Research Supports "Snowball Earth" Hypothesis 243
u2boy_nl writes, "A new U.S. study finds evidence for 'Snowball Earth,' the hypothesis that the entire Earth was ice-covered for long periods on several occasions, most recently 600-700 million years ago. The icy conditions (Earth's oceans frozen completely with ice more than a kilometer thick) ended violently under extreme greenhouse conditions — snowballearth.org suggests the meltdown could have occurred in as little as 2,000 years. Snowball Earth challenges long-held assumptions regarding the limits of global change. Wikipedia has more on the hypothesis."
Re:Shoot ... score one for the Bush admin (Score:3, Interesting)
The upshot of all this is that the researchers hopefully(?) have better evidence of their claims than a few buzzwords which don't really amount to a whole lot. 600 million years is not a long time, geologically speaking - or even evolutionarily-speaking - and I'm not convinced that every necessary process to get from Iceworld to habitable planet could occur in such a short space of time. I could be wrong, but I would need some VERY hard evidence.
What sort of evidence? Well, certainly volcanoes existed back then, and the eventual form lava takes depends on how rapidly it cools. Find me a lava bed in a land mass that would have been tropical at that time (based on current theories of plate movement) and which would not have been connected to open water, but where the rock structure shows clear evidence of cooling of the kind geologists associate with plunging molten lava into ice, AND where that rock also shows clear evidence of prolonged frost cracking. This would not be "solid proof", but it should be very persuasive.
Any other possibilities? Sure. Ice sheets and glaciers form very distinct U-shape valleys. Very very distinct from the V-shape of river valleys. If, indeed, no rivers existed 600 million years ago, only ice sheets, then it follows that any valley of that age or older MUST show the characteristics associated with such ice. Sure, a river may have cut through after, but that can't affect the sides of the valley above it. It can only affect the ground that it was cutting through at the time. The ice sheets, however, will have NOT been level with the ground but will have risen above it. Thus, the ice WOULD have reshaped any river valleys.
Thus, if a single valley, anywhere, shows clear and distinct evidence of cutting by water prior to 600 million years ago, OR if any valley of that time-frame does NOT show evidence of cutting by ice, the theory is falsified. Either will do.
If their claims stand up to the igneous rock test AND the valley test, then I'd be inclined to take the theory more seriously. As it stands, I simply don't see that they've enough to base their claims on. You know when academia is going south when Art Bell's old show could claim greater evidence and a more rigorous analysis. Hey, I happen to think the show has a lot of merit, both in examining controversial and unorthodox thinking that would not otherwise get the hearing it deserves and also as excellent entertainment, but we're in DEEP trouble when the fringiest of the fringe sound more careful, more exact and more scientific than highly-skilled, highly-trained, highly-paid experts.
Re:Shoot ... score one for the Bush admin (Score:2, Interesting)
Using the same logic, would Geologists in 600 Million years look back on today and say the Earth was covered by ice now?"
The answers to your questions are in the link marked "Snowball Earth" in the post. It is a link to an old (1999) publication about a snowball earth.
Anyway, I took the time to skim over the publication because I, too, wondered how the earth having an axial dipole justified an ice age 600 million years ago. If you don't have the time to read it, I can summarize my findings:
The snowball earth hypothesis is not simply justified by the earth's axial dipole. What is justified by the earth's axial dipole, however, are the measurements of the latitudes found of the rocks that appear to have been present under glaciers.
The way I interpreted the document was that the researchers found samples of rocks that could be geologically determined to have been underneath glaciers at a certain point (approximately 600 million years ago), then they determined the latitude those rocks would have been at at that point in time (since the continents drift, the rock would not be where it is today) based on the rocks' magnetic signatures (assuming the magnetic poles stay near the rotational axis of the earth). Since they found rocks that were under glaciers at low latitudes 600 million years ago, they concluded that glaciers were present at low latitudes (near the equator) at this time and thus must have been present around the globe. As a further explanation of a question that may arise, I believe the rocks were preserved in a manner such that their magnetic signatures would be those from 600 million years ago. (I am not a geologist, so I don't know how it works in particular. If you take the time to read the entire document "Snowball Earth", you might be able to understand better.)
Based on this, geologists 600 million years in the future would not guess that an ice age occurred right now, but would instead correctly guess (well, if it is correct in the first place) that an ice age occurred 1.2 billion years before their time, based on the age of the rocks they would find (which would be 1.2 billion years old).
Now, seeing that this paper was over 7 years old, what makes this whole idea newsworthy? Well, the research mentioned in the article supports the idea that the magnetic field of the Earth has not changed greatly over time, which means that it is safe for scientists to assume the magnetic poles do not travel far from the rotational axis of the Earth, and thus the magnetic signatures of the rocks found should, indeed, accurately represent their former latitude.
Summary of long post: Summary of article: New research supports the idea that certain rocks found where there were glaciers 600 million years ago were, at that time, near the equator, so there must have been glaciers around the world.