Starship Asterisk*

BMAONE23 wrote:Art,
You must realize though that the charts you presented are indicators of "Sea Ice" near the Ross Sea and not indicative of "Shelf Ice" extent. The increase of Sea Ice near the ice shelf only serves to act as a buffer against the potentially erosive tidal effect. Also increased calving of the ice shelf would act to aide in the increase of sea ice in the region. Further, sea ice in the region has proven to become more and more annual rather than residual in the Ross Sea area.

You are correct that I have confused "Sea Ice" with "Shelf Ice" and that even the mere possibility of "Shelf Ice" collapse due to global warming is a serious concern. However, I think that the observed Larsen B "Shelf Ice" collapse is serious enough, in itself, that discussion of a rather ambiguous Ross Ice Shelf situation should probably have not been included.

http://en.wikipedia.org/wiki/Ross_Ice_Shelf wrote:
<<University of Colorado's National Snow and Ice Data Center has been studying ice shelves and, in 2002, announced that, based on several break ups of ice shelves, including Larsen B, has begun to reassess their stability. Their scientists stated that the temperature of the warmest portion of the shelf is "only a few degrees too cool in summer presently to undergo the same kind of retreat process. The Ross Ice Shelf is the main outlet for several major glaciers draining the West Antarctic Ice Sheet, which contains the equivalent of 5 m of sea level rise in its above-sea-level ice." The report added that observations of "iceberg calving" on the Ross Ice Shelf are, in their opinion, unrelated to its stability. One opinion, given in 2006 based on a geological survey, suggested that the ice shelf had previously collapsed, perhaps suddenly, which could well happen again.>>

http://en.wikipedia.org/wiki/File:Glaci ... ctions.svg

BMAONE23 wrote:Try your math again. The problem is that both regions stated are in square kilometers which only refers to surface area and not volume or cubic meters.

I divided area (ocean) by area (ice shelf) to get a dimensionless ratio.

I multiplied this dimensionless ratio by height (sea level rise) to obtain height (ice shelf thickness).

This is all correct. My initial question "is my arithmetic wrong" was purely rhetorical (an invitation to readers to verify for themselves that it was correct).

You can multiply the area of the ocean by the sea level rise to get volume, and you can multiply the area of the ice shelf by its thickness to get volume. I provided rounded numbers for readability, but use the real numbers if you really want to torture yourself with this. But it is unnecessary trouble to convert the heights and areas all to the same units (as opposed to kilometers x kilometers x meters) and handle large numbers that drop out anyway.

There is no problem.

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Look at it this way:

I have a box 1 foot square and 1 foot deep full of water. I pour it into a second box 2 feet square (4 square feet). It fills the second box 3 inches deep (1/4 the depth of the first box) because the second box has 4 times the surface area. I got this answer without ever calculating the volume of the water (1 cubic foot).

Rocky Planet wrote:

BMAONE23 wrote:Try your math again. The problem is that both regions stated are in square kilometers which only refers to surface area and not volume or cubic meters.

I divided area (ocean) by area (ice shelf) to get a dimensionless ratio.

I don't think there's anything wrong with your basic approach. I figure that if the Ross Ice Shelf melts it will add around 5mm to sea level. I got that same value two ways: yours, and also a volume calculation. And it seems about right.

The confusion over the 5 meter value is that this is the amount of rise you would see from the West Antarctic Ice Sheet melting into the ocean. The loss of the Ross Ice Shelf might considerably hasten that, by destabilizing it, as well as by allowing a number of glaciers to drain into the ocean, rather than onto the shelf. I'd expect the time for the WAIS to melt would be long- centuries anyway- but even a fraction of 5 meters ocean rise over a few decades would be pretty disastrous. There's good reason to be concerned.

Chris Peterson wrote:... but even a fraction of 5 meters ocean rise over a few decades would be pretty disastrous. There's good reason to be concerned.

Climate does change, recorded history and the geologic record tell us that it does. So since the glaciers, ice caps, ice shelves, etc. aren't going to remain static, which would you rather have advancing or receding ice?

Had the cooling trend of the '40s '50s and '60s continued I'm sure we'd all be reading scare stories about how disastrous and concerning advancing ice and lower sea levels would be. Not to mention shorter growing seasons, loss of cropland, loss of habitat for endangered species etc.

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I suggest that one of the particular problems with the Larsen Ice Shelf might be that an enhanced global conveyor belt/Thermohaline circulation caused by a warmer & (through evaporation) a saltier North Atlantic would probably generate a strong salty upwelling within the Weddell Sea underneath the Larsen Ice Shelf. Such salty upwellings might cause the Larsen Ice Shelf to break up from below. This, in turn, would generate a surface influx of light melt water that would act as a POSITIVE feedback to further enhance global conveyor belt/Thermohaline circulation.

Such a unique Atlantic POSITIVE feedback loop would not be directly applicable to the sudden collapse of the Ross Ice Shelf.
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What the glo-warmers never mention is the volcanic acitivity in the eastern antarctic in recent years (The Larsen & Ross ice shelves are in east Antartica). Oddly enough, the warming is only occurring there.
http://wattsupwiththat.com/2009/01/21/a ... viewpoint/

I have to say that I am disappointed with APOD for promoting this farce masquerading as real science.

StACase wrote:Climate does change, recorded history and the geologic record tell us that it does. So since the glaciers, ice caps, ice shelves, etc. aren't going to remain static, which would you rather have advancing or receding ice?

Of course climate changes, as part of natural cycles. But it has rarely changed as rapidly as now, and rapid change in any direction has serious, possibly disastrous consequences for humans. And the evidence strongly suggests that we are causing most of the change. We know that in the past, change tended to proceed until the climate fell into some new metastable state. That's the sort of thing that can wipe out civilization (which is really rather fragile).

verkle wrote:I am saddened to see APOD put out a politically tainted topic today. There is not even any mention that a vast area of Antartica is actually COOLING rather than WARMING. There should be no place to make drastic claims like the sea level will rise by "5 meters" in the near future. Let's discuss supposed global warming in a scientific way, and please, not on an Astronomy related forum.

Thanks,

As the sun is involved in global warming I think the topic is appropriate .. but the 'five metre rise over the next few hundred years' should be changed to ' ... over the next two decades.'

Rocky Planet wrote:

Chris Peterson wrote:... showing melting ice ...

Tomorrow's picture: paint drying

Paint drying will increase absorbtion of heat from the sun, thereore it is of astronomical interest.

jlfonz wrote:Here is where the whole discussion gets side tracked. The vast majority of so called "deniers" will not argue the fact that there are global temperature variations--truly only a moron would argue that. What we "deniers" are against is the faithfulls doctrine that IT is caused by man. I have yet to get an explanation (a credible one) from any of the faithfull as to why we are finding villages UNDER receding glaciers or why we find written (in an non-extra terrestrial language) documents verifying a temperate climate in Greenland (with matching archaelogical evidence) or why the poles of other planets in our solar system are sharing the same percentages of polar melting at the same time we are.

You must be missing a lot of opinions, as the sun's effect on global warming is not, to my knowledge, denied.

Rocky Planet wrote:Years of listening to quacks with flimsy evidence alternately predicting the next ice age and catastrophic greenhouse effect led many of us to view all such claims with cynicism. But quackery has been replaced by better science and more measurements. It is time to take the modern view of global warming seriously.

"Quack, Quack," said the duck as it swam in the water covering the Empire State Building.

"Honk, Honk," said the Goose.

Ed IV wrote:What the glo-warmers never mention is the volcanic acitivity in the eastern antarctic in recent years (The Larsen & Ross ice shelves are in east Antartica). Oddly enough, the warming is only occurring there.
http://wattsupwiththat.com/2009/01/21/a ... viewpoint/

I have to say that I am disappointed with APOD for promoting this farce masquerading as real science.

Actually, the Larson Ice Shelf is on the Antarctic Penninsula on the North Western side of the continent and the Ross sea and Ross Ice shelf lie in the South Western side of the continent


http://maps.grida.no/go/graphic/antarct ... raphic-map

Chris Peterson wrote:

Of course climate changes, as part of natural cycles. But it has rarely changed as rapidly as now, and rapid change in any direction has serious, possibly disastrous consequences for humans. And the evidence strongly suggests that we are causing most of the change. We know that in the past, change tended to proceed until the climate fell into some new metastable state. That's the sort of thing that can wipe out civilization (which is really rather fragile).

So if climate is going to change, which you you prefer; warmer or cooler? And while you're at it state the reasons why.

StACase wrote:So if climate is going to change, which you you prefer; warmer or cooler? And while you're at it state the reasons why.

Long term, over centuries, I don't know that it matters much, since life adapts. On the whole, warm is probably better for land life diversity. Short term change like we're seeing now, either scenario leads to disaster- extreme weather events, major shifts in where food can be produced, political upheaval. If you're talking about rapid change, I think your question is like asking me if I prefer to be hit with a baseball bat or a golf club.

Chris Peterson wrote:

Long term, over centuries, I don't know that it matters much, since life adapts. On the whole, warm is probably better for land life diversity. Short term change like we're seeing now, either scenario leads to disaster- extreme weather events, major shifts in where food can be produced, political upheaval. If you're talking about rapid change, I think your question is like asking me if I prefer to be hit with a baseball bat or a golf club

Yes, on the whole, warm is better.

Disaster scenario? My crystal ball isn't that good, and I doubt that yours is either. As near as I can tell, the current temperature record through 2008 doesn't agree with the IPCC projections which are only a few years old. If you can't hit the broad side of a barn at 25 feet, you aren't going to hit the target at 100 yards. There's no way anyone with any sense should take the 100 year projections by the IPCC models as gospel.

Chris Peterson wrote:

StACase wrote:Climate does change, recorded history and the geologic record tell us that it does. So since the glaciers, ice caps, ice shelves, etc. aren't going to remain static, which would you rather have advancing or receding ice?

Of course climate changes, as part of natural cycles. But it has rarely changed as rapidly as now, and rapid change in any direction has serious, possibly disastrous consequences for humans. And the evidence strongly suggests that we are causing most of the change.

One of the most interesting (but from a practical standpoint most frustrating) natural cycles
is the 66 year Atlantic Multidecadal Oscillation cycle in North Atlantic temperature.


The 66 year AMO cycle reached minimum in the late 70's and should be at maximum right about now:

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Probably more than half of all SATELLITE DERIVED "global warming trends"
observed over the last 35 years are directly attributable to the 66 year AMO cycle.

Warmer vs Cooler........
Hmmmmm.........
History has proven that warmer cycles have always been followed by Cooling cycles. Warmer...Cooler...Warmer...Cooler... and that during the warming phases, there are smaller trends of the similar cycle. This being the case, the causes aren't completely understood and cause of much debate. But the effect is rather undeniable, as Warming phases always lead to cooling trends. The stronger warming phases also tend to lead to longer and deeper cooling trends (Ice Ages). I don't think that there is much debate as to weather we are in a warming trend or not (just the contributing factors). It does appear to be a warming trend equal to if not greater than the Medieval Warming Period (MWP) though if you look at the time involved since the beginning of the current warming period (the end of the Little Ice Age (LIA) and today) vs the time it took between the prior cold period and the height of the MWP you will see that the statistics indicate we are in a stronger warming cycle. This might be indicative of a greater Ice Age than the LIA is to follow.
So, While I vote for a warm climate rather than a Cold one, Too much heat Too fast has its consequences.
I vote to do ALL in OUR means to contribute as little as possible and maintain a stability in global temps.

StACase wrote:Disaster scenario? My crystal ball isn't that good, and I doubt that yours is either. As near as I can tell, the current temperature record through 2008 doesn't agree with the IPCC projections which are only a few years old. If you can't hit the broad side of a barn at 25 feet, you aren't going to hit the target at 100 yards. There's no way anyone with any sense should take the 100 year projections by the IPCC models as gospel.

Yearly records are completely useless. The shortest time scale that is used in models and predictions is decadal, and we are currently seeing a steady rise in temperature in decadal averages over the last couple centuries, more so this last half century. In particular, since we have a fair understanding of the role of greenhouse gases in producing this rise, it is not unreasonable to expect this trend to continue.

My opinion is that the U.S. (in its current form) could be largely taken down by a couple of major hurricanes. Like I said, civilization is fragile. Climate change is already creating political problems in the third world. Yes, I think these kinds of things can be considered disastrous.

Even if the worst case scenarios have only a few percent chance of happening, the ramifications are enormous. Most people would change their lifestyle if their doctor gave them a similar chance of survival over a few years.

neufer wrote:(snip)

This is an interesting chart. Is theredata prior to the beginning in the same format?
Looking at the top chart, it would appear that the heating cycles are increasing in serverity and the cooling cycles are also getting progressively warmer (Less Cool)

I would like to remind the APOD staff that this is an Astronomy pictures website. It is disappointing to look forward to seeing the daily photo only to be presented with an earth-based shot. Let's turn the cameras back to the skies, please.

Well, This subject certainly has increased posting to the BBS for this subject. I looked back over the thread and found that the majority of negative posts toward the APOD come from first time posters and about half of those only posted one remark. Only some, but not more than 1/4 have stayed to argue their point. It also seems that ALL of those first time posters stand against global warming. I guess the APOD regulars are by far more educated in such matters. Still,
Could you get the photographer to go back and take another picture of the same area showing current ice extent? Saying it has changed is vastly different from showing the effects of warming.

tomrich67000 wrote:I would like to remind the APOD staff that this is an Astronomy pictures website. It is disappointing to look forward to seeing the daily photo only to be presented with an earth-based shot. Let's turn the cameras back to the skies, please.

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The Thing from Another World (1951)

Ned "Scotty" Scott: "Every one of you listening to my voice, tell the world.
. Tell this to everybody, wherever they are. Watch the skies,
. everywhere, keep looking. Keep watching the skies."
..........................................................
http://www.youtube.com/watch?v=H6DarDHjyT0

BMAONE23 wrote:Could you get the photographer to go back and take another picture of the same area showing current ice extent? Saying it has changed is vastly different from showing the effects of warming.

This article linked from the APOD description leads me to believe that we would see nothing but open water where the level ice field is, but I too would like to see a more recent photo. I found the images on this web page (also linked from the APOD description) visually informative, but I'd like to know where the mountains from the APOD are located in these images.

Antarctica is a long trip to take a photo, but I'll go if everyone else chips in for expenses. For your money I will not only take a photo but I will install a solar-powered webcam so you can see the vista year-round without another special trip. If we have robots with cameras on Mars, why not Earth?

apodman wrote:Antarctica is a long trip to take a photo, but I'll go if everyone else chips in for expenses. For your money I will not only take a photo but I will install a solar-powered webcam so you can see the vista year-round without another special trip. If we have robots with cameras on Mars, why not Earth?

Maybe you can take Rocky and split expenses!

I worked hard today and forgot who I was. Maybe I can take Lois and Jimmy, too. (Kal-El doesn't need airfare.)