Naked Science Forum
Life Sciences => The Environment => Topic started by: thedoc on 05/10/2016 15:53:02
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timothy gillespie asked the Naked Scientists:
We know the melting of the ice caps will change the tilt of the earth axis. Will all this redistribution of water/ice weight cause more earthquakes.
Cheers Timothy Gillespie
What do you think?
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Melting ice caps would indeed cause some earth quakes. But small ones. And only around them selves.
They would also cause the day to lengthen. The mass moving from the pole to the general surface of the world.
Neither seems to be happening. The day length data suggests that the ice caps are in fact growing.
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The Pleistocene Epoch is typically defined as the time period that began about 1.8 million years ago and lasted until about 11,700 years ago. During the beginning of that period, glaciers covered huge parts of the planet Earth.
During the Pleistocene Epoch, more ice melted, than we have remaining. Based on Pleistocene melting, we should be able to tell something about the impact of large scale ice melting, by looking at what this melting did to the earth in terms of earthquakes.
I often wondered how did the earth do this, all by itself, when man was not there, making greenhouse gases. This period shows there is more than one way to get the same result. The question is, are these natural drives still happening today?
Who decided to stop the end of the ice age at 10,000 BC? Could there have been a pause, with the ice melt starting again. Does the Pleistocene Epoch show ice age glacier melt, being continuous or intermittent?
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I often wondered how did the earth do this, all by itself, when man was not there, making greenhouse gases ...
https://wikipedia.org/wiki/Milankovitch_cycles
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Will melting ice caps cause earthquakes?
In the last ice age, areas covered by thick glaciers sank down further into the Earth's mantle.
With the loss of ice after the last ice age, these areas are now floating higher in the mantle, a slow process call glacial rebound. This will cause many small earthquakes (and maybe a few big ones).
Despite the generally rising sea levels today, Scotland is experiencing falling sea levels, because the glacial rebound is causing it to rise faster than the sea level.
See: https://en.wikipedia.org/wiki/Post-glacial_rebound
and the map at: https://en.wikipedia.org/wiki/File:PGR_Paulson2007_Rate_of_Lithospheric_Uplift_due_to_PGR.png
We know the melting of the ice caps will change the tilt of the earth axis
I'm not sure about this, since the ice is fairly symmetrical around the Earth's axis. But movement of water from the poles to the equator will affect the speed of rotation slightly, as Tim mentioned.
One of the Milankovitch cycles will change the Earth's axial tilt about every 41,000 years, see:
https://en.wikipedia.org/wiki/Milankovitch_cycles#Axial_tilt_.28obliquity.29
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The Pleistocene Epoch is typically defined as the time period that began about 1.8 million years ago and lasted until about 11,700 years ago. During the beginning of that period, glaciers covered huge parts of the planet Earth.
During the Pleistocene Epoch, more ice melted, than we have remaining. Based on Pleistocene melting, we should be able to tell something about the impact of large scale ice melting, by looking at what this melting did to the earth in terms of earthquakes.
I often wondered how did the earth do this, all by itself, when man was not there, making greenhouse gases. This period shows there is more than one way to get the same result. The question is, are these natural drives still happening today?
Who decided to stop the end of the ice age at 10,000 BC? Could there have been a pause, with the ice melt starting again. Does the Pleistocene Epoch show ice age glacier melt, being continuous or intermittent?
The reason the ice we have around today is still there even when it's warmer is because of where it is.
Either it's in Antarctica where it so cold that it will not melt untill the continent moves away from the pole or it's at high altitude, in Greenland, where it's so cold that it will not melt untill we have a very considerable temperature increase, say +10c before we start worrying.
That's for the big bits of ice. There are lots of smaller little glaciers and stuff but they have so little ice inthem that they don'y really matter on a global scale.