasonable certainty coincided with heightened rates of star formation & destruction across the entire Galaxy — and hence — a heightened influx of cosmic rays.
Lord Monckton is fond of noting that during the most recent iceball episode, attributed here to ~715 million years ago, CO2 levels exceeded today’s concentrations several times over.
Why are some of you so negative about this.
Here are some scientists trying to find out something really cool and interesting about the history of the planet. This is pure science at its best. It is really hard to figure out what the planet was doing that long ago. Don’t knock them.
” Ian H (22:55:41) :
Why are some of you so negative about this.
Here are some scientists trying to find out something really cool and interesting about the history of the planet. This is pure science at its best. It is really hard to figure out what the planet was doing that long ago. Don’t knock them.”
NOT questioning scientists is what got us into the mess we’re in now…
Everyone knows that CAGW or CACC is a house of cards, except, of course, the president, the supreme court and the EPA…
I’m sorry, but the word “Models” just blew it for me. I found it interesting and plausible up to that point.
See what a hoax can do for you?
The ice ages typically occurred while the continental plates where configured as supercontinents mostly in the Southern Hemisphere, particularly astride the South Pole. Glaciation of the North Pole is extremely rare in Earth’s past. Some of the pre-Cambrian ice ages such as the Stuartian event suspected of resulting in a Snowball Earth may have resulted in great part as a consequence of anaerobic lifeforms being supplanted by aerobic lifeforms. They liberated vast quantities of oxygen into the atmosphere for the first time by reducing carbon dioxide levels from a 15 percent of the atmosphere to the present less than one percent levels.
Fine. Personally, I’m worried about my great, great, great, great, great grandchildren and whether or not they’ll have a sustainable habitat to live in. Think globally, act locally! Rock on, we’re saving the planet! Woo-hoo!
I simply don’t buy the role of CO2 melting the icecap in this theory..
It’s in bed with the AGW theory.
So, they really have to look for another explanation(s).
Fascinating, if true. Wouldn’t the Earth’s landmasses have to be organized in a particular way for this to happen? Or, at least, be more likely to happen?
Is there anything else that could explain the observations made by these scientists?
johnnythelowery (20:59:33) :
Dusting off my (ancient) biology degree I find myself wondering why biologists would fall for CAGW and all this extinction by CO2 nonsense. Ok, so they believe in AGW, but biologists should be the first to tell you how adaptable life is, shouldn’t they? Shouldn’t biologists be the first group to be laughing at the “CO2 pollution” idea?
D. Patterson (22:41:35) :
Why would it bounce back to those levels? Hasn’t atmospheric CO2 been steadily declining for many tens of millions of years?
give me a break
And plate tectonics had nothing to do with it , where were the continents 700 m years ago and where did the ocean currents flow ?
QED
Sounds like Al Gore’s erotic fantasy, snow ball earth
OK, I am open-minded about the Earth has ever been a snowball – it’s surely plausible and the geological evidence may be fine – but I think that the comments in the first diagram that CO2 greenhouse effect has brought us away from that regime are completely preposterous.
It is easy to see that CO2 changes in the last 542 million years were only linked to temperature changes by +-5 degrees or so, despite the concentrations’ reaching 4500 ppm (more than 10 times more than today), see
http://motls.blogspot.com/2009/04/birth-of-oil-geology-temperature-co2.html
To go from a snowball to a fully melted Earth, you need a warming by 40 °C or much more. It is absolutely inconceivable to achieve this warming with any concentration of CO2 – even if you managed to oxidize all the carbon on the surface of the Earth – because the dependence of the temperature on the concentration is really logarithmic. To change the temperature by 4 °C, you need to increase the CO2 by an order of magnitude, roughly speaking. So you would need ten orders of magnitude of a CO2 increase.
It’s just a complete nonsense. This paper, seemingly about an abstract purely Academic topic of the climate in geological eons in the distant past, is actually just another contribution to the AGW hysteria, designed as such. It’s a mixture of legitimate science and nonsensical tendentious interpretations that are the main driver of studies produced in this way – and also the main source of the funding for people like Schrag.
“The amount of carbon dioxide released by human consumption of fossil fuels is relatively miniscule and insignificant in absolute quantities and in physical effect upon the planetary environment.”
Every oil and coal field on the planet, if left alone, would eventually have a volcano erupt through it releasing more CO2 in a day than we might release in a decade.
All the CO2 in the atmosphere would eventually be turned into coal, oil, limestone, marble, and other forms and life would die if something didn’t come along and return that carbon to the atmosphere.
It has been hypothesized by many scientists that the demise of Earth will be by CO2 depletion if left to its own devices. Certain types of plants were already having a hard time due to CO2 starvation (gymnosperms were once the dominant type of forest on Earth). As more carbon is locked up in the Earth, the level of CO2 in the atmosphere falls, plant production declines, then animal production declines.
It has taken Earth over 4 billion years to evolve a species that can take that carbon out of the ground and return it to the atmosphere probably giving and extension to the period that it can support life.
Then there is the fact that the more CO2 you put into the atmosphere, the faster it is taken out. If you double the atmospheric CO2 currently available to pine trees, they grow four times faster and produce ten times more seeds resulting in an explosion of pine trees. By growing four times faster, I mean they put on four times as much biomass in the same period of time.
An article in the UK Telegraph reported:
There are some 60 million hectares of African forest designated as “forest reserves” which means they are currently absorbing 36 million tons/year more CO2 today than they were in the 1960’s if those figures are correct.
It has also been learned that global forestation numbers had been distorted by counting only deforestation operations and not considering the amount of new trees growing in places that had previous been farmed. Given a conservative estimate of 3.5 billion hectares of global forest, that would mean they are absorbing 2.1 billion tons of additional CO2 annually today on top of what was already being absorbed in the 1960’s and I haven’t counted increased biomass production from plankton and other aquatic plants.
The more CO2 you pour into the air, the faster it comes out. Carbon means life. More carbon, more life. More life leads to less carbon as it becomes sequestered and eventually life dies until something comes along to release that carbon again.
“From an evolutionary perspective,” he added, “it’s not always a bad thing for life on Earth to face severe stress.”
I remember reading an article that hypothesized that life was able to advance beyond simple organic compounds as a result of such a frozen environment. Basically the ice acted as a giant laboratory where simple organic compounds were contained in isolated fissures within the ice. These natural test tubes would then mix with others as the ice shifted and moved about. The end result of which was billions upon billions of random combinations that created more and more complex chains. If conditions were ideal and static these compounds would never have formed more complex versions.
Maybe we’ve been looking at this debate (or lack thereof) from the wrong perspective. Without the opposing view inducing stress in all of us we wouldn’t be advancing a better understanding of our world because there would be no incentive to.
So next time you feel like screaming, try thanking an alarmist for ringing the bell at the free market of ideas and may the best theory stand up to the scrutiny.
JM
Hi Charles. I don’t think I’m confused. There is pretty broad agreement as far as I’m aware that the Atlantic Ocean didn’t used to be there and Africa nestled up against South America. So, no Atlantic Ocean > 200mya. That’s all based on the spreading we see along the mid Atlantic ridge. Same thing is happening in the Pacific.
Reply: No…there is widespread agreement that the current solid rock on the sea floor wasn’t there 200 mya. It is constantly formed at spreading centers and returns to the mantle at subduction zones so after about 200 mya it has all cycled back to the Mantle. There have been oceans, although not necessarily in the same places, for much longer than that, at least according to current continental drift theory and research. Check out the Wilson Cycle. ~ ctm
The BBC reports of 716 million years ago were that in spite of the entire Earth being buried in ice up to and including the equator, it was all caused by man-made carbon dioxide “emissions”, and also proved their assertions that there is “an underlying warming trend”.
How confident are the scientists, that what they say realy happened like this?. Was any one their to see it?.Are they (scientists) 100% sure ,or is their some guess work here to make it fit into some other ideas. Just because a scientist says these things about the past is it realy true?.
Climate History shows a graph of earth swinging between 10 deg C to 25 deg C, compared to the current 15 deg C. (With some spikes to about 28 C.)
If nature happily endured temperatures 10 C warmer, what’s the big deal over a 1 deg C increase?
We have such a perfect – and unanimous – understanding of our current climate, that we should indeed start to figure out what happened to the climate 700 million years ago. Where is Michael Mann and his tree rings when you really need him? By the way I did not see anybody referring Nir Shaviv’s work who postulated that “Snowball Earth” periods occur when our solar system passes galactic arms with a high density of cosmic rays hitting the the Solar System and of course the Earth. This ties in with Svensmark work who also correlates the density of cosmic ray showers hitting the Earth with the climate. Of course Svensmark looking at the changes in the Sun’s magnetic behavior impacting the incoming density and energy of cosmic rays -and cloud covers and the climate – which are events measured in decades, or centuries- whereas Shaviv is proposing to explain very large climatic changes, “Snowball Earth” events, occurring in timescales of millions of years and typically separated on average more than a hundred million years.
716,5 see:
http://sites.google.com/site/earthquakepredictionbyjac/Home/Home/image004.gif?attredirects=0
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