Arctic Sea Level Falling?

HRH King Lerxst with a link to BBC News' report that "Arctic sea level has been falling by a little over 2mm a year — a movement that sets the region against the global trend of rising waters. ... It is well known that the world's oceans do not share a uniform height; but even so, the scientists are somewhat puzzled by their results."

Comments

First guess

[Nuffsaid]

May be connected to a slowdown of the Gulf Stream?

Re:First guess

[ajpr]

I think in a round about way, yes.

Freshwater ice is less dense than fresh water (which is less dense than salt water). As the ice melts it occupies a smaller volume (which is of course why ice floats). The difference is a fairly significant percentage and may explain the sea level drop. This in turn is evidence of large amounts of fresh water forming in the arctic and this leads to the theory behind slowing the gulf stream down.

However most ice on oceans is from seawater: "Sea ice, formed in saltwater, accounts for about 95 percent of ice found in the oceans. Ice covers about three percent of the world's water surface." - http://pao.cnmoc.navy.mil/pao/Educate/OceanTalk2/i ndexseawater.htm

So there's really two processes going on here. One is the melting of glaciers (mostly on Greenland) which results in freshwater being deposited in the oceans (and leads to the gulf stream slowing). The other is the melting of seawater ice. I'm guessing that the seawater ice is responsible for more of the melt than the freshwater ice. This would still lower sea level as the density of seawater is obviously more than seawater ice (or the damn icebergs would sink...). So my conclusion, half arsed as it sounds, is that seawater ice is melting at a much faster rate than the freshwater ice from glaciers. I'm sure someone can do the calc to compare the density changes between both types of ice and the rate at which you need to melt one in order to counter the other.

The key point I think is that freshwater ice melting is from land based ice masses (which add to sea level) and seawater ice is from sea based ice masses (like most of the polar cap ~95% according to that web site i referenced earlier, and doesn't add to sea level - in fact it looks like it lowers sea level).

Re:Gets you Al Gore!

[0xABADC0DA]

First of all there was not scientific consensus for any of those straw-man arguments you mention. Science has know the world wasn't flat for thousands of years and any confusion over that is due to religion and stupidity; just check the wikipedia article. Religion and stupidity also were the culprits in blacks being supposedly 'inferior' (as opposed to the more accurate 'slightly different'). And it's religion and stupidity that said Iraq had WMDs.

Second, get your facts straight. It's 1 degree celsius... just look at the damned graph... from -0.5 to .5 celsius is 1 degree. You reasoning is sound, but your conclusions are wrong because the so-called facts you are starting from are wrong. When this happens to an otherwise smart person there is one word for it: denial.

It's all relative.

[955301]

I can make the entire thing make sense in a matter of seconds!

Change

Arctic sea level has been falling by a little over 2mm a year - a movement that sets the region against the global trend of rising waters. A Dutch-UK team made the discovery after analysing radar altimetry data gathered by Europe's ERS-2 satellite.

to

Europe's ERS-2 satellite has been falling by a little over 2mm a year. A Dutch-UK team made the discovery after analysing radar altimetry data gathered over the Arctic sea level.

Re:Isostatic rebound

[Vreejack]

I would hope they had taken isostatic rebound into account. Actually what puzzles me is how they measured sea level. Are they comparing it to the earth's geode? For those who never heard this before, the geode is an imaginary surface that represents where sea level would be if water were magically allowed to flow without viscosity underneath the earth's land mass. It is not a sphere or even a spheroid but follows the local gravity variations so that it actually rises underneath mountains and dips over marine trenches. The net force of gravity is always perpendicular to the surface of the geode, and when they report the height of Mount Everest it is with respect to the geode, not to the sea level a thousand miles away (which is lower).

So again, how are they measuring this? I can't think of any measurement that makes any sense. The ocean cannot be above the geode in one part of the world and below it in another _by definition_. At least not on average over a year.

Okay, here is my off-the-wall speculation: a new change in wind patterns has resulted in a net outflow of wind at the earth's surface around antarctica, effectively blowing the water away.

Re:Could Be A Number Of Things

[Cryssen]

Talk to your high school science teacher, ice floats because it's less dense than water. As water freezes into ice, it expands. Floating in the water it would displace more water than the equal amount of water in said ice cube would take up. This is why if you place a full bottle of water in the freezer it explodes. Big words don't mean you're correct.

Re:Could Be A Number Of Things

[WarpedMind]

Maybe it has something to do with decreasing salinity. The ice floating on top would have been without salt. As it melted, the salinity would have decreased.

Not really a surprise

[dublin]

This shouldn't really be a surprise - after all, it's been known for several years that the water level of the oceans is going down, due to the "leaky seas" phenomenon. See New Scientist article from a few years ago at http://www.newscientist.com/article/mg16322030.200 .html (used to be free, but no longer), or a CNN summary at the time: http://www.cnn.com/NATURE/9909/17/leaky.seas.enn/i ndex.html

No one knows why - forming mineral hydrates, some other form of leaking into the earth itself, or global cooling - it's all speculation right now, just like global warming. The truth: The world is a complex place and we're not even close to understanding it.

BTW: Remember when "all the world's climate experts" warned of global cooling and an impending ice age only around 30 years ago? (Which would, of course, require many of the same environmental policy changes wanted by the global warming crowd now.) Those who forget history are doomed to repeat it.

Water expands when it freezes

[Hibernator]

Here's a possible explanation: When water freezes it forms hydrogen bonds that produce a crystalline structure that is less dense than water (this is why water ice floats). In a body of water near the freezing point there will be many water molecules constantly moving in and out of this fozen state (because of local temperature fluxuations). Therefore as you warm such a body of water you would expect fewer and fewer water molecules to be cool enough to bond together temporarily in a less dense crystalline fashion. In other words, as you warm a body of water that's near the freezing point, it should become less dense, and shrink.