THE END OF ICE

By: Dr. Ricky Rood , 11:44 PM GMT on February 28, 2007

MORE FAST ICE
I want to add a couple of more pieces to the ice melting picture. A year or so ago I saw two NOVA episodes on ice melting fast. One, NOVA: Descent into Ice, looked at glaciers in the Alps and investigated a devastating flood that destroyed a number of towns in the late 1800's. The other, NOVA: Mystery of the Megaflood, discussed the apparent massive flood that shaped large portions of the Northwest United States at the end of the last ice age. In both of these shows there were lakes of water which were held back by dams of ice. Since these lakes can form below the surface of the glaciers, they are not easy to see. The bursting of the dams represents a process which can release large amounts of melted water quickly. A number of you have commented on the recent discovery of new lakes under the Antarctic ice sheet ( BBC: Antarctic Lakes ).

Aside from the possibility of rapid release of water, scientists are interested in the possibility that liquid water flowing through glaciers and ice sheets might lubricate the base on which the ice sits and accelerate the flow of ice down mountains, perhaps to the sea. Let's return to Richard Alley's metaphor of ice sheets as a pile, similar to pancake batter placed in the middle of a pan. The batter will try to spread out. If the batter is on a flat griddle then it will spread faster than if it was on a waffle iron. If the surface is lubricated, say with Teflon, then the spread will be even faster. So if the water gets down to the land surface under the ice sheet, then it can lubricate the motion, speed the flow down the hill. If the surface is bumpy then the transport will be slower than if it is smooth. The motion can fracture the ice, loosening the connection with the land, reducing the friction. The water can both melt ice as it flows through the ice and lubricate the surface on which the ice moves.

The figure below shows a schematic of ice sheet dynamics which brings all of these pieces together.


Figure 1. From the National Snow and Ice Data Center: Schematic of Ice Sheet Dynamics

The top left part of the figure shows the stable ice shelf, grounded to sea floor. It rises and falls with the tide. The weight of the ice, the weight of the glacier is partially supported by the water. There is push back from the sea; this is the buttress holding up the pile, the spatula keeping the batter from spreading. As we saw in the last blog, the shelf can collapse rapidly. Water melts the ice from below; water from ponds of melt water melts it from above. If the sea is warming, the melting is speeded up. The loss of the buttress speeds up the flow of the glacier. This can be further accelerated by water lubricating the surface between the glacier and the land. There is the possibility of glacier collapse, accelerated melting, as ice dams break and lakes are released. This interaction of ice and water is only beginning to be appreciated on global scales.

Occasionally there is a comment that the Earth's climate goes through cycles, and we are seeing nothing different from a cycle. I've thought about this. It is true that there are cycles in climate. But because there are cycles does not mean that there are not also trends. We see cycles and trends mixed together all the time--look at the stock market. There is something different today than in the previous cycles--the large increase in carbon dioxide. We have solid scientific reasons to know that increasing carbon dioxide in the atmosphere would lead to warming. Still, if what was happening today was only a cycle, and we had knowledge of this cycle, and we could predict what was going to happen, should we do nothing simply because it is a cycle? If we can measure this rapid melting of ice, can predict the consequences of related sea level rise, shouldn't we use this knowledge to adapt whether it is a cycle or a trend?

ricky


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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88. sebastianjer
10:32 PM GMT on December 18, 2007
Thanks MLC,

Actually that is what I thought. lol.
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87. moonlightcowboy
10:27 PM GMT on December 18, 2007
1950
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86. sebastianjer
10:24 PM GMT on December 18, 2007
LOL MLC

You would think that would be obvious, but it's not. I really can not read what it says at the bottom for present day it looks like 1960 to me.

JER
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85. moonlightcowboy
10:10 PM GMT on December 18, 2007
JER, lol, you know your eyes are good! Don't let sal mess with you, man!

Trigger mechanism? Look towards that big, bright looking orange thing in the sky...there you'll find answers!
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84. sebastianjer
10:04 PM GMT on December 18, 2007
GS
Could you post a link to those charts, my eyes are emeritus and can't make them out very well. Does the present date say 1960, 80, or 90? Also what is the triggering mechanism for the downward turn, does anyone know? Seems like that would be important.
Thanks
Jer
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82. latitude25
9:55 PM GMT on December 18, 2007
63. Patrap 3:17 PM EST on December 18, 2007
Calving ..

Pat, air temps have very little to do with glaciers calfing.
Air would make them melt from the top.

Inorder to calf, they have to be sliding or coming loose at the bottom.
That might indicate ground temps, or something else.

I read that last night. lol
Made sense, but I dunno
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81. latitude25
9:52 PM GMT on December 18, 2007
vortfix is my graph a lie?

No Gulf, it's actually about as accurate as anything else out there.

You just fail to notice that the last 10,000 years, CO2 has shot off the chart,
while temps have remained more or less stable.
and that temps have been higher in the past.

What I see is that CO2 continuied to climb, passed temps by a mile
while temps more or less flattened out.


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79. moonlightcowboy
9:40 PM GMT on December 18, 2007
Any Greenland melting has absolutey ZERO to do with with near-surface magma! How many times does this sort of thing have to be posted?
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77. GulfScotsman
9:37 PM GMT on December 18, 2007
vortfix is my graph a lie?
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75. GulfScotsman
9:32 PM GMT on December 18, 2007
Vortfix.....

Being and ostrich does not change reality. The cyclical nature of climate change and "global warming" is established scientific fact. To my knowledge they have not found alien space craft in Lake Vostock... but they are still looking.

It really absolutely does not matter what the cause is or what the contributing factors are, or if man-made emissions are contributing to the current PEAK event. The question is what are the likely impacts if the current trends in warming and climate change continue, accelerate, or decline.

Accleration is bad. I may doubt the impact of man made carbon emmsions from SUV's and powerplants, certainly as being the horrible godless apostacy of the green faith that they may be.... but if in fact next summer the arctic melt, the antarctic melt and the greenland melt show continuing signs of acclerated loss.... it is quite likely that the first impact of rising sea levels will be that you drown with your head stuck in that hole.



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70. moonlightcowboy
8:52 PM GMT on December 18, 2007
Double post.
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69. moonlightcowboy
8:47 PM GMT on December 18, 2007
822. salvadore 7:36 PM GMT on December 18, 2007
Truth be told, the main reason I've been hanging around is because I enjoy calling people on their crap and seeing how they react. Lots of opportunity for that here and it has been amusing.


Yes, the truth is a good thing! Thanks, sal and glad to know the reason you're here is purely for psychological perspective and comical review. Evidently though, "truth" as you see it has little merit as evidenced in your belief that the IPCC is an unbiased, above reproach body of "true" science.

Now, that truly is comical!
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68. Patrap
8:35 PM GMT on December 18, 2007
Most Impressive ..

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65. Patrap
8:23 PM GMT on December 18, 2007
This animation shows the seasonal advance and retreat of sea ice over the Arctic from 2005-2006. The false color of the sea ice, derived from the AMSR-E instrument on NASA's Aqua satellite, highlights the fissures in the sea ice by showing warmer areas of ice in a deeper blue and colder areas of sea ice in a brighter white. The yearly cycle is repeated three times while the camera circles the Arctic, providing a view of the sea ice from a wide range of viewpoints.

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63. Patrap
8:17 PM GMT on December 18, 2007
Calving ..

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62. Patrap
8:12 PM GMT on December 18, 2007
Since measurements of Jakobshavn Isbrae were first taken in 1850, the glacier has gradually receded, finally coming to rest at a certain point for the past 5 decades. However, from 1997 to 2006, the glacier has begun to recede again, this time almost doubling in speed. As more ice moves from glaciers on land into the ocean, it raises sea levels. The ice stream's speed-up and near-doubling of ice flow from land into the ocean has increased the rate of sea level rise by about .06 millimeters (about .002 inches) per year, or roughly 4 percent of the 20th century rate of sea level increase. This animation shows the glacier's flow in 2000, along with changes in the glacier's calving front between 2001 and 2006.




About This Video
receding glacier in Juneau causes glaciers to move (more)
Added: July 17, 2007
receding glacier in Juneau causes glaciers to move

Link
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61. sebastianjer
8:08 PM GMT on December 18, 2007
Too much debate I guess, lol
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57. Patrap
8:02 PM GMT on December 18, 2007
Tsar Bomba Largest Hydrogen Weapon Exploded Oct 30,1961



Tsar Bomba (Russian: , literally "Tsar Bomb") is the Western name for the RDS-220, which was the largest, most powerful nuclear weapon ever detonated. Developed by the Soviet Union, the bomb had a yield of about 50 megatons of TNT and it was codenamed Ivan by its developers.

The bomb was tested on October 30, 1961, in Novaya Zemlya, an archipelago in the Arctic Sea. The device was scaled down from its original design of 100 megatons to reduce the resulting nuclear fallout
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55. crucilandia
3:25 PM GMT on March 07, 2007
A trend, without aliasing, in the long run may show a true periodicity and thus, become a description of a cycle. Melting and freezing of sea ice has happened for hundred of thousands of years.

Winter sea ice in Antarctica has been growing since 1979 and that continent's temperature has been decreasing 0.1C/decade (NASA report 2001)
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54. cbbeachbum
5:17 AM GMT on March 07, 2007
No idea... anyway still waiting on a decent explanation of how nuclear testing caused global cooling.....
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52. cbbeachbum
5:05 AM GMT on March 07, 2007
Yes they did cyclone they did a whole lot more and larger tests over the water causing if anything huge amounts of water vapor to be forced into the stratosphere... a greenhouse gas.
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49. cbbeachbum
4:58 AM GMT on March 07, 2007
Dr. Masters had a blog on limited nuclear war go check it out if you like. Testing did not cause massive amounts of soil to enter the stratasphere - nuclear war implies huge soil and ash from the cities they are blowing up due mainly to the burning of the cities.
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47. cbbeachbum
4:54 AM GMT on March 07, 2007
Testing does not equal War...... show me how nuclear testing has caused global cooling
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45. cbbeachbum
4:46 AM GMT on March 07, 2007
Nuclear War is not Nuclear Testing!! Big Big difference.
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43. cbbeachbum
4:41 AM GMT on March 07, 2007
Nope.. no theory there showing nuclear testing was the cause of global cooling.. try again.
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40. cbbeachbum
4:19 AM GMT on March 07, 2007
What theory would that be cyclone show me...
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38. cbbeachbum
3:57 AM GMT on March 07, 2007
Must be shoveling snow... You would think that someone that states something as a matter of fact would be able to say something about it..... or perhaps loose all credibility.
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I'm a professor at U Michigan and lead a course on climate change problem solving. These articles often come from and contribute to the course.

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