Research Supports "Snowball Earth" Hypothesis

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."

Comments

Frost post!

[Harmonious Botch]

Sorry.. couldn't resist it.

Seriously, I wonder if there could be evidence of organisms tolerant of saltier conditions if all that ice left the remaining water saltier.

Cavemen

[flyingfsck]

Those cavemen must have burned a hell of a lot of oil to cause sufficient greenhouse gas to get the earth to warm up again.

A little explanation is in order

[dsanfte]

From the website:

Deposition of glacial or glacial marine strata close to the paleo-equator during the Marinoan, Sturtian and Makganyene glaciations, indicated by a growing body of reliable paleomagnetic data from different regions.

This is a fancy way of saying that they have found deposits of submarine rock near the equator that should only be forming in an arctic climate, and which date to the period of 'snowball earth' in question. This sediment has magnetic signatures which signify it formed originally at the equator, in an equatorial magnetic field, and did not simply arrive at the equator after having been formed previously in the arctic.

Please note that we are speaking here of a process of lava cooling, and 'trapping' a fingerprint of whatever magnetic field was present at the time it cooled. That's how these fingerprints are formed and it is a well-known and documented process, and a basis for the current models of magnetic field shift.

Had the magnetic system been different in the past (not a two-pole magnetic field) it would have rendered these results useless, but this article itself explains that there is now evidence that the Earth's magnetic field has always been a dipole (two-pole) field and that these results are correct.

At least, that is my understanding.