As the 'joke elapsed', I wrote more info--enjoy the mind boggling icewater potential ahead.

Hello TODers,

jokulhlaup = glacial outburst flood

super-jokulhlaup = glacial outburst flood greater than twenty times the peak flow of the Amazon

Here is another newslink that is informative.

I think it might be instructive to consider the potential volume of water that might be released in a modern day Antarctic super-jokulhlaup by looking at super-jokulhlaups of the Antarctic past.

The Labyrinth is composed of many channels, thus it name, but the scientists write the biggest, single channel is 600m wide by 250m deep by 50km long [1,968.5 ft by 820.2 ft by 31.07 miles long].  It had the potential, if totally filled, of rapidly transporting 600 x 250 x 50k = 7.5 billion cubic meters of water to sea level.

Don't forget the average slope of Antarctica to the sea is the steepest of all the continents, and 38% [or more] of that unbelievably huge amount of ice is resting on ground above sea-level.  Take a look at this Wikipedia link please.

The Amazon River is:
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the largest, most voluminous river on earth, having a greater total flow than the next six largest rivers combined.

The quantity of fresh water released to the Atlantic Ocean is enormous: up to 300,000 m³ per second in the rainy season. Indeed, the Amazon is responsible for a fifth of the total volume of fresh water entering the oceans worldwide. It is said that offshore of the mouth of the Amazon potable water can be drawn from the ocean while still out of sight of the coastline, and the salinity of the ocean is notably lower a hundred miles out to sea.
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Back to my earlier example: 600 x 250 x 1 cubic meter/sec flowrate = 150,000 cubic/meters/second or about half the volume of the Amazon, but this is only one channel!  A rapid discharge from a subglacial lake would tend to create it's own labyrinth of outlet channels, so the aggregate volume racing to the sea could be much, much higher.  But don't take my word for it--let's see what scientists have to say:

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Iceland was buried under ice in the last Ice Age and all eruptions were subglacial. Remnants of the ice caps remain and Iceland continues to have numerous subglacial eruptions. Of the world's known subglacial eruptions, 83% are in Iceland. The most recent eruption, at Grimsvotn, is an example. Subglacial eruptions produce a special type of volcano, called a table mountain or a moberg mountain. Great volumes of meltwater, generated by subglacial eruptions, can burst out from beneath glaciers to produce enormous floods called jokulhlaup. The discharge can be as much as 20 times greater than the flow rate of the Amazon River.

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Don't forget that Iceland, and even Greenland, is much smaller than Antarctica.  Therefore, potentially a huge freshwater release could really cause a sudden jerk in climate change.  Imagine sub-glacial Lake Vostok, comparable in size to Lake Ontario [1,639 cubic kilometers or 1,639,000,000,000 cubic meters flowing to sea-level in just a week!  How many channels of the size mentioned above would this take?  It is not unusual for a steep river to flow 50k or 31 miles/day, that is only .6 meters/second, or 2 feet/sec [about a normal walking speed].  So take 1,639 billion cubic meters/7 days =  234 billion cubic meters/day. Divide that by the 7.5 billion cubic meter flowrate of the channel mentioned above, and you would have approx 31 channels of half-Amazon flowsize rushing simultaneously into the ocean for a week.  Imagine what that would do to screwup Antarctic ecology and subsea-currents around the Southern Hemisphere!  I think this is a conservative estimate of an Antarctic super-jokulhlaup as it is only 15 Amazons flowing seaward.

Bob Shaw in Phx,Az  Are Humans Smarter than Yeast?