Calculating the greenhouse effect
In another forum (on a planet far, far away), the following quote recently came up:
….the combined effect of these greenhouse gases is to warm Earth's atmosphere by about 33 ºC, from a chilly -18 ºC in their absence to a pleasant +15 ºC in their presence. 95% (31.35 ºC) of this warming is produced by water vapour, which is far and away the most important greenhouse gas. The other trace gases contribute 5% (1.65 ºC) of the greenhouse warming, amongst which carbon dioxide corresponds to 3.65% (1.19 ºC). The human-caused contribution corresponds to about 3% of the total carbon dioxide in the present atmosphere, the great majority of which is derived from natural sources. Therefore, the probable effect of human-injected carbon dioxide is a miniscule 0.12% of the greenhouse warming, that is a temperature rise of 0.036 ºC. Put another way, 99.88% of the greenhouse effect has nothing to do with carbon dioxide emissions from human activity8.
We've discussed the magnitude of the greenhouse effect before, but it might be helpful to step through this 'back-of-the-agenda' calculation and see what the numbers really give. (Deltoid has also had a go at some of these mis-statements).
The quote comes from a lecture by an Australian climate 'contrarian' and frequent contributor to the southern hemisphere op-ed pages. Where did he get this from? One might assume that reference '8′ was a scientific text, but one would assume wrong. It was in fact our old friend at Fox News, who may in turn have picked up his (junk)science from here. It is not clear whether this is the original source, but it's close enough.
So, starting at the top:
- "33 ºC" is the difference between the mean surface air temperature of the planet and the blackbody radiating temperature (i.e. the temperature a blackbody would need to radiate at to be in equilibrium with the incoming solar radiation given an albedo of about 0.3). So far so good. While that is one way to assess the strength of the basic greenhouse effect, another one is measure the amount of long wave radiation from the surface that is absorbed in the atmosphere (by greenhouse gases (incl. water vapour), clouds, aerosols, etc.). That is currently about 150 W/m2 and would be zero with no greenhouse effect at all.
- "95% of this warming is caused by water vapour". This is sourced to a couple of chaps who may have worked for Accu-Weather, but a) is misquoted - their '90-95%' is for both water vapour and clouds, and b) just wrong and c) irrelevant anyway.
Dealing with b) first, if you remove all water vapour and clouds you still absorb about 34% of the long wave radiation, and conversely, if you only have water vapour and clouds you absorb 85% (calculations here). Thus the effect of water vapour and clouds is between 66 and 85% - the range being due to the spectral overlaps with the other absorbers. These calculations were done with the GISS GCM radiation code, which matches line-by-line codes to about 10% - but the numbers are very similar to Ramanathan and Coakley (1978), and so probably aren't too far off what you would get with any decent radiation code. I'll get to 'c)' below…. - "The other trace gases contribute 5% … amongst which carbon dioxide corresponds to 3.65%". That is just 100 minus 95% of course, but really it should be 15 to 34% - of which CO2 on its own is between 9 and 26% (op cit). If you were to naively estimate the total temperature contribution of the CO2 it would be between 3 and 9 ºC - but see below.
- "The human-caused contribution corresponds to about 3% of the total carbon dioxide in the present atmosphere,". This one is blatantly false and is erroneously credited to the US Dept. of Energy in the original source (their Table 1)! The '3%' number actually comes from comparing the human emissions with the gross emissions from natural sources while neglecting to consider the large natural sink. Because of the rapid cycling between the biosphere, the atmosphere and the upper ocean, that is an irrelevant comparison - kind of like comparing the interest on your bank account and your salary and expecting to be able to say something about your savings without thinking about your spending. The correct statement is that CO2 is around 30% higher than it was in the pre-industrial period, and all of that rise is due to human emissions (fossil fuel use and deforestation principally).
- "Therefore, the probable effect of human-injected carbon dioxide is a miniscule 0.12% of the greenhouse warming". That's just 0.03*0.0365 of course - but even that is calculated wrong (it should be 0.11% by my calculator). But from our numbers, it would be between 3 and 8%.
- "a temperature rise of 0.036 ºC". More like 1-2.6 ºC actually, but although this gives numbers that are in the ballpark of the IPCC estimates (0.6 to 1.7 ºC warming for an increase of 30% in CO2 at equilibirum) this is not a sensible way to calculate climate sensitivty.
Why do I claim this is an irrelevant and not very sensible calculation? Firstly, it assumes linearity - all of the gases contributing according to their effects today when it is obvious that overlaps and saturation effects are large and important, and more importantly, it ignores feedbacks. The calculation above gives the impression that what you are calculating is the change of temperature that would result if you remove all the CO2. But since water vapour concentration is a feedback not a forcing, it can't be assumed to remain constant as the planet cools. Water vapour does in fact change (roughly keeping relative humidity, as opposed to specific humidity, constant) and this has been shown in the real world as a function of volcanic cooling (Soden et al, 2002) and for longer term trends (Soden et al, 2005, discussed here), and is well reproduced in climate models.
What then is an appropriate calculation? Well, it's simply the estimate of climate sensitivity for the present climate - how much would you expect the planet to warm if you doubled CO2? We've discussed this numerous times before, and in my opinion the best answer so far comes from looking at the difference between the last glacial period and the modern era - this gives a number around 3 +/- 1 ºC at doubling.
For the 30% rise in CO2 there has been so far, that would imply that would represent around 3% of the natural greenhouse effect - a good order of magnitude bigger than that suggested above. Of course, this is at equilibrium and not applicable to a transient change. If one takes into account the human-induced changes in the other GHGs (CH4, N2O, CFCs), you'd get something like double that. Given that even a 5 or 6 ºC cooling was associated with the huge ice sheets 20,000 years ago, and that 33 ºC cooling would reduce our planet to a near-snowball-like state, a potential increase of 5 to 6% of the natural greenhouse effect is not to be sniffed at… nor dismissed as irrelevent with highly misleading arithmetic.
One could make the point that my calculations are 'just another web page' no more and no less authoritative than the links above. In some sense that is correct (though I'd argue my sourcing is a little better!). But you will never find a peer-reviewed rebuttal of such a bizarre line of reasoning as we are dealing with here - basically because such a line of reasoning is highly unlikely to make it past peer-review itself. There are innumerable 'proper' references to estimates of the climate sensitivity though, and one should indeed hesitate to accept calculations like this example over the mass of peer reviewed studies.
21 January 2006 at 11:51 PM
Thanks very much for this one, Gavin. It comes up all the time on sci.environment and I have written arguments similar but without as good calculations and without the authority you bring to it! This will save alot of time.
One frustration I have is a lack of references for CO2’s and H2O’s share of the GH effect. I use your “Feedback or Forcing” article and this quote of a quote of an offline text book here.
Is there not some canonical reference (online) that presents a table such as yours out there? Is the table you did and the method you used as good as it gets? When people come to sci.environment with their 95% (sometimes 99%) I like to ask for a reference but don’t feel like I have a very solid offering of my own.
22 January 2006 at 5:50 AM
If H2O is not forcing it could not be a feedback.It must be a major contributor to the Greenhouse effect since its concentration in air on average is at least an order of magnitude greater than that of CO2 and it has similar spectral characteristics.
22 January 2006 at 5:54 AM
So let’s try to calculate the effect of doubling CO2 using David Archers Modtran 4 model here:
http://geosci.uchicago.edu/~archer/cgimodels/radiation.html
To do that we need to look up from ground surface to see the increase of radiation flux (W/m2). So we do two runs as function of pCO2 sensor looking up at 0 km in the 1976 US standard atmosphere. We also use constant Relative Humidity to imply water vapor feedback. leaving the other parameters on the default. A pre-industrial pCO2 of 280 ppmv gives us an output of 257.323 W/m2, the double value 560 ppmv yields 260,526. hence doubling CO2 gives an increase of greenhouse effect / radiation flux of 3,2 W/m2.
Now let’s get Stefan Boltman’s law out:
http://www.ldeo.columbia.edu/~kushnir/MPA-ENVP/Climate/lectures/energy/Greenhouse_Effect.html
expression 5:
G = sigma Te^4 = (1-A) S / 4
We can rewrite that as
Te= ( (1-A) S / 4 sigma)^ ¼
Substituting A (albedo) = 0,3 and S (solar flux) = 1367.6 and sigma=5.67E-8 we get the well known black body temperature 254.9 K or -18C.
Since the average temperature is supposed to be 288K or 15,0C we increase the pure flux with Greenhouse flux (GHF), assuming albedo is zero for IR flux, and hence adjusting the relationship as
Te= ( GHF/ sigma + (1-A) S / 4 sigma) ¼
To get the 288K, 15.00 C degrees we see that we have to give GHF the value of 150.75 W/m2. So what would the new temperature be when we add that 3,2 W/m2 (GHF=153.95) for doubling CO2 from 280 to 560 W/m2?
The answer is 15.589C..
Hence according to your own MODTRAN4 tell us that doubling CO2 under constant relative humidity (positive forcing) gives us a temperature increase of 0.589 C.
Hans Erren got a similar result: http://members.lycos.nl/ErrenWijlens/co2/howmuch.htm
dT=0.6833 centigrade for a doubling of CO2
Now some more about the positive feedback of water vapor. Soden et al developed their idea based on the eruption of aerosol giant Pinatubo and it’s apparent effect on MSU4 (stratosphere temperature) and MSU2LT (lower troposphere). However they failed to test their hypothesis to the other documented (radio sondes) aerosol eruptions of Agung 1963 and El Chinon 1982. That would have shown that stratosphere reaction would fit perfectly but the lower troposphere did not, which does no good to the credibility.
Alternative calculations of feedback are here also not supporting the positive feedback ideas:
http://www.aai.ee/~olavi/cejpokfin.pdf
http://www.aai.ee/~olavi/2001JD002024u.pdf
22 January 2006 at 6:56 AM
The contrarian seems well qualified to do the calculation he didn’t need Fox news.
Bob Carter is a Research Professor at James Cook University (Queensland) and the University of Adelaide (South Australia). He is a palaeontologist, stratigrapher, marine geologist and environmental scientist with more than thirty years professional experience, and holds degrees from the University of Otago (New Zealand) and the University of Cambridge (England). He has held tenured academic staff positions at the University of Otago (Dunedin) and James Cook University (Townsville), where he was Professor and Head of School of Earth Sciences between 1981 and 1999.
[Response:You’d think so…. -gavin]
22 January 2006 at 11:40 AM
A few more calculations.
Playing a bit more with our spreadsheet and see the difference between then (280 ppmv CO2) and now (375 ppmv CO2). The modtran run says: 258.673 W/m3, hence a difference of 1,35 W/m2 with the 280 value (257.323). We run it in the equation increasing the GH factor to 152.1 to find a temperature increase of 0,25 degrees.
Now how about the irradiation of the sun. What was that again. Look here:
http://www.space.com/scienceastronomy/sun_output_030320.html
“…The new study shows that the TSI (Total Solar Irradiance) has increased by about 0.1 percent over 24 years. That is not enough to cause notable climate change, Willson and his colleagues say, unless the rate of change were maintained for a century or more…..”
Really? now what if we increase the solar irradiance with 0,1 percent in our little formula? Hence S = 1381.3 and hence in the equation (G = 150.75) Te=15,44 C Hmmm A 0,44 degree increase.
Let’s take G =152,1 again and S =1381.3. Then we get: T = 15,69 or a 0.69 increase. Isn’t it getting rather close with GISS temp and Jones et al?
22 January 2006 at 5:06 PM
Let me repeat the last sentence of the article.
“There are innumerable ‘proper’ references to estimates of the climate sensitivity though, and one should indeed hesitate to accept calculations like this example over the mass of peer reviewed studies.”
Lots of highly qualified people have looked at the issue of climate sensitivity. Their estimates, appearing in peer reviewed literature, fall within a relatively narrow range. One has to be credulous indeed to believe that a random geologist, not specially knowledgeable about the area, or someone making comments in response to this article is going to find something that all these smart people have missed. I know that this sounds like an appeal to authority, but do we really have a choice about that? My experience with research in my own field has taught me that whenever I enter a new field, I have to make all the standard mistakes before I even begin to understand the real issues. Even with a good background in physics and mathematics, it would take me a minimum of three to five years to even get to the point where I could start making mistakes in this field. That is what we have graduate schools for.
22 January 2006 at 6:45 PM
Re #6
I shouldn’t say that climate sensitivity of current models is in a “narrow” range, as the effect of a CO2 doubling is calculated between 1.5 and 4.5 K. Or 1:3. Or the difference between a benign warming and a probable disaster…
The issue of climate sensitivity was already discussed on RealClimate: different climate models use different sensitivities for the different main forcings. Thus there are questions enough left for discussion.
[Response: Not so fast. Different models produce slightly different sensitivities for different forcings, mainly related to the forcings’ spatial and altitudinal distribution. For instance, solar and CO2 have opposite effects in the stratosphere, black carbon in the tropics from biomass burning has a different effect from anthropogenic black carbon in the mid-latitudes where it interacts more with snow albedo etc. But these are all results, not assumptions - and the differences are not huge. See Hansen et al, 2005 for more details. -gavin]
22 January 2006 at 7:49 PM
That’s Svante’s back of envelope, which is too much. Hansen makes it only 2.7. But this is an eqilibrium sensitivity which has a relaxation period of more than a century. Transient sensitivities (modeled and observed) point to 1 K/2xCO2 or 0.282 K/Wm-2
(this entry is logged in ukweatherworld)
22 January 2006 at 8:02 PM
The experts have to find keep faith with the conjecture that CO2 causes Global Warming in order to preserve government grants and keep their jobs.
No wonder they all agree.
There are lots of illogicalities cited to support the conjecture on this web site and also in many of the refereed articles that appear in scientific journals.
Read them with an open mind and you might also be enlightened
I used to be a convinced believer in antroprogenic GW but the more I’ve studied the more skeptical I have become.
22 January 2006 at 8:56 PM
Re #7: This last statement reminds me of Bjorn Lomborg’s claim that he used to be an environmentalist until his study of various environmental problems caused him to see the light. It turned out later that the only evidence Lomborg could produce of his claimed environmentalism was that he had once made a modest cash contribution (of which there was no record) to Greenpeace. In other words, the more likely explanation is that he made up the environmentalist bit since it would be an effective ploy to promote his book.
22 January 2006 at 9:05 PM
Re. #9
Strange, that. My experience is the opposite - the more I’ve studied the more convinced I have become.
22 January 2006 at 11:34 PM
re #9
Given that the current largest funding source of climate science is also the most antagonistic to evidence of AGW (ie the US gov’t), one would expect that any political pressure would be in the opposite direction of what you suggest.
23 January 2006 at 3:31 AM
Re #12:
I think most of us would be quite surprised if the scientists reviewing US grant applications for climate science research (those who decide which proposals are funded) were really “…the most antagonistic to evidence of AGW…”.
23 January 2006 at 3:37 AM
Re: #10
OK, Steve, I’ll bite: which statement in #7 do you feel is self-serving, and most likely untrue?
23 January 2006 at 6:56 AM
Re #7, Gavin’s comment:
Gavin, indeed I have a tendency to jump to conclusions too fast to follow for other readers. In this case, the difference in general sensitivity for different models is mainly the result of how models treat cloud feedback.
The difference in individual sensitivities by Hansen is based on different radiative responses in latitude and altitude. But even if this is a result of the GISS model, this largely depends on the assumptions made in the model for e.g. amounts and radiative effect of aerosols, which are far from settled. A recent study by Heald ea. shows that natural VOC induced aerosols above the boundary layer are mostly of natural origin (7:1), and comprise a 2:1 up to >10:1 amount, compared to SOx (SO2+sulfate) aerosols in the 0.5-10 km free troposphere, or 10% of the total aerosol optical depth measured by satellites… Add to that the effect below the boundary layer and the effect of other natural aerosols (natural fires, sea salt, sand dust, DMS, NOx), good for some 38% of the < 1 micron fraction of total aerosols (according to IPCC estimates)…
Further, Hansen concludes that solar sensitivity efficacy is around 0.92 the efficacy of CO2, while the Hadcm3 model only uses 0.5. I am interested to know what other models use as individual sensitivities…
[Response: They don’t use, they produce… PS. do not use a raw < symbol in comments, it is interpreted as html. Use “& l t ;” instead. -gavin]
23 January 2006 at 7:13 AM
Re #10&14:
I suppose that this is a reaction on comment #7 which is deleted?
I still am an environmentalist, be it less active than end 1960’s when being an environmentalist was very necessary and costed a lot of individual money (compared to the not so bad wages of some rich NGO’s today…). See my short cv here…
23 January 2006 at 9:07 AM
Re #1 Coby, One possibility is this paper by Kiehl and Trenberth.
23 January 2006 at 9:42 AM
Re#9: The funding/ ad hominum argument is wearing a bit thin.
The people who are involved in climate research are intelligent and highly qualified. If they wanted to they could get good jobs in the commercial world. Science does not pay very well. If a scientist would want more money (s)he would change jobs, not manipulate the research.
23 January 2006 at 11:35 AM
Re: #2, “If H2O is not forcing it could not be a feedback.It must be a major contributor to the Greenhouse effect since its concentration in air on average is at least an order of magnitude greater than that of CO2 and it has similar spectral characteristics.”
The first sentence is dead wrong. As a result of climate warming, water vapour increases, which is a feedback loop. This is caused by the increased moisture capacity of the atmosphere with increased temperature, as well as warmer oceans, seas, and rivers, which leads to increased evaporation rates.
Water vapour is a major contributor to the greenhouse effect. That is correct. However, it is a result of the feedback described above which increases water vapour in the atmosphere.
What is the principal cause of this feedback over the last century-and-a-half? Human activities which produce greenhouse gases, such as CO2, methane, and others!
What must we do to minimise this feedback loop and prevent long-term catastrophic events in the very near future? Reduce greatly our GHG emissions!
23 January 2006 at 11:53 AM
I’ve never really understood why people like to talk about the world without water vapor, because I surely wouldn’t want to live there.
It seems to me that if one wants to make an apples to apples comparison about the relative importance of different climate forcing factors, then one ought to be looking at their differential impact under modern conditions. In other words, if I increase substance X by 1% in the atmosphere, what is the effective change in radiative forcing (or temperature), either with or without water vapor feedbacks? I’ve never really seen anyone put it in these terms for the modern atmosphere, and I don’t really know why not, though some results on long-term forcing changes do allow one to ball-park the differential effect.
Is anyone here familiar with literature that compares the effectiveness of various forcing factors in the modern atmosphere under small perturbations?
23 January 2006 at 2:32 PM
> compares the effectiveness of various forcing factors …
Lots. Also depends on whether you measure at the source or after mixing.
http://pubs.giss.nasa.gov/abstracts/2005/ShindellFaluvegiBS.html (mention)
http://pubs.giss.nasa.gov/docs/2005/2005_Shindell_etal_1.pdf (PDF)
23 January 2006 at 2:50 PM
Re #s 10, 14 and 16: Just to clarify, what is now comment 9 was comment 7 at the time I submitted my response. This re-ordering happens sometimes when comments come in almost simultaneously. Just to clarify, generally I feel that someone’s background is irrelevant to the validity of their views on climate *except* when this particular conversion is claimed. Normally, as with Lomborg, there is little evidence to back up such claims.
23 January 2006 at 9:11 PM
I think I could make an argument why there’s no gravity on earth. For one thing universal gavity (according to my high school physics course) has to to with mass - the more mass the greater the gravity. Well, dah, the sun has a lot more mass than the earth and would be counterbalancing all of earth’s gavity many times over. Ergo, earth doesn’t have any measurable gavity that would affect us humans. But because we are suffering under the delusion that it does, we obstinantly cling to earth.
Then, of course, there are birds & airplanes that prove beyond any doubt that earth’s gavity just doesn’t exist, at least not in any significant amount that would affect any of us.
As for things that come back down to earth when we throw them up in the air, well that’s a matter to them bumping into all those natural & human-emitted GHGs up there & bouncing back.
23 January 2006 at 9:17 PM
Gavin-
The confusing thing for me is radiatively CO2 has its greatest absorption of IR radiation from about 14 microns to 20 microns wavelength….(which corresponds to -50C and below by wien’s displacement law). The Water vapor bands totally overwhelm the CO2 contribution above -50C….is that correct? So increased CO2 should have it greatest leverage on the climate system in places where the mean temperatures are -50C…which is Antarctica for example. There has been basically no trend there in the last 50 years as CO2 builds up. What gives here?
Also, in the ice core data, CO2 appears to passively follow the inferred temperature trends through the millenia suggesting
its concentration follows the glacial to interglacial periods and the increased solubility of the oceans at lower temperatures.
We all have to remember it is a trace gas….and it has increases 100 ppm in 140 years. Yes that is significant, but enough
to throw the earth’s climate out of whack?
Also, has anyone proven the increased absorption of IR radiation from increased CO2? Aren’t there satellites that measure outgoing long wave radiation? Shouldn’t we see less OLR for a given temperature at the surface. If you look at these curves….the higher the temperature in a region, the more OLR. Has anyone actually proven that CO2 is reducing OLR from the surface or lower troposphere for the same temperature? I have never seen this in the literature.
That would be a smoking gun!
The water vapor feedback is hard for me to understand. More water vapor eventually will equal more clouds and precipitation which is a sink of water vapor and a therefore primary greenhouse gas. Are we certain that the RH will remain the same? I saw your Mount Pinatubo stuff…interesting but it don’t feel conclusive to me. Also if there is a strong water vapor feedback, then when the CO2 concentrations rose 100 ppm between glacial and interglacial periods, why wasn’t the climate system thrown out of whack? Based on the modelling what is the “breaking mechansim” to keep the earth from becoming like venus?
I believe this is the precipitation, snowfall and ice accumulations.
The oceans also are a huge storage house for heat to stablize the climate system and restore balance. I would like to see some proof that CO2 increases are causing less long wave radiation to escape given a certain temperature. That would be neat.
What about solar forcing? The 20th century has had the highest solar activity in a long time (1000 years?)after a period of a quiet sun during the little ice age. Can’t this recent warming be natural from changes in solar activity?
Yes I believe the earth has warmed since the 1960s…but before that I think the records are questionable. The satellite record finally is showing some small warming. So i do believe we are on an upswing. It could end abruptly….I wouldn’t be surprised. Can we really say its from anthropogenic causes though? I am not convinced but open to learning more.
Thanks. Look forward to your reply. I am really curious about this stuff and find your blog very informative!!!
23 January 2006 at 10:07 PM
Re: #2, “If H2O is not forcing it could not be a feedback.It must be a major contributor to the Greenhouse effect since its concentration in air on average is at least an order of magnitude greater than that of CO2 and it has similar spectral characteristics.”
The second part is also wrong. The IR absorption spectrum of water is very different from CO2. To see this go to http://geosci.uchicago.edu/~archer/cgimodels/radiation.html
CO2 has two allowed IR absorptions, only one of which is very important for atmospheric processes (the bend at ~650 cm^-1). That is the big absorption you see if you run the calculation at the web site. (Wavenumbers are cm-1) The absorption bands of CO2 are compact, extending ~50 cm-1 on each side for atmospheric conditions. There is no allowed rotational absorption at lower frequencies.
Now set the CO2 concentration to zero and run the calculation again. Water vapor has an allowed rotational spectrum that extends from ~100 cm-1 to 700 cm-1 or so. That is the hash that you see in the figure. The lines are widely separated, unlike the case for CO2. The hash to the right of the figure at ~1200 cm-1 is the IR spectrum of the H2O bending mode.
The compact peak at ~1100 cm-1 is from ozone. You can see this by zeroing out the trop and strat ozone.
Rerun the calculation at ~ 1,2,3,4 km altitude with full O3 and CO2. The reason you see little net absorption at 1 km is that the emission from the relatively warm CO2 and H2O balances the absorption.
23 January 2006 at 10:24 PM
Oh yes, one other thing about http://geosci.uchicago.edu/~archer/cgimodels/radiation.html, that I think Andre misses. The surface temperature is fixed for the calculation, thus just holding relative humidity constant does not capture the full effect of any water vapor feedback. To do so, in a quick and dirty way, you have to raise the temperature in the “Ground T Offset Box” This makes quite a difference. If you raise the ground temperature 3 C, the intensity is 269.6 W/m2, an additional ~9 W/m2.
I REALLY like that site. Thanks again to the Chicago crew for maintaining it.
24 January 2006 at 5:37 AM
Re #3
Doubling the CO2 in Modtran 4 http://geosci.uchicago.edu/~archer/cgimodels/radiation.html creates an atmosphere that radiates more IR to the ground but that atmosphere also radiates LESS IR into space. e.g. looking down at 70km, a doubling of CO2 from 280ppmv to 560ppmv causes the radiation to drop from 260.023W/m2 to 257.197W/m2. The problem now is that the earth is no longer in thermal equilibrium, so even if the earth’s surface did only warm up by 0.589C initially, it is going to keep warming up until it achieves thermal equilibrium. I invite everyone to try Modtran to find what the surface temperature would be that achieves thermal equilibrium.
24 January 2006 at 11:15 AM
BLA BLA, ICE CORES SAY RAPID CHANGE HAPPENS. HOT OR COLD. TOSS A COIN
WHAT KIND OF PEOPLE SAY: “IF ALL THE ICE MELTED SUDDENLY, SEAS WOULD RISE. THEN GIVE AN ACTUAL NUMBER!?” WITHOUT KNOWING THE IMPACT TO PLATE TECTONICS ON THAT GEOGRAPHIC AREA??. REF: NEW MADRID ZONE STILL MOVING FROM LAST ICE AGE.
[Response: Please avoid all caps comments in future. They are inappropriately visually loud. Thanks. -Moderator]
24 January 2006 at 12:37 PM
I wrote a very crude, semi-gray RCM for Earth using a fixed convective adjustment of 6.5 K/km and accounting for 19 spectral bands for H2O, CO2, O3 and clouds. I used the Kiehl and Trenberth (1997) cloud scheme. The model ended when dT/dt for all layers becamse less than 0.001 K. The time step was 1 day, cutting in half after every 500 cycles to ensure convergence.
The first run, with 380 ppmv of CO2, gave a surface temperature of 288.3 K after 525.5 simulated days, with surface illumination 0.489 of incoming visual light, and wound up with a TOA discrepancy of 8.0%.
The second run, with 760 ppmv of CO2, gave Ts = 294.9 K, 349 days, 0.460 surface illumination and 9.3% I/O discrepancy at TOA. So my surface temperature increase by doubling CO2 alone (no H2O or other feedbacks) is 5.6 K. This is very much on the high side; Houghton (2004) makes it 1.2 K for doubling CO2 alone.
But if you represent the physics even close to accurately, you get a much huger effect from doubling CO2 than from the (contrarian) calculations above.
24 January 2006 at 4:26 PM
Re19
If H2O wasn’t forcing at a low concentration (Estimated to be between 0.7% and 1.0% at 15 degrees)It woulld not be forcing at higher concentration ( between 0.91 and 1.3% at 19 degrees) You cannot say that CO2 is causing the water vapour to rise. Temperature rises increase both CO2 (released from a warmer sea) and H2O {evaporated from same).
Water vapour must be the major temperature forcer because it present in air at a much higher concentration than CO2.
We could theorise that H2O has fed back on itself and but for clouds the earth would have overheated long ago
Increasing H2O in the air would produce more clouds producing perhaps a negative feedback.
24 January 2006 at 5:54 PM
Stewart wrote (#11.) : “Strange, that. My experience is the opposite - the more I’ve studied the more convinced I have become”.
Same with me, Stewart… although I became convinced six years ago… but I’m still learning. For instance,
Tom Brogle wrote (#9.) : “The experts have to find keep faith with the conjecture that CO2 causes Global Warming in order to preserve government grants and keep their jobs”. …
I learned quite a bit in reading at the links and article posted to RC Jan 2, 2006 titled Polar Amplification.
Reading Polar Amplification motivated me to create spread sheet temperature plots with data at climate stations in Alaska, SD_ND MN_WI MI_IND and WA_OR … (1888-2005).
After doing all that, and in actually seeing the high latitude warming amplification, the only kind of global warming that could be happening is greenhouse gas driven, in order to explain the amplified warm overnight low temperature observations shown in the data as occurring in higher latitude areas… where low humidity air is transitioning into air with higher humidity levels (H2O GHG). If we were to have global warming from a more intense period of solar radiation, the high latitude warming amplification would not be taking place in that manner.
The obvious explanation for the GHG driven global warming is the heavy CO2 accumulation in the atmosphere which is being observed and monitored by NOAA CMDL CO2, showing rapid accumulation of CO2 in the atmosphere at sampling points at many measuring sites throughout the world. From my perspective, the case is closed… the primary cause of the rapid global warming in progress is the billions? of tons of CO2 which have been emitted into the atmosphere by our burning of fossil fuels for power generation.
My surface climate station average temperature plots for AK, the Upper Midwest and the U.S. Northwest are at:
http://pg.photos.yahoo.com/ph/patneuman2000/my_photos
24 January 2006 at 6:27 PM
Re: #30, “Temperature rises increase both CO2 (released from a warmer sea) and H2O {evaporated from same).”
CO2 increases are, therefore, both a forcing and a feedback. CO2 is emitted due to human activities, forcing the temperature to rise. As the temperature rises, CO2 is emitted from the oceans, forests, etc., which is a feedback.
Increasing water vapour concentrations does increase clouds, but only in the situation of temperature increases, the current situation of which is primarily the result of human activities. This may help the Earth keep itself from burning up for the short term. However, clouds also increase incoming longwave radiation, which keeps the heat inside the troposphere, yielding warmer temperatures.
24 January 2006 at 8:20 PM
Re #3, specifically to the references to work by the Estonian statistician, O. Karner.
Karner has been taking single time series of diurnal temperature differences and showing that they act as if they are constrained to return to a fixed value. The statistical properties of this time series are “antipersistent” and may be associated with a feedback in a simple lumped parameter model. This is a purely statistical rather than physical model, and it shows there is a homeostatic process, with a number that can be considered “the feedback”.
Unfortunately, it appears to me that Karner confuses this mathematical property with the H2O amplification of radiative forcing, a physical quantity with which Karner’s feedback constant has only a distant relationship.
Indeed, there is an antipersistence in temperature anomalies on Earth, and the mechanism is well-known: radiative equilibration. In this phenomenon, water vapor plays an important role but it isn;t a soliloquy. Thus, when Karner says things like (see http://www.aai.ee/~olavi/2001JD002024u.pdf )
to my reading he is confused. (I am surprised this text passed review at JGR-A.)
His subsequent paper ( http://www.aai.ee/~olavi/cejpokfin.pdf ) seems to show increased awareness on the matter:
Karner’s methodology does not separate out specific physical mechanisms but is simply a way of characterizing a time series. It in some sense includes but (as I understand it) in no sense measures the impact of water vapor feedback on radiative equilibrium.
25 January 2006 at 2:26 AM
“2005 Was the Warmest Year in a Century”:
“The year 2005 may have been the warmest year in a century, according to NASA scientists studying temperature data from around the world.
Climatologists at NASA’s Goddard Institute for Space Studies (GISS) in New York City noted that the highest global annual average surface temperature in more than a century was recorded in their analysis for the 2005 calendar year.”
http://www.nasa.gov/vision/earth/environment/2005_warmest.html
25 January 2006 at 3:00 AM
Re 31
That is only a local effect (same as medieval optimum} so cannot be global.
Some of the highest temperature rises are in places where the population has increased over the last century Did you account for this effect in your calculations.
Why is Antartica coolng?
Why is the wjnter ice pack around it as extensive now as it was in 1912 (a bad year for ice)?
Why was Nansen able to sail his ship right up to 79th parallel above the East Siberian Isles in Nov 1893? I doubt that it will be possible in Nov 2006, it certainly wasn’t in Nov 2005.
Have a look at the crude Sea Surface Temperatures published in Nature in 1995 and you will see that SSTs in 1860 were as high as the were in 1980.
History does not agree with the CO2 causes GW conjecture.
25 January 2006 at 7:31 AM
To qualify the claim in No.34:
NASA states that the reason their result is higher than others is because they use a different method which includes more weight to the Arctic. This includes an extrapolation of temperature estimates to as much as 1200 km from a station. While they have faith in this method, they state; “in some cases this method can increase error by giving undue weight to one isolated station with anomalous temperature.” NASA aknowledges that results from other eminent groups do not rank 2005 as the highest, and state “the ranking of individual years depends upon differences of only a few hundredths of a degree, which is finer than the accuracy that any method can achieve given observational limitations.”
This is all in the link.
25 January 2006 at 1:41 PM
Hi Tom,
Which places are you thinking of? The most pronounced warming is occuring in the Arctic regions, where there is no urbanization. The Urban Heat Island effect is well studied, very minor and yes, it is accounted for. Check the details of the GISS anaysis here:
http://data.giss.nasa.gov/gistemp/2005/
Also look at the global anamoly map and you will see that urbanization is not a good predictor of warming at all. It is pretty clear that UHI can not explain the observed warming trend.
All that is not even to mention that satellite measurements show similar warming of the troposphere and borehole records also indicate similar surface warming. There is just no credible reason to doubt the surface temperature analysis.
Whatever website you are reading that is telling you UHI is the cause of a spurious warming trend is either very outdated, very uniformed or very dishonest.
I don’t believe this is a correct statement as you have it. What is your source? The continental antarctic AFAIU is showing very little trend, while the peninsula is warming. But as you pointed out regarding someone else’s information, this is regional, the causes will be regional. I believe regional factors in the Antarctic include currents in the Southern ocean and ozone depletion.
Source? But do you really consider a single anecdote from over 100 years ago to be cause to doubt the millions of temperature measurements we are looking at today? If the “GW alarmists” were telling you such stories with an opposite spin, from long dead Russian sailors, would you find that compelling? The best information about arctic ice is satellite information. Unfortunately we have not had satellites in orbit for long enough to use sea ice extent to confirm the 150 year surface temperature records. But it is notable that for as long as these records exist, they say the same things.
25 January 2006 at 1:47 PM
To qualify the qualification in 36 to 34
NASA also states:
Record warmth in 2005 is notable, because global temperature has not received any boost from a tropical El Niño this year. The prior record year, 1998, on the contrary, was lifted 0.2°C above the trend line by the strongest El Niño of the past century
As you say, it’s all in the link! (Though note that my quote came from http://data.giss.nasa.gov/gistemp/2005/)
25 January 2006 at 3:11 PM
Re#9, okay, skip the science. What’s impressed me is that the ocean has warmed by 1/2 a degree. Now air warming that much doesn’t impress me quite as much as the ocean warming. Do you know how vast all the waters in the oceans are? A half a degree is a really impressive indicator of the earth system absorbing extra heat. I may be wrong, maybe air is a better indicator, but I know in the kitchen, a 12 quart pot of water takes for ever to warm up, much less boil, even while inputting maximum heat from the burner. I think GW denialists should really spend more time in the kitchen.
As for other arguments–that there is warming, but not from human emitted GHGs–it seems to me all other explanations have been pretty well shot down. At the very least those explanations are no more the likely suspect than A-GHGs. So, it really does behoove us to reduce our GHGs, on the outside chance (as you seem to think) that we are indeed warming our world.
See, you don’t need to be a rocket scientist or even a climate scientist to figure things out, and what to do about them. And luckily most solutions also save us money! I really think denialists should try a few money-saving solutions, just give them a little try. I assure you you will not regret it. It’ll make you feel good, sort of like you’re cheating Economics 101 - saving money, while doing good to the world.
25 January 2006 at 3:55 PM
In 35: Tom wrote… “That is only a local effect” (#31.) .. “cannot be global”.
Tom,
Polar amplification isn’t global, the enhancement is in high lat. areas.
Furthermore, I didn’t do the calculations, cooperative observers with the NWS did, along with Microsoft Excel software. Furthermore again, Antarctica is not cooling. I pay attention to recent articles, data and reports by Will Steger, polar explorer from Minnesota by dogsled.
25 January 2006 at 4:33 PM
Tom — references, please? Assuming you know for sure what you’re saying is true, you can give us links or footnotes so we can find exactly the same thing. If you got it from a second-hand source, give us your source.
If you don’t have a reference, you’re asking us to check for you whether what you’re posting has facts behind it. Probably it does, but everyone’s got a life, don’t ask us to find your facts based on what you say, eh?
25 January 2006 at 5:52 PM
Re #31:
Pat, if the Alaska/Arctic warming was 100% solar driven, this would have the same effect, even more pronounced, as solar has it’s highest effect in the tropics and in the stratosphere (while CO2 effects are more evenly distributed in the troposphere). This causes stratospheric temperature differences which drives planetary waves / jet stream position / rain/clouds more to higher latitudes. And has an effect on the Arctic Oscillation, where warmer/moister air is driven into the Arctic. Thus it is difficult, if not impossible, to say what is attributable to GHG forcing (with feedbacks) and what the part of solar forcing (with feedbacks) in the amplified Arctic warming is.
The recent warming in the Arctic anyway is not direct from regional CO2, as the observed warming needs a heat/radiation unbalance which is an order of magnitude larger than the direct change in radiation caused by CO2 increases…
25 January 2006 at 8:42 PM
Ferdinand, in 42 you wrote: “Thus it is difficult, if not impossible, to say what is attributable to GHG forcing (with feedbacks) and what the part of solar forcing (with feedbacks) in the amplified Arctic warming is”.
It isn’t that difficult, and certainly not impossible, to see the difference between global warming triggered by GHG emissions and global warming initiated by a solar radiation surge. For example, the hot and dry dust bowl years, early 1930s, cannot be attributed to GHG accumulations. If that were true, warmer and more humid conditions would have lasted for centuries, not years.
25 January 2006 at 10:53 PM
Re 43,
Careful here, Pat, you are talking about weather, not climate! There are plenty of predictions of drought in the coming century due to GHG driven warming. On smaller spatial scales and smaller temporal scales (such as ~10 yrs and a portion of the continental US) climatic trends can easily be dominated by regional effects.
26 January 2006 at 12:07 AM
Coby,
I don’t see how you interpreted what I said in #43 to be what you said I said, in #44.
In saying what I said, in #43, I was thinking about what it says below.
“One look at the graph below shows some interesting results. The first of which is the minima beginning in 1924 and lasting until 1937. This stretch of lower dew points matches well with the dust bowl era when precipitation was also at a minimum”.
103 Years of Twin Cities Dew Point Temperature Records: 1902-2005
http://climate.umn.edu/doc/twin_cities/mspdewpoint.htm
26 January 2006 at 12:22 AM
Colby,
I read this article on solar variability by Drew Shindell a few years ago, which may help explain what I was trying to say in #43.
“Through this coupling, however, solar variability affects the lower atmosphere by changing the distribution of the large amount of energy which is already present. The impact on global average temperature seems indeed to be small; however, changing the flow of energy produces large regional impacts”.
Solar Variability, Ozone, and Climate
By Drew Shindell - March 1999
http://www.giss.nasa.gov/research/briefs/shindell_03/
I consider weather to be what happens in the short term, less than 90 days. NOAA’s NWS Climate Prediction Center gives “climate” predictions (outlooks) for the U.S. for periods extending to 90 days, 120 days, etc.
26 January 2006 at 2:19 AM
Pat, I have always thought climate was much longer term than a few months. I am sure I have seen 30 years thrown around, though I don’t know if there is a consensus definition of this or not. That’s why I thought it was incorrect to infer anything about a climate change, much less what forced it, from a regional drought that was less than a decade.
I did reread the thread, and I think I still agree with Ferdinand about not being able to seperate solar forcing vs GHG forcing based on regional responses.
26 January 2006 at 2:42 AM
#43, 45 & 46
“It isn’t that difficult, and certainly not impossible, to see the difference between global warming triggered by GHG emissions and global warming initiated by a solar radiation surge.”
You still have not made a case for the above claim. Neither the dust bowl of the 1930’s nor dewpoints in the Twin Cities point to a source of global climate change. If we could look at regional weather or even regional climate and deduce the source of global climate change anyone could be a climate scientist.
26 January 2006 at 2:49 AM
42, Ferdinand, Although RC scientists have patiently debunked this solar effect, I repeat myself through 2 pictures in order to reinforce this debunking in near real time, it is hoped that you will appreciate the meaning of this January’s incredibly warm winter (Moscow appears back to normal temperatures now), and contrast it with 2004-05 winter. Your reasoning is that the signal given by much warmer temperatures may not be attributable to CO2, and only solar forcing generated this winter heat wave, rings wrong. On my website look at the news item on the top of the page, the two sun comparison, the one to the left ( early November 2004) shows a huge sun spot, the summer/ fall of 2004 had several sun spots, in large contrast to the summer fall of 2005, almost none were seen, 2005 was a weak year for sun spots. You would probably agree that solar activity was less in 2005, yet 2005 was #1 warmest in history. Go back to the sun disk comparison , the one to the right devoid of sun spots (October 30 2005) taken at the same astronomical elevation, is almost round compared to 2004 shot. You are looking at sun disks penetrating 200 km of high arctic troposphere, and clearly 2005 disk shows by a refraction analysis a less colder atmosphere than 2004. Despite lesser solar activity, it is warmer. So what triggers this warmth? In less than a year… It is likely as explained a combination of gradual GHG heat build up, (ice melting) finally triggering more specific humidity , a greater water vapor presence, especially due to open water of the more open Arctic Ocean Your solar explanation fails and should be put to rest. You may continue defending this idea, I can’t see how given this sun spot conundrum.
26 January 2006 at 4:30 AM
re #39 Lynn
Remember that the ocean is heated from the surface, and that warmer waters would have less tendency to sink. Increases in surface temperatures don’t necessarily mean that the bulk oceans have warmed.
Wouldn’t this in fact be a very slow process anyway? And to get warm water to sink it would have to be very saline indeed. Has anyone done any detailed work on heating of water columns?
26 January 2006 at 5:18 AM
Ferdinand is right - in GCMs, at least, there is considerable overlap betweent he effects of solar and GHG forcing - at least down here on the surface. Regarding the Dust Bowl, according to Schubert et al, 2004, it was caused by anomalous Pacific SSTs. However, there is no consensus, as far as I know, that this anomaly was caused specifically by solar warming. Certainly, I’m not aware of any study showing this. It may simply have been natural variability - such multidecadal droughts have happened in the past.
26 January 2006 at 10:28 AM
47.
Coby,
The meaning of “climate” which is used by NOAA’s NWS Climate Prediction Center is much shorter-term than the meaning of “climate” used in discussions on global or regional climate change.
NOAA/ National Weather Service
National Centers for Environmental Prediction
Climate Prediction Center
http://www.cpc.ncep.noaa.gov/
Coby, also…
Regarding your reply: “That’s why I thought it was incorrect to infer anything about a climate change, much less what forced it, from a regional drought that was less than a decade.”,
I believe that the early 1930s drought and heat wave was extreme in more ways than an absence of rain. The humidity was extremely low across very large regions (Great Plains, Midwest …). There have been other “droughts” in the Midwest which occurred after the dust bowl years. BTW, I didn’t use that term in my reply to Ferdinand in #43, you added the term drought in your comments which followed. Droughts that occurred in the Midwest after the dust bowl years until current (1976-77, 1987-88) have been much less severe than the dust bowl dry period, without the prolonged extremely low humidity in the early 1930s. I’ve made comparisons in Mississippi River monthly flows at Minneapolis for the early 1930s vs other dry periods… the flow on the Mississippi River (used for Minneapolis-St.Paul water supply) was much lower in the early 1930s than other low water years that occurred later in the 20th century. The dust bowl years was a very unusual period of extreme dryness and no clouds. It seems likely to me that the humid warm years, which followed the early 1930s heat and cloudless period, were heavily influenced by prolonged El Nino, ENSO which too place mid-1930s to 1940s, and may have been triggered by the extreme dry hot and clear dust bowl years (which may have been occurring over the ocean, leading to the subsequent El Ninos during the decade that followed the dust bowl years of the early 1930s).
In my input to public comment on draft U.S. Strategic Plan (18 Jan 2003), http://groups.yahoo.com/group/ClimateArchive/message/2696
My comments on the draft CSSP Strategic Plan in 2003 included:
“Please, add: Temperature data by itself is inadequate in monitoring changes in climate. Changes in enthalpy (temperature, humidity, phase change - latent heat exchanges) are very important. It can be misleading to look only at temperature measurements without considering changes in humidity (dewpoints). Near surface humidity is very important in determining the rate of snowmelt, and ice thaw due to the latent heat exchange from the condensation of water vapor on cold surfaces.” … “All dewpoint and relative humidity data from historical records should be made available in digital format for modeling and analysis.”
I haven’t seen any action taken on the above, which I considered as very important in Jan 2003 (and still do).
Coby, also…
After rereading what you wrote: “I did reread the thread, and I think I still agree with Ferdinand about not being able to seperate solar forcing vs GHG forcing based on regional responses”.
I still disagree with you (and Ferdinand), based on my discussion (above) and based on statements made by Drew Shindell - March 1999, in: Solar Variability, Ozone, and Climate, at:
http://www.giss.nasa.gov/research/briefs/shindell_03/
26 January 2006 at 11:04 AM
In comment #48 by JohnnyBGoode it says: “You still have not made a case for the above claim”.
The claim I made in my comment #43 to Ferdinand was that: “It isn’t that difficult, and certainly not impossible, to see the difference between global warming triggered by GHG emissions and global warming initiated by a solar radiation surge.”
It not clear to me what kind of a case Mr. JohnnyBGoode is looking for. I think I have made a case, above. From my experience in hydrologic modeling and prediction, many river gaging sites show a quick surge in flows and levels from local runoff, followed by a more gradual but larger increase in flows and river levels from the larger portion of the river basin further upstream. It takes a sharp eye and focused attention to notice these types of characteristics in physical systems. Also, like increasing river flows, if the rate of rise during the beginning periods of a flood event (or warming climate trend) is much quicker than was earlier expected, it may not be just the timing that’s off. It’s more likely that the volume (or warming maximums) are being underestimated. For example, “David Field, another Scripps researcher who has been working with several Mexican and US colleagues, has found evidence that global warming is beginning to penetrate the ocean today. Dr. Field, now at the Monterey Bay Aquarium Research Institute, and his co-researchers described that warming earlier this month in Science.” http://www.csmonitor.com/2006/0126/p16s01-stss.htm
26 January 2006 at 11:05 AM
All the climate models omit a strong negative feedback that only applies to greenhouse warming. Briefly put, a narrowband greenhouse effect will not warm a moist planet because the photons will be shuttled to cover the entire IR spectrum and hence energy will be lost to space through the IR windows. A detailed explanation is given below.
The absorption coefficient for liquid water as a function of wavelength is given at http://www.lsbu.ac.uk/water/vibrat.html (see the figure near the end). Thermal infrared in the Earth’s atmosphere is around 10 to 20 microns where the absorption coefficient (A) is about 1000 cm-1. For the transmission in liquid water (T), we have
T = exp(-A*L)
where L is the depth of penetration. For the case where 1/e or 27% of the incident photons remain unabsorbed and with A=1000 cm-1, then L= 1/1000 cm = 0.01 mm. 98% of the incident photons will be absorbed within 3 times this distance. So one can see from the figure, than practically no infrared photons penetrate beyond 0.03 mm. A more precise estimate of A is 5000 cm-1 at 15 microns where carbon dioxide is emitting radiation, so 0.006 mm is a more accurate number for the depth of penetration of 98% of the photons arising from carbon dioxide forcing. Since the liquid water is such an effective absorber, it is a very effective emitter as well. The water will not heat up, it will just redirect the energy back up to the atmosphere much like a mirror, but not exactly a mirror, and this is an important point.
For A = 5000 cm-1 at 15 microns, the implied water emissivity is 0.9998 implying that of the incident radiation only 0.02% of it will ultimately be absorbed in the water. The emitted radiation will closely follow a blackbody emission curve whereas the incident flux from carbon dioxide is confined to a band centered at 15 microns. The implication of this is that much of the radiation emitted will escape directly to space through the IR windows, so it could be viewed as a negative feedback. Alternatively, this mechanism implies that climate will be less sensitive to greenhouse gas warming than it would be to an equal solar radiation forcing. In addition, there are many moist areas over land, so this negative feedback or reduction in climate sensitivity may also be operable over portions of the continents.
The above mechanism works because the initially absorbed infrared energy cannot be transferred to the ocean depths by conduction (too slow), by convection (too small an absorption layer compared to the size of convective cells), or by radiation (too opaque). It must escape by the fastest way possible meaning upwards radiation away from the water.
Consequently, the only way to explain the ocean heating in depth is for the solar radiation to change and decreasing clouds, as measured by ISCCP, indicate increasing solar radiation is occurring right where the ocean heating is reported to be occurring. The Willis paper does not even mention the ISCCP data that has a similar geographic distribution to the water warming. Simply put, where clouds decrease in amount, the water warms. It has nothing to do with carbon dioxide. A handy plot of the ISCCP results can be found as Figure 3 at http://www.worldclimatereport.com/index.php/2006/01/11/jumping-to-conclusions-frogs-global-warming-and-nature/ where clouds are shown to decrease for 1987-2000. In the Willis paper, Figure 4b, covering 1992-2003, is the one that should be compared to Figure 3. Although the dates do not exactly overlap, the spatial patterns are very similar. There is a need to plot both variables over the exact same time interval, but it is unlikely it would change the major conclusions presented here. Clouds have large natural variations going up and down entirely independent of any greenhouse effect. The climate models do not predict these variations and apparently Willis and others are unaware of these variations.
[Response: The idea that ocean warming can only occur by SW radiation is erroneous. While SW does penetrate further into the interior, fluxes at the surface (which include sensible and latent heat as well downwelling long-wave) affect the mixed layer equally. The mixing of the upper ocean (to produce the ‘mixed’ layer) is dominated by the wind (with some buoyancy related effects) and serves to mix surface fluxes of both heat and freshwater over the mixed layer in it’s entirety. Clouds both influence and react to sea surface temperatures and correlations between SST and clouds would be expected. The fact remains that the oceans have been warming at a rate of at least 0.6 W/m2 over the last ten years, demonstrating clearly that the planet is out of energy equilibrium - as the climate models suggest. -gavin]
26 January 2006 at 11:14 AM
In #51, Tom Rees wrote: …
Posts which I already made earlier this morning in reply to Coby and JohnnyBGoode were counter to the comments which Tom Rees made in #51, thus there is no need for me to reply that I can see now.
26 January 2006 at 12:10 PM
Re sunspots — aren’t sunspots COOLER than the rest of the Sun’s surface, since the magnetic field strength is greater in a sunspot and the “molecular” (ion) motions accordingly less random? Please correct me if I’m wrong.
[Response:Yes. However,that is balanced by the surrounding faculae which are more bright than the sunspots are dark. See some of Judith Lean’s papers for details. - gavin]
26 January 2006 at 12:18 PM
Gavin,
One hardly knows where to begin replying to your confused comments in #54. The heating of the ocean will be dominated by solar radiation and lead to the creation of a mixed layer. The mixed layer does not cause the heating.
Much of the reported ocean warming occurs in areas where there is little or no wind. How could downwelling infrared radiation heat the ocean in such circumstances? In your world view, it could not.
Your worst mistake is to assume a slow moving mixed layer is a better transport of heat than infrared radiation. The 15 micron radiation is absorbed in a layer much thinner than a human hair. It will escape from that layer by the most efficient means possible, meaning predominantly radiation upwards back to space.
You really need to think the problem through and it is clear that you haven’t.
[Response: The confusion is all yours. Solar radiation on it’s own is stabilising and would not lead to mixing at all. Even in the climatological average, LW heating is dominant over SW. If such large values of downwelling LW were all being absorbed and re-radiated at the skin layer, the skin SST would be tens of degrees warmer than the mixed layer value. As it is, the differences are around 0.5 deg C at max. The physics of that skin layer can only be explained with significant mixing down into bulk ocean. I suggest you read some of the relevant papers (wick et al, for instance). Your claim that warming occurs in regions with no wind (and presumably no mixed layer?) is completely unfounded. The southern oceans for instance (Gille et al, 2002)? Plenty of wind there! - gavin]
26 January 2006 at 12:53 PM
#53
Not only have you been unable to support your claim, but now you claim to be an authority of some sort and jump to a different subject about rivers. Your claim that it isn’t difficult to differentiate between solar driven and GHG driven warming shows a lack of understanding of the complexities of this subject.
The Shindell paper points to early 20th century warming being driven by solar forcing and it does make the case that the last 3 decades of warming agree with models of GHG driven warming. This is based on models of forcings and their correlation with observed global temperature trends. What the Shindell paper does not do is show the dust bowl of the 1930’s or Twin Cities dewpoints are in any way related to or a sign of specific causes of climate change. Such regional changes do not even provide an accurate picture of global climate and definitely do not point to a specific driver of global climate change.
Perhaps Gavin could explain this from his science based perspective before people read your comments and wrongly assume that regional weather and/or regional climate is actually an accurate indicator of the drivers behind global climate change.
26 January 2006 at 1:13 PM
In #58 JohnnyBGoode wrote: “What the Shindell paper does not do is show the dust bowl of the 1930’s” …
JohnnyBGoode,
There were no human satellites to even estimate the amount of clear skies and solar radiation over the ocean in the early 1930s. I know from personal observations of lake ice that a clear sky with no snowcover on area lakes can weaken the ice a great deal, even during periods when the air temperature is below freezing. Such was the case in Minnesota and Wisconsin during a recent winter. Lots of snowmobiles, pickups and SUVs went through the ice that year who were not aware of the penetration of solar radiation through clear ice can do to the ice.
26 January 2006 at 1:19 PM
Sorry, Gavin, but your arguments are not convincing. For one thing, turbulence is damped close to the surface so any heating of the upper 6 microns cannot be carried lower by turbulence. Conduction cannot compete with radiation in transferring heat out the 6 micron layer. The reason that layer does not heat up is because it is efficiently radiated away. I am not talking about perturbations to the downward longwave radiation over the entire thermal IR spectrum. In that case, perhaps some of your points would have some merit. I am talking about a perturbation in the 15 micron band of the spectrum caused by carbon dioxide. A narrowband perturbation to the downward longwave radiation will be damped as I have pointed out in #54, whereas a broadband perturbation would not be damped. I think all your references are referring to broadband perturbations.
This will be my last post on this subject.
26 January 2006 at 1:51 PM
Hi Pat,
It does not bother me to disagree on the main points we were discussing. I did want to note the following:
Climate - The average of weather over at least a 30-year period. Note that the climate taken over different periods of time (30 years, 1000 years) may be different. The old saying is climate is what we expect and weather is what we get.
This is from here, a part of the NOAA site you referenced above. You undoubtably have good reason to have come away with the impression they use a shorter term working definition, but at least officially 30 years seems to be the time frame.
26 January 2006 at 2:43 PM
More household science, a bit closer to topic. Water vapor really doesn’t stay in the air very long, expecially in cold times; we have to keep refilling our humidifier. Fried fish smell, however, will last for days, long after the steamy effect has ceased (this goes beyond CO2, but that’s as close as I could come, just using bodily senses to estimate effects).
Another argument (gun-lovers will love), “Guns don’t kill people; people kill people.” Water vapor does not heat the earth (by itself), but the heating that increases the WV heats the earth, & gets WV to help out. The warming causes more retention of water vapor. As we know from my above experiences, that water vapor is constantly vanishing (not into thin air, but back into the solid & liquid environment, I suppose), being replaced by more vapor. I think they refer to it as the hydrological cycle. This is quite natural, & we wouldn’t expect any net increased warming from that.
So we have to look at what is causing increased water vapor in the atmosphere. Who’s pulling the trigger on the gun? Must be the warming. But if it were only warming from the WV effect, then I’d be able to cook without a heat source — just let the steam effect feedback into heating up my pot.
So now we’re back to either it’s CO2 (& other forcing GHGs), the sun, or Godzilla who’s heating up the planet.
26 January 2006 at 3:26 PM
Lynn,
I think I made it pretty obvious (in #31) that the heating up of the planet in recent decades is due to CO2 accumulation in the atmosphere from fossil fuel burning, not the sun. I think Godzilla should be ruled out too.
Regarding a #58 by JohnnynotBGoode,
One should note that annual temperatures in Oregon were warmest of record at climate stations in 1934. Thus, dust bowl heat in 1934 extended from the Great Lakes to the west coast, and perhaps out to sea, - a very large “region”.
http://pg.photos.yahoo.com/ph/patneuman2000/my_photos
26 January 2006 at 4:57 PM
Pat (#63), yes, the scientists tell us there has not been any overall increase in solar output, so for now it cannot be blamed for the earth’s warming.
However, I have to thank the denialists for drawing our attention to the sun as possible source of heating. I suppose solar output could increase in the future and add to our warming woes. Which means we should redouble our efforts to reduce our GHGs (even more than we might need to for AGW) to be on the safe side, just in case the sun starts contributing more heat. Afterall, we can’t do much to turn down solar radiation.
I’m sure denialists would agree with that - the sun can be a very dangerous thing, be prepared, do what we can do…
26 January 2006 at 6:03 PM
Lynn, I think you’ve been found out - surely a contrarian stooge.
26 January 2006 at 7:03 PM
Coby,
I hope you will forgive the mistake I made in one of my earlier post where I called you Colby instead of Coby. I’m originally from near Green Bay, Wisconsin.
In #61 you wrote … “Climate - The average of weather over at least a 30-year period”…
In a post to Pittsburgh IndyMedia Center titled “Winter not coming” I show a plot of annual temperatures at Minneapolis from 1960 to 2005, and a discussion of a change (increase) in the 30 year average or “normal” annual temperature at Minneapolis as the calendar went to the next decade in year 2000. The increase went from an annual temperature of 44.7 F to about 45.3 F, reflecting the average for the latest 30 year period increasing about 0.6 F. Do you want to comment on that?
However, the main purpose of my Jan 19 post to Pittsburgh IndyMedia Center was to show that annual temperatures at Minneapolis have been above “normal” since 1997. In looking at the right side of the plot at the link below, it really looks strange to me. I’ve notice the same pattern at other stations in the Upper Midwest and Great Plains, showing that what used to be fluctuation about the 10 year trend line is recently showing all at or above it. It also appears that the variance about the mean in recent decades has been decreasing, but I doubt that will continue beyond the next El Nino year (ouch).
http://pittsburgh.indymedia.org/news/2006/01/22241.php
26 January 2006 at 7:39 PM
No problem about the name, Pat, I’ve been called Corby, Toby, Colby, Cody, Cory and even Doby not to mention the numerous phonetically correct mispellings! (Ok, “Doby” was by a 3-yr old, it was very cute
But it takes more than that to get under my skin.
Your indymedia post does raise an interesting point about redefining normal. I have thought about that often listening to weather reports about “N degrees above/below normal today”. I imagine that it is standard practice at all weather bureaus to update the benchmark averages in the face of long term trends. It should perhpas be local news when such an adjustment is made. Surely there is a risk that these long term changes are then forgotten when normality is just redefined, then again we have to put the stick in the sand somewhere!
What should continue to alert people are the record breaking events. It is a tempting mistake to think that given a steady climate, we should expect to see on average a steady rate of extremes recorded. But actually, every time a new extreme hot or cold is recorded this should reduce the probability of that record being broken again in any given year. Eventually, a record high or low would be extremely rare.
I don’t know if there have been any studies of the rate of occurence of extremes but this would be an interesting and possibly informative exercise. It would not be surprising though if there is too much uncertainty in individual measurements to draw any conclusions.
26 January 2006 at 8:07 PM
Coby - “I imagine that it is standard practice at all weather bureaus to update the benchmark averages in the face of long term trends.”
Indeed it is. See for example http://www.metoffice.gov.uk/climate/uk/averages/index.html where they state as such, and also have 1961-1990 and 1971-2000 averages to compare [no difference maps though!].
As to your final point, I believe that there was an earlier RealClimate post which touched on the subject of extremes in timeseries data.
Yes - found it! http://www.realclimate.org/index.php?p=175#more-175
An interesting read.
26 January 2006 at 8:17 PM
#59 #63 Pat Neuman
You jump from topic to topic but never address the points. This isn’t a contest to see who can submit the most comments to RealClimate.
We all realize that you can’t back up the claim that it isn’t difficult to see the difference between warming from solar and GHGs. You can’t because it’s simply not true. If it wasn’t difficult you could easily provide scientific references instead of jumping from Oregon weather to no satellites in the 1930’s to SUV’s breaking through the ice in the upper Midwest.
This topic is complex enough without you making such such unfounded and unsupportable claims.
26 January 2006 at 9:44 PM
This is for Mr. Mann…..The Fox News “Science Reporter” has been exposed for taking $95,000 from big tobacco, while writing attacks on second hand smokings effects. I believe he was used in the attacks on Mr. Mann. Was he getting checks from big oil too? Here’s the link:
click here
26 January 2006 at 10:04 PM
re #69
Johnny,
It is not difficult for me to see the difference between climate warming from solar and GHGs, as I explained in post #31 and subsequent posts today (all in reply to posts by others - not “a contest to see who can submit the most comments to RealClimate” as you said). It’s like many other things which people do and become good at… after awhile a person develops a knack for what to look for to get the right answer, like putting a 500 piece puzzle together (which I’m no good at because I don’t do 500 puzzles). On the other hand, because I’ve done a lot of looking at what happens in hydrology, my track record on flood predictions has been very good (some have said “almost uncanny”).
26 January 2006 at 10:31 PM
I was hoping that somebody could tell me the answer to this question:-
If humans had all dropped dead from a disease 300 years ago then what would be the current climate trend according to the best climate models? Would things be cooling down or warming up or staying static?
27 January 2006 at 12:28 AM
Re 71
You can see some model hindcasts of the 20th century here: http://www.grida.no/climate/ipcc_tar/wg1/figspm-4.htm - both with and without anthropogenic forcings.
They seem to agree that things would have cooled very slightly.
27 January 2006 at 1:48 AM
re #64 - Lynn and Pat,
NASA reports show that the Sun is indeed “warmer” than in the past:
http://aom.giss.nasa.gov/srsun.html
It is very difficult to overlook this. A slight imbalance in Solar insolation could easily cause a +ve temperature gradient.
Compare that diagram to the “CO2 as cause of warming” theory.
To give you a visual perspective, the monitor you are reading this web-site on, is probably set to 1280×1024 which is a bit over 1 million pixels. CO2 is measured at around 330 parts per million, lets scale it up a bit to 400 ppm, since there are > 1m pixels.
If drawn side by side they would make a line less than a third of the way across one scan line of the display.
Scattered about the display you would be hard pressed to notice them.
Faced with this simple logic is it so difficult to see that people would hold contrary views, without needing to label them “denialists” ?
thanks
Robert
27 January 2006 at 4:03 AM
Robert, it’s good to know we have nothing to worry about from bird flu since we are so very much larger (by a much bigger factor than your example) than those pesky little virii. Also, we don’t have to sweat the Iranians getting their hands on a few dozen kilos of highly enriched uranium, since after all such a comparatively tiny amount of material couldn’t make much of an explosion.
Speaking of proportions, you should perhaps have a look at the scale on the left side of the chart you linked. Also, note that the modern era of direct insolation measurements, roughly since 1950, is pretty flat even on that exaggerated scale, which is to say other forcings have been dominant.
27 January 2006 at 6:52 AM
Going back to the very first post in this thread, my layman conclusions on the oft-cited calculations that were rebutted there would be as follows:
a) The anthropogenic contribution to the current amount of the trace gas CO2 in the atmosphere is not a mere 3% but rather around 30%.
b) H2O is another, much more abundant, greenhouse element in the atmosphere. But its relative contribution to the greenhouse effect is not as big as that of CO2, and its total contribution does not reach 95% but, at most, 85%.
c) In the current conditions a better calculation of the global temperature increase due to the anthropogenic portion of atmospheric CO2 could be estimated at around 0.99 °C (3% of 33°C), instead of 0.036 ºC.
d) There is still scientific discussion on the dimensions and even on the net sign of the other greenhouse elements feedback following the increased CO2 atmospheric concentration but the surface temperature records of the last 3 decades are not inconsistent with a net positive feedback that could be enhanced as the CO2 concentration continues to rise.
Would everyone agree on these conclusions?
[Response: Not b). Water vapour and clouds absorb more than CO2, just not as much as the quote claimed. -gavin]
27 January 2006 at 6:54 AM
Robert: “A slight imbalance in Solar insolation could easily cause a +ve temperature gradient.”
Indeed. The max change in solar imbalance implied by that graph is ~ 3 Wm^2. This is comparable to the radiative forcing for all GHG [CO2+CH4, etc] to date and is less than the ~4 Wm^2 figure for doubling of CO2 alone.
I don’t understand why you think the forcing from the sun would be more important than the larger forcing from GHG. The most important difference that I can see is that we can do something about the forcing from GHG, whereas we have not yet mastered control of the sun [although if we really wanted to we could try putting up some kind of parasol to reduce incident solar insolation].
It’s also worth bearing in mind that the figure you quote has no estimate of the error. There are other historical reconstructions of solar output and they don’t agree.
I find the contrast with the error estimates given with the much-maligned Mann et al (1999) temperature reconstruction for the past 1000 years [aka “Hockey Stick”] to be quite marked.
Where does all the sceptics scepticism go when they are faced with data that agrees with their pre-conceived notion that humans aren’t affecting the climate?
[Response: Note that the forcing from solar needs to be adjusted (for the albedo and geometry) to be comparable to the forcing from GHGs. So for an insolation change of 3 W/m2, the forcing is 3*0.7/4 = ~0.5 W/m2 - much smaller than GHGs (2.4 W/m2 and counting). - gavin]
27 January 2006 at 10:58 AM
Just a rather short comment on absorption depth. Evidently the argument that Douglas Hoyt uses has been popularized recently, at least I have seen it a couple of times in the last few days, however, in detail it is wrong.
The calculation is based on Beer’s law, ln(I/Io) = -sigma N L or, if you prefer the decimal version log10(I/Io) = -A L, where A is the absorbance, and L the length (If you are interested in the first version you understand what N and sigma are, they are related to A fairly simply). The problem with, what I believe originated with Fred Singer, is that when the wavelength of the light exceeds 1/A, Beers law does not work anymore and the situation must be analyzed using Maxwell’s laws. That is the case Hoyt discusses. OTOH, the actual absorption depth even taking this into account, is pretty short, maybe 0.05-0.10 mm at most.
27 January 2006 at 2:15 PM
GISS records show the slow cooling of the South pole since 1957. The extent of Antarctic ice in Dec 1914 is detailed in the book “South” by Ernest Shackleton(1919) recently republished (2000). The extent of antarctic ice today can be found at
https://www.fnmoc.navy.mil/products/SATELLITE/US058SCOM-IMGatp.SPOLE_IC_PS.gif
Data for Nansen I found with aGoogle search for “fridtjof nansen 1893″The extent of Arctic ice can be found at
https://www.fnmoc.navy.mil/products/SATELLITE/US058SCOM-IMGatp.NPOLE_IC_PS.gif
Nansen and Shackleton were not just sailors.There were many sailors sailing the polar regions (mainly south) every year hunting whales, no doubt there were many reports from same but they are not being investigated by climatologists.
27 January 2006 at 2:40 PM
Eli Rabett — thank you for the detail, and possible source for the ideas in the absorbtion argument.
27 January 2006 at 3:24 PM
RE the warming ocean. I interrupt the angels on pinhead counting to bring you this news from http://www.climateark.org/articles/reader.asp?linkid=51405
“Earth could warm up fast
Recent studies of some of nature’s environmental “records” show that global warming can penetrate deep into the ocean faster than scientists have realized. In fact, some such penetration may have already begun…
Geophysicists call the event the Paleocene/Eocene Thermal Maximum. Several degrees of global warming caused major changes in global ocean circulation patterns. This, in turn, brought warm water into normally frigid deep sea depths. It was accompanied by mass extinctions of bottom-dwelling marine life, according to the fossil record. This massive climate change happened in less than 5,000 years. However, Drs. Nunes and Norris point out that it may have happened even more quickly.
Commenting on this in the Scripps announcement, Nunes said that the key finding is that “the Earth is a system that can change very rapidly.” The climate change involved a substantial rise in greenhouse gases such as carbon dioxide and methane. Although there was no human input, this is another example of the important role such gases play in climate change…
There does seem to have been a massive release of methane from the sea bed when warming thawed out frozen methane reservoirs there. This is a hazard in our own time. In the announcement of his group’s findings, Dr. Field said that “changes since the 1970s have been particularly unusual and show that ocean ecosystems in the northeastern Pacific have passed some threshold of natural variability.” “
27 January 2006 at 3:34 PM
re #79
I’m all for getting data from as many places as possible. I am however, always surprised that the same people who (rightly) wonder about the certainty of the long-term sea surface temperature records because they are based on ship readings for the pre-satellite era will in the same breath point to 100 year old testimonials of polar ice extent.
Look, sometimes you have to take a step back and look at the whole picture. Are you really trying to say the world is not warming? Are you balancing modern satellite readings, 145 years of direct measurements, borehole analysis, well documented studies of sea ice over the last decades, ocean temperature studies etc, balancing all that against anecdotal accounts of sea ice in specific regions in specific years and concluding that the real trend is cooling?
Is that what you have learned that caused you to go from being convinced of AGW to being a sceptic?
27 January 2006 at 3:46 PM
Robert (#74), I wouldn’t call people who speak of increased solar radiation causing warming as “denialists,” only those who do not think our human emitted GHGs can also cause warming. That is, they “deny” that our human emitted GHGs are causing or can cause warming, so the label would be accurate. And they would be “contrarian” in that they go against the bulk of science on this.
Now let’s hope that somehow the denialists & contrarians are right, the Galileos of our time, because the converse is really quite serious and dangerous. Maybe we’ll all wake up from a bad dream somehow.
Meanwhile, I’m doing what I can to reduce GHGs, just in case the bulk of scientist happen to be right. In fact, I think they might even be wrong in underestimating the dangers that may lurk ahead, as my previous post suggests scientists didn’t know just how rapidly the oceans can warm.
27 January 2006 at 5:18 PM
There are several issues here. First, it can not be a good thing changing considerably the atmospheric content of CO2 so we should do everything to cut emissions. Second, it’s clear now that temperatures are indeed rising. Third, GH models are the only thing that we do really understand, and they do reproduce some major aspects of Earth’s climate, although there are issues with things like cloud cover that I think are mostly empirically put in models (am I right?). Fourth, people here think that the only issue about the Sun is sunspot number and total energy output. In fact the issue is most likely galactic cosmic ray (GCR) flux, which depends on solar acivity (less GCR during solar maximum) and might have something to do with cloud cover. But solar activity (sunspot number) is not the whole story, the tilt of the sun’s magnetic neutral line affects also the GCR reaching the atmosphere during solar minimum. GCR flux seems to correlate well with the increase in temperature but it may be an accident, people are still trying to find a causal physical mechanism. So pelase do not dismiss the Sun based on sunspot numbers. Unfortunately we probably need another full solar cycle to understand how the Sun affects the climate. The problem is that a solar cycle is 22 years long.
By the way, these things about the warmest year on record and such always puzzle me. How do we average temperatures for the atmosphere globally? I understand that one can average heat content which depends on local temperature but also on the level of water vapor. How does the average temperature relate with the total heat content of the atmosphere?
27 January 2006 at 5:22 PM
#71 Pat Neuman
Ok, thanks for the explanation. [rest of comment removed]
[Response:Please keep comments constructive and focused. -gavin]
27 January 2006 at 5:46 PM
#85 Gavin’s response
OK Gavin, could you please explain why Mr. Neuman can make such absurd claims without you ever stepping in?
Let’s be realistic sir, such comments do more to make this topic look foolish than any contrarian ever could, yet you remain silent. Why?
And wouldn’t a contrarian who claimed to be able to tell warming was by solar forcing be quickly corrected, if not completely censored? And yet Mr. Neuman’s unfounded opposite claim goes unchallenged?
I’m sure this comment will also be removed/censored, but at least as you delete it realize that such a biased treatment of comments is noticed by the public at large reading your blog.
[Response: My editing was a function of your tone, not your content. Feel free to crticise Pat or anyone else, but do it in constructive ways and leave the sarcasm at home. -gavin]
27 January 2006 at 6:55 PM
Johnny,
I think I have supported my claims (in earlier comments and in #31. ref: … ” temperature plots for AK, the Upper Midwest and the U.S. Northwest at: http://pg.photos.yahoo.com/ph/patneuman2000/my_photos
Re your #58, where your wrote: …”now you claim to be an authority of some sort and jump to a different subject about rivers”. …
Johnny, I have extensive experience in modeling and prediction of river flows and levels in the Upper Midwest (29 years and six months), and I have a master of science degree from the University of Wisconsin, Madison campus, in hydrology and water resources. I paid my own way through college, and I did not depend on government money until accepting a position in river forecasting in 1976.
In my understanding, accurate and timely prediction of river flows and levels is done not with physics and math alone, but also with developed understanding and judgment which is acquired by one’s self, and can not be passed on to others by seminars and training, particularly if those wishing to acquire similar operational expertise in hydrology have had little background or have little interest in hydrology. I think the same holds true for understanding climate change. A person must have a will to observe the details which can hide the relationships that are driving climate change. It is not any easier for me to explain how I am able to differentiate between solar driven and GHG driven warming, than it is for me to explain and teach another how I am able to make accurate operational flood predictions. Understanding and judgment need to be acquired by one’s self, in my view.
27 January 2006 at 7:41 PM
To Pat Neuman and others with similar convictions.
I am a hydrogeologist (which includes surface water hydrology). I am experienced in 3D computer modelling (of groundwater flow) and am fully aware that ‘modelling’, while highly useful for understanding the world, can never represent a ‘proof’ - as it is so highly dependent on assumptions. I detest GW Bush and everything he stands for. I believe strongly in protecting the environment (One-car family, with a diesel rather than petrol/gasoline car, recycling most of our waste, etc, and detest SUVs in urban settings). What I request is that you (and others) do not fall into the trap of assuming that those who do not agree with you are either indifferent to environmental protection or in the pay of the ‘right wing oil producers’. My principal concern is that ’science’ is not distorted by ‘opinion’ or political agenda. Whatever YOU may believe, there remain many who are unconvinced by the case for AGW. I do not have a closed mind which is why I read this site.
28 January 2006 at 2:57 AM
In post #74 it was noted that if 400ppm were viewed on a computer monitor with a million pixels it would be hard to detect on the screen. Please note that the number of molecules in a cubic centimeter of a gas under standard conditions is N = (60.62 ± .03) x 10 to the 22nd power. That is 606200 million million million molecules. There are a lot of molecules of CO2 in that cubic centimeter of air at the ~370 ppmv we have now. So much so that at even 280 ppmv it is observed that the atmosphere is already opaque to outgoing infrared radiation - at the wavelength CO2 absorbs it.
The CO2 molecule absorbs (and reradiates) infrared radiation at the 15 micron wavelength (700 cycles/cm frequency) bend absorption band most effectively. This band is saturated. Most of the infrared radiation from Earth at this wavelength is retained by the atmosphere and ultimately reradiated toward the ground. The question regarding CO2 then is how does an increase in CO2 add to the heat retained by the atmosphere?
The answer is that IR absorption can still occur at the edges of the 700 cycles/cm bend absorption band.
See: http://geosci.uchicago.edu/~archer/PS134/ps134_notes.ch3.pdf
The absorption of infrared radiation in the wings of the 700 cycles/cm bend band by a doubling of CO2 from 280 ppmv is thus calculated to go up proportionately to the log of the CO2 concentration. This gives us a small number of degrees centigrade elevation in atmospheric temperature - 2º to 5ºC for a doubling of CO2.
28 January 2006 at 6:06 AM
There are many records of ice extent especially in the Antarctic from whalers (who went there every year} as well as explorers suuch as Shackleton, Nansen. Bruce, Filchner .Amundsen,etc.
For a description of the pack ice extent in 1914 read “South” by Shackleton (1919) republished in 2000.
For Nansen and the others I did Google searches. Pesent day ice extent can be found at https://www.fnmoc.navy.mil/products/SATELLITE/US058SCOM-IMGatp.NPOLE_IC_PS.gif
https://www.fnmoc.navy.mil/products/SATELLITE/US058SCOM-IMGatp.SPOLE_IC_PS.gif
Tre record of the South polar temp can be found at GISS
As a child my favourite light reading was polar exploration nowadays it is archeology. The archeology of Greenland indicates that Vikings were livestock and cereal farming in the 12th century about the 80th parallel.
You say that must have been a local effect but my historical knowledge of Europe Asia and South and Central America indicates otherwise.
In Australia if you compare temps listed in GISS as rural sites with those at populated sites you can easily infer that the Urban Heat Effect has not been accounted for.
For the UHI in Alaska see
http://www.geography.uc.edu/~kenhinke/uhi/
28 January 2006 at 8:13 AM
PHEaston,
I think it’s good that you shared that information with the group (in #88). Outside from this group, my principal concern is the life of young people, especially those trying to make decisions on whether or not to have children. I don’t want to see people be hurt or feel guilty for having brought a loved one into t