Posted by greg2213 on March 6, 2010
If you Google (or Bing or Y!) Snowball Earth (or go here) you’ll find something akin to the following idea. Some 700+ million year ago the Earth was covered in ice. That ice extended all the way to the equator. Some say it’s happened at least twice. Around 715 million year back and again at around 600 million years.
WUWT has a post in the subject: “sea ice extended to the equator 716.5 million years ago” Fascinating stuff, i think. It’s also likely that CO2 was far higher in those days, so why did it the world freeze over? There have been a few other ice ages since then, long before the current set, despite higher CO2.The article doesn’t actually say anything about CO2, though the graphic does.
I’ve seen some remarks by Geologists who suggest that land-masses at the poles are necessary for ice ages, along with certain formations of the continents. Circulation is cut off and the world cools. Enough ice forms, albedo increases, the cooling accelerates, and you have an ice age (I’m way over simplifying here.)
The article and the commenters raise some questions:
- Are there any papers which contradict the idea? One commenter said a paper has already debunked it.
- Are there any other hypotheses that would explain the scientists’ observations? Axial tilt? Weaker sun combined with…? Asteroid hit causing massive planet-wide volcanic activity, combined with the correct placement of the land masses?
- The article admits that they don’t know the triggering causes for the Earth becoming a snowball, or for leaving that phase, though there is a vast igneous province that suspiciously dates to about the same time. Super volcano?
- A commenter says that while Geologists generally believe that CAGW is complete bunk, biologists are believers. Why? I have a biology degree (ancient, moldy, but still there.) I’d think that biologists would be the first group to be hollering that more CO2 is a good thing and that life shows remarkable adaptability.
- Another commenter states that when the current series of ice ages ends (in a few million years) CO2 will bounce back to a more normal 1200ppm to 2500 ppm. Why? Outgassing from the oceans?
Posted in Global Cooling, Uncategorized | Tagged: Climate History, Cooling, Geology, In the Past | Leave a Comment »
Posted by greg2213 on January 16, 2010
So says Penn Prof. Bob Giegengack. As you might guess, he takes a dim view of Gore’s view, even though he voted for Gore in 2000 and would again (in 2008.)
I found this in my “stack o’ stuff” – it’s a 2007 article in PhillyMag and gives an geologist’s view of why Al Gore’s version of events is nonsense. Nothing has changed since the article was written.
As Giegengack says to his class:
“What I’m going to try to do the rest of today and also probably on Tuesday is bring you up to date on this. I’ll try to avoid editorializing or politicking. I’ll just tell you some stuff. Give you information. There’s lot’s of stuff, and it’s very complicated.”
Gieg gazes upward toward his young charges. “Every single one of you knows more about this than Al Gore,” he tells the undergrads. “And vastly more than anyone in this present (Bush) administration.”
Here’s the rest
Of course, the current administration (Obama’s) hasn’t shown that it knows anything more than Bush’s. Giegengack seems to take a dim view of Republicans (as shown by his remark about Rove) and so do I, but probably for very different reasons. I hardly think he can be dumped into the “Right-Wing etc” group of skeptics.
Anyway, the article is a pretty good GW primer and is very accessible. No math required.
Posted in Scientists Say | Tagged: Al Gore, Geology, Giegengack | Leave a Comment »
Posted by greg2213 on January 15, 2010
In the beginning, it was warm…
Then it cooled (and there was an ice age)…
Then it was warm again…
Then it cooled, again…
And then it was warm again…
After which it cooled, but not quite as much…
Of course, after that it warmed again…
And then the most recent series of ice ages started and the Earth cooled…
Except for a few short interglacials, when it warmed again, and we are in one of those interglacials.
The late Ordovician period (about 450 million years ago) was an ice age with CO2 levels 10-12 times higher than today’s levels.
This page shows a history of the Earth over the last 600 million years. Even with the uncertainty of measurement, it’s still fascinating. Among other things, it notes that the Earth has been cooling over the last 30 million years. It also offers a geological hypothesis for ice ages.
Check it out: Climate and the Carboniferous Period
Posted in In the Past | Tagged: Climate History, Coal, Geology, Ice Age, In the Past | Leave a Comment »