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Originally Posted By: Arcturus66
@Canuck RE: "please don't quote any ice core data."

Can you cite a good reason as to why they should not use such data? Don't the samples yield a direct measure of the atmospheric components at the time the ice formed (limited to available ice, of course)?


Just to make it clear, it was not I who said "please don't quote any ice core data". That was RicS.
To answer the question though - it's that first assumption that you really have to validate. Are the air bubbles contained within the ice, really uncontaminated samples of historic atmosphere?
John is right - cores taken meters apart have shown to have vastly different CO2 concentrations. Would it shock you to know that cores with CO2 levels that greatly fluctuate with time, are commonplace? And that these cores are simply discarded as "contaminated"? How do the scientists know they are contaminated? (ready for this) It's because we know, historic CO2 doesn't vary that much. shocked
Talk about a self-fulfilling prophecy. Declare that CO2 levels are constant without man's impact. Drill cores, analyze them. Discard the cores that disagree with the theory of constant CO2 levels. Use the cores with no variation as proof as the current rise in CO2 is something out of the ordinary.

But to get back to the original assumption - are the bubbles representative of historic atmospheric gases. We have absolutely no way of knowing if they are. Do the bubbles get polluted by the current atmosphere during drilling or testing? Is water held within the ice (we know ice can hold water down to -74 C with sufficient pressure), altering the gas fractionation of the bubbles? Is the youngest ice really at the top, with older ice at the bottom - or has the ice been folded back upon itself (like some rock)? Were the bubbles created by air being entrained into the snow (that eventually became ice), or were the bubbles created from a chemical process occurring within the ice?

The very fact that they are excluding a number of ice cores that do not fit with their theory should give anybody moment for pause.

The fact of the matter is, there are other proxies (leaf stomata) that have been tested under the existing climate (so we have an idea of what the proxy should be telling us), that suggests CO2 levels being much higher than 280 ppm in the very recent past. Unfortunately, some people choose to ignore any other data, and focus on the bloody ice cores.

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Thank you John M Reynolds and Canuck for the replies. I am new to this and, while I find the idea of ice-core paleoclimatology interesting, it is nothing I have any experience with. I had wrongly *assumed* that the measured gasses were those dissolved in the water or snow crystals at the time of freezing. I've been 'googling' some and see that I was greatly mistaken (infiltration of 'firns', dislocation, and whatnot).

--"Would it shock you to know that cores with CO2 levels that greatly fluctuate with time, are commonplace?"

No. It would not.

As for samples meters apart being very different, I can *imagine* a situation such as a path being carved out (by whatever mechanism)or that there may have been a deeper 'drift' so that the depths don't match up. I note that some of these issues have been addressed in the 'dating' of the ice. Perhaps a larger number of samples separated spatially (but also locally, if that makes any sense) and compared to other such samples across the globe could yield better data.

It does seem logical that interpretation of the samples may need to be somewhat *subjective* by nature. That is, If one knows that they've just sampled a past hill or a ditch then...

Still, careful selection of certain sites which are assumed to be somewhat undisturbed thus 'linear' are to be more trusted in the data they yield. Surely such data should be included in the record?

Yes, *assumed* is a big 'if' here; But if the ice-cores are able to illustrate such periodicity then it is reasonable to assume that they have a valid story to tell. That story may be subject to mis-interpretation and exaggeration as it is passed along but it is probably still based in some root truth.

--"there are other proxies (leaf stomata) that have been tested under the existing climate (so we have an idea of what the proxy should be telling us)"

I like that idea. Stick a past-known plant in a box, give it a CO2 concentration, measure the pores, and compare to fossil records, is it? Still, there is that ever-present problem of adaptation along such time scales, isn't there?

{I promise to learn to use the quote function soon, guys!}

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I couldn't find the link here that talked about this "problem" with the ice data, but I found this "representative sample" that may sound familiar:

http://www.tacticalgamer.com/sandbox/85905-new-global-warming-thread-37.html#post786756
Quote:
Ice Core data suffers from a number of faults. One, ice is not a closed system which is the assumption that must be made in order to accept that the CO2 is trapped. Two, if you take snow from the surface, it will not have a representative amount of CO2 represented even in the cracks. Three, chemical processes still occur deep within the ice always altering the chemical makeup of trapped air bubbles. Four, the pressure differential from being brought from well below the surface to 1 bar pressure causes the air to expand, the ice to break and the air to escape. The ice refreezes with any number of continuing chemical processes that can occur when mixing with our air. Nextly, in order to drill the ice, they use a liquid mud mixture of water, zinc and iron that taints the results. Lastly, scientists knowingly discard outrider data that doesn't fit within their agenda which can be as high as 43% of their data. Source Zbigniew Jaworski They are manipulating the data to drive a result.

With all this anectodal hearsay of the "great variability" in ice core data, I can't figure out why someone hasn't made a name for themselves by publishing evidence on this problem.

Isn't that how people get ahead in science; publish or perish?
...or is this another part of the conspiracy?

~Later smile

p.s. Evidence that these "problems" in ice cores with measuring air bubbles, etc. have been looked into, may be found at:
http://www.scienceagogo.com/forum/ubbthreads.php?ubb=showflat&Number=27013#Post27013

Last edited by samwik; 07/08/08 09:21 AM. Reason: add p.s.

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Originally Posted By: Arcturus66
{I promise to learn to use the quote function soon, guys!}

Just put the quote within quote tags -- that is, start with the word quote enclosed in square brackets. The ending tag is the same except there is a / between the [ and the q. To get fancy, you can put quote=Samwik in the opening tag to show who you are quoting.

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Trying an example using the code tags:
Code:
[quote=Arcturus66]{I promise to learn to use the quote function soon, guys!}[/quote]

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Quote:
Isn't that how people get ahead in science; publish or perish?... or is this another part of the conspiracy?


Well, that would nessecitate *a whole lotta fudgin' going on* but stranger facts have been obscured in the recent past!

I wonder if a situation has ever arose where someone felt it was more like "publish AND perish?" (/sarcasm!)


{Hey, the 'quote thing' worked! Thanks.}

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More on my 26985 post, here is a link that shows we are still almost a million square kilometers ahead of last year's melt.

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Originally Posted By: John M Reynolds
More on my 26985 post, here is a link that shows we are still almost a million sq. kilometers ahead of last year's melt.
...and only about 3/4 of a million sq. kilometers below average.
.
.
http://maps.grida.no/go/graphic/trends-i...od-of-1979-2007


"Trends in Arctic sea ice extent in March (maximum) and September (minimum) in the time period of 19792007. For the Northern Hemisphere (primarily the Arctic), observations using remote sensing technologies have been used to measure the extent and the to assess the development. Despite considerable year-to-year variability, significant negative trends are apparent in both maximum and minimum ice extents, with a rate of decrease of -2.9% per decade for March and -10.5% per decade for September (linear least squares reqression). The differences in extent are calculated as anomalies compared to the 1979-2000 average, which was 7.0 million sqkm2 in September, and 15 million sqkm2 in March. September 2007 presented a record low extent, with only 4.3 million sq km2, an indication of ongoing climate change. Please note that this figure was not originally published in Global Outlook for Ice and Snow, but is updated from a figure in that publication."


http://nsidc.org/arcticseaicenews/index.html
July 2, 2008
"Arctic sea ice extent averaged for June stood at 11.44 million square kilometers (4.42 million square miles), 0.72 million square kilometers (0.25 million square miles) less than the 1979 to 2000 average for the month. This is very slightly (0.05 million square kilometers; 0.02 million square miles) lower than the average extent for June 2007, but not the lowest on record, which occurred in June 2006."

So, currently we're only "0.72 million square kilometers ...less than the 1979 to 2000 average for the month."

Well, that's looking good....
wink



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Hey buddy boy samwise gamgee - why the focus on the Arctic? I thought we were talking about global warming??
How about we look at the global ice cover?
Or does global warming only effect the Arctic?
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/global.daily.ice.area.withtrend.jpg

Why do some people love cherries so much?

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Right Samwise. We are back to the level we were near the level the had in 2000 according to your graph. The text you quoted is slightly confusing though.

Any thoughts on my background climate data extrapolation?

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Lunchtime, but be back later....

Originally Posted By: post script
John, I'm sorry the United Nations Environment Programme (UNEP/GRID-A) quoted text from my link was confusing for you. I have to say that your reply is confusing to me. Maybe tonight I can look at it closer.

Canuck,
The title to this thread mentions "climate," not "global warming." Since the Arctic is a major terrestrial influence on our climate....

Why am I talking about the Arctic?
Originally Posted By: Canuck
Just to make it clear, it was not I who said "please don't quote any ice core data". That was RicS.
...and then you go on for 3 long paragraphs to repeat the lot of blogospheric, out-of-context, anectodal speculation on ice-core problems;
as if all of that stuff hasn't been thought of and already addressed in the scientific community.
>see: http://www.scienceagogo.com/forum/ubbthreads.php?ubb=showflat&Number=27013#Post27013
...and then JMR goes on to make a seemingly significant claim, with several links, about the Arctic.

Why am I talking about the Arctic? Because everyone else is, it seems....

But if you'd like, we could talk about the 100+ Gigatonnes of yearly ice-loss in Antarctica;
or the close to 100 Gigatonnes of yearly ice-loss from the world's mountain glaciers;
or why some glaciers are advancing, even while losing ice mass.
...or CO2, or some other complex facet of climate change...?
.
.
.

Oh, I see you've again pulled out that old, uiuc.edu "area.withtrend" chestnut.
Does this make seven different Topics that graph has been cited on; or is it only five?
I know I've commented before on how lame that graph is. What is it supposed to show; that it plots a reversal in global warming over the last few months?

The last few months!? Talk about cherry picking....
...and it's not a reversal; it's a slowing of the increased melting relative to last year.
But from this site that you (and ImranCan, and JLowe, and JMR) have cited....

http://arctic.atmos.uiuc.edu/cryosphere/
"You've heard Al Gore comment that the "Earth has a fever"? It may also have major tooth decay. The 40Mb animation at the left shows the dramatic loss of multiyear sea ice over the past year. Multiyear sea ice is older and generally thicker ice - sea ice that has survived at least one melt season (shown in brighter white)."

Unfortunately, the current "extent" of ice cover is increasingly composed of "first-year" ice; and not the multi-year ice that gives stability to the ice-cap.
As I recall, I was chided for introducing "complexity" into the question, when I tried to talk about more than "ice extent," the last time this old chestnut was resurrected.

Can you find any graphs of increasing ice mass (perhaps E. Antarctica)?

wink


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Originally Posted By: John M Reynolds
Right Samwise. We are back to the level we were near the level the had in 2000 according to your graph. The text you quoted is slightly confusing though.

Any thoughts on my background climate data extrapolation?


Hiya John,
Can you point out the parts that are confusing or not clear?
I'm not sure what your point is about comparing now with 2000. At any given point in time, one can usually find a similar reading from the past; especially since, in this case, last year was a record breaker.

The important thing to look at is each trend line, the linear least squares regression.
I'm sure that with the more recent data, the trend lines will be a little less steep, but they're still pointing downward (increasing average ice-loss).
You know about the meaning of the "slope," right?

I recall some models predict a kind of decade-long 'tipping point' for the arctic ice related to the loss in albedo, etc. The models had predicted this would happen around mid-century.
However the recent behavior is paralleling what they had predicted for that mid-century 'tipping point.'

It'll be interesting, in a few years, to see if this decade-long tipping point has alreaday started so much earlier than predicted (falsifying the models, btw), or if this is just a minor fluctuation along the road to a blissfully moderate climate (or a climate that does sorta follow the IPCC projections). My greatest fear is that we'll trigger some sort of "cold mode," possibly precipitating a partial or even full glaciation.

Originally Posted By: JMR
Any thoughts on my background climate data extrapolation?

The thing with the 3 rough mid-points, and the 30 year cooling/warming cycling? Well, as you said,
"This little thought experiment of mine... This is a very poor sample... This is just 'back of an envelope' type of calculation.... guessing at the mid points and assuming that the mid points...."

It's hard to say whether the lack of agreement with the predictions is due to the fallicy of the thought experiment itself, or the roughness of the calculations (or both).
Or neither! I'm not sure if your ideas even relate to the predictions, but I'll look at it from beginnning to end again. It's an interesting 'thought experiment,' to divide up the different forcers.

My other thought was that maybe the two cooling periods that you mentioned were just interruptions in a long warming trend; cooling interruptions caused by Krakatoa, in 1883, and the huge increase in sulfate pollution that began with WWII and ended with 'cap & trade' of sulfates back in the 70's (to clean up acid rain).

http://wgntv.trb.com/news/weather/wgntv-weatherwords-v,0,2765479.story
Volcanic cooling: A decline of average global temperatures following volcanic eruptions. Global temperatures fell about one degree Fahrenheit in the few years following the eruptions of Krakatoa (between Sumatra and Java) in 1883 and Aging Volcano in Bali in 1963.

http://isbndb.com/d/book/learning_to_manage_global_environmental_risks_a04.html
"In 1973 the first EC Environmental Action Program (EAP) was adopted."
"...efforts to deal with climate change, ozone depletion, and acid rain from 1957 (The International Geophysical Year) through 1992 (the UN Conference on Environment and Development)."

Well, just a thought....
smile


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