Antarctic ice melt numbers in perspective

According to a recent paper in Geophysical Research Letters, Antarctica is losing 159 billion metric tonnes ( 159 gigatonnes) of ice each year. On average West Antarctica lost 134 gigatonnes of ice, East Antarctica three gigatonnes, and the Antarctic Peninsula 23 gigatonnes in each year between 2010 and 2013 – a total loss of 159 gigatonnes each year. That number is based on measurements collected by the European Space Agency’s CryoSat-2 satellite mission, which carries an altimeter specially designed for this task. At first, that sounds like a great amount of water added to the ocean.

So how big is 159 gigatonnes with respect to sea level rise? According to the paper, this melting of Antarctic ice can raise global sea level 0.45 millimeters per year. That’s less than half the thickness of a penny per year or 1.7 inches per century. Are you prepared?

The paper is discussed in more detail on WUWT. The discussion also links to conversion factors for units of water mass and volume, see here.

Just for reference from that second source:

How much does one gigatonne of melted ice (1 km³ of water) raise the oceans?
The oceans occupy 361 million square kilometers ( 361 x 106 km²) of the Earth’s surface.

If one cubic kilometer of water (i.e., one gigatonne of water) is spread evenly over the entire 361 million square kilomters, the thickness of the new layer of water will be given by:

1 km³ / 361 x 106 km² = 2.78 x 10-6 meters = 2.78 microns

Or, in terms of gigatonnes:

1 Gt x (1 km³/Gt) / 361 x 106 km² = 2.78 x 10-6 meters = 2.78 microns / Gt

That is, one cubic kilometer of water (i.e., one gigatonne of water) will add less than 3 millionths of a meter to the oceans!.

According to Wikipedia, Antarctica holds 26.5 million cubic kilometers of ice. Using the figures above, we can calculate that if the entire ice sheet on Antarctica melted, it could raise sea level by 73.7 meters or 241 feet. At the current rate of melting, that would take 161,000 years. The Earth would probably have gone through another glacial epoch and be in another interglacial by that time.

See also:
The “Unstoppable Collapse” of the West Antarctic ice sheet – the rest of the story

UPDATE: After I wrote the story above, I became aware of other studies. These other studies show that East Antarctica, which represents more than 90 percent of the area actually had a net gain of 49 Gt/yr of snow from 2003 to 2008. Another paper shows that from 2009 to 2011 heavy precipitation dumped 350 Gt of snow on East Antarctica. The ocean evaporation necessary to supply than moisture is equivalent to a decrease in global mean sea level at a rate of 0.32 mm/yr over this three-year period. See more details here: http://wattsupwiththat.com/2014/05/23/climate-alarmists-make-major-blunder-in-reporting-antarctica-ice-loss-results/#more-110016

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