Trees and Ice Are Links to Past Climate
Here is additional information from Dr. Richard Alley, Evan Pugh Professor of Geosciences at Penn State, talking about climate proxy.
Question: Dr. Alley, is any one climate proxy more accurate than the others? Does any provide more information than the others?
Dr. Alley's Answer: Consider the width of a tree ring. It records how "happy" a tree is by how much the tree grew. Go to a very dry place, and a "happy" tree is one getting rain, so the tree rings are rain gauges. Go to a very cold place, and a happy tree is a warm one, so the tree rings are thermometers. But, the tree will also notice if it is being eaten by beetles, or shaded by neighbors, or other things. So the history of thickness of tree rings from one tree is unlikely to be a very good climate record. But, use a lot of trees, and you start to average over the changes in beetles and neighboring trees, and to see the climate signal. With enough trees, and enough cleverness, you start to learn about temperature and rainfall, over large areas.
Consider the isotopic composition of nitrogen and argon in ice-core bubbles. When snow falls on an ice sheet, the weight of the new snow squeezes the old snow until bubbles are pinched off, trapping air samples. Usually, the snow gets a couple of hundred feet deep, so the bubbles are being trapped way down there. The spaces in the snow are interconnected from the surface down to a couple of hundred feet, but the spaces are small enough that the wind doesn't mix the air, which instead mixes by diffusive processes.
If you warm or cool the surface, it takes a century or so for the temperature to change down where the bubbles are trapped (it takes a short while to burn the thin skin on your finger if you touch a hot burner, much longer to cook a hamburger, and much much much longer to cook a turkey; roughly, make something twice as big and heating it takes four times as long, so the couple of hundred feet to the bubble-trapping depth does take a century or so).
During that century, the temperature at the top and bottom of the snow will be different. When communicating gases not mixed by the wind have a temperature difference imposed, the gases separate (by a TINY amount) with the heavier ones on the cold end, in a process known as thermal diffusion, which is very well understood by physicists. This makes the trapped gases slightly different from the free atmosphere. If one measures characteristics (such as the isotopic composition of nitrogen and argon) that cannot change rapidly in the atmosphere (because there is so much nitrogen and argon up there, and such small gains and losses), then you can learn the deviations, and thus the temperature differences across the snow, and thus the history of temperature change at the surface. This is almost entirely a history of temperature change in the near-surface (there is a "tweak" because the gases also separate a tiny bit under gravity, and the thickness of the snow hence the gravitational effect may change a bit, but by measuring argon and nitrogen isotopes, the temperature and gravity effects can be separated because they affect nitrogen and argon differently. Then, because the gravity depends on the snow thickness which depends on temperature and snowfall rate, you can learn something about snowfall, too.). This is a much easier thermometer than a tree ring, because the gases don't worry about neighboring trees or beetles (which are notably absent on the ice sheets). But, we don't happen to have an ice sheet in Kansas, so we have to use tree rings or something else there rather than ice-core gases.
In short, nature gives us lots of indicators, the indicators are not as easy as going out and reading a thermometer, but we can read the indicators with a bit of effort and care.
Comments (18)
What is the actual range of temperatures that can be determined by such techniques? I can see general trends but my guess is that there could be ranges of anywhere from 5F-15F (At least!) in the range of temperatures determined by these techniques.
Posted by M. Plishka | February 23, 2007 2:36 PM
Exactly the same question comes to my mind as to M.Plishka, what is the accuracy of this method? Can you even devolve an accuracy for such a procedure? Seems to me to be a great bit of science under less than great conditions. Over how many years are we talking about in the past and can you ever "synch" it up with other observations that might have a real meaning?
Posted by Darren | February 23, 2007 5:37 PM
I see the pro-warming crowd has tampered with ice core records:
"Until 1985, the published CO2 readings from air bubbles in
pre-industrial ice ranged from 160 to about 700 ppmv, and occasionally
even up to 2,450 ppmv. After 1985, high readings
disappeared from the publications! To fit such a wide range of
results to the anthropogenic climatic warming theory, which
was based on low pre-industrial CO2 levels, three methods
were used: (1) rejection of high readings from sets of preindustrial
samples, based on the credo: �The lowest CO2 values
best represent the CO2 concentrations in the originally
trapped ice�;23 (2) rejection of low readings from sets of 20th
century samples; and (3) interpretation of the high readings
from pre-industrial samples as representing the contemporary
atmosphere rather than the pre-industrial one."
Link: http://www.21stcenturysciencetech.com/2006_articles/IceCoreSprg97.pdf
Posted by Chris | February 23, 2007 7:50 PM
Chris, you're joking, right?
You're citing a paper "published" by Lyndon LaRouche (see http://www.21stcenturysciencetech.com/about). Do you know anything about Lyndon LaRouche? LaRouche is so crazy he makes L. Ron Hubbard look like a Nobel Prize winner. The author of the paper you've cited has no climatology expertise. He has been published only by LaRouche. He, like LaRouche, is simply a crackpot. Do you guys use Nigerian investment schemes, too?
With all the many thousands and thousands of climatologists who are "skeptical", surely you skeptics can find more reliable sources than Lyndon LaRouche! Oh, and please, we've already read Dr. Lindzen's piece, we don't need that one recycled again either.
I ask Dr. Allen to please accept my personal apology on behalf of "Chris", for insulting you by mentioning such lunacy. I'm sure that Chris wouldn't have offered this "contribution" had he understood the origin of his cite.
Posted by BrooklineTom | February 23, 2007 10:17 PM
Okay, not the best source for info, but the paper was written by Dr Zbigniew Jaworowski. Here's a link for different publications:
http://www.google.ca/search?hl=en&q=falsified+ice+core+data&meta=
Posted by Chris | February 24, 2007 4:14 PM
Brookine Tom, I agree with you regarding unuthoratative quotes out of context and without refernce to the author. However, I disagree that there are "thousands and thousands" of climatologists who are skeptics. If you mean that they don't necessarily buy the whole package, okay, but the vast majority of climatologists agree, in general, about the fact of GW and Man's contribution. They may disagree as to the extent of long term effects. This is probably the reason that Chris and others, who are not scientists, don't understand scientific methadology, but are skeptics for other philosophical reasons, have to quote those far fringe "scientists" such as La Rouche and Lindzen.
Posted by Laurie Schwartz | February 24, 2007 7:07 PM
Ok so what about microscopic things living in the ice changing the makeup of the air in the bubbles? Wouldn't algae use the CO2? Even though I am no scientist, I remember from High School talking about microscopic organisms living in ice and subfreezing temperatures. How do these doomsday scientists explain changes created by them?
Posted by Rose | February 25, 2007 7:26 AM
Laurie, Richard Lindzen's credentials are as good as any on the pro-warming side, and a the Oregon Petition gives thousands of names of scientists who disagree that man is the cause of this warming. http://en.wikipedia.org/wiki/Oregon_Petition
Posted by Chris | February 25, 2007 9:31 AM
Laurie,
Brookline Tom was just being sarcastic with his comment about thousands and thousands of skeptical climatologists. The denialist crowd often talks about how there are "thousands" of climatologists who don't believe in GW; however, they always cite the same three or four people. His comment was tongue-in-cheek.
Posted by Mark | February 25, 2007 2:31 PM
Thank you, Mark. Yes, Laurie, I had my tongue firmly in my cheek. I apologize for being less clear than I perhaps should have been.
Chris, you seem to misunderstand what a "peer-reviewed publication" is.
The Wikipedia entry you cited regarding the Oregon petition contains this:
In 2005, Scientific American reported:
Scientific American took a sample of 30 of the 1,400* signatories claiming to hold a Ph.D. in a climate-related science. Of the 26 we were able to identify in various databases, 11 said they still agreed with the petition -- one was an active climate researcher, two others had relevant expertise, and eight signed based on an informal evaluation. Six said they would not sign the petition today, three did not remember any such petition, one had died, and five did not answer repeated messages. Crudely extrapolating, the petition supporters include a core of about 200 climate researchers -- a respectable number, though rather a small fraction of the climatological community.
One newspaper reporter said, in 2005:
In less than 10 minutes of casual scanning, I found duplicate names (Did two Joe R. Eaglemans and two David Tompkins sign the petition, or were some individuals counted twice?), single names without even an initial (Biolchini), corporate names (Graybeal & Sayre, Inc. How does a business sign a petition?), and an apparently phony single name (Redwine, Ph.D.). These examples underscore a major weakness of the list: there is no way to check the authenticity of the names. Names are given, but no identifying information (e.g., institutional affiliation) is provided. Why the lack of transparency?
As I've said before, Dr. Lindzen's credentials in climatology are comparable to those Dr. Edward Teller brought to the SDI debate. Whatever his credentials, his writings on the issue (like Teller's on SDI) are not viewed as authoritative.
The scientific community does have a process, evolved over several thousand years, for validating hypotheses, theories, and premises. Peer-reviewed publication is an important aspect of that.
The theory and criticisms of AGW deniers utterly fail to meet the standards set by this process. This is why the mainstream of the climatology science community, and the mainstream press, pays so little attention to the deniers.
Posted by BrooklineTom | February 25, 2007 4:45 PM
Why is it 20 years ago you hardly ever heard of a Climate Scientist and now that man-made global warmimg is supposedly occuring you suddenly have millions of them coming out of the wood-works.Just curious???
Posted by steve palmer | February 25, 2007 5:39 PM
Why is it 20 years ago you hardly ever heard of a Climate Scientist and now that man-made global warmimg is supposedly occuring you suddenly have millions of them coming out of the wood-works.Just curious???
Millions? I doubt it. I know it's hard to believe, but there is a difference between "hundreds", "thousands", "millions", and even "billions". Powers of ten and all that.
Why is it that 20 years ago you never heard of a blog, and now our dialog is filled with references from them?
Why is it that 20 years ago you had to go to a library and make photostats of research papers (if you were lucky) and today you simply Google the web?
Steve, I wonder -- how many of YOUR comments were published in 1987, and how many people read them, in comparison to today?
For better or worse, all of us -- including scientists and YOU -- are FAR more able to make our voices heard today than we were twenty years ago.
We do, today, swim in a sea of information.
Perhaps Laura or someone might offer an estimate of the number of credentialed climatologists active today. It might be interesting to compare this with the number active in 1987. It might also be interesting to compare this with the total number of credentialed scientists for the same period as well.
Posted by brooklinetom | February 26, 2007 11:11 AM
Brookline, you're right you never heard of the word blog. But you have to remember the same guy that created the wonderful world of the internet is the same guy that just won an oscar for his documentary. So with out him none of us would have the priveldge to talk about the heated topic of GW. Think of where we would be if it wasn't for him. If he hadn't been so gung ho about GW would we even really care about GW?
I don't know about most of America, but I don't think the War in Iraq has been money well spent. I'm sure all that money could have gone to a better place....like paying of the national debt. Instead our boys are dying left and right. But the Republicans are pro war, and the democrats are all touchy feely save the earth. Where do people fit in if they don't like war, and they want to be more efficient in technology but at the same time don't quite believe all the hype that GW is caused by man? Is there a happy medium out there?
Posted by Julie | February 26, 2007 3:04 PM
But you have to remember the same guy that created the wonderful world of the internet is the same guy that just won an oscar for his documentary.
...
Where do people fit in if they don't like war, and they want to be more efficient in technology but at the same time don't quite believe all the hype that GW is caused by man? Is there a happy medium out there?
Julie, whether you realize or not, when repeat the tired canard about Al Gore's comments about the internet, you magnify the very "hype" that you claim to oppose.
As someone who has access to the internet, you have greater ability to check your own sources and educate yourself than any scholar has EVER had. If you can exercise a small amount of self-discipline, you can go a very long way towards finding a place to "fit in".
For the record, your cheapshot against Al Gore is just that, a cheapshot. Is that your idea of how to best contribute to the society around you?
It's a cheapshot because he never said it. I refer you to, for example, Snopes.com (http://www.snopes.com/quotes/internet.asp).
From the Snopes piece:
Claim: Vice-President Al Gore claimed that he "invented" the Internet.
Status:False.
Origins:Despite the derisive references that continue even today, Al Gore did not claim he "invented" the Internet, nor did he say anything that could reasonably be interpreted that way. The "Al Gore said he 'invented' the Internet" put-downs were misleading, out-of-context distortions of something he said during an
interview with Wolf Blitzer on CNN's "Late Edition" program on 9 March 1999. When asked to describe what distinguished him from his challenger for the Democratic presidential nomination, Senator Bill Bradley of New Jersey, Gore replied (in part):
'During my service in the United States Congress, I took the initiative in creating the Internet. I took the initiative in moving forward a whole range of initiatives that have proven to be important to our country's economic growth and environmental protection, improvements in our educational system.'
Clearly, although Gore's phrasing was clumsy (and perhaps self-serving), he was not claiming that he "invented" the Internet (in the sense of having designed or implemented it), but that he was responsible, in an economic and legislative sense, for fostering the development of the technology that we now know as the Internet. To claim that Gore was seriously trying to take credit for the "invention" of the Internet is, frankly, just silly political posturing that arose out of a close presidential campaign. Gore never used the word "invent," and the words "create" and "invent" have distinctly different meanings — the former is used in the sense of "to bring about" or "to bring into existence" while the latter is generally used to signify the first instance of someone's thinking up or implementing an idea. (To those who say the words "create" and "invent" mean exactly the same thing, we have to ask why, then, the media overwhelmingly and consistently cited Gore as having claimed he "invented" the Internet, even though he never used that word, and transcripts of what he actually said were readily available.)
If it's a "happy medium" you want, why do you then continue to repeat ugly partisan lies?
Posted by BrooklineTom | February 27, 2007 2:34 PM
Brookline/Julie/Mark:
I would like to thank all of you for really illustrating the entirety of the GW issue. Shall we briefly review?
The article initiating the thread discussed tree rings, ice cores and how their study can play a role in devolving past climates and possible relevance. The first comment questioned the science and validity. I responded asking similar more direct questions that go to the "core" of the GW issue. The next comment cited research bringing into question the validity of the ice core data. Brookline then seperates from the science, and raises questions about the source. Not the reasoning in the article but the source. Sarcasm is then employed to belittle his opposition. We then have a tit for tat about who believes what and then the question about the profession of "climate scientist". To which, we are treated to the infamous argument that things change over time throughout life therefore it makes sense to create new jobs to fit the needs of society.
We then get to the crux of the issue, it is not about GW, not about new types of sceince jobs, not about science, it is solely about those who dislike our current administration. More specifically, they dislike anything other than the political persuasion Republican. I recall vividly that the first mention of a warming planet was during the mid to late 80's, the Reagan years. Then the hype died down during the 90's, the Clinton years. The theories then were the same as they are now, the only difference is that now, unlike the 90's, man is definitely the cause. Amazing that the Global War on Terror is brought up in a discussion about ice cores. It shows the exact reasoning that the problem is not necessarily GW but the current government.
I have yet to hear anyone who supports the position of man-induced GW spout long-term data sets as to the physics of how man is changing the environment. I all I aver hear is the mantra that man is doing it and AMERICA is the primary problem. Take this thread for example, specific science based questions were asked and we get no response other than it IS happening and questions about GW leaders are inapproriate. While it is certainly OK to postulate that based solely upon extrapolated data that GW is happening, it is patently incorrect to assert that this same data is questionable at best, flat-out altered at worst.
Simply put, the fundamental physics supposedly involved in man-induced GW do not make any sense whatsoever as they are described by the supportes of man-induced GW. There is never an explanation other than it "just" happens. When you then take the theories in the context of their "solutions" you quickly see that the real point is not to "save" the planet but merely to promote a tax on all peoples who violate some arbitrarily set values relating to modernization. I have yet to hear exactly the point of this tax other than to reditribute the money to less developed countries. There is NEVER a solution that does not involve some sort of penalty (tax).
You know, this reminds me of the description of a Socialist/Communist government. Take from the wealthy, give to government for the good of the common people. Not saying that is the case but it sure sounds like it.
Posted by Darren | February 28, 2007 10:54 AM
Thanks, Tom for pointing out the fact I was wrong. I was actually meaning my statement sarcastic...everyone know the internet was actually created by the military. For everyone who took it literally, please for give my sarcasm.
Posted by Julie | February 28, 2007 10:59 AM
Thank you Darren for a succinct post worthy of more thought and development!
Posted by M. Plishka | February 28, 2007 12:21 PM
M.Plishka Thanks for the compliment.
I really just wish that those people who feel that GW is man-induced would simply work to answer the questions that you so adroitly posed. The truth of the matter is they really can't answer the questions for a couple of reasons with the main one being that it would invalidate the research. Do that, and the primary source of funding, world governments and the UN (funded by world governments) would instantly dry up.
This reminds me of a project I worked upon for a State University in which it was shown that in the end, would be a waste of funds. Even though I stated that the project was not needed, they went ahead with it because if they had not, their budget may have been lowered for the following year. In essence, the sole purpose of the project was to provide an expenditure of money so as to maintain and grow the budget. It just seems to me that that is the whole purpose of the man-induced GW supporters.
Posted by Darren | February 28, 2007 2:22 PM