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Re: [Phys-L] Iceberg melting and sea level rise



On 03/22/2014 03:04 AM, Savinainen Antti wrote:
John C. stated a that "But iceberg melting does not contribute to sea
level rise.". Here is a link to a paper which challenges this idea:
<http://scitation.aip.org/content/aapt/journal/tpt/48/5/10.1119/1.3393068>

A short excerpt from the abstract:

":..the sea level will rise. The analysis shows the wrong
conventional answer [such as the statement above] is due to the wrong
assumption that water from a melted iceberg has the same density as
seawater."

Physics is a tool. Like any tool, it can be used wisely
or unwisely. We should train students to use physics to
solve problems people actually care about.

People care a great deal about sea level rise, especially in
newly-submerging nations such as Vanuatu and Bangladesh.

Nobody cares about the melting of an individual iceberg, or
even multiple icebergs. Things they care about include the
melting of land ice, such as the ice cap in Antarctica.
This ice is not floating, so TO A GOOD APPROXIMATION
100% of the melt-water contributes to sea level rise.

This stands in contrast to the Arctic ice, which is floating,
and therefore TO FIRST ORDER does not contribute to sea
level rise when it melts. The AJP paper points out there
is a second-order effect. However, this is academic in
the worst sense of the word. It is the sort of thing that
makes "academic" a dirty word in some circles. It is one
and a half orders of magnitude smaller than the first-order
effect. A 40 cm rise will cause unimaginable amounts of
suffering. A 1 cm rise, not so much.

================

Furthermore, melting is not even the only significant effect.
You have to consider plain old thermal expansion of the sea
water. The coefficient of thermal expansion for water is
exceptionally large ... and this gets multiplied (roughly
speaking) the entire volume of the ocean, which is huge
compared to the amount of ice in the world.