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What conclusions do you draw from this paper?
I know this paper isn't new, but it is often cited in response to "is Global Warming real?" types of questions.
Griggs and Harries. "Comparison of spectrally resolved outgoing longwave data between 1970 and present"
What conclusions do you draw from this paper with respect to AGW?
http://journals.ametsoc.org/doi/pdf/10.1175/JCLI42...
If the link doesn't work, then please search Google for this whole string. The paper is the first item returned.
Comparison of spectrally resolved outgoing longwave data Griggs-07-IRIS-IMG-AIRS
Reply.
For Jeff M. Thankyou for your considered response. Re “I conclude that some of the current warming is attributable to CO2 and methane up to this point due to an increase in concentration and an increase in retention”
I wonder how you reach this conclusion, as the authors make no corresponding claim.
They offer no conclusion at all on the effect of increasing atmospheric CO2 on brightness observed, and note both decline and increase of brightness in the CH4 spectrum over the times they sampled.
They make no claim at all regarding change in radiation to space in the frequencies affected by CO2 absorption... please correct me if I am in error.
Radiation to space in the absorption frequencies for CO2 is not measured in this study.
Their study frequency range is 700-1400 wavenumber (cm-1), which excludes almost the entire CO2 spectrum. Less than 1% of the absorption of CO2 lies above 700 wn. Here is a plot of the absorption range of CO2 at atmospheric concentration (from ‘sp
continued…
(from spectralcalc.com) http://farm9.staticflickr.com/8045/8449787216_722f...
They note both increasing and decreasing brightness in the CH4 bands. In the period 1997 to 2003 they note increasing brightness (more radiation to space) despite continued rise in CH4 concentration.
They do not claim, from their observations, that radiation to space has decreased due to increased GHG concentrations.
Edit for Jeff M.
I have read this paper, in its entirety, many times over.
" Changing spectral signatures due to CH4 , CO2 , and H2O on decadal time scales are observed..."
Yes, they inspected the data, and found (very limited) change, but what was this observed change that they found?
When you read the detail in the main text you find that there is no claim of increased brightness attributable to CO2 except at the incredibly narrow 720 'blip' point. This negative brightness blip is found in the 1970-1997 comparison, but not in the 1997-2003 comparison. Not only is this a tiny change (5 k of brightness), in a tiny span (approx 5 wn), but it is not observable AT ALL except when comparison is made to the oldest sensor. Even if this blip is real, and not an artefact of the differences in the sensor technologies, it wouldn't create enough heat to boil an egg.
Re "The Harries paper states ", I wasn't asking about the earlier Harries paper, but this o
continued
... but this one. However you draw my attention to figure 4-5 which shows how CO2 frequency absorption varies with concentration. I would point out that my linked snapshot from "spectralcalc" was plotted for atmospheric concentrations. CO2 has only a tiny absorption potential above 670 wn,
There is nothing in this paper that supports your conclusion.
5 個解答
- Jeff MLv 78 年前最愛解答
I conclude that some of the current warming is attributable to CO2 and methane up to this point due to an increase in concentration and an increase in retention. This was an extension of a Harries paper from 2001 to include AIRS data.
There was a further extension of the paper in the question by Chen.
This, of course, only deals with frequencies within the atmospheric window so water vapour is not measured. to see the effect increased atmospheric water vapour has I'd look at Wang's paper concerning downward radiation frequencies located here:
Sorry can't find a freely available version.
It has been claimed that these papers use modelling. These papers actually use real world data to test modelling characteristics, as stated in some of the abstracts. The person claiming such obviously had a misunderstanding.
Note that this does not state where that excess CO2 and other greenhouse gases are coming from. What this does show is that there is warming due to an increase of these greenhouse gases. If we want to look at where these greenhouse gases are coming from we need more information than just this paper, which I have provided in my previous answer where this link is posted. These papers, of course, deal with the absorption frequencies related to different gases in the atmosphere which is just another link in the puzzle pointing to AGW being correct. Taking one link out of the plethora of links I provided, each pointing to a different part of the puzzle, and claiming that that link does not show AGW to be true by itself, when I specifically included many other links pointing to other parts of the puzzle, is a fallacy.
The conclusion to your question about "What conclusions do you draw from this paper with respect to AGW?" therefor is it does not state anything about AGW. It does show where additional warming is coming from and it does show that yes, indeed, an increase in CO2 over the time periods measured does cause more energy retention in the atmosphere and thereby more warming. One of the things self proclaimed skeptics claim can not occur due to their claims that CO2 is 'saturated'. This shows that claim to be false and it shows that more energy is being retained via the increase in these gases concentration.
OM's statement "What can not be concluded from this paper is that increases in CO2 can lead to catastrophic warming" is another fallacious statement if he is talking about my post. I never contended that this paper stated anything of the sort. What my posting of this paper was in reference to was that increases in CO2 and other greenhouse gases are contributing to the current warming. Catastrophic warming was never stated in this paper or by anyone, to my knowledge, that used this paper in their posts. again he is taking a piece of the puzzle that this paper was not written to show.
Edit: You do notice that there is more energy within the troposphere at those absorption wavelengths do you not? There is more retention of heat. Where do you think that heat goes? Magically disappears? And the edge of the carbon dioxide band is the edge that will change the most due to CO2 forcing because this part of the CO2 band is not 'saturated'. See figure 4-5 in link 1 below. Regarding your further statement you did not read the study but only the abstract. On page 3997, in the conclusions, it states the following: "Using the AIRS data with data from the IRIS project allows a difference spectrum to be generated for the period 2003–1970, a period of 33 yr. Changing spectral signatures due to CH4 , CO2 , and H2O on decadal time scales are observed using the new AIRS data, thus adding confidence to the previous 1997–1970 study." If we look at the graphs on the page we can see exactly what is occurring.
The Harries paper states "This reflects the increase in the concentrations of gases such as CO2 , CFC and CH4 between 1970 and 1997...Thus we see the greenhouse gases increases reflected in the emission spectrum of longwave radiation."
DaveH: You are absolutely wrong. This paper states that there are observed changes over a 33 year time period. The associated graphs indicate that the greatest changes are in the CO2, CH4 and water vapour bands as well as the O3 bands.As I have shown in my link the greatest retention is on the shoulders of the main CO2 band located at 667cm^-1. This is exactly what we see. You are seeing what you want to see and not seeing what the actual paper states. There ius even a reasoning, which you may not have read, for the limited time of the 6 years between 1997 and 2003.
資料來源: 1. http://forecast.uchicago.edu/archer.ch4.greenhouse... Harries (2001): https://workspace.imperial.ac.uk/physics/Public/sp... Chen: http://www.eumetsat.int/Home/Main/Publications/Con... Wang (2009): http://onlinelibrary.wiley.com/doi/10.1029/2009JD0... OLR http://yly-mac.gps.caltech.edu/Radiance/Anderson_A... DLR http://www.juergen-grieser.de/publications/publica... ftp://ftp.orbit.nesdis.noaa.gov/pub/smcd/spb/lzhou/AMS86/PREPRINTS/PDFS/100737.pdf - Ottawa MikeLv 68 年前
The paper provides evidence to support something everybody already agrees upon, increased CO2 causes warming (i.e. a greenhouse effect).
Further, it can be concluded that man is increasing the greenhouse effect by increasing the CO2 concentration levels in the atmosphere using this study.
What cannot be concluded from this paper is that increased CO2 will lead to dangerous or catastrophic warming. Nor does it draw any conclusion about the "enhanced" greenhouse effect which is speculated to result from feedback processes involving clouds and water vapor. This paper specifically eliminates data areas on the Earth with cloud cover.
However, this does not stop some people from claiming that CO2 is a problem by including studies like this one in long lists of peer reviewed articles as if some sort of numerical superiority wins the day. You could have a zillion studies like this with 100% support from scientists around the world yet not be able to say a single thing about real world climate sensitivity which is the main question and needs to be addressed by analyzing feedback processes.
- ?Lv 68 年前
To Sagebrush:
<<It is a good honest attempt to answer questions. However, it has evolved and is more accurate now than it was at its conception. This is normal and the quest for knowledge is always a good thing.>>
You'll be pleased to know then that the author of the paper, JA Griggs, is referenced twice (along with co-author JL Bamber) in the IPCC's upcoming AR5 report.
- ?Lv 45 年前
My findings have revealed, or as a consequence of, or you are able to merely state your thesis returned and then use the various speaking factors of your essay to returned up the thesis on your very final paragraph. wish this helped
- SagebrushLv 78 年前
It is a good honest attempt to answer questions. However, it has evolved and is more accurate now than it was at its conception. This is normal and the quest for knowledge is always a good thing.