Background: In the distant past, during a discussion of ice cores, Jorge pointed me to the creation "model" of ice ages: there was only one, and it took 700 years. I did a back-of-the-envelope calculation of the energy imbalance involved, and showed that this was physically impossible. He has, just recently, asked me for a formal summary of the problems with the model. I'll use this thread to work out the issues involved, since i hope it will provide a little insight into scientific reasoning. Plus, if i goof, maybe someone will catch it.
So, the fact that the creationists accept that an ice age exists means that they accept the indications discovered by scientists of the full extent of the ice sheets during the most recent glacial period. And, really, they're hard to miss; all of Long Island is a giant glacial moraine, and there are plenty of other indications around. The question, however, is what would it take to make these things come and go? Specifically, in this case, we can figure out how much energy was required.
To do that, we need to figure out how much ice there was. If we take the last glacial maximum (about 20,000 years ago), then the northern hemisphere ice sheets looked like this:
sheets.JPG
So, how much ice is there? For the Laurentide, there's a good reference:
http://onlinelibrary.wiley.com/doi/1...00885/abstract
26.5 x 10^6 cubic kilometers at the last glacial maximum.
The Cordilleran has been estimated at 2.9 x 10^6 cubic km.
The Innuitan ice sheet, which covered the Canadian archipelago, is estimated at 1.4 x 10^6 cubic km.
Both of those from here: http://www.geo.uzh.ch/~chuggel/files...allQSR2002.pdf
That's 30.8 x 10^6 cubic kilometers and counting. I can't find an academic paper on the rest (Scandinavian, Barents-Kara, and Patagonian). Based on this site:
http://academic.emporia.edu/aberjame/ice/labs/lab01.htm
It looks like the majority of the rest of it was in Antarctic sheets, which i've said we're ignoring.
Is there any way to verify this number? Yes, it's possible to tell what happened to the oceans when all that water was locked away as ice. Ocean levels created new shorelines, and allowed shallow water organisms to grow at greater depths. So we know how much water had to have been in the ice to drop the oceans this much, which provides an independent measure.
Based on sea level changes, you get an estimate of 52 x 10^6 cubic kilometers of water locked up in ice. That's well above our 31 million cubic km, but we were ignoring a few major contributors. So, as a rough estimate, i think going with 31 million cubic km of ice is reasonable, even if it is extremely favorable to the creationists.
So, with the ice nailed down, we can do energy calculations. Remember, pretty much all that ice got there because it fell as snow, which means the water must have evaporated at some point. Then it had to be melted. I'll try my hand at the calculations in the next post, then in a 3rd, compare that to solar output.
So, the fact that the creationists accept that an ice age exists means that they accept the indications discovered by scientists of the full extent of the ice sheets during the most recent glacial period. And, really, they're hard to miss; all of Long Island is a giant glacial moraine, and there are plenty of other indications around. The question, however, is what would it take to make these things come and go? Specifically, in this case, we can figure out how much energy was required.
To do that, we need to figure out how much ice there was. If we take the last glacial maximum (about 20,000 years ago), then the northern hemisphere ice sheets looked like this:
sheets.JPG
So, how much ice is there? For the Laurentide, there's a good reference:
http://onlinelibrary.wiley.com/doi/1...00885/abstract
26.5 x 10^6 cubic kilometers at the last glacial maximum.
The Cordilleran has been estimated at 2.9 x 10^6 cubic km.
The Innuitan ice sheet, which covered the Canadian archipelago, is estimated at 1.4 x 10^6 cubic km.
Both of those from here: http://www.geo.uzh.ch/~chuggel/files...allQSR2002.pdf
That's 30.8 x 10^6 cubic kilometers and counting. I can't find an academic paper on the rest (Scandinavian, Barents-Kara, and Patagonian). Based on this site:
http://academic.emporia.edu/aberjame/ice/labs/lab01.htm
It looks like the majority of the rest of it was in Antarctic sheets, which i've said we're ignoring.
Is there any way to verify this number? Yes, it's possible to tell what happened to the oceans when all that water was locked away as ice. Ocean levels created new shorelines, and allowed shallow water organisms to grow at greater depths. So we know how much water had to have been in the ice to drop the oceans this much, which provides an independent measure.
Based on sea level changes, you get an estimate of 52 x 10^6 cubic kilometers of water locked up in ice. That's well above our 31 million cubic km, but we were ignoring a few major contributors. So, as a rough estimate, i think going with 31 million cubic km of ice is reasonable, even if it is extremely favorable to the creationists.
So, with the ice nailed down, we can do energy calculations. Remember, pretty much all that ice got there because it fell as snow, which means the water must have evaporated at some point. Then it had to be melted. I'll try my hand at the calculations in the next post, then in a 3rd, compare that to solar output.
Comment