Global warming, ice ages, and what's "normal"...

[zippetydude]

I recently discovered that, except for a few ice ages, the normal state of the earth is "ice free". I was amazed. If global warming is really just returning the earth to a normal state and helping to avoid a catastrophic ice age, maybe it would be the first time that human intervention actually turned out positive!?

Unfortunately, I'm in the same camp with Alan K who maintains that almost every human intervention (along with its unintended consequences) turns out horribly wrong. (Alan, please correct me if I'm wrong in that assertion.) But maybe, just this once, against impossible odds, it might be neutral at worst, and protective at best...

Anyway, I thought it was interesting and was curious what others would think of it. Did anyone else know that ice-free was the normal state? Any ideas on what the climate would be like in the Sierra or perhaps Palm Springs? Just speculating.

z

[Hikin_Jim]

Zip,

Ice free? Even at the poles?

Sounds like an interesting bit of info. Got a link?

HJ

[zippetydude]

I see I'm not alone in my surprise. Here's a quote:

There have been at least five major ice ages in the Earth's past (the Huronian, Cryogenian, Andean-Saharan, Karoo Ice Age and the Quaternary glaciation). Outside these ages, the Earth seems to have been ice-free even in high latitudes.

and a timeline:

http://en.wikipedia.org/wiki/File:Glaci ... otated.jpg

and the full article:

http://en.wikipedia.org/wiki/Ice_age

I know, it's just Wikipedia, but the article seems to suggest that this is the accepted point of view, not a controversial stand or something like that. Caught me off guard, I thought the ice merely moved to lower latitudes at times, but always existed on the poles. It would seem I was incorrect.

z

[AlanK]

The Earth is an evolving system. I don't see that it makes a lot of sense to think about a fixed, "normal" state. The real issue is that human civilization has evolved under a set of circumstances that we humans are rapidly changing. That is not "fixing" anything. If hundreds of millions of people are displaced from low-lying areas, for example, don't expect them to thank the rest of us.

I don't recall saying that every human intervention in anything went horribly wrong. That seems pretty silly. But we certainly do things that end up having unintended consequences!

[Hikin_Jim]

Fascinating article. The thing that really struck me is that they don't know what causes "Ice Ages" and inter glacial periods. Lots of competing and contradictory theories, many of which seem to have a piece of the puzzle, but there's not unifying explanation that ties everything together.

HJ