Earth "Iced" by Giant Space Clouds?

Palomar · 2005-03-03 16:18:33

*Nope, it's not a joke nor the name of a 1955 "B" horror film.

I think this article deserves its own thread.

http://www.spaceref.com/news/viewpr.html?pid=16285]NASA study

They're considering that -- hundreds of millions of years ago -- global extinctions may have occurred because of these clouds (covering the entire Earth). Also discusses "snowball glaciations." I don't recall ever having heard nor read speculation in this regard:

One paper outlines a rare scenario in which Earth iced over during snowball glaciations, after the solar system passed through dense space clouds. In a more likely scenario, less dense giant molecular clouds may have enabled charged particles to enter Earth's atmosphere, leading to destruction of much of the planet's protective ozone layer. This resulted in global extinctions, according to the second paper. Both recently appeared in the Geophysical Research Letters.

They discuss "indications" from 600 to 800 million years ago, that at least 2 of 4 glaciations were "snowball glaciations."

Mentions uranium 235 -- wild. A "must-read" article.

--Cindy

Shaun Barrett · 2005-03-03 19:45:54

This is very interesting stuff for various reasons.
There's the scary thought that we could hit another cloud in the future - imagine the oceans frozen almost all the way to the Equator!

But it makes you wonder about Earth's recuperative powers in the case of major climate swings like this. If maybe 90% of the planet was ice, the albedo would have been extremely high and, even after the space cloud was gone, how did Earth ever gather enough warmth from the Sun to thaw out again?
I guess volcanism continued, as usual, and the CO2 must have built up steadily in the atmosphere because there was so little oceanic surface for it to dissolve in, and little surface rock for it to react with via rainfall (maybe no rainfall either! ). Eventually, the escalating CO2 concentration must have compensated for the high albedo by inducing a very strong greenhouse effect, allowing the planet to thaw out.
An incredible demonstration of our world's ability to revert to its natural state. And it seems Earth did this more than once in its history.

Last, but not least, I wonder what was happening on Mars at these times. Mars must have been subjected to the same changes as Earth - perhaps more so because it's farther from the Sun and more vulnerable to compression of our star's protective magnetic shield.
Could cosmic 'deep' freezes' like these have triggered major climatic changes on the Red Planet, too, and might this be offering us clues as to the huge swings in surface conditions believed to have occurred there over geological time?

Yep .. very interesting stuff all round! :up:

Palomar · 2005-03-04 10:35:00

But it makes you wonder about Earth's recuperative powers in the case of major climate swings like this. If maybe 90% of the planet was ice, the albedo would have been extremely high and, even after the space cloud was gone, how did Earth ever gather enough warmth from the Sun to thaw out again?...
An incredible demonstration of our world's ability to revert to its natural state. And it seems Earth did this more than once in its history.

*I'll say. :-\ It's a mind-boggling article. Again, I'm quite sure I've never read anything similar to this. Ice age, yes -- massive glaciers and etc. But this? We know so little of the history of our own planet. Before Sol goes kaboom, I wonder if Earth can "bounce back" from overpopulation and the resultant strain on natural resources (not to mention certain abuses).

I guess volcanism continued, as usual

A world of fire and ice.

and the CO2 must have built up steadily in the atmosphere because there was so little oceanic surface for it to dissolve in, and little surface rock for it to react with via rainfall (maybe no rainfall either! ). Eventually, the escalating CO2 concentration must have compensated for the high albedo by inducing a very strong greenhouse effect, allowing the planet to thaw out.

I wonder how long that process would have taken.

Last, but not least, I wonder what was happening on Mars at these times. Mars must have been subjected to the same changes as Earth - perhaps more so because it's farther from the Sun and more vulnerable to compression of our star's protective magnetic shield.
Could cosmic 'deep' freezes' like these have triggered major climatic changes on the Red Planet, too, and might this be offering us clues as to the huge swings in surface conditions believed to have occurred there over geological time?

And maybe killed off (mostly -- except for microbes perhaps) whatever life might have been taking hold there? And had a devastating effect on the once-lusher atmosphere, thereby weakening/crippling it?

--Cindy

C M Edwards · 2005-03-04 12:44:45

Ah, the "Snowball Earth" hypothesis. Interesting indeed, and it might even have happened. Evidence for such an event predates this theory about interstellar dust clouds and reducing the ozone layer.

A better description, without the additional bells and whistles, can be found here:

Hoffmans]http://www-eps.harvard.edu/people/faculty/hoffman/snowball_paper.html]Hoffman's Snowball Earth Hypothesis

Palomar · 2005-03-04 13:04:44

Ah, the "Snowball Earth" hypothesis. Interesting indeed, and it might even have happened. Evidence for such an event predates this theory about interstellar dust clouds and reducing the ozone layer.
A better description, without the additional bells and whistles, can be found here:
Hoffmans]http://www-eps.harvard.edu/people/faculty/hoffman/snowball_paper.html]Hoffman's Snowball Earth Hypothesis

*You know, I just remembered something. If you can refer to the old testament of the Judeo-Christian bible in a historical context, there was a mention in Genesis about only dew being on the Earth in mankind's early days, but apparently no falling water (rain of course). Then some sort of "covering" fell from the sky and after that it began raining.

This wasn't mentioned in conjunction with some alleged supernatural occurrence, etc. It was simply noted as something that happened. Maybe I should look it up, but will have to do that later -- am busy right now.

Anyway, taken in a historical context and pertaining to events thousands of years ago...I wonder if it could have been an after-effect of sorts. Of course the snowball glaciation thing supposedly happened millions of years ago, but who knows for how long it persisted or for how long and through what processes Earth became what it is today?

I'm probably going waaay off-track here, but thought I'd mention it.

--Cindy

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#1 2005-03-03 16:18:33

Re: Earth "Iced" by Giant Space Clouds?

#2 2005-03-03 19:45:54

Re: Earth "Iced" by Giant Space Clouds?

#3 2005-03-04 10:35:00

Re: Earth "Iced" by Giant Space Clouds?

#4 2005-03-04 12:44:45

Re: Earth "Iced" by Giant Space Clouds?

#5 2005-03-04 13:04:44

Re: Earth "Iced" by Giant Space Clouds?

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