by Eric Grimsrud
In my first Post called “1. A Common Sense View of AGW”, I presented a simple qualitative view of the AGW problem in order to relate the essence of what the debate is primarily about. In this Post 6, we will move on to consider some basic quantitative aspects of AGW. In this section, we will be searching, in particular, for good expressions for what’s called the temperature “Sensitivity” for CO2. That number indicates the increase in average global temperature that would be caused by a doubling of its concentration. To better appreciate the immediate importance of this number, recall this. Atmospheric CO2 was at 280 prior to the Industrial Revolution. It is now 392 and rising at a rate of 2 ppm per year. Therefore, a “business as usual” course will lead to a doubling CO2 within the current century (by about 2094).
If the quantitative expression for CO2’s sensitivity is only say about 0.2 degree C, as is claimed, for example, by H. Leighton Steward in his book Fire, Ice, and Paradise, page 23, then we could indeed conclude that AGW does not pose a problem of such great immediate concern. If CO2 sensitivity is much higher, however, then we have to be very concerned about this issue and that level of concern should be in proportion to the actual value of CO2’s Sensitivity.
So what is the best way to determine or at least get a good estimate of the Sensitivity of CO2. This is being done by model calculations using huge computers to “simulate” the entire Earth. I will not be using the results of those studies here, however, because there is a much more reliable way to determine Sensitivity and that is by looking at the historical record. Even the computer modelers acknowledge this and, in fact, use that historical record to test their models. After all, the real world acts in accordance with the effects of all of the relevant variables – whether we are aware of all of them or not. So I will be taking the advice here of one of America’s most popular philosophers, a man named Yogi Berra, who is reported to have said “predictions are hard to make, especially about the future!” and “a person can observe a lot just by watching!” So let’s now do some “watching”.
In this post, we will be focusing on the “Last Major Ice Age” in which we all presently live and which began about 35 million years ago. While I understand that there have been about four previous Major Ice Ages hundreds of millions of years previously, we know much more, of course about the most recent one and have a great deal of information concerning it, as we will see.
First, let me introduce you to a single reference that I will be making extensive use of here. This reference is a paper entitled “Target Atmospheric CO2” by Hansen et al. published in The Open Atmospheric Science Journal, in 2008, volume 2, pages 217-231. This journal is available to the public and this article can be retrieved from the internet at http://www.bentham.org/open/toascj/openaccess2.htm. Use of this reference is also appropriate here because it summarizes great deal of relevant literature while providing new information and insights. In addition, a separate and even more extensive article entitled “Supplemental Material” is provided with it. In my many years of teaching, I have found it to be essential for the students to have materials from which they themselves can read and interpret the data and figures I use in the classroom. My use of this reference here will serve that purpose. At the same time, of course, all of the literature is important and will be referred to as needed. Careful considerations of this one paper, however will get us quite a ways down the road initially.
First, in order to see where the Last Major Ice Age occurred in time, please have a look at Figure 1 (all figures, unless indicated otherwise, come from the reference cited about).
Figure 1. This graph shows the temperature of the Deep Ocean over the last 65 Million years before present (My BP). (These determinations were made by the isotopic analysis of the oxygen atoms found in the CaCO3 remains of foraminifera shells found in ocean bottom core samples. Please see Hansen et al. for the details of this widely used procedure). The period of the Late Major Ice Age in indicated by the blue line beginning at about 35 My BP. Note that temperatures are shown a variations relative to the present time.
We will come back to and use this figure in future discussions, but for now will use it to gain some temporal perspective on the Last Major Ice Age. First, note the temperature rise that occurred right after the extinction of the dinosaurs, about 65 My ago. This initial rise before 50 My BP is thought to have been caused by the continental shifts at the Asia-India interface and associated volcano activity causing CO2 to increase to approximate 1500 ppm. After 50 My BP a slow and steady temperature decrease began. Until 35 My ago the world was ice free with a sea level of about 70 meters above the present level in 35 My BP and about 200 meters in 50 My BP (due to thermal expansion at high temperatures).
The blue line starting at 35 My PB, indicates temperatures after ice began to build up on our planet, first on Antarctica and then on Greenland and then of the other continents. The world had thereby entered the Last Major Ice Age. At the very right side of the graph temperature is shown over the last few (2 or 3) million years during which ice formation was often extensive over most of the continents, including North America. Note how temperature rose and fell quite remarkably over this most recent period. This latter period includes the cold Glacial and warmer Interglacial Periods of the Last Major Ice Age. Often these glacial periods are referred to as “ice ages” in the literature. In order to avoid the confusion that thereby results, I will refer to them as “glacial periods.”
Now let’s move on the Figure 2 shown below.
Figure 2. These data were obtained from the Ice Core Records, which I’ll assume for the moment that you have heard about. By examination of these ice core samples, it is possible to determine many things including the temperature of Antarctica (and Greenland) over the last 800,000 years and the historic background concentrations of various minor components of the atmosphere. The measurements shown here of temperature and the greenhouse gases, CO2 and CH4, over time serve to illustrate an important point – their high level of reproducibility. Shown here are many measurements made by different scientific groups at different times at different locations in the Antarctic. Similar measurements from Greenland’s ice cores (not shown here) are also in close agreement The ice core records are clearly trying to tell us something about the most recent period of the Last Major Ice Age.
Now let’s move on to Figure 3 where the same sort of data are shown along with some analysis of that data.
Figure 3. (a) Measurement of two major GHG’s and also Sea Level are shown. Sea Levels can be derives by several means (see Hansen et al.) (b) Climate Forcing value have been calculated here from the GHG data and sea level data (Hansen et al. provide a good explanation to the term, Climate Forcing, at the beginning of their article). (c) From the expected Climate Forcing values, expected average global temperatures have been calculated and then compared to measured temperatures. In this case, an estimate of the average global temperature variations have been obtained by dividing the measured Antarctic temperature variations by 2. This is because temperature variations on the Antarctic are typically about twice the observed changes in average global temperature. Note that the fit between the calculated and observed temperature variations thereby obtained is very good.
[A short time out: The term, albedo, means the fraction of incoming solar radiation that is reflected back into space. The present albedo of Earth is about 0.30. During a glacial period, it is about twice that, or about 0.6 0.32 [Edit on 1/4/11]. The temperature of the Earth is primarily determined by three factors. These are sun’s intensity, the greenhouse effect and the Earth’s albedo. All of the many other detailed factors we will be discussing affect temperature by their effect on either the greenhouse effect or the albedo].
Now the reason why the general agreement between the calculated and observed temperatures shown in Figure 3c is so significant here is that this level of agreement can only be obtained using values for CO2 Sensitivity that are very much greater than the negligible level of about 0.2 degree C mentioned at the beginning of this post. The results described here could be explained only with use of a CO2 Sensitivity of about 3 degrees C for “fast feedback” processes and about 6 degrees C if slower surface albedo feedbacks were also included.
Let me explain the fast and slow feedbacks a bit more. As the temperature rises due to any “Forcing Agent” that causes a change relative to the normal, other changes also quickly occur – including increased water vapor and changes in cloud formations. All of these fast changes contribute to the CO2 sensitivity expected in the short term of a few years or a few decades. These changes can also cause slower changes in the albedo of the Earth, however, by causing the melting of sea ice or changes on land such as the conversion of barren snow covered regions to vegetated regions. While all of these factors are complicated and might be beyond our present ability to describe them well in computer simulations, Mother Nature is revealing the magnitudes of their net effects via the ice core samples.
So it appears that Mother Nature is telling us that the Sensitivity of CO2 is somewhere between 3 and 6 degrees C depending on the time span you wish to use. Figure 3b suggests that the Forcing caused by the GHG effects and the albedo effects are approximately equal. The GHG effect acts faster, but with more time, the albedo effect adds to the initial GHG effect thereby doubling the net sensitivity of the GHG’s.
All of this is can be additionally explained by bringing in Milancovitch’s calculations of the Earth’s subtle motions relative to the Sun’s position which became important during the recent glacial and interglacial periods of the Last Ice Age. A summary of this is as follows. As the Earth goes through its subtle variations of distance, tilt and precession as it revolves about the Sun, slight changes in the solar intensity in the both hemispheres occur. What happens in the Northern Hemisphere is most important because of its greater land masses. If the Northern Hemisphere happens to have a worse than average summer, the ice on it tends to grow. If it has a better than average summer, the ice on it tend to retreat. These changes in ice area cause large changes in the Earth’s albedo. In this case, we call this change a “positive feedback” because the albedo change reinforces the initial direction of change. Only after the information of the ice cores started to be revealed in the 1990’s did we realize the calculations of Milancovitch back in the 1920’s where of great importance. Until then, Milancovitch’s Theory was just one of many that awaited testing by measurements.
So the slight motions described above are now thought to initiate a change in global temperature. Then, as expected, both the albedo of the Earth and GHG’s will follow in their expected ways. For example, if that initial orbital change causes some harming, ice will retreat and the albedo will decease – causing more heating by the Sun. At the same time, more GHG’s will be emitted by the oceans as they warm up – causing more increased temperature due to their GHG effect. A lag between the initial increasing temperature and changes in both albedo and GHG concentration is expected. These secondary changes, however, will greatly contribute to the subsequent net warming (the initial forcing of the orbital change is small relative to those of the albedo and GHG changes). For the case of CO2, the ice cores indicate that its delay of change is typically about 800 years, which is small relative to several millennia of accelerated warming that then follows.
Let’s now consider Figure 4.
Figure 4. Most of this graph should now look somewhat familiar to you. Most of it shows the record (over 800 years this time) of temperature measurements via ice core data along with just the Forcings of the GHG changes this time. The GHG forcings have been arbitrarily scaled (for convenience sake) so that they are more easily compared to the observed changes in temperature. In the very right portion of this graph, however, modern changes GHG Forcing is shown on an expanded time scale along with the global temperature (purple line – ignore the black line for now, as we will discuss it extensively in my next post concerning “the Age of Man”)
So what’s to be learned from Figure 4? First, notice how temperature has closely tracked Forcing by the GHG’s for the last 800,000 years. Yes, changes in the GHG’s follow initial temperature change, but temperature also followed subsequent changes in the GHG’s.
Now look at where we are today. During the last century changes in GHG Forcing has gotten ahead of changes in temperature. (Note also that that has never happened before during the 800,000 year record of the ice cores). This lag is due to the heat inertia of the planet (mainly its oceans) and is evident in Figure 4 only because we have used a less coarse time scale for the modern data. At the same time, we know from the long term record shown on the left that temperature will catch ups with GHG Forcing.
If we want to avoid that temperature increase in the upcoming decades the question then is can we bring the GHG Forcing down relatively quickly before temperature catches up. In addition, do we really want to increase the present GHG Forcing with “business as usual” practices? We will hopefully have that discussion soon, if we agree that there is problem here that needs to be addressed.
Looking ahead a bit, some will say that GHG’s forcing is going to come down naturally – possibly by CO2’s transport into the oceans. While the existing literature on that point will offer little hope along those lines, we will consider it and other related aspects in future posts.
The most important point I have tried to make here in this Post 6 is that the Sensitivity of CO2 is somewhere between about 3 and 6 degrees C depending on whether we are talking about a short term (say several decades) or a longer term (say several centuries) period. This deduction has come from direct measurements of the past via the ice core samples. Therefore, it appears that Mother Nature is telling us that CO2 sensitivity is likely to be about 15 to 30 times greater than more comforting, estimate of about 0.2 degrees C offered by Mr. Steward (as described above) via his greatly oversimplified and purely theoretical arguments (they can be seen on the internet at http://www.montanapetroleum.org/assets/PDF/articlesReports/2010-Treasure-State-Journal.pdf).
A General Discussion of the Ancient Atmosphere as Revealed by Figure 1.
In an effort to keep this as brief as possible, I will make just a few comments below that I think will be relevant to future discussions of AGW.
[1] First, note how high T became at about 50 My ago.
A major reason for the increase during the prior 10 Mys is thought to be due to continental shifts occurring at that time. Most importantly, it is thought that the then island continent of India was then moving “rapidly” northward and was crashing into and sliding under the larger continent of Eurasia. The volcanic activity associated with that event is thought to have thrown large quantities of CO2 into the atmosphere over that 10 My period, thereby increasing CO2 levels to about 1500 ppm +/- 500 ppm. (The methods used for both CO2 and temperature are probably same as used for figures shown previously in Temperature and CO2 History. If needed, we can go into those details later).
[2] Then note that a long slow decrease in T occurred until about 35 My ago.
This decrease in T is thought to be accompanied by a decrease in CO2 so that by 35 My ago, the CO2 level is thought to have decrease to about 450 +/- 100 ppm. If that approximately 1000 ppm decrease occurred smoothly over the time span between 50 and 35 My ago, the rate of that change would have been only about 0.0001 ppm per year. This is even slower than the maximum rate of CO2 change observed over the 800,000 year record of the ice cores (about 0.01 ppm) and, of course, is many orders of magnitude smaller than the present rate of change (about 2 ppm).
The major cause of this slow removal of CO2 after 50 My ago is thought to be “weathering” by which the CO2 in raindrops and in the oceans reacts with inorganic matter (rocks) and is slowly converted to solid matter such as limestone, CaCO3. The freshly exposed granite of the Himalayan Mountains (formed by India’s undermining of Asia) is thought to have facilitated this weathering process.
[3] Although both the CO2 and T data is not as accurate as that obtained from the ice cores, we can nevertheless deduce a rough estimate of CO2 Sensitivity from it.
A decrease from 1500 ppm CO to about 450 ppm CO2 between 50 and 35 My ago is equivalent to about 1.7 “halving” (in order words, the reverse would be about 1.7 doublings). Over that period T appears to have changed from about 13 to 5 degrees C relative to the reference T of today – a total change of about 8 degrees C. The temperature being shown here for the Ocean Bottom and the corresponding variations in average global T might be high or lower. Hansen et al. assigned this uncertainty of conversion to be about +/- 50%. Going with the 8 degree value (no conversion factor used), we come up with very rough estimate for CO2 sensitivity of about 5 degrees C with a conservative estimate of the net uncertainly of about +/- 3 degrees C.
Next it is informative to consider what type of CO2 Sensitivity this is. Is it closer the the fastback or slow feedback types discussed previously in our analysis of the ice core data? The answer is clear. During the period between 50 and 35 My ago, the Earth was a “water world” – there was no sheet ice on the planet – as there was increasingly after 35 My ago. Therefore the Sensitivity term we just estimated is of the fast feedback type for which the feedbacks of water vapor and clouds are dominant. There was no ice and its effect on albedo that needs to be consider over this period.
Now note that that the ice core data suggested that the magnitude for the fast feedback sensitivity of CO2 was about 3 degrees C, Thereby being in agreement with the rougher estimate of the same parameter just deduced from T and CO2 changes occurring between 50 and 35 My ago.
[4] The Paleocene-Eocene Thermal Maximum (RETM).
Note the slight peak in T seen in the year 54 My ago. This is called the RETM and is thought to have been caused by a sudden huge burst of methane thrown into the atmosphere at that time. The cause of this is generally thought to be the conversion of solid “methane-hydrates” to gaseous methane which in turn was caused by the increase in ocean bottom T occurring at that time. (Note this form of methane-containing ice is what formed and then caused the pipes to block last summer in attempts to capture the oil and methane escaping from the damaged Gulf Coast well head).
When the CH4 that entered the atmosphere during the RETM, it was oxidized quickly (within a few decades ) to CO2 thereby providing us with a unique and natural “experiment” from which to learn. One thing we learned is that is appears to have taken about 150 millennia in order to remove the excess CO2 that the RETM punched into the atmosphere. This observation is in good agreement with the very long lifetimes for EXTRA CO2 that many modelers presently claim in simulations of this process.
Another point concerning the RETM becomes clear when we consider the fact that the Earth is now literally loaded with methane hydrate deposits in their coastal sea bed. If the oceans at allowed to heat up sufficiently (and we don’t know how high a T this would require) those methane hydrated deposit will release. This event would indeed constitute what is known as a “tipping point”, at least, or even a “point of no return” as generally defined to represent two different levels of distinctly “bad news”.
[5] Speaking of “tipping points”, the major point of Hansen’s et al.’s paper is to show that we have already passed one with 392 ppm CO2 in the atmosphere.
He argues that the Forcing associated with that level of CO2 is moving us in the direction of an ice free world and that level of forcing – even if not raised further increased by business-as-usual putting 2 ppm additional CO2 into the atmosphere every year – has to be reduced “quickly” before the initial effects of sheet ice changes are overcome. More specifically he argues that we have to get down to 350 ppm in order to get safely away from that tipping point. Since Hansen et al. have related all of this in detail in there paper, I will stop there.
As we, “jurors”, can see from the above presentation complied from Hansen et al work, the data are of highly speculative and imprecise character.
To start, no definition of “global temperature” was given, as was expected by many. Now we must deal with new object, “ocean deep temperature”. Again, what is that? Contrary to the pointer, the Hansen article contains no details on this “widely used procedure”, which I suspect is refereed to highly speculative procedure of conversion of oxygen isotope ratio into undefined “global temperature”.
Now, the “Last Major Ice Age”. What is that? It is a customary term in climatology that last major ice ages occurred every 100,000 years, and bout 40,000 before that. The Hansen’s article contains zero occurrences of “Major ice age”. Why do you invent new and potentially confusing terminology?
Then, you promised to use data mostly, and restrain yourself from using models. Yet your charts frequently contain “calculated temperature”, all compared to other calculated “observed temperatures” from ice cores. We all know how accurate is the isotope fractionation map into “global temperature”, and even then you mention a fudge factor of 2X when comparing these speculatively calibrated time series. I am not even asking about accuracy in timing of the events.
Again, even assuming that the isotope data were correctly converted into (still undefined) global temperatures (which is already a logical nonsense), and dissolved gases in ice samples correctly represent ancient air composition (after only year of sitting in storage and decompressing), the allegation of climate “sensitivity” of 3 to 6K/2xCO2 are unfounded. According to the Vostok data for deglaciation episodes, the relationship {CO2=>T} formally produces climate sensitivity of 18 K per 2xCO2 (if we assume the AGW concept as “CO2 is the major driver of climate”).
see:
Vostok
and
Correlation
Modern instrumental records {Mauna Loa CO2 => “Global Average T”} produce “climate sensitivity” of 2.26K per 2xCO2,
(see raw data here )
This is surely a 8-fold discrepancy that needs a serious explanation, not hand-waiving.
To avoid repetition of arguments about “slow feedbacks” and “unknown factors” during several past deglaciations, please visit this funny discussion with few determined climatards.
What the Mother Nature may be telling us is that changes in CO2 have no measurable effect on climate, and {TCO2} relationship just appears as a side effect ocean and biosphere warming (due to yet unnamed other suspects).
I short, I am not disappointed, this is all as expected. The prosecutor’s case against CO2 is completely circumstantial.
Dr. Eric:
As a scientist, certain assumptions are important for me to understand.
Forgive me for my ignorance (I’m not a climatologist), but I am not sure of the degree of sensitivity you (and Hansen, et al) have.
What, for example, was the average global temperature for 2009?
2009. Second warmest year on record. Warmest decade on record – as per NASA.
http://www.nasa.gov/topics/earth/features/temp-analysis-2009.html
Using http://data.giss.nasa.gov/gistemp/tabledata/GLB.Ts+dSST.txt , we get an annual mean of 14.56C.
Hi Al,
Yes, terms can get used differently and that cause confusion. Some are careful to use the last “glacial period’, as I do, rather than the “last ice age”, as many do, when referring to the event that ended only about 15,000 years ago. Since the terms glacial and interglacial generally have only one meaning, I’ll stick to that usage here. As you point out, however, some who refer to the “last ice age” could be referring to two very different periods.
While we often prefer to talk about and compare global average temperatures, unfortunately direct measurements don’t ever come to us that way. Therefore, we also have to use names that indicate where the measurements come from. Thus, names such as “ocean bottom temperatures” or “polar region tempertures” and even “proxy temperatures” appear everywhere in the literature. If I every implied that I could remove this complexity in a prior statement, I certainly would deserve the criticism you dished out. Instead, I should have warned you, I guess, that the science and its communication can be complex.
And what’s that your are suggesting? Discussions of science without models? Do you think our science books should consist of a multitude of facts and no “stories” linking things together? That can’t or at least shouldn’t be done – unless you want your science to be incomprehensible by the human being and boring as can be. In doing research, “theory guides and experiment decides”. In this way good models that explain the result can be identified and used. Only models and not facts suggest cause and effect relationships. Let me write that again === Onlyh models and not facts suggest cause and effect relationships.
More on this point. There are no facts that will ever prove that a hypothesis is true. For example, in a couple hundred years from now, if the entire world has turnd out to be toast, that “observed fact” would not prove a cause and effect relationships such as described by the hypothesis of AGW. By then, the model of AGW will probably still be intact (in spades in fact), but it will still be just a theory. Scientist know this and you should learn the point – that we advance in science by proposing models and by continuously testing them in order to find the best one.
Therefore, you should not be so surprise by finding the word such as “models” or “ocean bottom temperatures” incorporated into discussions concerning science.
Sorry, I can’t help you with your dissappointments any more than that – but I do hope my remarks help. A far worse option for you, of course, is simply to deny the validity of science altogether – as many have done throughout history whenever they don’t like it’s message. I hope you will not become one of that crowd.
@2 John,
Post #6 involves the “forest” of many millions of years. In one of my next posts, I will focus on the Age of Man and the last century in particular. In that post details such as the temperature in 2009 will be related and discussed.
Dear Dr. Eric, I appreciate your concern about my options of being denier of science. I don’t deny science, I deny AGW climatology as being science, and your posts give me plenty of justification for this. Let’s recoup the standing:
(1) You failed to provide definition of your major term, “global average temperature”. Therefore all your subsequent constructions have little to no ground, scientifically speaking. How we can compare something we cannot define and therefore calculate or measure?
(2) You jumped right into criticism of “climate sensitivity” without giving a definition what does it mean. You alluded that the true definition is based on huge computer models that you don’t need to discuss because there is “much more reliable way by looking at the historical record”. You even expanded that “the real world acts in accordance with the effects of all of the relevant variables – whether we are aware of all of them or not.” I could not agree more on that. So, I looked at historical record, Vostok ice core data, and I found that the formal (as I understand it, dT/dC in differential form) sensitivity of global average temperature to change in CO2 is 18K per CO2 doubling. Are you saying that this is the number we should expect when CO2 increases?
(3) You also forgot to introduce the concept of “climate forcing”, especially from GH gases.
(4) You have “corrected” the temperature variations for Antarctic by 2, because of what? Why this crude fudge factor doesn’t concern you, and you declare this fudge as “pretty good fit”? Is this the typical way how climatology “works out” discrepancies in data from different sources? Do you want us to believe that fudge factors as 2X are scientific, especially when your statements are eventually concerned with 0.3% changes in “global average temperature” over the course of 100 years?
(5) Further you are saying that you can achieve this fit only if you assume climate sensitivity to CO2 as 3K to 6K. What were your assumptions about cloud cover during this period of time? As I demonstrated in comment 68@4, 1% change in cloud cover exceeds effects of CO2 variations in ice record, and there is an observational fact that cloud cover did change by many % on decadal scale, and no observations exist for longer scales. I ask again: could you provide records of %% of cloud cover during several ice ages? If not, why should we believe that CO2 is the only suspect?
(6) You said: ” So what’s to be learned from Figure 4? First, notice how temperature has closely tracked Forcing by the GHG’s for the last 800,000 years. Yes, changes in the GHG’s follow initial temperature change, but temperature also follow subsequent changes in the GHG’s.”
No, this is a loaded speculation, we cannot learn this from Fig.4. Alternative and most logical explanation of similarity in two curves is that CO2 is some simple proportional function of T, and no further and more complicated explanation is necessary.
So Dr. Eric, could you please clarify the above points for “jury”?
This has become a farce. I know, I am sure a lot of people who read this blog know, and I am even more sure Dr. Ed knows, that you cannot prove CAGW using the “scientific method”. It wouid appear that Dr. Eric knows this as well. So he has abandoned the IPCC approach, knowing full well that if he tried to defend it, he would lose the argument hands down.
So Dr. Eric has proposed a non-peer reviewed, short treatise, which he claims proves that the climate sensitivity is high. I dont believe it, and I am not going to waste my time looking at it in detail.
Dr. Eric:
I’m sorry I picked a date outside of your discussed range.
How about I rephrase and ask: what is the average global temperature for 1800?
Thank you.
Dr. Eric,
Although this particular topic would ordinarily be of some interest to me (as per my previous posts), the choice of Hansen as a starting point precludes anything resembling a rational discussion. In the first instance, Hansen, by his very own words (see raft of emails obtained by CEI under FOIA) has proven himself to be what many claimed him to be: “The Lysenko of our Times”. Even contemplating the effort it would require to dissemble the many sundry ruminations of such a scoundrel would categorically degrade this to a “pissing match” instead of a discussion of science as we once knew it.
I will leave you, and the readership, to ponder the implications of trotting forth such a “foundation”.
I look forward to the next topic. Let us hope it is as well chosen but decisively better founded.
We witness a strong debate on the correlation of CO2 air concentration and earth surface temperature. However, the cause of that correlation, and the sources of the driving force(s), are at best obscure, not at all settled science. . . I note the role of sea water, and glacial polar ice as well, as a moderator or buffer. From daily experiences with carbonated beverages, the historic method of making champaign (cold winter air temperature allows uncorking of young champaign bottles to dribble out solid residue without loosing any CO2), etc, it is quite clear that it is more probable that temperature rises due to processes other than anthropological releases of CO2 from energy producing activities are instead the driving force. This includes vulcanism heat issuing from the molten planet interior (which I suspect for Venus), and solar energy variation (variation in the “Solar Constant”). winter/summer solar constant variation is indeed due to our seasonal variation of sun-distance, a well established elliptical path in our time. If one postulates that this distance can change monotonically, show me the energy and momentum sources that can affect such! I think there are none. We do have tidal energy dissipation, which acts to slow the rotation of the earth, but this is known to be just some microseconds per year. Axiomatically, if we were spiraling in toward the sun, our years would be getting shorter. In our age of “atomic clocks”, this will be easily detected if it were happening… perhaps microseconds per year? Any volunteer here to bring us up to date on those? …
Precession of the earth’s rotational axis on the sun-earth plane rotation plane: Right now, our axis points near Polaris, but that’s known to be changing at a rate that indicates a 26,000 year total period… But that only determines when our seasons occur. More significant is the migration of the earth rotational pole about the surface; that affects who gets more evenely divided nights vs days, and who gets temperate climates, who gets polar weather. In the first approximation, both these precessions affect the distribution of temperature, not the average temperature.
That leaves the champaign effect to be understood and evaluated. It is clear, to me anyway, that CO2 absorption/emission from the sea, lakes and rivers is an active process day in, day out, summer, winter. “Acid rain” is a highly suspect carrier in this process. So far I have seen only one or two verbal reports (no data) that those few such CO2 meters find variations with altitude and with latitude as well.
Therefore if CO2 concentration meters are in use (pray that some are trotted around daily – as common as thermometers) to give us a diary of how much CO2 is where to tell us where it’s going, then we should have a better understanding of its sources and its sinks.
One should expect that the warm El Ninio High should pick up CO2 from the sea, while air masses stagnated over cold seas should have a lower CO2 concentration. CO2 concentration in winter “Alberta Clippers” carrying Polar Continental air may be somewhere in between; but who knows how well cold glacier ice absorbs CO2? Likely it is just the precipitation (snow) that is the carrier… and that snow fell from air that was previously wrung clean of much moisture and CO2 via acid rain.
Finally there is the cause-and-effect issue to study: Records reviewed here recently indicate that indeed, CO2 concentration increases lag in time behind temperature increases and vice versa. That makes sense where the water bodies are acting as absorbers and emitters.. Where is the correlation function analysis that connects the two?
AND most of all where are the error bars indicating the confidence limits (marking the three band) of a hypothetical temperature rise? May we depend on honest scientists to process and report these variable values and graphs?
To demonstrate the competence of the science in promulgating CO2 behavior, I want to see data (and their error analyses) on CO2 distribution and migration issues (CO2 3D concentration and CO2 migration trails. Is there a CO2 “gulfstream”?
On the basis of as yet unreported error bands (the three sigma ranges of uncertainty), just how reliable is the inference that we are headed for “trouble”? Which of our national wealth, time, taxation and angst must be flung against this “trouble”? When? How much (if any)?
Angelo what does CO2 have to do with acid rain, third paragraph? I thought sulfur dioxide (SO2) and nitrogen oxides (NOx) are the primary causes of acid rain.
@ 9
Henry,
Please reread the prevailing wisdom in previous posts concerning the sources of information to be used here. Ed and many others have declared that the source of information does not matter, only the content of their communications matter. So, on that basis, are you really suggesting that we throw out a paper from a peer-reviewed paper authored by many scientists from many institutions.
Hope we don’t loose you, Henry, for such a silly reason.
@6 Dear Al,
Please reread my Post 6 for two reasons.
One is that I upgraded it a bit to be clearer about some things – including the various terms that can be used for ice ages. Another is that if you try harder you will see that several of you questions were answered in my post. I believe, for example, that I explained what the term, sensitivity, means.
Also the things you say I said about sensitivity in your point 2 are simply made up. I did not, for example, suggest that true sensitivity determinations have anything to do with computer models. In point 2, you say stupid things and then ask me to defends those stupid things.
In responding to the comments of viewers, I don’t want to be bogged down in defending myself again nonsense such as this. So before I do get bogged down in that way, I would like you to kindly reread my post 6, think a bit more about each of your points and then write again.
@7 Jim,
Excuse me, but I am not here to defend what you call “the IPCC Approach” or “the Al Gore Approach” or any approach other than my own. My approach comes from participation in the field of atmospheric science since 1973. This included doing research myself, constant study of the literature and communication with others through teaching and writing scientific papers. I was never on the IPCC committee, and although I respect the work they have done over the years, I am in not position to defend their reports.
Sorry that you misunderstood who I am, but think I understand why. Those that are trying to discredit the science of AGW (and you tell me that they have been successful with you), like to suggest that their “opposition” consists of a United Nation’s agency, called the IPCC, and a former American Democratic politician (who never was a scientist). They tend to not include the Traditional American Communities of Sciences, which constitute the most influential of the world and whose Official Associations have almost uniformly come our with position statements declaring both the reality and urgency of the AGW problem. For your information, I come from that community of scientists.
It is a curious point – that you don’t seem to care what the recognized US community of scientist thinks – on this one specific subject – as if they are corrupt or stupid on it while being honorable and smart on all of the others. I’ll leave you to ponder that one.
Dear Dr. Eric,
I can happily withdraw my point that there was no definition of sensitivity. The definition in fact was given in independent section
http://climateclash.com/definitions/ . I apologise, my bad. However, the rest of my Pragraph(2) is a precise account of your third paragraph, including precise quotation of very long sentences of yours.
Your text is:
“So what is the best way to determine or at least get a good estimate of the Sensitivity of CO2. This is being done by model calculations using huge computers to “simulate” the entire Earth. I will not be using the results of those studies here, however, because there is a much more reliable way to determine Sensitivity and that is by looking at the historical record. Even the computer modelers acknowledge this and, in fact, use that historical record to test their models. After all, the real world acts in accordance with the effects of all of the relevant variables – whether we are aware of all of them or not.”
My account of the above is:
“(2) … You alluded that the true definition is based on huge computer models that you don’t need to discuss because there is “much more reliable way by looking at the historical record”. You even expanded that “the real world acts in accordance with the effects of all of the relevant variables – whether we are aware of all of them or not.” I could not agree more on that. So, I looked at historical record, Vostok ice core data, and I found that the formal (as I understand it, dT/dC in differential form) sensitivity of global average temperature to change in CO2 is 18K per CO2 doubling. Are you saying that this is the number we should expect when CO2 increases?”
Therefore, please kindly point out which “things” did I copy incorrectly, which one I made up, and which ones are “stupid”.
Again, according to the definition you and Dr.Ed agreed upon, http://climateclash.com/definitions/, the global climate sensitivity inferred from Vostok proxies is 18K. How it is a good fit to models and modern instrumental observations?
@9 Dear William (sorry to have called you Henry before).
Some more here concerning your criticism of using the work of Hansen.
Entirely aside from who Hansen is personally (I have never met him but have not read much about him in the police reports), please consider how science works so that it is removed from personality, personal preferences, ect, as much as possible. The only things that matter as what’s reported in the open literature. This material is studied and either duplicated or corrected continuously by others. That it, and as I have said previously, the reason we believe in the laws of gravity today is not because Sir Isaak Newton was a nice guy. It is because his work stood up to the examination of the many others that were able to read about it in the literature. In studying Newton a bit, I have learned that he would be considered to be a bit wakko in some other areas, but that is of no relevance to the question of how good those laws of gravity are.
So, if you can denigrate the reputation of Hansen based on his scientific work, that might be relevant to our discussions here. If you can do that, please let us know where in the literature he has disgraced himself in that way.
If, however, you are the victim of intentional attempts to discredit this American scientist based personal matters and preferences, that is a different matter. Just because you don’t like his message and because you might not like the fact that he is indeed a universally acknowledged leader in this scientific area caries no weight in science and should not in this discussion.
Dear Dr. Eric, I am enjoying this debate and look forward to future posts from both you and Dr. Ed. It does seem presumptous to assume that the pre-industril CO2 level was 270PPM. I recognize that many have accepted that but others, including Nobel Laureates have done sampling over the past 180 years which show a much different picture. I refer you to the works of the late Ernst Beck and A. Jaworowski. Discard that piece of information and the rest of your post is suspect. I also point out that although you were quite enthused about the conclusions regarding Figure #3, there was a significant disconnect in my mind. Forget about the time relationships between the events which are obscured by the large span covered, forget that you must use a factor 2X what has been determined to be be the CO2 sensitivity, and forget that all this happened without the benefit of mankind. You completely ignore all of the other “forcings” that could have played upon the Earth. For example, the magnetic link between the Earth and Sun, which varies significantly even reversing in alternate solar cycles, has been shown to affect cloud cover. As mentioned above that is significant. You show no regard for the epitrochoid orbit of the Sun caused by the motion of the Jovian planets which has excellent correlation with Earth’s climate. (I know correlation is not causation but without correlation you have nothing.) The models you mention disregard the effect of the solar irradiance because of its small variation within a solar cycle but which varies significantly from cycle to cycle, not to mention the UV component which exhibits even greater variability (more than 6% in the last solar cycle) As Piers Corbyn has suggested, transpiration caused by CO2 improved vegetative growth may actually decrease temperature. Sorry if I reiterated some of the above comments but other specifics in relation to these points needed to be raised.
@2 John, This internet graph will provide you with the global average temperatures since 1880 up to your year of interest, 2009.
http://en.wikipedia.org/wiki/File:Instrumental_Temperature_Record.png
Acid rain…. rain can contain carbon dioxide as well as the other compounds mentioned. I believe that even common rain has pH sligtly below 7, an acid indication, on the basis of the dissolved CO2, which combines with water to make carbonic acid, to wit (Wikipedia):
Citizen’s question: “In testing local creek water and rainwater, I found a rather substantial difference in pH. The rainwater was about 5.7 pH while the creek waters averaged around 7.9. What could account for these differences? What sort of conclusion might I be able to draw from this?”
Wiki Answer: ” First, the rainwater in your area sounds “normal”. Most rainwater has a pH of 5.6 to 5.8, simply due to the pressence of carbonic acid (H2CO3). The latter is formed from dissolved CO2 gas and H2O. The source of the CO2 is the atmosphere, which presently contains about 380 ppm CO2…………….”.
Another answer (unaudited): “From MemphisP – Rain water on average now in 2009 has a pH between 4.3 and 5.6….”.
Hmmmm- further south, rainwater has lower pH…. or is it urban rain water…?
Ange
Dr. Eric,
I have a comment and question I would like you to respond to (more to come later).
The comment relates to the expansion of sea water. If the bulk of the oceans went from 12 C to 2 C (the full range from 65MY ago) the volume would only decrease sea level by 7 m. In fact if it went from 4 C to 2 C (the range from 35 MY ago to present), the change would be near zero. Almost all of the actual effective sea level change due to thermal effects occur in the surface layer (top 500 m). Increasing this by 1.5 C by 2100 would only cause about 1o cm increase, which is the maximum thermal expansion effect likely in the next several hundred years. Almost all of the significant increase or decrease in sea level is in fact due to ice melt or accumulation over LAND (almost all on Antarctic or Greenland). The 70 and 200 m examples were due to large land glaciers forming during glacial periods. Let us stick to those facts.
You have expounded that temperature rise from what had to be a small solar perturbation was than amplified by CO2 with about 800 year lag. Please explain how once the temperature was greatly raised, how the temperature then dropped after a short time (about 10,000 years), and also this drop had a CO2 lag? Are you telling me a small perturbation decrease due to solar effects then had a CO2 generated negative amplification?
Dr Eric,
The significant increase in CO2 about 55 MY ago was almost certainly caused by the Deccan Trap super volcano system which erupted violently for many thousands of years, and emitted millions of cubic km of lava. This event may in fact have been triggered by the asteroid strike at Chicxulub (see: http://docs.google.com/Doc?id=dnc49xz_68c623b7gs&hl=en ). The increase of CO2 was also associated with many other increases, including particulates, acid clouds, water vapor injected into the stratosphere, etc., so the CO2 may not be the cause, but associated with it.
I personally think the particulate material coated ice enough to change albedo and cause massive ice melting. This also caused heating as the albedo change retained more solar heat.
There are several periods in geological history where even higher CO2 levels than 1500 ppm were not associated with higher temperatures, so you really need to be careful when you try to associate CO2 with temperature. I am sure there is some effect, but it is the level of positive feedback we are debating.
@7 Jim,
Upon reading over some comments again, I noted the follow remark you made:
“Dr. Eric has proposed a non-peer reviewed, short treatise, which he claims proves that the climate sensitivity is high”
What non-peer reviewed short treatise are you referring to ? To my knowledge, I have not yet used any information sources of that description.
I have claimed “proof” of something, already? Do you know the difference between providing evidence and proof?
@jim & others,
May I suggest that if a specific response to a particular claim (by anyone) is not made, that comments not be made. A source may be questioned, including why it is not likely reliable, but it is particular claims that are under discussion. Also please keep this friendly. I want to see discussion from both sides.
@21 Leonard,
Of course, it is the level of positive feedback (known as “sensitivity”) that we are discussing here. I think I made this clear in my first paragraph. And when I did describe sensitivity determination, I used only the ice core data, not the less well founded data associated with the periods periods prior to one million years ago.
In fact, I have not learned yet why we think we know what the CO2 concentrations were prior the the ice core record. I mentioned one value I have seen mentioned for that about 50 My ago, but, I will admit, I don’t know what sort of measurement or theory it came from. I’ll bet you can help me there, so please do, while I also try to figure that one out.
@17 Dear Kirk,
By all means, have a go at tying any one or all of the factors you mention into a viable explanation for the ice core record. In doing so I will be most interested to see how well your ideas explains the observed repetitive cycles of temperature between glacial and interglacial periods as they have been revealed in the ice core sample.
While the GHG and albedo feedback effects, in concert with the Milankovitch cycles, do exactly that, perhaps you can put something together with these other factors might quantitatively explain the ice core record, just as well. No one else has, to date, but don’t let that discourage you.
I am not going to attempt to do that here – even though it might merit a Noble Prize if I could.
@15 Al, OK, I can see how you could have taken my comment to imply that computer models of sensitivity were the best. What I meant, of course, was the opposite, and I think comes through in the rest of my paragragh.
So just for the record, historical measurements are the best indicator of the future. I comment the computer modelers and support their work. But the complexity of the system under investigation is great and they don’t know enough about all of the variables. On the other hand, observations of the past have everything included. of course, even if we don’t understand or even know all the variables. And as I tried to illustrate in my Post, we can extract GHG sensitivities from those observations.
Dr. Eric. Thank you for your comments. I probably expressed myself badly. I thought that this discussion would center on climate sensitivity (CS). I am familiar with the way CS has been estimated by the IPCC, and from my somewhat limited understanding, I think the approach is fatally and fundamentally lflawed. I was hoping that this discussion would center on the mathematics of the IPCC approach, and I would see a discussion, from which I could learn a great deal.
Please correct me if I am wrong, but what I think you have presented is your own analysis, which has not been published anywhere else. If it has been published elsewhere, could you give me the reference so that I can look it up in the journal where it has been published.
However, if my guess is correct, and this has not been published elsewhere, then I am at a loss to see how a sensible discussion can take place here. There cannot be many scientists who have had time to look at your calculations in detail, so how a sensible discussion can take place I have no idea. This is surely the heart of the idea of peer review. Publications are looked at for content before publication, and then the scientific communtiy as a whole can critique the ideas after publication.
This would not appear to have happened in your way of arriving at a figure of climate sensitivity. I find this to be disappointing.
“More on this point. There are no facts that will ever PROVE that a hypothesis is true. For example, in a couple hundred years from now, if the entire world has turnd out to be toast, that “observed fact” would not prove a cause and effect relationships such as described by the hypothesis of AGW. By then, the model of AGW will probably still be intact (in spades in fact), but it will still be just a theory. Scientist know this and you should learn the point – that we advance in science by proposing models and by continuously testing them in order to find the best one.” (My capitalisation).
Yes, Dr Eric, but I am still waiting patiently to find out what would FALSIFY the AGW hypothesis. I am starting to think that your answer to the question will be “nothing”.
“So what’s to be learned from Figure 4? First, notice how temperature has closely tracked Forcing by the GHG’s for the last 800,000 years. Yes, changes in the GHG’s follow initial temperature change, but temperature also followed subsequent changes in the GHG’s.”
I need the last part of the above paragraph to be explained. As written, I just don’t get it.
Dr. Eric:
Thanks for the graph of temperatures.
In #8 I asked for the average global temperature for 1800, which is not on that chart.
Thank you.
@15 Al, More response here.
Your comment that dT/dC in the ice cords which the Earth was changing between glacial and interglacial states would be about 17 decrease C (of K) makes sense. This would not be the global GHG sensitivity, however, because the temperature variations at the poles are greater than the parallel variations of global averages. We have been able easily track both in the modern era and find that the pole variations are about twice those of the globe. Therefore, if we divide 17 by 2 , we get 8 degree for your starting estimate. This would be the “slow feedback” values (as I explained in my post) because it is being determined over periods of several millenia. From Hansen et al’s analysis of the ice cores I reviewed in my post, they came up with a slow feedback sensitivity of 6.5 degrees C. Therefore, your comment is in close harmony with what I have presented here.
Note also that about half of the slow feedback sensitivity is the fast feedback portion of 3 degrees. That applies to shorter term periods of say several decades or say to the end of the current century. After that the net sensitivity term for change since the beginning of the Industrial Age would be greater as it increases towards 6 degrees C. Either of these values for sensitivity, however, are far too great for comfort.
Dr Eric,
You have not yet responded to my question: “You have expounded that temperature rise from what had to be a small solar perturbation was than amplified by CO2 with about 800 year lag. Please explain how once the temperature was greatly raised, how the temperature then dropped after a short time (about 10,000 years), and also this drop had a CO2 lag? Are you telling me a small perturbation decrease due to solar effects then had a CO2 generated negative amplification?” In other words, why does the temperature go down? You try to say CO2 is necessary for it to go up, and when the CO2 is at a peak, it then goes down. Why?
BTW, I can explain why the temperature ramp down is slower than the ramp up if you need that information. It has nothing to do with CO2.
@32 Leonard,
Yes, It does appear in the ice core record that the ramping up goes faster than when temperature goes down and I would be most interested in hear you “expound” on that topic.
However, my understanding of what initiates both the up and down changes are that provided by the Milancovitch-based model along with the albedo and GHG positive feedbacks. In my post 6, I used the example of temperature going up. Now lets consider the case when it goes done.
During and after a warming trend has produced something either part way or all the way to a comfortable interglacial period, the magnitude of summer solar irradiance of the Northern Hemisphere can change enough and swing low enough for an extended period (driven mainly by the tilt of the planet relative to the sun) so that ice sheets begin to increase in area once again on the continents. As cooling then occurs, positive feedbacks for additional cooling will be causeed by both the albedo and GHG changes. The concentration of atmospheric CO2 will decrease because it is more soluble in the increasingly colder oceans. Thus CO2′s change in this downward direction will lag the temperature change, just a CO2 lag occurs when temperature is increasing.
We should also remember that H2O is the strongest GHG and its concentration tracks instantly with all temperture changes and thereby provides the major portion of the GHG amplying feedback at all times. So as the planet gets relatively hot or relatively cold, for whatever reason, changes in water vapor and cloud formation will be very large. These fast feedbact effects are also incorporated into the ice core record even though our understanding of cloud dymanics the greatest cause of uncertainty for the scientists who try to determine sensitivities by computer simulations. Mother Nature has essentially done these complex calculations for us in the past and is revealing Her results in the ice core record.
In other words, the direction of temperature change is determined by a prolonged effect of Northern versus Southern Hemisphere irradition. This is the factor that varies with time in accordance with the Milancovitch Cylces. The net magnitude of that directional change is then amplifed by the albedo and GHG feedback effects.
@7 Jim,
Your wish that I would have used the “IPCC approach” deserves additional comment. IPCC reports are distillations of the results of scientific studies carried out by other scientists throughout the word. These results are blended into something that is hopefully understandable to policy makers and the public. The results of studies are emphasized with the presumption that these results and associated recommendations come from the best scientific personnel available of the world (and this statement is correct). Now if that’s enough for you, Jim or anyone else, please just read the IPCC reports and accept them. I happen to agree with most of their recommendations both for the reason related above and also because I happen to understand much of the underlying science and have come to similar conclusions.
Now if you chose to distrust the IPCC reports, where do you go next? I would think it would be to understand more of the basic science behind those results and recommendation. That, of course, is what we are trying to do here and what you call a “farce”. So you don’t trust our best scientists views and you think trying to learn more of it yourself is a farce. I would encourage you do reconsider and try either one or the other of these two options. A third option, of course, would be to find some demagogue who would be pleased to tell you want to think.
Dr. Eric, You have not answered my question. What is the reference to the publication where you work presented above, is published? Or if is has not been published, would you confirm it has not been published.
As to my relationship with the IPCC, I have read and studied the physics presented by the IPCC, and believe it is fatally and fundamentally flawed. However, my physics is not good enough to prove this. So I am looking for any discussion of what the IPCC has presented, so that I can try and understand better what the physics means. That is why I was disappointed that you presented an altermative approach. As to whether I distrust the “best scientists”, is a moot point. If the people you refer to have got the science wrong, then I suspect they are not the “best scientists”. I am a believer in Richard Feynman “Science is the belief in the ignorance of experts”. I look at the science which is presented; not the reputation of the presenter. Nullius in Verba.
Dr Eric:
I realize that you are busy with larger matters, but I would appreciate knowing what the official average global temperature was for the year 1800.
Thank you.
@35 Jim,
That’s great. I always liked the sage wisdom of Feynman too and being able to question everything is partially why I went both feet into science. As I mentioned before I respect the thoughts of the IPCC, not just because they are those of “the experts” but also because I have studied the science extensively and have arrived at similar conclusions all by my lonesome.
So as I said, your next choice seems to be to learn the science. Please do that any way you wish – my approach might not fit your preference.
But if you do decide to stick with the program here, your should consider actually reading my post 6. In doing so, you will find the reference you have been look for. It is described in detail at the very beginning of Post 6 with the usual form of literature citation and with an internet button as well. So just go back there, push that button and it will appear before you. Also note the Supplementary Materials part which was also described in Post 6.
Finally, forgive me for not answering your question the first time as directly as I just did, but did not want to appear to be condescending by pointing out the obvious – and hope I have not done that here when I was essentially forced to.
Have to thank you, Dr Eric, for a great reference, set of resources.
(Though when we start out with 150 reference papers, we’d probably be better off looking into one of those online textbooks.)
@33,
Once the CO2 increase is in place, the temperature starts going down BEFORE the CO2 starts dropping. If SMALL changes due to planetary inclination can drive the process, the CO2/feedback concept is not needed. Keep in mind the down trend starts down at a much higher temperature than the uptrend, so the temperature is well above the value that caused positive feedback. If CO2 causes a positive feedback, saying it can also cause a negative feedback at a HIGHER temperature is contradictory. Using the excuse that more CO2 dissolves in the oceans while still at the higher temperature is wrong.
The reason the down slope is slower than up slope is due to the specific gravity variation of seawater. Warm water sits on the surface, cold water sinks. Thus a small amount of warming (due to reduced ice cover caused by planetary tilt), melts some ice and decreases albedo, which raises the surface temperature of the ocean fairly rapidly. The warmer water increases water vapor pressure, giving positive feedback. When the tilt back increases the albedo, the cooling cools the surface fairly rapidly, but the cooler water sinks and replaces the surface with less cool water, so the ocean volume that has to cool is much larger than the volume that has to heat. This slows down the ramp down, due to a smaller feedback down.
@00, Dr. Eric, is there a scientific hypothesis somewhere in Post #6? If so, would you be so kind as to describe exactly what the scientific hypothesis is?
@ 31 and 15, Al
I responded too quick to your question in 15. Please ignore my 31 and let me try again.
First, what is dT/dC? It can not be an expression for sensitivity, which is defined to be a constant value expressing the change in T with each doubling of C.
The value for sensitivity you mention of about 18 degrees seems much to high to me to be real (I hope). If this was meant to be the sensitivity of the polar temperature, it would be in the ball park, as I explained in response #15.
@ 39 Hi Leonard,
First, let me thank you for your explanation of why things go colder much faster than they go warmer. Your explanation makes a lot sense.
It does leave me wondering however about the importance of a little detail concerning water. Liquid water, as I am sure you know, has a maximum density at 4 degrees C (pure water that is). It becomes less dense at the temperature is either raised of lowered from that point. So, unlike to atmosphere where colder air always sinks (if it can overcome the lapse rate, of course), why does 1 degree water at the surface sink since it is less dense than 4 degree water that might below it.
Since the thing you describe can be measured, I suspect you are correct and perhaps the riddle I pose does not apply to sea water.
In any case, I appreciate you explanation of this climatic phenomenon.
I will response separately to you first paragraph in an separate post to follow.
@39,
Sorry Lenard, I meant, of course, “why things to warmer faster than they go colder”.
@ 39, Leonard,
A couple of details here you have failed to consider in your first paragraph:
The albedo effect is equally important and it appears (in the data) to respond somewhat more quickly to the initial temperature reversal caused by the orbital change. Somewhat later, GHG effects also appear to kick in (see the data) and off we go to a colder world.
Another factor you need to consider is that the GHG effect is not linearly related to the temperature change. That is dT/dCO2 is not a constant but is a continuously decreasing value as the concentration of CO2 increases. So at the higher CO2 concentrations that exist during the interglacial periods, dT/dCO2 is not as large as it was in a colder word and, therefore, dT is then more influence by the small effects of orbital changes than it was during the cooler periods.
I hope that the inclusion of these factors helps you understand why a reversal in the direction of temperature change could occur during the interglacial periods.
@ 40, Ed, I will be glad to help you find my hypothesis in Post 6. You will find it in my last summary paragraph – its first sentence should do. It reads:
“The most important point I have tried to make here in this Post 6 is that the Sensitivity of CO2 is somewhere between about 3 and 6 degrees C depending on whether we are talking about a short term (say several decades) or a longer term (say several centuries) period”.
If you require more scientifically formal language that this, please let me know – so that I can be in strict compliance with your own view of the “Scientific Method”. The meaning of such a statement, however, will be essentially the same.
@45, So the hypothesis does not specify the processes that cause the stated Sensitivity? Or the conditions wherein the hypothesis may be true or false? Or any reasons why the Sensitivity changes with time?
Dear Dr.Eric,
Your comment #31 contains substantial inaccuracies.
First, Vostok ice records show peak-to-peak _estimated_ variability of only 12C. The number 18C comes out of the fact that the CO2 swing was not 2X either, so the actual “sensitivity” accounts for this.
Second, Vostok ice records contain only d18O as a proxy for temperature. To translate it into temperatures, some poorly-specified calibration relationship is required. The literature is not clear on whether it is “average low troposphere temperature”, or local temperature, I have seen both labels.
Third, it is widely known that AGW theory (aka models) do not exhibit polar amplification for Antarctic, and they have plenty of excuses for this.
Forth, observations do not show any amplification in Antarctics, see Alley 2003 or Jones 1999, or this one:
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=265063
“Observations show a highly variable Southern Ocean ice cover that decreased significantly in the 1970s but, overall, has increased since the late 1970s.”
Fifth, modern records do not support polar amplification in Arctic either, see:
http://www.agu.org/pubs/crossref/2002/2001GL011111.shtml
“Arctic and northern-hemispheric air-temperature trends during the 20th century … are similar, and do not support the predicted polar amplification of global warming. … If long-term trends are accepted as a valid measure of climate change, then the SAT and ice data do not support the proposed polar amplification of global warming.”
Therefore, there is no evidence for polar amplification in neither hemisphere (and especially in Antarctic, where Vostok borehole is situated), such that reducing the ice core observations by half has no justification. This lack of “polar amplification” also explains why ice core temperature scale can be (and was) used interchangeably, either as local or global. Your entire account of the situation is pure misinformation.
Regarding the second step of your adjustments, AGW theorists keep talking about “slow feedbacks” and associated “heat in the pipeline” as opposite to “fast feedback”. However, this entire construction is inconsistent with basic observations.
Regarding “fast feedbacks”, the basic observation is that surface temperatures do not need “several decades” to adjust to radiative forcing. It is well known that when the forcing changes, average weather follows and adjusts in a matter of few months. This effect is commonly known as “seasons”. You would not deny the existence of seasons, would you?
Now, the basic fear from “slow feedback” also doesn’t have much physics behind. The slow feedback is usually explained by changes in global average polar albedo, which is supposed to have drastic effect in long term and amplify the global climate sensitivity by another 3C. However, we all know that ice cups retreat and advance seasonally by whopping 50%, such that seasonal albedo changes vastly exceed the tiny annual difference (of 1-2%). If climate is so sensitive to this tiny annual difference, and the fast time constant of climate is of the order of half year as we know it, what could be the amplification effect of this seasonal albedo change? It should be devastating, while it is not. Therefore, it looks like fears of huge climate sensitivity are highly exaggerated.
In short, you attempt to explain the order of magnitude discrepancy in alleged climate sensitivity to CO2 between instrumental records and ice core records has failed in eyes of jury. The simplest explanation of this discrepancy is that CO2 doesn’t affect climate to any significant degree, and that’s why the CO2=>T relationship is a simple slave function CO2 = f(T).
Cheers,
– Al Tekhasski
@45,46 Not only that, but due to “lag” which can be anything we want it to be, the hypothesis is not falsifiable. For instance, the lag in the records shows CO2 lagging Temperature by 600 years, but now the lag is with temperature lagging CO2 by the same amount. The magnitude stays the same, we just invert the sign?
@42, Hi Dr. Eric,
The surface water is not that cold except possibly very near the poles. In addition the surface salt concentration increasing near the poles (from evaporation) lowers the freezing point, increases the density, and also lowers the temperature of the density reversal point. I need to verify, but I think for temperatures up to the ice location, the surface density is continually increasing with cooling (that is why the thermohaline current goes down there). However, it is the larger surface areas away from the poles that are most affected by GLOBAL temperature variations, and for those the surface temperature is much above freezing.
@44,
This comment “GHG effects also appear to kick in (see the data)”, has no data supporting it. The GHG rises from the warming of the oceans. The temperature continues to rise. Water vapor and cloud effect are much more likely the source of positive feedback, and selecting the GHG was a pure speculation with no support. The argument that models can’t explain the difference otherwise just shows the models can’t handle clouds (which they admit)!
The statement “Another factor you need to consider is that the GHG effect is not linearly related to the temperature change. That is dT/dCO2 is not a constant but is a continuously decreasing value as the concentration of CO2 increases. So at the higher CO2 concentrations that exist during the interglacial periods, dT/dCO2 is not as large as it was in a colder word and, therefore, dT is then more influence by the small effects of orbital changes than it was during the cooler periods.” is astonishing. We are in an interglacial period, thus the CO2 level, even without human contribution, would be in a range of lower sensitivity. At the elevated actual range and projected ones, the sensitivity would be even lower. If a very small tilt variation at 280 ppm has very little direct effect (it did not change average insolation, only caused some selective freezing or melting, thus changed albedo a bit) then how does this very small variations cause a large effect. We have a disconnect here. You imply that CO2 effects are important to pump the temperature up, but they are not able to hold them up with small variations in the same parameter.