Posted on 03/05/2010 12:55:48 PM PST by Ernest_at_the_Beach
American boffins say they have discovered evidence that almost the entire world was covered in sea ice and glaciers at certain points in the remote past, during so-called "snowball Earth" periods where the polar ice sheets met at the Equator.
It were grim in the old days.
Geologists probing conditions seen in the ancient world have long considered that there was a cold spell known as the Sturtian Glaciation about 716 million years ago. However there has been disagreement in boffinry circles as to just how severe this glaciation was.
Now, researchers from Harvard uni in the States, funded by the US government, say they have found ironclad proof that there were glaciers right down on the Equator at that time. Tropical rocks from the Sturtian, which have since migrated up to remote northwestern Canada, show unmistakable signs of having been covered in big ice back then.
"This is the first time that the Sturtian glaciation has been shown to have occurred at tropical latitudes, providing direct evidence that this particular glaciation was a 'snowball Earth' event," says geology brainbox Francis Macdonald of Harvard.
"Our data also suggest that the Sturtian glaciation lasted a minimum of five million years," he adds.
"Ice may have covered the entire planet then," comments Enriqueta Barrera, federal science bigwig, "turning it into a 'snowball Earth'."
(Excerpt) Read more at theregister.co.uk ...
The big picture: 65 million years of temperature swings
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Greenland Temperatures - last 10,000 years. Are we headed for an ice age? (See below for more detail.)
It's a cycle, it's a cycle, it's a cycle!
****************Video at web site********************
"The greatest danger we face from global warming is that politicians pretend they KNOW something about it."
Thanks, Ernest. I knew the meaning of “boffin”, but I’d never seen “boffinry” before (boffinacious? Boffinistical?)and then when he referred to the other guy as a “brainbox” I thought the article was laying it on a bit thick. Yeah, we know they’re highly edumacated.
LOL...it is strange,...I don’t care for the terminology.
Generally, we can explain the Snowball Earth episodes (there were at least 5) by Continental Drift.
The Earth goes through non-regular cycles of Super-continents coming together and then breaking apart (the stress on the crust eventually breaks them up into plates again).
When these Super-continents congregate at one or both of the poles, glaciers build up the pole, spread out across the available land (and glaciers do not build up on the ocean), Albedo increases (more sunlight is reflected and not allowed to heat up the Earth), it gets colder, more glacier builds up, even more sunlight is reflected and eventually, everything is frozen except the tropics.
The continental drift reconstructions show that there really was Super-continents in the right place at least 715 million years ago and 635 million years ago (the last Snowball period).
The Albedo of all that ice on a Continent over the south pole 20 times bigger than Antarctica is calculated to increase the amount of sunlight reflected from 30% today to 50% in the Snowball periods which is just the right amount to freeze over the whole Earth other than the tropics.
Snowball period ends when Super-continent breaks up and the plates move away from the poles and the ice melts.
So continental drift, rather than greenhouse gases.
Here is how the continents looked at the last Snowball period and how far the 5 km high glaciers could have grown.
Interesting. But the references made to CO2 somehow warming things up is BS.
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Thanks Ernest_at_the_Beach. Two lists, one ping, it's like I should get the Nobel Peace Prize for saving bandwidth, or maybe something that's actually got some prestige associated with it. And then I'm going to retire from posting and start living off my income from selling bandwidth credits. |
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bandwidth credits....
now there is an idea.,...
This kind of throws ice water on all that AGW stuff, if I understand correctly
Ah! Now Leo Kottke’s choices of album names makes more sense. ;’)
thank you for this.
You’re welcome. I downloaded all 5 parts to RealPlayer and next will stitch them together with Windows Movie Maker or some other program. I actually saw the episode several times and have it on VHS somewhere. But of course it’s a lot more convenient to have it on the computer. It was an excellent program.
I'd like to see the climate "scientists" that have this kind of prediction in their models. Personally, I think climate is too complex a system to be modelled given our technology at the moment. It may very well never be possible due to sensitive dependance upon initial conditions (the butterfly effect). We need more data, and more samples. I hereby volunteer to man a spacecraft to the nearest solar system with probable planets such as ours so we can have more data to work with.
To end the Snowballs, I’ve calculated CO2 levels would have had to increase to between 286,000 ppm (29%) to 800,000 ppm (80%) (and even more but that wouldn’t make mathematical sense unless the volume of the atmosphere increased as well).
There is not enough volcanic emissions of CO2 to come even close to those kind of numbers over even tens of millions of years.
The only estimate of CO2 at 715 million years ago is 6,000 ppm and the only one at 635 million years ago is 12,000 ppm.
The scientist is named Svenmark; he's a Dane. Here is his theory which seems pretty solid:
Cosmic rays are necessary for cloud formation. When they hit the earth's atmosphere they produced charged droplets which attract other molecules of water, forming clouds. More cosmic rays mean more clouds. More clouds means more heat is reflected back into space, causing cooling.
When the sun is active, it produces a stronger magnetic field which deflects some of the cosmic rays from earth, making fewer clouds and more heat. When the sun is "lazy" (like right now) more cosmic rays reach the earth and there are more clouds, hence cooler.
He had a pretty convincing correlation between solar activity and temperature, and also did experiments producing clouds in a chamber with cosmic-type rays.
He even correlated ice ages with cosmic rays. The solar system orbits around the Milky Way over hundreds of millions of years. When the solar system passes through an area of heavy star concentration, the cosmic rays produced by the extra stars overwhelm any effect the sun has, and the earth cools significantly, causing ice ages. He had done work with an Israeli astronomer to correlate the times of ice ages with passage through those star belts.
I highly recommend looking for that special on line. It has English subtitles in the few areas where people aren't speaking English. It convinced me, and although I haven't worked professionally in years, I do have a degree in geology.
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