Ice Sheet Complexity Leaves Sea Level Rise Uncertain

New Scientist ^ | 3-16-2007 | Catherine Brahic

[blam]

Ice sheet complexity leaves sea level rise uncertain

13:41 16 March 2007
NewScientist.com news service
Catherine Brahic

Ice shed from the giant sheets covering Antarctica and Greenland is responsible for just 12% of the current rate of global sea level rise, according to a new review.

The authors emphasise that it is now clear that the ice caps are losing ice faster than it is being replenished by snowfall. But exactly why this is happening remains unknown, making it difficult to predict the extent of future sea level rises.

The remaining 88% of the current rise is due to the expansion of water as it warms, and melting from mountain glaciers and ice caps outside Greenland and Antarctica. Yet the shrinking of Greenland and Antarctica remains crucial because together they hold enough water to make sea levels rise by 70 metres, submerging vast swathes of land and displacing millions.

Over the past 10 years, satellite measurements have vastly improved the quality of data detailing changes in the ice sheets, say Duncan Wingham from University College London and Andrew Shepherd from the University of Edinburgh, both in the UK.

Having reviewed the latest data, the pair conclude that losses from the ice sheets of Greenland and Antarctica contribute 0.35 millimetres per year to the total rate of sea level rise, estimated at 3 mm per year.

This contribution is close to the Intergovernmental Panel on Climate Change's latest estimate of 0.41 mm from the Greenland and Antarctic ice sheets. According to the IPCC, measurements since 1993 show that the thermal expansion of water is responsible for 1.6 mm of the annual rise and other melting glaciers and ice caps for 0.77 mm.

Ice flow

The satellite data have revealed how the ice sheets are losing mass. "It has become

[Knitting A Conundrum]

The world is a dynamic place...glaciers come and glaciers go...Anybody who expects the world to stand still and be the same always is going to be disapointed.

[Not now, Not ever!]

This still doesn't explain why the Ross tide mark, placed in the 1800's is above the waterline.

[ccmay]

Three-tenths of a millimeter a year! Man the pump handles! We're all going to drown!

-ccm

[claudiustg]

Let's see now:

---Yet the shrinking of Greenland and Antarctica remains crucial because together they hold enough water to make sea levels rise by 70 metres, submerging vast swathes of land and displacing millions.---

So:

---Having reviewed the latest data, the pair conclude that losses from the ice sheets of Greenland and Antarctica contribute 0.35 millimetres per year to the total rate of sea level rise, estimated at 3 mm per year.---

It would take 200,000 years @ 0.35 for them to contribute there 70 meters to our catastrophe and at a rate of 3mm/year it would take 23,333 years.

And what are we going to do? Buy carbon offsets?

[doc1019]

In other words … they don’t know what will happen!

[secretagent]

3 mm per year x 100 years = 300 mm per century or 30 cm per century or 11.8 inches per century rise, at the current rate.

Of course that could change, but I think Gore predicted a 20 foot rise - over what period I don't know.

I've heard 20 inches, too.

[PA Engineer]

current rise is due to the expansion of water as it warms

Say What?

[leadhead]

current rise is due to the expansion of water as it warms

Real scientist! Never had a glass of Scotch and Water.

Dummies!

[claudiustg]

---Say What?---

Say whatever it takes to reel in the suckers!

[idkfa]

Water also expands as it is cooled down from about 39.5 degrees.

[RegulatorCountry]

These people never understood why ice floats, so why be surprised at this?

[FreeperinRATcage]

Well, in this particular case they aren't talking about floating ice, rather ice supported by a land mass.

Of course, going from that to "We're all gonna die and it's Bush's fault!!!" is the strech that the global warming/anti USA (same bunch) crowd does that proves they're a few ice cubes short of a scotch on the rocks....

[seastay]

further south, there is no problems with ice formation, take a look at this glacier formed in the cinder cone of Mt St Helen's in just a few decades. Over the last 21 years, snow, ice and rock debris have accumulated behind the Lava Dome to an average depth of 100 meters (325 feet) thick.

[hermgem]

For those with memory recall: There was a ship, 100 years ago, called the unsinkable Titanic, which tried to make a maiden Atlantic crossing in record time.
Problem: An iceberg floated in her way, collided with this sip and caused this unsinkable boat to...sink.
The blame universally was attributed to the Captain who was judged to have disregarded icebergs floating in the Atlantic for the previous 100 years.
And this goes like that:
The Titanic sunk 100 years ago caused by the then well known fact that for the previous 100 years or a total of 200 years ice broke up...in Greenland and drifted into the Atlantic.
Haven't noticed any rise in sea levels yet or are catastrophic floods just around the next melt?

[Farmer Dean]

Better yet,buy stock in the companies selling carbon offsets.

[Farmerbob]

Wouldn’t global warming lead to more moisture in the atmosphere…which would lead to more snow fall in northern and southern (cooler) latitudes…which would lead to more glaciers…which would lead to lower sea levels… Now if someone can explain why my engine temp rises when I drive up hills…

[lepton]

Real scientist! Never had a glass of Scotch and Water.

Take your chilled scotch and water. Let it warm. Once past 4C, it will expand.

[xcamel]

FReepmail me to get on or off

Click on POGW graphic for full GW rundown

Ping me if you find one I've missed.

---

I believe a good bit of this has been debunked.

[exmoor]

Fill a glass about 3/4 full with water...put in enough ice cubes until water level is at rim and some of the ice is projecting up higher than the glass rim. Set aside and let time do it's thing. I've yet to have the glass overflow.