Archaeologica.org

While this article isn't really all that ground breaking or newsworthy it does offer a nice, succinct explanation of how the GRACE satellite is able to estimate the extent of ice loss in
landlocked glaciers. I had been wondering for some time now how climatologists were coming up with their estimates. The explanation is near the end of this short article. Now I'm
wondering how accurate the estimates are. Does anyone here have any input into that process?

http://worldnews.msnbc.msn.com/_news/20 ... downsizing

Before anyone jumps on any bandwagon on this data it is worth looking at within context.
The first point is that this seems to be an effective method of measuring ice volumes, the differences between it and previous 'guesstimates' tell us that we can not rely on the previous data.
That means any valid measurements can in future only be compared with the new figures, all earlier ones are now invalid! The graph starts now!

Roy.

There are photos all over the web which show how glaciers have melted. This really can't be news.

Glaciers retreating Min, that does not mean that they are not gaining mass. They probably aren't, but glaciers melting ignores precipitation, which is one reason why melt flow measurements are useless.
There are several hundred thousand glaciers on the planet, and if I recall correctly only a couple of hundred are currently monitored, that's what makes GRACE such an improvement, and also invalidates all previous calculations.

Roy.

August, 1941 US Geological Society





August, 2004 US Geological Society

Muir Glacier, Glacier Bay National Park and Preserve, Alaska

From Yahoo:

Glaciologists say the above photos reflect real change that is taking place. "Alaskan glaciers are really shrinking a lot," according to Marco Tedesco, an assistant professor at the City College of New York. "There is no debate about Muir Glacier. It's a dramatic change to liquid water."

This is not a retreat, Dig. It's a rout.

Sauve qui peut

Agreed Min, but according to reports I've read some are advancing, this is why the GRACE method is so much better, it measures mass!
I would also point out that none of this proves MMGW only GW, currently we have, A Glaciers retreating in many parts of the world, B CO2 up and C temps down!
Thus linking them together makes no sense.

Roy.

I would like to see a photo of an "advancing" glacier.....one which preferably had not been photoshopped by Exxon.

Your wish is my command....

http://www.google.co.uk/url?sa=t&rct=j& ... ag&cad=rja


http://www.google.co.uk/url?sa=t&rct=j& ... ag&cad=rja

The official organ of the God of MMGW over here is the Guardian newspaper, and the high priest is George Monbiot, he of the 'Gulf Stream will stop flowing' and other such 'Facts'.
Thus it is interesting to note that of recent months the phrase, 'Global Warming' has vanished, both from Monbiot's 'Facts' and the Guardian's headlines. The buzz word is now 'Climate Change'.
Same format, different menu.

Roy.

I must say, Dig, this

But as the Yahtse advances, it is also thinning, underscoring the mystery behind exactly how these glaciers change over time.

makes it sound as if this glacier may be "advancing" to its own extinction. A glacier which flows into the ocean, breaks off ice bergs and does not thicken further up slope is not long for this world.

Earlier this summer the Jakobshavn shed a 2.7-square-mile chunk of ice – about twice the size of New York's Central Park – after a mild winter that saw no ice form in the surrounding bay.

This sounds pretty dire as a matter of fact.

Oh Lord Min, I wish you hadn't noticed that as it puts me into lecture mode!
A wrming planet will result in an increase in total precipitation, for two reasons.
1. higher evaporative temps,
2. a reduction in atmospheric pressure.
The precipitation will move to higher latitudes, resulting in an increase in desertification near the equator and increased preciptation further north, in the case of the northern hemisphere, these results we are currently seeing.
This means that glaciers south of the precipitation will lose mass, those north enough will gain mass.
This statement will be heavily modified by local geography so that it is possible to see both results in the same mountain range, as altitude will affect precipitation.
A glacier that gains mass on the higher levels will accelerate its ice flow, as this happens less snow falls on a given spot in a given time, so it thins.
A glacier that gains at high altitudes but has its tail at dryer lower altitudes will lose support from its leading edge and that too will accelerate, and thin, and retreat.
HTH.

Roy.

The key point seems to be that the glaciers are getting "thinner" and breaking off at the same time.


Were I a doctor looking at a patient who had pieces falling off and kept losing weight my prognosis would not be good.

No Min, the key point is mass, whether they are gaining mass or losing it. GRACE is the first time it has been directly possible to measure ice mass. All previous measurements were incapable of more than estimating it. The recent correction on the Himalayas simply serves to demonstrate how inaccurate all previous measurements were.
Supporters of MMGW love to point out the funding that antis recieve from industry, Mann was bleating about it today, yet a report states that the funding is 3500 to 1 in favour of MMGW, I have no problem with either, what I do have a problem with is the pro's scare tactics and their errors in the past. I also object to the fact that they BS the general public with figures and pseudo science that sounds good but is rubbish.
I will give you an example. According to the IPCC the melting of glaciers will raise sea levels by such and such amount.
Two items in their statement are ignored to produce this slanted info. One is that only some glaciers are affected, high altitude ones are unlikely to be so and two is their total ignorance of, or refusal, to mention air pressure.
A warming planet will lower sea level air pressure, warm air is less dense than cold, now that may seem of little significance, but nothing could be further from the truth.
In chemistry and physics we have such things as Black Body Radiation and a Standard Atmosphere, in reality these things do not exist.
It is only in the last few years that any attempt has been made to establish whether air presuure is falling or not, in a controlled environment it is easy to establish, in the 'wild' it is extremely difficult 'cos air pressure can vary hour by hour. So as with the GRACE measurements, the graph starts with the recent tests!
Obviouly with something as variable as air pressure the only method is to take thousands of measurements from the same sites over many years to check for any changes. The results are not yet in.
But does it matter?
Melting ice will add to sea levels and fresh water bodies, but an air pressure drop of one mb will raise water levels by one centimetre! In the deep ocean basins, that makes a few low level glacier melt figures totally insignificant!
A tropical storm can locally raise sea levels by several feet due to the drop in air pressure.
On Valentine's day we had a wind speed of 14mph here, the air pressure difference from the North sea to the Irish sea was 16mbs, that equates to over 6 inch difference in sea levels from one side of our island to the other, tide phases discounted. That is a hell of a lot of water on the move!
Wake up IPCC!

Roy.

I don't know,Dig.

There are a series of side-by-side photos here which indicate that the ice is shrinking ( and thinning) rapidly.

http://www.mnn.com/earth-matters/climat ... g-ice-caps

Now the question is -- what are we going to do about it?

Now the answer is -- nothing.
Min, thinning at the extremities has nothing what so ever to do with the total mass. Why do you think that an expensive satellite has been launched to monitor mass if checking the edges gave the answer?
The Greeland ice cap can shrink to a bath tub sized perimeter and still retain the same amount of frozen water if thick enough.
I read an artical recently on the Net about sea level changes and atmospheric pressure, it was in answer to a question as to how GW would affect each. The reply stated that atmospheric pressure was a function of mass, that regardless of temp that mass remains the same and as such temp has no effect on pressure.
Where this guy learned his chemistry I know not, but it was accepted by the questioners.
A recent report concluded that the shrinking of the northern polar ice cap was due to changes in sea currents. The same for antarctica.
Taking Antarctica as an example, parts of the Ross shelf are being lost, but at the same time the mass is increasing elsewhere, atmospheric warming can not be that selective, but currents can.
Also a warm current that melts the extremities should dump more precipitation on the ice due to temp drop, which seems to the case in Antartica.
Skeptics take the rise out of Mann's Hockey stick, but all previous warming episodes have been dramatic, ie, Hockey stick. The last GM is suggested as ending within 50 yrs, that is some temp rise!

Roy.

Figure 1: Observed sea ice changes. This animation shows sea ice coverage shrinking from 1979 to 2005, by roughly half. Source: NASA

It would have to be getting AWFULLY thick some where else to offset this, Dig.