A commenter on the most recent edition of het's AWOGWN asks an interesting set of questions:
How would temperature data have been seen during the last 10,000 years prior to the peak of each of the previous Milankovich cycles? What caused the temperature to reverse course in those cycles and why would we not expect it to occur again this time?
First, here are the quick answers to those three questions, then some discussion. 1. It is not currently possible to resolve the temperature record that long ago to anything close to what we have today. 2. The cause of the temperature reversal is not well understood but probably due to a feedback of falling temperatures, growing ice sheets and falling CO2 levels initially triggered by Earth's orbital variations (Milankovich cycles). 3. We do not expect this to occur again at this time because the orbital cycle is different and not due to exert a cooling effect for several 10's of thousands of years and because CO2 levels are simply through the roof compared to anything in the past two or more million years.
So to expand a bit about the temperature records during past inter-glacials: it is true that temperature proxies that far in the past can not currently resolve to time scales finer than centuries. The current warming period has barely cleared one century. From a strictly data-centric, context-free, statistical viewpoint, a warming like ours, were it to reverse as quickly as it has come, could come and go in between the dots on our graphs of ice core analyses. However, many possibilities can be eliminated as implausible or very improbable through our understanding of the factors that control annualized and globalized average surface temperature. These data are, after all, emphatically NOT just abstract, context-free bits on a hard drive, they represent real physical properties with known behaviors and constraints.
One of the most compelling contextual factors comes from our understanding of the way temperature correlates with CO2 levels.
(image credit: http://en.wikipedia.org/wiki/File:Co2-temperature-plot.svg)
The magnitude and rapidity of the CO2 spike today is stunning and there is no natural mechanism, known or even speculative, that can reduce that level of atmospheric CO2 on anything less than millennial timescales. Such a pulse could not be invisible in the ice core records. So were we to postulate a warming as rapid as today's it would imply a very drastic decoupling of the CO2 - temperature record and therefore some other mechanism of climate forcing. Now there are of course other climate forcings in nature, but the only truly dramatic ones cause cooling, things like violent volcanic eruptions and asteroid impacts. Non-greenhouse gas causes of warming are generally very slow: melting ice sheets, continental drift, orbital changes. It is theoretically possible that the sun brightened rather dramatically and then dimmed equally as dramatically in between our data points, but as well as seeming highly unlikely, that would not be very relevant to understanding what is going on today. We know what the sun is doing now, even if we don't know what it was doing on short timescales 120K years ago.
The global climate may well be changing constantly on many timescales but there simply are no plausible mechanisms that fit the data or the current understanding of the earth-atmosphere system that could have produced an as yet undetectable spike in the temperature record analogous to today's.
As for our understanding of what actually did happen at the end of previous inter-glacial periods, as I said above that understanding is not perfect. Modeling can explain it roughly as follows: small changes in orbital variations caused the growth of ice sheets in the northern hemisphere. This increased the albedo (reflectivity) of the earth, a further cooling influence. Dying forests became permafrost and carbon drawn from the atmosphere became sequestered under the growing ice. Cooling oceans also began to draw down CO2 levels in the atmosphere. Falling levels of this greenhouse gas contributed to even more cooling in a self-limiting feedback loop eventually seeing the average global temperature drop around 5 degrees Celsius. The precise timing of all these factors is somewhat murky. It is not a simple story, to be sure, and as such is an opportunity for denialists and contrarians to cherry pick and obfuscate their way to many standard climate "skeptic" talking points. You can refer to this article or perhaps this one as well. No one said life was simple!
Today, a process like this would not start for many thousands of years as the Milankovich orbital cycles are not yet aligned in a way to reduce insolation. Further, if we continue unabated on our current carbon trajectory we may well see the actual end of all permanent ice on the planet, a truly astonishing achievement. The CO2 we are pumping out today will be here for centuries, even thousands of years, which may be long enough to see the near complete melting of Greenland's and Western Antarctica's ice sheets. I doubt anyone can say with confidence what would happen to the East Antarctica ice sheet. If it did all melt, who knows when planet Earth would again see permanent land ice?
- Log in to post comments
This paper shows that there can be considerable smoothing of the CO2 profile in polar ice: http://www.geocraft.com/WVFossils/Reference_Docs/CO2_diffusion_in_polar…
Because this would considerably reduce the concentration difference between ice age and interglacial, your claim that the current CO2 level is unprecedented is not proven.
This is because the diffusion in deep ice is comparable to that in the firn.
Furthermore, to assume the end of ice ages is by CO2-GW is unproven; you can easily explain it by biofeedback decreasing cloud albedo once you correct Sagan's faulty aerosol optics physics.
Thanks, Alec, that's an interesting paper. It does however seem to be discussing diffusion of very short lived spikes. If you look at fig. 5 they are modeling a 10yr spike in CO2 levels, and their results indicate that over 70kyr this could diffuse across almost a century of ice layers. It does not look to support the idea that a multi century long spike could diffuse across many millennia. Do you agree?
I think this does reinforce the theoretical possibility of a large and very brief spike being hidden in the ice core records, but absent any plausible mechanism for drawing down such a spike that quickly it does not seem to leave the realm of intellectual curiosity and become something relevant to reconstructing the essential features of geologic history.
Thank you for posting my questions.
There are a few gaps I am still not seeing. The spikes in CO2 shown in past Vostok data seem consistent to what we are seeing today, especially considering smoothing. Also, does the absorption by CO2 not have a diminishing effect such that each increase in concentration will have less effect on warming? I believe we are essentially saturated now.
The orbital cycle is now different? It appears based on periodicity that we are on schedule for another cooling trend.
Do we know that the ice sheets were not completely melted in previous cycles? This could cause yet even completely different effects if the ocean currents were changed.
I am not a denier, just someone seeking to understand. There are far too many gaps in the discussion for me to just blindly accept it.
Russell, could you please indicate where you get that "saturated" statement? It's an important thing to know, as the source of your misinformation can help clear up how much effort people would have to spend on getting you back on track.
Regarding the "saturated" argument, you can start here:
Marco - Why must there be such hatred on both sides of the equation? I am actually one of the few who isn't decided on the issue. I would appreciate you treating me with more respect. I have read many websites on both sides and not found a single one that is truly unbiased.
Neither of the papers you cited compares how much energy is absorbed in the atmosphere at "typical" levels of CO2. It would be interesting to see this charted at 100, 200, 300, ppm CO2 etc... This would provide more information on the actual impact.
Also, any information you could provide on my other questions and comments would be appreciated. Science should be a discussion, not an argument.
Thanks in advance.
can you briefly explain why you appear to like ice so much
You ask for respect and indicate you are undecided, yet you make statements like ".. The spikes in CO2 shown in past Vostok data seem consistent to what we are seeing today..." and "..I believe we are essentially saturated now...".
You also claim not to be a denier. Well, let me tell you that I have my doubts. Too many times I have seen deniers who claim to be seeking knowledge, when all they are doing is trying to produce a "gotcha" moment to us "true believers".
But if you are truly seeking answers, you are going about it completely the wrong way - and it is obvious in your statement that ".. I have read many websites on both sides and not found a single one that is truly unbiased..."
There's your problem right there. Instead of reading blogs, how about you read some real science published in real science journals written by real experts who have been studying the problem for decades. It's all there you know, and has been there for years.
You are right, science should be a discussion, not an argument. But if you want to be part of the discussion, you should know what you are talking about. And if you truly want to to that, then read some science and not the opinions of the ill informed.
Science should be a discussion, not an argument
Agreed, 100%. But I will suggest to you that it takes two to argue but only one to advance a discussion. You will not advance a discussion by seeing "hatred" or even just disrespect in a reply like Marco's reply to you.. I also advise people that they don't have to respond to everything and if you really want to learn and discuss, don't respond to things you see as unproductive posts unless you can do so productively. End meta...
There are a few gaps I am still not seeing. The spikes in CO2 shown in past Vostok data seem consistent to what we are seeing today, especially considering smoothing.
No, not at all. I think you are being fooled by the timescale. The sharp-looking rises in that record happened over 10-5Kyr periods, today's comparable jump (so far, we are not finished) has happened over 100. That is at least 50x faster. I am not sure what you mean by "smoothing" or how it would alter that conclusion. Smoothing reduces a trend, it does not increase it. Smoothing could remove spikes but that does not contribute any evidence to your proposition that there is nothing anomalous about today's CO2 trajectory it merely fails by itself to eliminate the possibility.
Have a look at the graphic on this page: http://www.brighton73.freeserve.co.uk/gw/paleo/20000yrfig.htm and you will see that the slopes of the most recent ascent out of glacial maximum and today are not at all comparable.
Do you agree? (Note that the red line above stops about 30ppm short of the 400ppm level we have already exceeded)
Also, does the absorption by CO2 not have a diminishing effect such that each increase in concentration will have less effect on warming? I believe we are essentially saturated now.
Yes, the effect diminishes. No the effect is not saturated. This is why one talks about climate sensitivity to doubling and not to, say, a 100ppm increase. I think Venus is a pretty compelling refutation of the "we are saturated" argument. I don't think Marco was unreasonable in requesting to know where your current belief came from. Are you able to model this mathematically yourself? I am not, so I am not trying to "shame" you or anything, just wondering the best way to engage you about it.
The orbital cycle is now different? It appears based on periodicity that we are on schedule for another cooling trend.
The orbital cycles are not different in the sense that anything about the earth's motion has changed, but they are combinations of many cycles with differing periods and the combining is not regular on 100Kyr intervals. Today's combination of parameters is not the same as 100K or 200K years ago. Don't assume a simple extrapolation from the past 2, 3 or 4 cycles! The wiki page is very informative, specifically the section on the future.
Do we know that the ice sheets were not completely melted in previous cycles?
I think this is a bit of a hasty question! The only way we know about these cycles is because of ice core records that go back nearly 1 million years, so clearly the ice never melted during this period, and longer because we know ice sheets melt from the bottom as well as the top.
I am not a denier, just someone seeking to understand. There are far too many gaps in the discussion for me to just blindly accept it.
I am happy to take you at your word on this, and no one should blindly accept anything! It will help move things forward if you can be candid when you feel your questions have been adequately addressed (eg. the ice core records do not show trends remotely comparable to today).
coby, mandas, WRONG
[freddy, you are going to be strictly moderated on this thread for on-topic and substantive contributions only]
there is no convincing scientific evidence of human influences on climate: 1. CO2 sensitivity HAS NEVER BEEN MEASURED. any modeling results on this are only virtual bur not substantiated in reality. 2. the error magins of all relevant measurements (e.g. surface temperatures, satellite altimetry etc.) are far too wide to allow any safe conclusions in any direction.You can give up your behavior of feeling as goog priests of your good faith of being member of the true climate church. be assured that neither Einstein, nor Plank, nor Galilei, nor Kopernikus would be members of this your political, environmentalist climate movement. the mentioned true scientists were far too intelligent to "believe" in such unproven rubbish of programmed computers. BTW, i don't believe in paleodata at all, like Prof. Lindzen, who knows hundred thousands times more on the subject than you all.
"...freddy, you are going to be strictly moderated on this thread for on-topic and substantive contributions only.."
That's the end of freddy then
Russell, I can't see where I have been hateful in any way. It is, however, in my opinion important to know where people get their information. That "saturated" argument is one that has been debunked by science about 60 years ago, so it is in my opinion fair to ask where you obtained that *mis*information.
I'm sorry for not being patient, Marco. If any thing I am probably over informed. You tell me not to trust blogs, but that is what I am reading now. One of the most interesting I am reading now is www.drroyspencer.com.
Here is where I have a problem.
CO2 is seen as a strong driver.
CO2 was released from the melting ice.
Increasing CO2, increases temperature, melts more ice, releases more CO2, etc...
Solar radiation shifts are seen as a weak driver.
The ice did not completely melt.
All of the CO2 was not released.
Increasing temperature should have continued to release more CO2 and continued the cycle.
What stopped the cycle? How did such a sharp increase in temperature and CO2 concentration reverse using a weak driver to overpower a strong one?
What is seemed to be unrecognized is you are trying to compare past heat driven rise in CO2 to modern CO2 driven heat rise. Accepting correlation and causation in reverse to develop some expected "climate sensitivity" number.
Clearly, this line of thinking has serious flaws, even a laymen can perceive. But when ideology intervenes, anything is possible.
"You" above, are the hand wringers, not russel.
Sry if there was any misunderstanding.
Russell, although Roy Spencer is amongst a very small minority of climate scientists in his views on climate change and its causes, he's not the worst, so there is a start.
But allow me to explain the concept. It involves some simplification, and be aware that there are boundary conditions (at very low CO2 concentrations and/or at very high temperatures) where the situation changes. Let's ignore those for the moment.
The general concept is that we have a certain rise in CO2 concentrations upon increasing the temperature, and a concomittant further release of CO2 upon an increase of temperature. However, whereas the latter is a somewhat linear relationship, the former is logarithmic.
To use a hypothetical example, divided into steps (in reality this is a continuous process, but this allows me to illustrate better.
Step 1: Supposed we have a forcing by orbital cycles (Milankovitch cycles) that increases the temperature by 1 degrees.
Step 2: That 1 degrees causes the release of 50 ppm CO2 into the atmosphere, increasing the concentration from 150 to 200 ppm.
[the release is not (just) from ice, but from the ocean itself]
Step 3: Suppose that same increase in CO2 causes an increase in temperature of about 1 degrees. Thus, another 50 ppm CO2 is released into the atmosphere.
[note that at this time the Milankovitch forcing may already have significantly reduced]
Step 4: Going from 150 to 200 ppm causes a larger temperature increase (1 degree) than going from 200 to 250 ppm, due to the logarithmic relationship. Let's say it is 0.75 degrees.
Step 5: that 0.75 degrees increase causes the release of 37.5 ppm CO2. We now go from 250 to 287.5,
Step 6. That new increase in CO2 again increases the temperature, but by perhaps only 0.4 degrees. This causes the release of 20 ppm.
Continue this ad infinitum, and I guess you will be able to see that there is a maximum.
Now note that there are processes that take *excess* CO2 out of the atmosphere again (mainly rock weathering). However, these processes are very slow, so it takes about 5,000 years before the CO2 uptake mechanism is as fast as the CO2 release. But then it takes over, because the CO2 release becomes slower and slower, because the temperature rise stops.
Thus, we get into the process of lower CO2 concentrations = lower temperatures = lower CO2 concentrations = lower temperatures. There are still some orbital movements present, which are less extreme than those that cause the glacial-interglacial transitions, so it isn't a very smooth transition.
PaulinMI, please stop projecting your own problems in keeping your ideology in check onto us.
Thank you for making my point for me. Marco. It is obvious to me that our current rise in CO2, which has spiked extremely rapidly, has not had the same impact as previous concentration increases on temperature . That is what I was referring to previously by saturation. Unless these limitations exist, the temperature would never have reversed in the past.
Do you think there is any possibility that the models are giving too much emphasis on CO2 or neglecting any resulting negative forces such as cloud cover. Water is much more plentiful than CO2 and higher temperatures obviously increase evaporation.
I am a chemical engineer so you don't need to simplify things for me. I also doubt that anyone associated with this site has credentials any where close to those of Dr. Spencer. Please be honest with yourself and read some of his works with an open mind.
Russell, saturation is not the same as a logarithmic function. Moreover, as simplification is not necessary, then you should also know that with increasing concentrations other absorption bands of CO2 become important. As a result the function of CO2 vs increase in temperature is not a simple logarithm. David Archer has some useful models on his website to try out. In fact, he has a whole course you can follow online:
Regarding your "possibility": the models don't just include CO2, but also water and clouds. See also
for more on the role of water. Note that (excess) water has a rather short lifetime in the atmosphere, especially compared to CO2.
Finally, it doesn't matter that Roy Spencer may have better credentials than any one of us. The fact remains he presents a (very small) minority position amongst climate scientists. Peter Duesberg knows a hell of a lot more about viruses and such, but his view on HIV still is far, far away from that of people with equal or better qualifications in the same field. Pointing that out is of relevance to those who themselves do not have the qualifications to make a qualified assessment (and you don't have the qualifications, Russell - your questions make that clear).
Look at how actual temperatures have compared to the climate models over the last 30 years and then ask yourself when are the models going to be corrected and where is there source of error. They all overestimate the increase in temperature. Some by a gross margin.
Saying that a science has been decided is even more closed minded than wanting more information to correctly make a decision.
If you would keep your focus on real data instead of wishful thinking your ideology would have somewhat lesser impact.
That open mind thingy Russ brings up is a good starting point.
Russell is one of those deniers (he will deny that he is) that assumes (incorrectly) that climate scientists only consider CO2 forcing when they discuss climate change. This is of course complete nonsense but is eagerly promoted on the denier web sites he likes to frequent,.
Of course there are a number of other forcing factors which affect temperature. When they are considered the resultant data show the linear increase in temperature due to the CO2 forcing. This is discussed here:
Stay tuned for next ipcc report to begin release later this year.
At some point they will accept reality in their prognostications.
The last SREX report is a good example of more honest science than is typical within this industry.
Beware Ian, he has disqualified himself from further comment due to pulling race card as an argument.
Watch carefully, pure ideology on display.
Ian also has trouble with real data. But he does apparently acknowledge that some % of the observed warming is not from CO2.
Hope springs eternal.
More rubbish from pauline. Why does he call me a racist? I suppose he cannot argue with my assessment of the science so uses ad hominem attacks instead. That only shows his own ignorance, arrogance and hatred towards science and scientists.
Look at how actual temperatures have compared to the climate models over the last 30 years and then ask yourself when are the models going to be corrected and where is there source of error. They all overestimate the increase in temperature. Some by a gross margin. Saying that a science has been decided is even more closed minded than wanting more information to correctly make a decision.
Russel, this comment of yours is perplexing. Forgive me for profiling you for a moment and allow me to say that it exhibits one of the most telltale signs of a fruitless conversation. You have come here saying you want to learn and discuss. That is fine, even admirable, given your predisposition to the climate contrarian camp. But what you are doing now is a standard tactic of one with no interest in entertaining alternative view points. It is not consistent with wanting to learn, or at least wanting a genuine discussion. You started out with a couple of main issues: is the current rise in CO2 unusual in geological history and should Milankovich cycles lead us to expect cooling now. I tried to address those points and asked you if you now agreed that the ice core records do not show any comparable rise and I pointed you to information indicating Milankovich cycles on their own would be expected to cause cooling only in some 10s of 1000s of years.
Rather than continue the discussion by agreeing or offering a counter point, you have introduced in your last comment two more completely unrelated very standard arguments that are just as based on misinformation as your initial ones, and two others in the comment just above that. Those standard arguments have standard debunkings, on this site as well as Skeptical Science (some links already provided). Here are the answers to your concern about clouds, about water vapour and about warming having stopped. However, it is my advise to everyone that we resolve issues one at a time and I am not going to go into these new arguments with you until we settle your initial issues.
So can you please respond, on the substance, to my previous detailed reply to you?
Regarding Dr Spencer, yes he is a trained climatologist and an expert in this area. Since you are the one who has brought him up as an argument from authority, I will say two things about him. Firstly, Marco is correct, he is in an extreme minority of expert opinions, so you should have very compelling reasons if you wish to take his word over the other 97% of scientists. Secondly, Dr Spencer is a creationist and as such has some very rigid preconceptions about the world. You say above "Saying that a science has been decided is even more closed minded than wanting more information to correctly make a decision". (Ignoring that this is a red-herring: hear, hear.) Can you please tell me what this statement says to you about the balance between a closed mind and the search for information:
Dr Spencer signed that statement. Do you really think that inspires confidence in his open-mindedness? I really would like to hear your response to that.
It is obvious to me that our current rise in CO2, which has spiked extremely rapidly, has not had the same impact as previous concentration increases on temperature .
I am a chemical engineer so you don’t need to simplify things for me.
As a chemical engineer, is it possible that you are unaware of the existence of self-limiting feedback loops? You already know that CO2 concentration has a logarithmic effect, so the next logical step in understanding the geological record is about as mysterious as 2+2. You can then add ice sheets and the curvature of the earth to the other diminishing feedback effects.
As for the the divergence of CO2 and temperature today is is purely a matter of thermal inertia and time. Again, something a chemical engineer should have absolutely no trouble understanding.
Come on Russel, let's dispense with these more vapid objections quickly and get down to the interesting issues above!
Please explain to everyone where your unwarranted claim of me being a racist was first exhibited.
A lack of recollection of facts is typical of a scoundrel.
I stand by my assessment that Ian is unqualified for further comment and he doubles down to prove it.
Move along Ian, your type is not welcome in my presence.
Russell wishes to compare reality of the data with the (now over estimated) model projections. And you chastise.
Really? That is the best you can respond?
Thermal inertia and time ??
Really? Our best climate science practitioners just forgot to address this in the models? Or are you claiming they knew nothing of it?
Either way, which are admitting there is pause in the warming not consultant with the predictions and which are calling those who observe the data as flat as deniers?
Try coby your credibility is falling fastener than the temperatures.
Russell, as you know, you have the facts correct.
Move along Ian, your type is not welcome in my presence.
You are the one who should move along since this is a science blog and anti-science scoundrels and science haters are not welcome here. Please show everyone how much of a liar you are by showing where I accused you of being a racist. Of course your ignorance and obvious lack of skill in English grammar probably means that you misinterpret most of what any intelligent person has to say, especially if it shows up your ignorance, arrogance and other despicable characteristics of AGW deniers.
If Russell exhibits predisposition as a climate contrarian (whatever that is) do you exhibit a predisposition as a climate alarmist?
And which is a denier?
Just to prove my earlier comment about pauline's lack of skill in English grammar he comes up with this beauty:
Can some one please translate this into understandable English?
Ian pulls the race card, see here and please read in context.
Ian your credibility is poof, gone.
May 31, 2013
#148, my apologies.
Ahh, race card, the last refuge of the defeated.
It wouldn’t be something as simple as making sure our backgrounds are compatible to understand context would it?
And how do you know I am not of one of the protected classes who can not be racists?
Perhaps you may try again? What is being denied?
You are a kook and proven user of the race card, so now defeated.
Anti science. That's rich.
Denier, 97%, two warmest decades, consensus.
Got any more ??
What a piece of work.
Maybe you can tell us how kooks move from point A to point B?
Paul: "Russell wishes to compare reality of the data with the (now over estimated) model projections. And you chastise."
For changing topic, yes. He came here initially wishing to compare ice cores data to today's data. I merely want to finish that discussion before changing topic. That is the only way to have a useful discussion, and when it is intentional, it is the only way to prevent its derailing.
You are also derailing this conversation and I would prefer if you might address some substance.
Paul: "Thermal inertia and time ?? Really? Our best climate science practitioners just forgot to address this in the models? "
Yes, really, thermal inertia and time. I don't think that is hard to understand. But, no, the climate models do not forget this, the people who expect temperatures to already be ~5oC higher than pre-industrial are the ones who forget this. Please recall that what I said was in response to Russel saying: " It is obvious to me that our current rise in CO2, which has spiked extremely rapidly, has not had the same impact as previous concentration increases on temperature ."
He is forgetting thermal inertia and time, climate models are not. I hope that clears that up for you, it really should, if you are after a productive discourse. (If you acknowledge that point, it won't surprise me, but you will surprise others I bet! )
I didn't intend for the conversation to go this direction. I thought I had a valid question and it is one I still have not seen answered sufficiently; why each of the previous temperature cycles did not reach "escape velocity" and what was the mechanism that pulled them back.
I will continue to search and look for information on the web, but will be less likely to comment or extend questions. The beliefs of Dr. Spencer outside of climate have no bearing on how I see his expertise in this area.
I am skeptical, but am not a "denier". Those on both sides of the issue would benefit from listening instead of labeling. My current beliefs if anyone is concerned before I go...
The earth's climate is now warming as a result of its natural orbital cycles.
There is definitely a human source for the current increase of CO2.
I am uncertain of the impact the increase in CO2 may have on our climate.
I believe there are many other forces influencing climate behavior in ways we cannot hope to understand; some amplify and some dampen, some perform in different ways in different conditions.
I feel we would be better served if the science were openly studied and peer-reviewed instead of having a united front against any opposing theories.
Well, since Russel seems to be exiting it is worth accepting that he is dropping for good the unanswered threads of the discussion and instead we can evaluating his final post.
He says " I thought I had a valid question and it is one I still have not seen answered sufficiently; why each of the previous temperature cycles did not reach “escape velocity” and what was the mechanism that pulled them back.
Yet this was not his initial question at all. It is merely one of the latest and not even a prominently stated one. He has chosen to ignore the answers to his original queries. This is not the behavior of someone trying to learn anything.
He says "The beliefs of Dr. Spencer outside of climate have no bearing on how I see his expertise in this area." which is fine. But I showed him that Dr Spencer believes the climate system is a self-correcting creation of God's infinite power. Apparently this does not have any bearing on Russel's faith in Dr. Spencer's opinions about said climate system.
He says "Those on both sides of the issue would benefit from listening instead of labeling." but seriously, has he shown any sign of listening? Marco and I both listened to what he asked and we both responded specifically and substantively. He did not respond in kind, he changed the subject and now he departs claiming no one will answer his questions. This is very disingenuous.
His final "statements of belief" are as valuable a contribution as you might expect from someone exhibiting such obvious prejudice and disinterest.
On the plus side, I do appreciate that he was at least civil in his minimal responses, as was Marco and even mandas(!).
We should all keep in mind that recent study showing how bickering and nastiness in comment threads serves only to deepen everybody's preconceptions. A thread like this will at least have some utility for genuinely inquisitive lurkers.
Bye, Russel. But feel free to pick up where we left off in comment 8.
a) I explained why there is no run-away, which you accepted (albeit described incorrectly as "saturated"). Now you walk away from that again. Sad
b) Spencer's beliefs are not outside climate science, since it directly refers to climate. If Spencer had solely kept himself to making remarks about evolution and intelligent design (he has done so, too), you may have a point, but he actually signed a petition that says God does not allow climate change to be dangerous to humans.
c) the science *is* openly studied and peer-reviewed. Unfortunately for you, that science in large majority indicates the earth is warming because of our addition of greenhouse gases. The natural orbital cycle is presently one of *cooling*. The opposing hypotheses by and large fail, some often even basic logic (as in the case of one of Roy Spencer's publications, which switched around cause and effect).
In short, listening is nice, but if people claim to listen and then show they actually didn't, as in your case (see my point a), why should be bother with you?
Why are AGW deniers such as pauline so insulting and nasty? I did not use any "race card", he is the one who was being racist by making nasty comments about my first language and cultural background. That is what is racist, not any of my comments.
He is a liar and does not have a clue about climate science or any other aspect of science. It is obvious that he only appears on this blog to hurl insults at anyone who tries to explain to him the simple facts of climate science and how continued increases in CO2 concentrations will have a detrimental effect on the well being and health of those having to live in the coming years.
"Russel, this comment of yours is perplexing. ... You have come here saying you want to learn and discuss."
He is not buying it yet.
Because one says it, doesn't make it true.
Unless apparently, your ideology is warmest hysteria.
Ian you are hearing what you want to hear.
As I stated before, culture and first language go to understanding between individuals, not to race as you brought up (first).
More rubbish from pauline. He is so stupid he doesn't realize he is being racist by commenting on first language and cultural background. For goodness sake what else determines race? Why do deniers only have a grade 3 education ?
# 39 russell
Peak interglacial temperatures are a lagged response to peak orbital forcing as discussed earlier on this thread. Once orbital forcing is reduced the NH ice sheets begin to grow, and various positive feedbacks reverse the temperature trend and the slow descent into the next glacial begins.
This is all discussed above.
My original question - How would temperature data have been seen during the last 10,000 years prior to the peak of each of the previous Milankovich cycles? What caused the temperature to reverse course in those cycles and why would we not expect it to occur again this time?
My exaggerated, yet same question later - Why did each of the previous temperature cycles did not reach “escape velocity” and what was the mechanism that pulled them back?
You have my personal e-mail address if you wish to discuss. Usually the host of a blog tries to avoid grandstanding if at all possible especially if one's goal is to educate and reach others. You can write me off as a denier or you can contact me directly to discuss.
As you said in your original post, "As for our understanding of what actually did happen at the end of previous inter-glacial periods, as I said above that understanding is not perfect. "
I just have more difficulty taking the leap of faith with something so serious. I look forward to future discussions.
Russell, what do you mean by “escape velocity”? Temperatures do not have velocity. No wonder people are making fun of you. If you are in fact an engineer you should be aware of your nonsensical statement. Or are you like pauline and like to try and confuse people by using big words which seem to be scientific but are just nonsense?
The global climate is a very complex interaction of many factors. Even the very simplistic feature we all seem to most focus on, global average temperature, is a complex function of many factors.
In the case of the long, slow rise from glacial maximum to glacial minimum seen happening roughly every 100-120K yrs in the ice core records, our best understanding is that changes in orbital forcing due to Milankovich cycles began a slow retreat of ice sheets in the northern hemisphere. This set in motion a complex interplay of mostly self limiting feedback effects involving albedo and greenhouse gas forcings and resulted in a total rise in global average temperatures of around 5oC. I *think* the relative weight of these factors is around 40% GHG, 40% albedo and 20% orbital forcing, but that is from memory only.
No faith involved.
Stop with the pretence about trying to be civil and about trying to find answers to your questions - you're not. And stop with the claims about being a sceptic - you're not.
I have already told you what to do if you really want answers to your questions. Stop reading blogs and go away and read some real science. Go to Google Scholar and look for the answers in real science papers written by real experts which have been peer reviewed and published in real science journals.
All the information is there and has been for decades.
A classic case of "cain't get no satisfaction" from Russell.
What do you want, Russell? An alternative paleoclimate? No can do. So we are stuck with what we can *infer* from this one. Which is this:
~6W/m^2 forcing and the consequent ~4.5C change in GAT separate and maintain the Holocene from the LGM. So S to 1W/m^2 change in forcing is ~0.75C. I'm sure you can work the rest out for yourself.
coby: "I *think* the relative weight of these factors is around 40% GHG, 40% albedo and 20% orbital forcing"
this is pure speculation and there is NO scientific proof for this assertion, or can you reference a reliable scientific source?
For people (unlike freddy) actually interested in the answer to his question, I think this is a good starting point:
One thing apparent in the first figure on that page is that, as I tried to explain to Russel, the different interglacial peaks in the semi regular cycles are not uniform and more detailed analysis suggests that every 400kyr there is a much longer period of warmth. There was one 400kyr ago and the one today is expected to last several 10s of thousands of years.
Of course, the anthropogenic influences will overwhelm the orbital signal for a long time to come.
If the Holocene is set to be a re-run of MIS11 - and the orbital dynamics do support this - then it kills the old contrarian meme that AGW is "staving off an ice age" stone dead.
I almost feel sorry for Russell; bringing a knife to a gun fight. Cody simplified things though, for his benefit, and made me think when he said that, "I *think* the relative weight of these factors is around 40% GHG, 40% albedo and 20% orbital forcing, but that is from memory only."
If we are sitting at a cyclical maximum for temperature, we have the following conditions:
Maximum CO2 = maximum GHG contribution
Minimum ice = minimum albedo
Does orbital forcing overcome 80% of the factors at their most optimum conditions for warming? The only explanation I have is that GHG's do not contribute as much as theorized or there are other strong factors at play. As stated, it would take a serious leap of faith to get the temperature to turn at face value. Cody may have to keep his mind open to more possibilities, but then he might be in danger of losing HIS religion.
Gordon, the way it works does not require the orbital forcing to overwhelm the entire maximum contributions of the other forcings, it merely tips the balance a bit. This causes those other forcings to begin moving in the same direction. So to describe it as a discreet step simplified process: weak orbital forcings cause the ice sheets to expand a bit, and cause oceans/permafrost to draw small quantities of carbon out of the atmosphere. These small reductions in albedo and GHE further reduce the temperature beyond what the orbital forcing can do on its own. This additional drop in temperature grows the ice more and decreases the CO2 again and so it continues until the ice growth runs into climates that are not cold enough, even if cooled, and the ocean CO2 levels are again in equilibrium with the atmosphere.
If you want a better explanation than what words alone can provide, (ie better than "the only one you have" hand waving), you have to do some math.
The link I provided above will provide some of that and get you to all the research papers that have built up this understanding. This one:
(it's "coby" BTW)
It is worth recalling that the entire cooling process takes 50K - 90K years depending on the particular cycle you wish to examine. This is because it is much easier to melt an ice sheet than to grow one.
On the issue of whether or not GHG contribute as much as theorised, you might wish to take a look at the following video produced as lecture material by Andrew Dessler, an atmospheric physicist from Texas A&M.
He makes the point that physics points to a temperature sensitivity of 1.2C from a doubling of CO2, and that this is not a controversial number and it is agreed by everyone who studies the physics of the atmosphere. The issue is feedbacks, and whether or not they are positive or negative, and to what degree.
In the video he explains that there are some feedbacks which we know for a fact are positive - increased water vapour and decreased albido - which, when factored in, bring the climate sensitivity to around 3C. Then there are others such as clouds and aerosols which we are unable to definitively quantify. Aerosols are almost certainly negative (but to what degree we don't know), but clouds could be either because they both increase albido and increase infrared absorption. This is where the real debate among is in climate change.
Orbital forcing obviously exists, but it is over very long timeframes - of the order of thousands of years - and is not a factor in current climate change.
And here's the link:
re coby @59
Sorry Coby I'm only about 3 years late on this thread :(
Just wondering about Russeli's question (not sure if you actually explained it or whether it just went over my head?). You explained the mechanism by which past interglacial periods maxed out temperature wise by way of the ever diminishing effect of increased CO2 on temperature and how orbital forcing eventually tipped the pendulum back towards a cooling trend.
However, I think what Russell was getting at when he talked about "saturation" and "escape velocity" (however improper those terms may be) was why do you think that those same limiting factors that turned around the previous temperature peaks will not restrict our current trajectory (if that is in fact what the concern is)? Is there a danger of reaching a type of event horizon climate wise from which there will be no return like what happened to Venus? (or is the prospect of a naturally limited 5-6 degree temp rise bad enough in of itself?)
As far as I'm aware, no serious climate scientist believes that a Venus type situation is plausible on Earth. I think this is due to limiting factors such as availability of CO2 (Venus is 95% CO2) and proximity to the sun. Yes, 5-6oC is bad enough on anything less than a multi-thousand year time frame.
I think the best answer to why the climate will not self-limit in a way/at a level similar to past glacial minimums is this graph from the original post:
Aside: it's worth noting that CO2 today is yet higher than in the chart above, at around 400ppm
Thanks Coby for replying to my late queries. I take your point on the venus comparison.
So given that there is a temperature lag in response to CO2 increases and a certain degree of thermal inertia, what kind of temperature rise are we likely to get if CO2 concentrations were to somehow stabilize at 400ppm? Is the <2oC target aims of the UN a feasible one or just wishful thinking?
Also, given the CO2 abundance on Earth, and taking into account other limiting factors, is there a theoretical maximum temperature range that Earth could hypothetically reach?
Stabilizing at 400ppm will not result in warming <2oC, I think that is a scientifically safe assertion. Given the current assessment of climate sensitivity (3oC) to a doubling of CO2 since pre-industrial levels (ie ~560ppm) stopping at 2oC warming would require stabilization in the neighbourhood of 350ppm. We can (theoretically) exceed that level if it is brought down in time and stabilize at 2oC.
It is often ignored/overlooked that this 3o climate sensitivity only takes into account short term feedbacks (H2O, terrestrial carbon sources and sinks, albedo changes from snow cover and sea ice response). It does not account for long term feedbacks like CO2 out gassing from oceans and melting permafrost (the source of CO2 in glacial-interglacial transitions) or ice sheet melting. Nor does it consider very uncertain things like thawing methane clathrates.
I don't know much about a "theoretical limit" in modeling, it can go pretty high in the extreme scenarios and very unlikely uncertainty ranges. Geologically, I think there is evidence of possible global climates as much as 8-9oC higher than today.
That's a sobering thought if the modelling is conservative, especially given that global CO2 emissions are yet to peak.
Once again, thank you for taking the time to respond to my queries and for sharing your insight on these subjects.
No worries, thanks for the comments!
"I think this is due to limiting factors such as availability of CO2 (Venus is 95% CO2) and proximity to the sun."
We have plenty of Carbon, but we have plate tectonics and water which Venus doesn't (and hasn't for a long time), which ensure that Carbon is locked up in rocks here on Earth and are capable of doing so on Venus.
For us to get to the same state we'd have to stop plate tectonics at least (the water will eventually boil off as H2O is split into H, O, O, and the H flies off into the interstellar medium.
If that happens, we're far more fubar'd than merely AGW.
Haha fubar'd indeed!
I guess the role that plate tectonics plays in influencing climate is most obvious when it produces large scale volcanic activity which releases previously trapped gases and rapidly affects the atmospheric composition (ie. the flood basalt eruptions of the Siberian Traps at the end of the Permian).
Large scale volcanic activity like the supervolcanoes of half a billion years ago, andrew.
We have a distinct dearth of those today.
So our climate change isn't due to volcanoes.
And, given you accept that CO2 from volcanoes CAN change the climate if there's enough of them, the FACT we're doing 30-60x as much as volcanoes do really just goes to show that AGW is very much acceptable to you.
Yes @Wow I agree totally, I used the super volcano example to highlight the fact that this is the type of natural activity that would cause the type of CO2 increases we're seeing now. Clearly there's no equivalent natural process occurring at the moment so the dramatic CO2 spike we're currently experiencing could only be caused by human activity.
Thing is, deniers won't agree. They accept the supervolcanoes produce global climate change through their CO2 emissions, but won't accept that CO2 emissions elsewhere will do so, if that "elsewhere" is "from humans".
They don't see anything wrong in accepting climate changes in the past as evidenced by scientists whilst refusing the evidence that CO2 has a definite effect from human activities.
It's like humans produce some magical CO2 that doesn't do what every other form of CO2 does.
But it's probably just they don't think about it.
Easy answer to wow: volcanoes can influence air temperatures near the surface when they produce dense smoke which sun rays cannot pass. Your obsession with any co2 molecule is irrelevant regarding climate: it cannot be directly observed in an experiment. period.
Yes @Wow, deniers are a strange bunch, they try to use pseudo-scientific arguments to support their positions but usually just end up demonstrating how little they actually know about the science.
I guess that's usually because they're religious and so they already think they have the answer and are just trying to work backwards to justify their belief. No amount of logic or reason will ever convince them because their beliefs are based on emotion, not reason.
@freddy - The greenhouse effect of CO2 and other GHG's can be measured and observed, just because the effect isn't physically visible doesn't mean anything. Can you see water evaporating?....no but that doesn't mean it isn't happening. There isn't a scientist around who rejects the fact that certain gases in the atmosphere have the ability to trap heat. The only point of contention is from a very tiny percentage who believe that humans aren't playing a significant role in changing the atmospheric composition, and their reasoning has more to do with their religious beliefs or who's funding their research than it does with their application of rigorous scientific method.
Andrew, I recommend to you as an obviously ambitious layperson that you study the new handbook of meteorolgy of Möller and Kramm (Alaska) on all the subjects where you show lacking knowledge regarding the atmosphere. Thereafter I promise you that you will have to revise your errors in your copied opinions.
Freddy do you have any links to this handbook? There's one called 'Lectures in Meteorology' by Moelders and Kramm?
Anyhow, as Wow pointed out, it would be useful to know exactly what errors in my opinion you are referring to? I certainly don't profess to be any kind of expert on thermodynamics or climate science but I'm interested in the general principles behind the accepted views of the general scientific community.
"@freddy – The greenhouse effect of CO2 and other GHG’s can be measured and observed, just because the effect isn’t physically visible"
Electricity isn't physically visible.
Stick your fingers in an electric socket, freddyboriskaibot.
"handbook of meteorolgy of Möller and Kramm"
There are thousands of texts on meteorology. Tens of thousands.
But you seem to be missing something, freddykaiboristroll, what it is you think is missing from Andrew's knowledge.
As far as you've said, there's NOTHING missing.
In which case, why should he read anything more than he already has???
"volcanoes can influence air temperatures near the surface when they produce dense smoke which sun rays cannot pass"
It's already included in the GCMs that indicate the threat of AGW is real and present.
And what handbook are you blithering on about? There is no such handbook.
Is this yet more indication that there's nothing new for Andrew to learn,despite your insinuations?
wow wrong: "@freddy – The greenhouse effect of CO2 and other GHG’s can be measured and observed, just because the effect isn’t physically visible”
You mix up infrared absorption and greenhouse effect. A greenhouse is warmed by blocking convection of warm air. In the atmosphere there is no blocking of convection. You are welcome.
Andrew, here is the link to the handbook coauthored by Prof. Kramm, an eminent scientist in atmospheric physics and micrometeorolgy:
Prof. Kramm has an estimated 200000 times the knowledge and experience with the atmosphere compared to a Mr. Wow.
You, as an interested layman should try to learn from first-class scientists in the field of scientific meteorology like Prof. Kramm, instead of listening to other laymen like Mr. Wow.
"You mix up infrared absorption and greenhouse effect. "
Since the GHG effect is because of IR absorption, how could that be even possibly true, freddiekaiboristroll?
"Andrew, here is the link to the handbook coauthored by Prof. Kramm"
Since you claimed a different authorship, you fail to admit your mistake.
"an eminent scientist in atmospheric physics and micrometeorolgy:"
Nah, he's not eminent. He's retired. And "believes" the moronic and ridiculous G&T paper, a clear case of wishes blinding him to reality. And meteorology has almost nothing to do with climatology, he's running well outside his expertise, the expertise of other eminent scientists in similar status who insist AGW is real and present.
Moreover, you have still failed to explain what it is Andrew has wrong. All you've done is try to fluff up his sales.
And let us not forget that this "estimation" is from someone who doesn't even know what pseudonym hes running under, and who "believes" the crap record of denier "scientists" like this:
somehow indicate that AGW is false.
"A greenhouse is warmed by blocking convection of warm air. In the atmosphere there is no blocking of convection."
The atmosphere isn't a greenhouse. You should stop trying to think that there's a literal roof to the heavens.
@Andrew, as already said and despite Mr. Wow's respectless "remarks" I recommend to you to study the handbook coauthored by Prof. Kramm, who is infinitely superior to a Mr. Wow in all matters of atmospheric science. You can only learn from such an expert and not from naked laymen devoid of profound knowledge and experience in a scientific discipline because they did not study it and have not worked as scientists.
Thank you and best regards
But Andrew has neither got anything wrong, nor have you identified where you "think" he has something wrong.
All you have is that "something is wrong" and "read this book which I won't tell you the contents that disprove your errant assumption defined above".
IOW fuck all.
We need to plant more trees!
Is there a chart for CH₄?
There's only so much room for trees. Planting trees means planting something of the order of 200 billion tons of new growth tree EACH YEAR, and that would only offset what we output, so unless we stop that, we will run out of space for trees.
wow@85 said: "... And meteorology has almost nothing to do with climatology ..."
You cannot believe this seriously, because it is ridiculously wrong. Even J. Hansen and Gavin would object your assertion furiously.
You can believe that seriously, since climatology is a boundary problem and entirely different from meteorology.
There should have been a bit of a hint that there are two entirely different academic qualifications for the two enterprises.