|May30-12, 06:21 AM||#1|
Missoula floods and an energy problem
As I was reading Hanson et al 2012...
So Hare triggered me to do some very rough order of magnitude calculations on the back of an envellope to find that the melting of the ice sheets in the last glacial maximum would have required some ROM of 30 W/m2.
Now looking at the July insolation graph on 65 North latitude lowest one here we see insolation variations of 50-80 W/m2, so that seemed not unreasonable initially.
However in combination with Hanson et al 2012 and the earliest dating of the Missoula floodings after 21,400 years ago, a question arises. If you have a flood, you need to melt the ice first and looking at the insolation graph, we were at a minimum at that time and the ice should have been accumulating - insolation wise. So where did the energy come from? What is wrong here?
|May31-12, 11:51 AM||#2|
|Jun2-12, 05:06 PM||#3|
I meant to return here sooner, but some study needed to be done first, anyway.
With repeated floodings you would expect an ice sheet advancing stage required to restore the ice dam after the breach.
The problem here is that several studies suggest a rather early retreat for the Cordilleran like this here suggesting 16 Ka BP calibrated to about 19.3 Ka Cal BP, so there are several thousand years that an ice dam appeared to have restored by advancing in a generally retreating scenario.
I'll study some more.
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