Commentary- Hansen Draft Paper: Paleoclimate Implications for Human-Made Climate Change

Thanks Dr. Hertzberg good post. Hansen, and Holdren, are certifiable and it is a worry to me that the US government does not gag Hansen since they employ him. Perhaps they are working together to further tax increases on the long suffering Americans.

Wow.
Some times I am baffled by my own oversights. Of course the orbital eccentricity leads to more summertime irradiance. This is the opposite of what I learned at the university, where the view presented by Hansen was the common perception.
A suggestion:
I think a thorough presentation of the Milankovic cycles would be much appreciated, as the Wikipedia entry is (methinks) a bit too short and somewhat difficult to comprehend.

If the AGW proponents were correct about CO2, the earth would have tipped long ago and had temperatures nearly as high as Venus. The fact that there has never been a tipping point confirms that earth’s atmoshere is remarkably stable and self regulating and the fact that we are here today to debate this issue confirms that the AGW argument is not correct.
It appears that Hansen only ever half thinks things through, and this explains why he comes up with half baked conjectures. I share the sentiment that Hansen speaking at this symposium is an insult to Milankovic.

In my opinion, beginning a supposedly serious piece of writing by saying
“It is hopeless to expect that Hansen could possibly analyze data objectively – all he has in his head is “CO2 climate forcing” and everything else has to be “forced” into that ridiculous paradigm. It makes no difference to him that the predictions of his past half-baked computer models based on “CO2 climate forcing” were completely wrong.
It is not worth my time (or anyone else’s in my opinion) to try to critique the entire paper…”
makes it not worth my time reading any further.
It is clear that the author is not objectively discussing the science pesented but is using this as a platform for his own biased opinions.
I would much rather read an unbiased, balanced, thoughtful critique which this is obviously not.

“It is hopeless to expect that Hansen could possibly analyze data objectively – all he has in his head is “CO2 climate forcing” and everything else has to be “forced” into that ridiculous paradigm. It makes no difference to him that the predictions of his past half-baked computer models based on “CO2 climate forcing” were completely wrong.”
This is what happens when you put a Venus specialist in charge of researching the Earth’s atmosphere. He knows what happened to Venus, therefore he knows what’s going to happen to Earth: runaway global warming.
He is the first victim of Venus Syndrome. The sooner he retires the better.

Louise says:
“It is not worth my time (or anyone else’s in my opinion) to try to critique the entire paper…”
makes it not worth my time reading any further.”
Louise, I remember when I finally decided I had to find proof to back up my assumption that global warming must be true, because there was no way so many people would believe it unless it was well backed.
After several months wading through paper after paper after paper, trying to track down that illusive “foundation” of manmade global warming theory, I began to realise that there’s nothing behind all these statements except statements that there are statements that back up their statements.
There comes a point when doing them the courtesy of reading what they wrote … giving them the benefit of the doubt … become gullibility not to see through the blanket that hides the lack of any scientific basis for what they say.

@Louise: agree that the opening is impatient bordering on petulant, which is unfortunate because the substantive discussion that follows is, I think, intriguing and worth closer study and reflection. I would like to see a little math answering John Day’s point (longer summer but at less-intense level of insolation =?= shorter summer at more-intense level of insolation). That kind of accounting for energy/irradiance over time presumably has been done to support the argument about Milankovitch cycles, and it would be good to see it at least summarized or referenced here.
It would then be appropriate to call Hansen a fool and a charlatan –at the END of the paper!

Louise wrote:
“I would much rather read an unbiased, balanced, thoughtful critique which this is obviously not.”
So did you read the article to see what it was about and to come to that conclusion?

“half-baked computer models”? My local baker would take offence at any comparison of his excellent product and Hansen’s rubbish models.
http://thepointman.wordpress.com/2011/01/21/the-seductiveness-of-models/
Pointman

Dear Dr Hertzberg,
Thank you for this interesting post. In particular your point about the implausibility (or absurdity) of the climate establishment’s explanation of glacial/interglacial transitions as a small initial Milankovic-cycle-generated temperature change kick-starting a delayed and much larger CO2-mediated positive feedback chain reaction deserves wider prominence.
However I don’t think your argument is strengthened by your statement that “Thus, it is reasonable to argue that the current increase in CO2 during our current Interglacial Warming, which has been going on for the last 15,000 – 20,000 years, is merely the continuation of a natural process that has nothing whatever to do with human activity.” In fact I groaned inwardly when I read that passage.
Yes, a small part of the recent increase on atmospheric CO2 can be attributed to continued warming and degassing of the oceans. But most of it? Hm. The levels didn’t get much above 300ppm during previous interglacials, so either there is something wrong with the ice core CO2 data, or there is something out-of-the-ordinary causing the recent rise to over 380ppm. I suspect most well-informed people, including sceptical climate scientists, would prefer the latter explanation.
The misinterpretation by the IPCC and the rest of the climate change establishment of the glacial/interglacial temperature-CO2 relationship is IMO one of the weakest points in the whole AGW paradigm. I fear your attribution of recent CO2 rises to a continuation of the natural post-glacial de-gassing will simply make it easier for your (and my) opponents to ignore or sideline the more telling points you have made. I’d drop that bit.
But keep up the good work!

I agree that the introduction to this post is a little OTT and may detract from the substance of the post. The introduction is unnecessary and pales beside the significance of the observation made half way through the post, namely that:-
“There is a simple way to tell the difference between propagandists and scientists. If scientists have a theory they search diligently for data that might actually contradict the theory so that they can fully test its validity or refine it. Propagandists, on the other hand, carefully select only the data that might agree with their theory and dutifully ignore any data that disagrees with it.”
I think set against that observation, one can see to which camp Hansen belongs.
sHx says:
January 24, 2011 at 4:13 am
“This is what happens when you put a Venus specialist in charge of researching the Earth’s atmosphere. He knows what happened to Venus, therefore he knows what’s going to happen to Earth: runaway global warming.”
I question whether he actually properly understands Venus since he fails to take into account the effect caused by the pressure of that atmosphere.

Patience is a virtue, Louise, for which you would have been rewarded if you had not been impatient. I, too, found the intro something of a ‘turnoff’, but kept going and now appreciate the authors’ viewpoint in this excellent post. In the recent past I have struggled to understand the import of the Malinkovitch Cycles as much of the referrence material I searched seemed impossibly obscure but this article pulled the curtain of my own ignorance aside for me!
I guess Hansen’s wildly anti-American and hyperbolic speeches tend to make more rational and patriotic American scientists more than a little scornful of him.

I have a question if someone can answer it: If ice ages are brought on by variations in the earth’s orbit relative to the sun, then shouldn’t they predictable? Shouldn’t we then know – perhaps to the year – when the current interglacial will end? My sense is we don’t know. Why?

I have attempted to engage Believers on the issue of the historical lag between temperature and CO2. Their first response is this theory that the Milankovic cycles are the weak signal that starts the cycle, but the CO2 provides a positive feedback that makes for a much larger swing in the cycle. My response is “then why is it that when CO2 is at its highest, this ‘weak’ signal can start an Ice Age, and when it is at its lowest, the ‘weak’ signal can end it?” The only thing I’ve heard back is a dismissive “you need to be more familiar with the literature; this is old stuff that’s already been dealt with.” But then they don’t actually deal with it. They provide no inkling of how to resolve the conundrum.
No one has ever answered the question satisfactorily.

As Leif Svaalgaard pointed out, the total insolation received from the sun would be greater in winter than summer, outweighing the longer summer factor. The glaciers melted 10,000 years ago , when the northern hemisphere winters were longer, but we were closer to the sun in norther hemisphere winter.
Going on to greenhouse gases, as opposed to Milankovitch theory,
Some data I picked up surfing the internet:
“Glaciation
For a number of reasons, the volume of glacial ice near the poles
waxes and
wanes over time. As a result, water is alternately taken from or added
to the
world oceans. This can result in sea-level oscillations of up to 200
meters. For
example, modern continental glaciers are 1.5 to 2.5 km thick and have
a total
estimated volume of 33 million km3. If we assume the maximum volume
of
Pleistocene glaciers to have been 71.3 million km3, Flint, 1971 then
the
difference is 38 million km3. Using the assumption that glacial water
volume is
91.7% of the volume of sea water from which it is derived, a sea-level
drop of
106 m can be accounted for by Pleistocene glaciation. Melting of the
present
Greenland and Antarctic glaciers would produce a sea-level rise of
approximately
60 meters.
The specific latent heat of fusion of ice at 0 ºC, for example, is 334
kJ.kg-1.
This means that to convert 1 kg of ice at 0 ºC to 1 kg of water at 0
ºC, 334 kJ
of heat must be absorbed by the ice. Conversely, when 1 kg of water at
0 ºC
freezes to give 1 kg of ice at 0 ºC, 334 kJ of heat will be released
to the
surroundings. (Note for educators).
“The total mean mass of the atmosphere is 5.1480×1018 kg with an
annual range due to water vapor of 1.2 or 1.5×1015 kg depending on
whether surface pressure or water vapor data are used; somewhat
smaller than the previous estimate. The mean mass of water vapor is
estimated as 1.27×1016 kg and the dry air mass as 5.1352
A 4C rise or higher this century would see the world warm almost as
much in 100 years as it did during the 15,000 years since the end of
the last ice age.”
Putting it all together, 71.3 million k3 ice *0.917 vol ice/vol
water=
65.3821 million cubic kilometers of water.
1 cubic meter= 1000 kg.
1 cubic km = 10^12 kg
65.3821 million cubic km= 65.3821*10^18 kg
Total heat to melt glaciers =65.3821 *10^18 *1000*334 kj=2.18*10^25
joules
Cp air= 1.012 joules/gram K
1012 Joules/kg K * 5.148^10^18 =5.209776 *10^21 joules
4degree increase=2.0839 *10^22 joules
So about 1000 times as much heat went into melting the glaciers at
the end of the Pleistocene as went into heating the atmosphere,
implying CO2 had only a negligible effect- A. McIntire

I can not believe there are still sceptics who believe that CO2 levels didn’t get much above 300ppm during previous interglacials. Amazing. This is the most obvious thing to be sceptical about.

Nylo says:
January 24, 2011 at 5:14 am
“where did all that CO2 come from during those past warming periods when the human production of CO2 was virtually nonexistent? The answer is apparent to knowledgeable scientists: from the same place that the current increase is coming from, from the oceans.”
“These falsehoods damage the skeptic position much more than whatever any warmist may say. Knowledgeable scientists have become convinced long ago that the source of the current increase of atmospheric CO2 is human, and that oceans are currently a sink for CO2 because of the imbalance of the concentrations created by our emissions. It wasn’t like this in the distant past, when there weren’t human emissions. But it is that way now.”
=======================================================
lol, Nylo, your statement harms the warmists position. You and your kindred’s refusal to address this inconsistency speaks volumes. And you didn’t answer the question. The question is, where did all of the CO2 come from when the earth was warmer in the past? Reading your statement, you seem to be asserting that suddenly the oceans are now a sink but have never been in the past. But, even your assertion doesn’t answer the question. OK, for the sake of argument, let’s say it didn’t come from the oceans. Then, where did the CO2 come from?

Precession and orbital eccentricity are hard for a lot of people to wrap their heads around when written in text. I loved this post, but I’m left feeling like pulling out Starry Night and making some videos to explain these cycles to the layperson.
It shouldn’t be that hard, All you have to show is the eccentricity from the top-down, show the earth orbiting sped up, then zoom in periodically to show the position of the hemispheres at different points back through time (perhaps I could also use an inset of the vostok data to show the temperature). Also, perhaps I should start off with a highly eccentric orbit to show how orbital mechanics “slow” objects down at aphelion. I’m liking this idea more every time I think of it. Someone link me to a video doing this and I’ll stop fantasizing.

Warning: All of science is in trouble because it took the “greenhouse effect” as true, when it is not. Don’t be so quick to take the Milankovitch theory as true. Look into the criticisms of that theory, and take THEM to heart, not the easy speculations of those who uncritically accept them. People who confidently proclaim they know the temperature 500,000 years ago, or how the temperature varied over that long an interval, should be considered as all too likely self-deluded. A science that says, “Venus is hot not because of its huge, dense atmosphere, but because of a runaway greenhouse effect” is not to be trusted when it makes equally self-assured claims that “the Earth regularly goes in and out of ice ages, over millions of years, due to variations in its orbit.” It is a fundamental error to try to disprove one bad hypothesis (the greenhouse effect) with another equally questionable (Milankovitch theory). That is the hard truth.

“Really? The graph was made from ice core data. What is corrupted and uncertain about it?”
I basically agree with this:
http://www.john-daly.com/zjiceco2.htm
I also agree that CO2 follows temperature and that some of the annual cycle is caused by vegetation (photosynthesis, decay), but most of it is ocean anual breathing.

Alan McIntyre said:

So about 1000 times as much heat went into melting the glaciers at
the end of the Pleistocene as went into heating the atmosphere,
implying CO2 had only a negligible effect- A. McIntire

Heh. Similar approaches tell us why it is just so stupid to believe that the heat capacity of the atmosphere can drive the melting of the remaining glaciers and the heating of the oceans.

Thanks for the info, Dr. Hertzberg. It hadn’t occured to me that the eccentricity of the earth’s orbit must perforce lengthen the time it spends around aphelion and shorten it around perihelion. This effectively cancels out the difference in insolation between perihelion and aphelion at this point in the cycle:
http://physics.ucf.edu/~britt/Climate/L12-Astronomical%20control%20of%20solar%20radiation.ppt
The glacier building, according to the link above, happens when the NH winter is at aphelion which extends the winter instead of the summer by 8 days.
And yes, being the devoted skeptic and fact checker, I did count the days for myself by entering Mar 20, 2011 and Sep 23, 2011 (spring/fall equinox dates for this year) into a Julian calander converter then subtract the first Julian date from the second which comes out to 187 days centered on summer solstice and 179 days centered on winter solstice.

Said it before & I’ll say it again, that man, Hansen, needs to be fired. His advocacy (in denial of routine scientific principals) if carried through in governmental policy would severely damage the very taxpayers WHO PAY HIS SALARY. People who condemn their employers routinely lose their jobs. Why should ‘that man’ be exempt?

Bob from the UK ,
Go to:
http://www.carboeurope.org/education/schoolsweb.php
and choose:
CO2 concentration, start 1-12-2008, end 1-12-2010, NL StellingWerf College, Oosterwolde
and see what the kids measured. OK, I cherry-picked that station, but it’s still interesting.
Global temperature AND CO2 drop -> checkmate -> game over for warmists

Thank you Dr. Hertzberg for a most enjoyable read! Now I understand much more about the implications of the Milankovic cycles. A very nice post indeed.
Please continue giving the warmers a bloody nose ever so often.

John Brookes says:
January 24, 2011 at 8:02 am
Jeremy January 24, 2011 at 7:03 am:
OK, so I shouldn’t trust Wikipedia. Do you have a link to a graph showing the Milankovitch forcings for the period of 100k years either side of today? Thanks!

Well lets first be clear here. Your first graph didn’t specifically attempt to show “Milankovitch forcings”, it was titled “Insolation at 65N Summer Solstice”. There’s a subtle difference here in that insolation is (presuming this theory to be true) the result of a mixing of these multiple orbital-mechanics frequencies. I presume this graph to mean exactly what it says, exposure to the sun at 65N at summer solstice, which does not show all frequencies contributing. Since the periods of glaciation cannot fully be accounted for by the blended “forcing”, it is silly to limit ourselves to just the single blended Milankovich cycle “forcing” and say, “well it’s going down, so this warming cannot be natural.” . Second, your plot didn’t show 100kyear on each side, it showed 800, making your meaning of a “trend” in the plot to mean either an overall trend over a 1.6 million years (half of which are in the future), or you mean to look at the “now” and say, “well it’s going down”, with that very bad resolution. It would be nicer to have a plot closer to the present day, with fewer data points plotted, and ALL of the presumed orbital forcings present in some form, not just the combination.
I found this one, which I again don’t like as it only shows the “overall forcing” cycle:
http://www.climatedata.info/Forcing/Forcing/milankovitchcycles_files/BIGw02-milankovitch-and-temperature.gif.gif
It also comes from a blog source, so look at it with whatever salting you like. What is interesting though is that you see the drop in the cycle started long before Humans ever started pumping CO2 into the air, yet the temperature (as shown in the plot) did not follow. So while the Milankovich cycles aren’t a full explanation as to what the temperature will be in some future date (or the past), they’re at least not so obviously wholly disproven by Hansen’s own reasoning that ‘because the cycle is dropping, only mankinds influence is keeping it warm.’ It simply isn’t CO2, and Hansens usage of the M-cycles to prove his point are amateur at best.

I think that most people who review the Vostok ice core data and argue that the increase of temperature is caused or not caused by CO2 miss a very important detail. Rather than fixating on the rise of the temperature, study should be concentrating on the decline into the glacial period. Although the increase of temperature and CO2 have similar derivatives the decrease in temperature is precipitous compared to the slow decline in CO2. IMHO this is the proof that temperature change is independent of CO2 and that CO2 follows temperature. This fact seems to agree with The Monster’s reasoning.

“”””” redneck says:
January 24, 2011 at 6:13 am
@ Lief Svalgaard
Although the insolation during the NH winter is significantly higher is it possible that the lower angle of incidence, due to axial tilt, and the higher albedo, due to snow and ice cover, more than compensate for the higher insolation. “””””
What Leif said is absolutely true; the total insolation is highest during Northern Winters since earth is closest to the sun then. So the total Watts (rate of energy input) or the total Joules received by the eath in one 24 hour day (I don’t care which type of day you choose), is greatest during Northern Winter.
BUT !!
That greater energy input is falling mostly on the Southern hemisphere; not on the Northern hemisphere, because of the axial tilt.
So Southern Hemisphere summers receive more solar energy, and Southern Hemisphere winters receive less solar energy; because then the sun is further from earth.
And since the Southern Hemisphere is mostly ocean, which has a low albedo contribution, then I imagine that the earth stores much more solar energy during Northern Winters (Southern Summers) than the other way round.

Nylo says:
January 24, 2011 at 7:49 am
First, I am a skeptic, regarding the effect that CO2 may have in our climate, which I think it is probably very little. I am only not a skeptic regarding where the current increased CO2 concentration in the atmosphere has come from.
Oceans are a sink when their temperature is too cold for the amount of atmospheric CO2, meaning they tend to absorb CO2. They have been a sink in the past, in periods of cooling, when the change in their temperature made them more capable of absorbing CO2. They have been a source of CO2 too, in the past, in periods of warming, as the Vostok ice cores show, again because of their increasing temperature making them less able to have CO2 dissolved.
======================================================
Ok, I’ll buy that, but what I don’t buy is how you know this process isn’t occurring now. Later, you state, “The oceans’ role as a source or a sink depends mostly on 2 things: the ocean’s temperature and the existing atmospheric concentration of CO2. A “sudden” (in geological terms) increase of the atmospheric CO2 like the one we have caused breaks the balance between the CO2 concentration in the oceans and in the atmosphere, making CO2 go to the ocean. The ocean acts like a sink. IF the CO2 concentration was now 280ppm instead of 390ppm, the oceans would be acting as a source and not as a sink, given the increase of temperatures. But because the atmospheric concentration is so high, even though the oceans are a little bit warmer now, they are still absorbing CO2.”
I have a problem with this. Your use of the 280ppm number implies you believe that to be the “normal” atmospheric concentration. I don’t believe this has been demonstrated. What of the Ordovician- Silurian and the Jurassic-Cretaceous periods? Were the properties of CO2 and ocean waters different then? And, again, the question still is, where did the CO2 come from?(Some say the concentration was as high as 4000 ppm.) Given your explanation, how would increased atmospheric CO2 be inconsistent with coming out of the LIA? You speak of “geological terms”, but consider events during a 100 year time period as relevant? Isn’t that like saying the average daily temp for the world is 55 degrees and expressing alarm when the days high temp reaches 100?
Nylo, at the end of the day, I think the explanation you gave is as credible as Hertzberg’s. But both have questions that need to be answered before they should be asserted as factual.(IMHO) But I do thank you for the time you took to give a greater explanation of your perspective.

@hr says:
January 24, 2011 at 4:55 am
Well that is really a point of debate. What were the CO2 levels in the past. There are in fact many reasons to think they were in fact similar to today.
Plant stomata records indicate the high 300’s as a likely figure.
The idea we can reconstruct with reliability the CO2 levels of the past from ice cores is seriously flawed. The compaction rate of ice fern, (measured in hundreds and thousands of years to closure to the air), the isotopic fractionation issues, the actual depth to age relationships, all have massive error bars associated with them.
Not to mention using pelagic fauna for CO2 and sea water temp reconstructions. Well, they are pelagic, (free swimming), and tend to move up and down the water column in oceans in response to temperature fluctuations rather than revealing the absolute temperature.
The stomata records, paper on WUWT somewhere, seem to be much more interesting with regard to CO2 levels in the past.
That’s not even considering the fact that there is an a actual limit, (even if you take the CO2=warmer hypothesis as “the truth”), of CO2 forcing, the curve for insolation is strongly asymptotic.
Up to around 250, there is a strong warming from CO2, after 300, it is pretty much all done and the increase in temperature, (though I strongly dispute the positive feedback AGW followers suggest exists), are so fractional as to be meaningless.
Perhaps I will find the time to submit a post on ice cores, paleoclimate is a special interest of mine 🙂
Albert Frankenstein.

Well it should be possible to construct a theoretical model; even a simplified one; say no relativistic stuff; just plain Newtonian or Keplerian model of earth’s orbit around the sun, using the current values of orbital elements (ellipse focal length and eccentricity) and take some solar cycle average value for the sun’s total emittance (maybe black body equivalent), and then simply calculate total earth intercepted energy for each day of the year. How difficult is it to make a table of 365 or 366 tabulated values; based on some mathematically tractable and simple eliptical orbit. Why doesn’t such a table exist; or be publshed in say books on solar energy for example. I don’t recall that you need elliptic integrals to calculate that sort of thing; and if you do, then all the more reason for someone to make a table. I’m not going to, because there’s a whole raft of mathematicians out there wasting their time doing trend lines and r^2 calculations, who should be more mathematically fleet of foot than I am. And I’m only casually interested in the result; because I think there are bigger fish to fry.
Does it not seem odd to you, that Ice Core records, such as Vostok, or Dome C, and the other deep ones, apparently record the last 8 or so ice ages, and interglacial periods; but they also document the simple fat that over that entire 400,000-800,000 year time frame, that Antarctic ice melted has NEVER completely melted or slid off into the southern ocean; yet these Glacial Researchers du jour, keep on telling us how high the sea level is going to rise, when something that has never yet happened in the last million years, suddenly happens.
It seems that we know from the record at Vostok; for example the existence of Vostok Lake, that the bottom of the ice sheet in contact with the ground, must be constantly melting from internal heat from the earth. And that melt water would either pool in lakes like at Vostok, or else it will runoff through river systems, eventually into the Southern Ocean. And this could have been going on for millions of years. I don’t know how long the Geologist Tectonites believe that Antarctica has been roughly where it now is; but that ice sheet could have been there for many millions of years; we are just seeing the last million years or less of what is left after the earlier layers melted and disappeared. I don’t believe that the bottom of the Dome C ice coresw, was deposited on or near bed rock, 800,000 years ago. It probably was deposited on two miles of thick ice, that has long since melted.
But why do they keep telling us the whole thing is going to slide into the sea; it hasn’t ever happened in any time frame of interest to us; and isn’t going to happen in any time frame of interest to our descendents.

Leif,
I think you’re referring to peak to peak (min/max) power TSI at TOA.
What is the total power to the NH during ‘summer’ versus what what is the total power to the SH during SH ‘summer’ as defined by the equinoxes and by the incoming power along the orbital path for that time.
The claim is that the extra days make up for some of the power levels.

It is encouraging that Dr. James “Thumbs On The Temperature Scales” Hansen acknowledges the work of Milankovich. Perhaps in the not-to-distant future TOTTS Hansen will also acknowledge Landscheidt’s Impulse Of the Torque (IOT) and oscillating transferrence of angular momentum and spin orbit coupling between the Sun and planets, which totally explains the oscillating climates on these bodies. To not acknowledge these titanic forces and spend all your time analyzing a trace gas as the driver of climate is ignoring the elephant in the room to the exclusion of the flea on the elephant’s ass.

John Day says:
January 24, 2011 at 3:50 am
“The seasonal difference in solar irradiation is about 100 watts per square meter, much larger than the CO2 and other GHG “forcings” that we read about. So the more time spent at the lower insolation means more climate cooling effects. Right?”
But, that difference is mostly due to lower projected surface area due to tilt, not due to the extra distance. The distance to the Sun is about 150 million km. The radius of the Earth is 6378 km. Multiply that by the sine of the obliquity and, noting that irradiance decreases as 1/r^2, the reduction in isolation at the North Pole during winter is 0.0034%. But, the reduction in exposed surface area is something like 8%.
oMan says:
January 24, 2011 at 4:24 am
See above.
hr says:
January 24, 2011 at 4:55 am
“I suspect most well-informed people, including sceptical climate scientists, would prefer the latter explanation.”
Who cares what they might or might not prefer? What are the reasons to prefer it?
Nylo says:
January 24, 2011 at 5:14 am
“Knowledgeable scientists have become convinced long ago that the source of the current increase of atmospheric CO2 is human, and that oceans are currently a sink for CO2 because of the imbalance of the concentrations created by our emissions.”
A little knowledge is often dangerous.
“It wasn’t like this in the distant past, when there weren’t human emissions.”
We do not know that. We only have open ended experimental ice core data which cannot be verified.

Hertzberg say “What Hansen fails to realize is that when we are further from the Sun in NH summer we move more slowly in orbit, and are therefore exposed to the summer sun for a longer period of time.
From the graphs in the web-site http://individual.utoronto.ca/kalendis/seasons.htm , one can calculate that in 2010 the NH summer half of the earth’s orbit from the Spring Equinox to the fall Equinox lasts 186.1 days. The NH winter half of the orbit lasts 179.0 days. So the summer half gets 7.1 more days of solar insolation than the winter half. (Go to your calendar and count!)”
Rebuttal from Bob Maginnis
OK, then 186.1 / 179 = a ratio of 1.0396 to 1, but using the summer and winter distances from the Sun and knowing that radiation will be the inverse square of the distance, then:
152,097,053 km / 147,093,602 = 1.0399 to one, BUT, we must square that to get a ratio of 1.081, compared to a ratio of days at 1.0399, so Dr. Hertzberg wouldn’t have gotten his doctorate with such sloppy thinking. BTW, I only calculated for the solstice or near solstices, but Hertzberg still flunks physics.

What Hansen fails to realize is that when we are further from the Sun in NH summer we move more slowly in orbit, and are therefore exposed to the summer sun for a longer period of time.
…………………………………………………..
This is an excellent point. However, it does cast some doubt over the entire Milankovitch theory per se, since it would imply that contrasts in insolation between the seasons at times when the Earth’s orbit has a high eccentricity would be lower, and therefore less likely to force transitions to and from glacial and inter-glacial periods.
My own take is that rapid (in geological terms) transitions between solar insolation maxima and minima at high latitudes is the crucial element :
For example, daily insolation anomaly values at 60N peaked at +120 during the last interglacial (125K yrs BP), but fell to -80 just 10K years later, before rising to +100 at c.105K years BP.
During this time, the climate appeared to “flip” between inter-glacial to glacial and back to inter-stadial again.
Between 85K BP and 70K BP there was another rapid transition from +80 to -40 which, possibly combined with the huge volcanic eruption of Toba (c.74K BP) coincided with a transition to glacial conditions which persisted until :
Another rapid transition from -20 during the last glacial maximum (23K BP) to +80 at 10K BP “happened to coincide” with the end of the last glaciation and the beginning of the current inter-glacial period.
Feedback mechanisms associated with the building (disintegration) of continental ice-sheets and falling (rising) of sea-levels also play a crucial role, IMO.
The building of continental ice sheets profoundly changes the topography of the NH, perhaps to a similar extent that the formation of the Himalayas and the Tibetan Plateau did, – before which there is little geological evidence for ice sheet formation in the Northern Hemisphere. Consider the effect that raising the Canadian Shield to 10,000 feet above sea level would have on today’s climate………..
A sea-level fall (rise) of 150m is, in itself, enough to cause land temperatures to fall (rise) by 1C – a considerable amount. You also have to consider the possible feedback effects of, for example, the building of the Bering Strait land bridge, which sealed the Arctic Ocean off from the influence of the Pacific. Potentially at least, that one event could have had huge implications.
Could GCM’s not be used usefully to try and quantify the effects of these processes?

“Multiply that by the sine of the obliquity and, noting that irradiance decreases as 1/r^2, the reduction in isolation at the North Pole during winter is 0.0034%.”
Or, would be, if the North Pole were in daylight. So, there is greater reduction due to shadowing, but that is part and parcel of the reduced area argument, and not significantly a result of increasing distance from the Sun.

The polar ice-core data indicates that CO2 levels follow temperature changes.
CO2ppm hvae varied between ~200ppm during cold periods to 300ppm when it warms. The CO2 level follows temperature up AND down with a lag.
This ~100ppm change in |CO2 levels flows a temperature change of ~8degC
The physical chemistry of CO2 solubility in sea water is complex, but it is within human knowledge to calculate the amount of CO2 which will be dissolved or released for a given temperature change or partial pressure of CO2.
Whatever figures you take for sea surface temperature rise, and how ever much of Tenbreth’s missing heat you put into the deep ocean to warm it and reduce the solubility since the LIA you can’t get to here from there
The rise in temperature isn’t enough to account for an increase of around another 100ppm when it takes ~8degC to do it during ice-age transitions.
But the increase in CO2 levels works against the release of CO2 from oceans as they warm. The effect of increasing the partial pressure of CO2 is greater than the effect of warming the oceans.
After all when they are putting the CO2 into the bottle of soda they put more effort into increasing the pressure of CO2 than in cooling the soda.
And some may have noticed that if the bottle is at room temperature the bubbles don’t appear until after the pressure is released.
Works with beer too…

George E. Smith says:
January 24, 2011 at 10:49 am
Well it should be possible to construct a theoretical model; even a simplified one; say no relativistic stuff; just plain Newtonian or Keplerian model of earth’s orbit around the sun, using the current values of orbital elements (ellipse focal length and eccentricity) and take some solar cycle average value for the sun’s total emittance (maybe black body equivalent), and then simply calculate total earth intercepted energy for each day of the year.
I wrote a simple Newtonian simulation model of the solar system a couple of years back (it got briefly wheeled into battle on these threads during the “barycentre” affair). I used NASA data to initialise the planets. And I set up a spinning earth too, complete with a map of the continents.
It’s not very accurate and has a number of bugs that need fixing, but I occasionally think of dusting it off and developing it further in a variety of ways. One of those has been to take a look at Milankovich cycles.
Unfortunately it’s too slow and inaccurate to be able to leave just leave it running for 100,000 simulated Earth years. And anyway I don’t understand how to model variations in the Earth’s axial tilt and obliquity and precession (t, o, p).
But… thinking about it today, it seemed to me that if I could find out how all these things (t, o, p) varied I could run the simulation for one Earth year with the requisite values of t, o, and p at 1000 year intervals. And I could use my tilted spinning earth to total up incident solar radiation over a range of latitudes.
But what would I find, and what would it tell me? I suspect that I’d come up with some small cyclic variations in surface heat gains which would be Milankovich-like. How would those variations translate into glacial and interglacial periods? Or would I have to build a simple climate model as well? My understanding is the forcings due to these variations are pretty small, and as yet don’t fully explain glaciations.

@-Bart says:
January 24, 2011 at 2:46 pm
” And, if I do not understand it under my assumptions which are non-negotiable, then it cannot be, quod erat demonstrandum.”
…Fixed that for you.”
Actually my assumptions ARE negotiable.
All it needs is evidence rather than latin tags.
Got any evidence for a mechanism to release as much CO2 from the oceans in the last century as it took 8degC and ~1500 years of warming from the ice-age?

Bob Maginnis says:
January 24, 2011 at 12:29 pm
“Rebuttal from Bob Maginnis
OK, then 186.1 / 179 = a ratio of 1.0396 to 1, but using the summer and winter distances from the Sun and knowing that radiation will be the inverse square of the distance, then: 152,097,053 km / 147,093,602 = 1.0399 to one, BUT, we must square that to get a ratio of 1.081, compared to a ratio of days at 1.0399…”
That is the wrong calculation. You need to integrate something proportional to 1/r^2 over each half of the orbit, such as:
P = integral(dt/r^2)
For a Keplerian orbit, dP = dtheta/(thetadot*r^2) = dtheta/h
where theta is the orbit angle (true anomaly) and h is the orbit momentum. Hence, integrating over the two halves of the orbit gives you pi/h, i.e., the ratios are 1:1. So, both you and Hertzberg are wrong. But, so is Hansen.
izen says:
January 24, 2011 at 4:36 pm
“Got any evidence for a mechanism to release as much CO2 from the oceans in the last century as it took 8degC and ~1500 years of warming from the ice-age?”
Firstly, you have already assumed you have an incontrovertible record for what happened with CO2 over the last 1500 years. I maintain that you do not. Secondly, the onus is not on me to prove that your hypothesis is wrong, it is for you to prove it is right.

@-Bart says:
“Firstly, you have already assumed you have an incontrovertible record for what happened with CO2 over the last 1500 years.”
I don’t consider the record, direct from ice-cores and indirect from geochemistry, is incontrovertible.
I am not aware of any strong evidence that calls that data into question. If you have a reason for dismissing the confluence of evidence for the record we have perhaps you can present it. (please don’t cite Beck!)
And I doubt the basics of physical chemistry that govern the solubility of gases has altered.
“Secondly, the onus is not on me to prove that your hypothesis is wrong, it is for you to prove it is right.”
Proof is for maths and liquor.
I have a hypothesis that is falsifiable, although I have yet to see any evidence that refutes it.
I can present evidence that supports it.
A lack of an alternative falsifiable hypothesis does not confer upon you the ability to reject mine.
A strong alternative or even evidence that falsifies mine does.
Not word games with provability.

Alan McIntire
Thank you for the maths. I wish more policy were made using it.
“So about 1000 times as much heat went into melting the glaciers at the end of the Pleistocene as went into heating the atmosphere, implying CO2 had only a negligible effect”
We should be grateful that 1000 times more heat is being used to melt the arctic ice than its atmosphere. Latent heat used to melt the ice seems to be acting as a brilliant buffer against the warming of the arctic sea and arctic air. I only worry about what will happen when this buffer melts. All that heating will have to go somewhere. Are my worries justified. Everything seems so gloom and doom!

izen says:
January 24, 2011 at 5:41 pm
“And I doubt the basics of physical chemistry that govern the solubility of gases has altered.”
That is the sort of statement which tells me your mind is closed. You don’t really care how CO2 is fixated in the ice or how it diffuses over time, effectively low pass filtering the data and eliminating sharp peaks or rapid cycles. Somebody told you it was a reliable measurement, and you believed them. To the depths you have plumbed, the explanation is consistent with simple models which you can understand so, end of discussion.
The epochal evolution and regulatory systems of the Earth are not simple, and if you think a simple argument or lab experiment proves your point, then you are evading reality.
“Proof is for maths and liquor.”
So saith the Shepard, so saith the Flock! Burn the witches and torch their houses. Who can wait for proof when we have fear to guide us?
If you want my take on the topic and why I believe the evidence is distinctly lacking, you can read through the thread here.

Thanks Jeremy@January 24, 2011 at 8:45 am for supplying a link to Milankovitch forcing at 65 degrees north – apparently the latitude that the forcing corresponds most closely with the beginnings and endings of ice ages. However, the graph shows exactly the same information as the Wikipedia one – that there has been a steady decline in the Milankovitch forcing since the start of the current interglacial. And there has been a steady decline (with bumps) in temperature over the same period. Hansen says exactly this, and gets taken to task for not understanding stuff. Anyway, it would be pointless to go on about this, other than to ask Hertzberg to provide his calculation of orbital forcings over the last 10,000 years.
We appear to be at the start of a gentle increase in orbital (Milankovitch) forcing.
BTW, for those of you wanting to calculate the orbital forcings from first principals, I’m pretty sure its already been done. How else could Hertzberg know that Hansen is wrong?
The general denigration of Hansen is ridiculously over the top. There is an advertisement currently showing in Australia which starts by saying something like, “Sean of Sydney writes, ‘My gran could bowl Shane Watson'”. The scene then moves to a cricket oval with Sean’s gran bowling to Shane Watson, who proceeds to clobber the ball for six. The commentary then says, “Perhaps you meant your other gran, Sean”. The typical criticism of Hansen in this blog is rather similar to Sean of Sydney’s criticism of Watson.
And thanks Bart for your excellent comments, particularly the one at January 24, 2011 at 2:46 pm.

Lucy,
That’s interesting reading about Venus. It is not at all surprising to me. The only astronomer who would be slow to consider this result wold be those who have a stake in not looking the fool. Any real scientist would be excited by the new understanding to be gained about planetary formation.

If you want actual computations of the insolation over time and latitude, Peter Huyber’s web site at eps.harvard.edu has them. Be aware that nobody has ever been able to produce a quantitative explanation glacial-interglacial climate change by using orbital forcing alone – or even come close. There are a number of reasons – the magnitude is too large, the change is (to zero order) symmetric in both hemispheres, the 23 and 41 kyr orbital forcings are greater than the 100 kyr forcing, but the 100 kyr period dominates the last million years, etc. The work that does the best job of simulating both the onset and end of ice ages includes orbital forcing, CO2 feedbacks, and ice sheet dynamics. In direct contradiction to the claim in the original post, climate models can indeed produce glaciation at 280 pm CO2 (the “warm” interglacial value), triggered by insolation variations but amplified by ice sheet, CO2 and albedo feedbacks. There is simply no basis for the statement about “everlasting glacial warming”. The author is presumably not familiar with the literature, otherwise he’d never say something so far off base.

Here is the crucial mistake in Dr. Martin Hertzberg’s post – “Exposure time in this case is more significant that daily insolation caused by our further distance during the NH summer”.
This is incorrect. A basic understanding of the Milankovitch cycle concerned, together with some fairly simple maths involving Kepler’s laws of planetary motion, would tell you that total annual solar insolation is not effected – distance from the sun and the length of the seasons effectively cancel each other out.
So when Dr. Hertzberg says “…the summer half gets 7.1 more days of solar insolation than the winter half…”. – “daily insolation caused by our further distance during the NH summer” cancels out this effect. Total annual solar energy received by the earth is NOT effected. The whole point is how this solar energy is DISTRIBUTED throughout the year/seasons.
This is fairly basic stuff. It betrays either a complete lack of understanding or willful distortion. Was this article peer reviewed by experts in the field before publication on this site? I think not. Dr Hertzberg is completely and utterly wrong. I find it quite depressing that this has been published as fact and then uncritically praised by readers in the above comments. Although as Louise hints at in an earlier comment, the opening couple of paragraphs of the post should have warned me that this was nothing more than a anti scientific rant.

Regarding the first part of this piece, see Tamino’s rebuttal.
Regarding the CO2-lags-temperatures argument: Do we really have to go through the “blanket” analogy again? CO2 is not a source of incoming energy – it merely reduces the rate at which energy escapes to space, shifting the equilibrium, but not annihilating long cycles.
Imagine that you have a heater that works for a few days, then stops working for a few days, then works again, etc. Putting a huge blanket over you and the heater will definitely make you warmer during the times the heater is working (that is, warmer than you would have been with just the heater and no blanket). Try it!
However, when the heater breaks down, the blanket will allow you to remain warm a little bit longer, but in the end the heat will still escape away, and you will end up just as cold as you would have been without the blanket.
So a “heat retainer” will increase the warmth from incoming energy, but will not create energy out of nothing when your energy source goes down. Is it really so controversial?

Tamino is correct. But we must add in the final piece of the puzzle, obliquity. Interglacials only begin when NH summers are approaching perihelion, earth’s orbit is more elliptical AND obliquity is approaching it’s maximum tilt. Because the periods of these cycles are not equal interglacials do not happen unless all three favorable conditions are present.

Sorry. Pet peeve.
We are farther from the sun. Not further.

Obviously it’s not foolproof – but my little book of skepticism says that if someone is flaunting their academic credentials on a subject outside their area of competency – ie Dr Martin Hertzberg – then it’s time to put my extra woolly skeptic hat and ear-muffs on.

“…kept at medium heat…”

Bart said… “John, that’s a double edged sword. From my perspective, it’s the climate scientists whose field of study is at an infant stage, and who overestimate their understanding of a very complex system.”
Somehow I don’t think that 150 years of science qualifies as a field of study at an infant stage. Don’t forget much of the physics of atmospheric radiation was worked out by the US military in the 1950’s for work on heat seeking missiles.

Apologies if some of the above had already been answered (and I just saw an ice age comment.) I had only read through about half the comments when I wrote that.

Which is longer, a piece of string, or a piece of rope? Are you serious Bart?
Total solar insolation is NOT effected, it’s distribution throughout the seasons IS.
You seem to have an apparent familiarity with a sense of your own self importance. Maybe you would like to submit a paper regarding your expert knowledge to a prominent scientific journal for peer review?

Quentin says:
January 25, 2011 at 10:51 am
“Which is longer, a piece of string, or a piece of rope? Are you serious Bart?”
It depends on which is longer. I think the kettle analogy is rather more transparent, as most of us have at least a vague sense for the thermal time constants of liquids we typically heat on the stove.
“Total solar insolation is NOT effected, it’s distribution throughout the seasons IS.”
Or even affected. Yeah, I derived that result before Tamino, Sparky, at January 24, 2011 at 5:01 pm above. But, what you do not seem to grok is that the energy retained by the Earth is affected by that “distribution throughout the seasons”.
“You seem to have an apparent familiarity with a sense of your own self importance. Maybe you would like to submit a paper regarding your expert knowledge to a prominent scientific journal for peer review?”
Been there, done that. Not in climate science specifically, mind, but in something rather more rigorous and mature, and sorely needing to be applied in that field.

While I knew about the proximity of earth to sun in the Winter (NH), I never counted the days to figure out if there were more days in the summer!
I’ll take the more days! But it is things like that, while obvious to some such as Dr. Hertzberg, that come as enlightening moments to the less observant of us. Thanks!

P.S. Thanks for correcting my spelling mistake.

Bart says:
January 25, 2011 at 1:18 pm
“Hence, I think it is likely that Hertzberg is right that it is the duration which matters more than the distance, and Hansen and (shockingly – well, maybe not so much) Tamino are wrong.”
Having thought this over, I would like to retract this statement (except for the gratuitous knock against Tamino, whom I consider insufferable, dogmatic, simplistic, and opposed to the free exchange of ideas). I used too simple a model ;-).
Quentin says:
January 25, 2011 at 1:47 pm
“But what are you really trying to achieve ? Are you trying to achieve a better understanding? Are you trying to further the scientific endeavor?”
Yes, and yes. I believe the rush to judgment has been premature, ridden with confirmation bias, cherry picked data, simplistic models, and squelching of honest debate. I see a lot of conjecture accepted as fact. I see evidences which do not fit the narrative which have not been addressed. I have learned the hard way, over a lifetime of experience, that computer models don’t mean a damn thing if they haven’t been verified with extensive data taken from the real world covering a sufficient time interval to observe all the major processes.
izen says:
January 25, 2011 at 2:05 pm
“I would agree with much if not most of what was posted by Joel and especially Ferdinand. “
What a shock.
You appear to have missed my main points to Ferdinand and Joel:
A) the apparent but superficial similarity between the curves quantifying CO2 measurements and accumulated emissions is in no wise remarkable or dispositive
B) the emissions data contains cycles which do not appear in the measurements of CO2, which is impossible if the emissions data are reasonably reliable, and if they are not, then even the superficial similarity between the curves is open to question

Nylo says:
January 25, 2011 at 4:13 pm
“Won’t there be an update to this post now that Tamino has clearly debunked its claims?”
Has he? I think he has merely made a conjecture. Temperatures may peak higher in summer at perihelion, but the higher temps last longer at aphelion. Ice melts at 0+eps degC regardless.
I think there needs to be a great deal more analysis done, or references to such analysis provided, to settle this dispute. Can you explain why you believe otherwise?

Quentin says:
January 25, 2011 at 1:47 pm
“Are you trying to further the scientific endeavor?”
One other thing you might consider, Quentin… If this thing comes a cropper, if temperatures fail to rise or, God forbid, I am right and CO2 will eventually begin to decline all on its own, can you imagine the damage that will be inflicted to the name of “Science”?
Can you just hear the Creationists smirking, “yeah, well, you sure got that Global Warming thing right, didn’t you?” We’ve already got swaths of people refusing to inoculate their children based on incoherent fears that it somehow causes autism. The list is endless. It’d be a complete disaster. The scientific community is betting the ranch on this thing. Personally, I’d prefer better odds with such high stakes. Any responsible scientist, with experience confronting the twists and turns of pernicious Nature, should.
Adam R. says:
January 25, 2011 at 5:08 pm
Adam, I will ask you, too. What is your evidence that Tamino is right beyond his say so? How about asking for a response from Hertzberg before pronouncing him guilty? (Trial first, verdict after. What a concept!)

Well the earth goes around the sun in one year; pick your favorite year; the one that gets you back to the same point in the orbit; discounting the precession of the perihelion; which is quite small for earth.
In that time frame, which pretty much repeats time and time again, year after year, the earth pretty much repeats its path at the same distances from the sun; not exactly at the same time on the same calendar date; but close enough.
So we know enough to calculate to total energy received by the earth in the form of solar radiation with a little bit of variation for solar outbursts and the like; but not much of anything in it.
To a first order; the total energy from the sun received by earth, repeats year after year. There are small changes as to where it lands on earth due to the fact that the orbital year is not an integer number of days; and for the same reason, on each and every calendar date, the rotation angle will not be the same, so again the radiation beam will shift slightly; but who wants to complain about the very small year to year differneces in the toal amount of that solar energy that say enters the deep oceans, for example.
So you can fiddle with the seasonal changes all you want; the total energy incident on the earth (extra atmospheric) doesn’t change from one year to the next (by anything to worry about). And since the earth’s atmosphere is well mixed; well then that energy ought to spread around until it replicates Kevin Trenberth’s cartoon energy budget.

Smokey says:
And no, I won’t go to tamino’s blog. In general, he’s not very credible.

You prefer, evidently, to take Hertzberg at face value and not be troubled with possibly contrary facts. Wonderful loyalty, sir. You deserve another ribbon on your choir robe.

Adam R. says:
January 25, 2011 at 7:02 pm
“You prefer, evidently, to take Hertzberg at face value and not be troubled with possibly contrary facts.”
Pot, meet Kettle. Did it occur to you, Adam, that Tamino’s response, which boils down to “it’s hotter on midsummer’s day, ergo there is more melt”, is incomplete at best? So, it’s (for the sake of argument) hotter on midsummer’s day. So what? What matters is, how high the temp is above zero degC, how long it is there, and the rate of melt as a function of temperature. In the reductio, if it were 30 degC on midsummer’s day, but -2 degC the rest of the summer, that will cause less melt than if it were 20 degC all summer long.
This is a typical Tamino analysis – enough info to get the choir singing, but not enough to make a genuine point.

Milankovic Cycles and Climate Change
Is it distance from the sun, or length of summer?
By Ed Caryl
A draft paper by Dr. James Hansen and Dr. Makiko Sato triggered a rebuttal by Dr. Martin Hertzberg on WUWT. The Hansen paper made a claim that weaker insolation in the Northern Hemisphere (NH) due to distance from the sun in NH winter should lead to cooling, but that this is offset by increasing CO2.
The Dr. Hertzeberg rebuttal claimed that the warming was due to the longer length of summer in the NH. Both are wrong! Both are victims of Confirmation Bias, seeing only data that confirms their beliefs.
http://notrickszone.com/2011/01/25/milankovic-cycles-and-climate-change/

I read Hertzberg here, and Tamino, and Tamino seemed more competent to me. Of course I could be wrong, as I don’t know so much, but Hertzberg seemed to be more of a handwaving argument, while Tamino seems to be saying, “Do the maths, and this is what you get”. When talking about quantitative things I prefer maths to words.

Tamino wins. Hands down. Sorry. Hertzberg doesn’t do the analysis appropriately and it shows.

Robert says:
January 25, 2011 at 9:16 pm
“Hertzberg doesn’t do the analysis appropriately and it shows.”
Neither does Tamino.

Keith Battye says:
January 25, 2011 at 10:58 pm
You Tamino myrmidons are really out in force tonight, aren’t you? A complete lack of critical thinking skills. Just sad.

@-Bart says: You appear to have missed my main points to Ferdinand and Joel:
“…
B) the emissions data contains cycles which do not appear in the measurements of CO2, which is impossible if the emissions data are reasonably reliable, and if they are not, then even the superficial similarity between the curves is open to question”
No, I saw that, but the fact that emissions are twice the measured atmospheric rise so that it is logicaly inescapable that they are a component of any measured rise is conclusive IMO.
The fact that the variations in emissions are also below the annual variation in bio-productivity and sinks also means as far as I can see that it is inevitable that emission variations are swamped in the measured rise by the interannual variations.
Back on the Milankovic cycle dispute;
The ‘standard model’ attributes the influence on the climate to the intensity of the insolation at high Northern latitudes, conventionally 65N, during summer. The duration of the seasons is not considered to be much of a factor. This based on observations and the hypothesis that the summer melt is crucial, while winter temperatures just modulate ice accumulation rates.
This is NOT a popular misconception of the Milankovic theory, its is the shared version in the scientific community and I do not see that Hansen is contradicting that.
Hertzberg is suggesting an ALTERNATIVE hypothesis about the influence of the Milankovic cycles, that the duration of the seasons is a factor. I dont see any observational or physical processes put forward that supports his contention.

“…emission variations are swamped in the measured rise by the interannual variations.”
On this, in particular, in interannual variations are at a completely different frequency. They cannot “swamp” anything at another frequency. What matters is the noise floor. Look for that phrase in the thread where I discuss why it is important.

“I dont see any observational or physical processes put forward that supports his contention.”
It should be self-evident that both temperature and duration of its application affect quantity of glacial melt. The question is, which dominates? Hertzberg asserted duration. Tamino did some math to say they were equal, then bizarrely proceeded to assert that temperature dominates. And, you guys lapped it up like he had succeeded in some ingenious proof. I guess you were dazzled by the integrals. Note to Hertzberg: next time, throw in some integrals.

I feel confident now in reasserting a modified version of what I stated at
January 25, 2011 at 1:18 pm. If the dominant thermal time constant (assuming there is one, or constants if there are perhaps several significant ones) is on the order of days, which it almost surely is, then I believe it is likely that Hansen/Tamino are wrong, and Hertzberg is right. This comes about because the thermal time constant acts as a low pass filter which does not so much affect the slowly changing insolation around aphelion, but beats down the faster changing peak at perihelion.
My analysis is admittedly coarse, based on my knowledge of all the factors involved. It is perilous to project the behavior of complex systems based on simple models without direct observations to confirm it. So, I am not proclaiming my hypothesis to be “truth” absent that. Nor am I going to seek some ridiculous measure of assurance based on whether some other “authority” of unexamined qualifications agrees. The reader would be well advised to be wary of people who proclaim 100% assurance based on such criteria.
I am merely making a truthful observation without assertion based on known facts: thermal processes are typically low pass, and the insolation at perihelion progresses more rapidly, hence heating will be attenuated by the low pass response. Were it not, the math presented by both me and by Tamino argues that the energy input, and hence the glacial melt, would be approximately equal overall. Any thinking person who can process information logically would conclude that Tamino is out on a limb.

@-Bart says:
“his is known as ad verecundiam argumentation, izen. It is one of the fundamental, classical logical fallacies. Milankovic cycles are not in any way, shape or form cut and dried and laid to rest. Again, you have the problem that there is no closed loop, no control experiment you can do to replicate the condition.”
You are misconstruing my argument here, its not from authority.
As always what Nature does comes first. (and last)
The OBSERVATIONS indicate that glacial cycles closely match Milankovic cycles. The timing, magnitude and rate of ENERGY delivery (not temperature) at 65N is the largest variable that most closely correlates with the observed climate behavior. When I then give the ‘standard model’ explanation for that observation I am NOT claiming that the standard model is correct because some overriding percentage of scientists accept it. I am showing that what Hansen has referenced with the short paragraph that caused Heretzberg to characterize him as a propagandist is not ‘a popular misconception’ but the explanation of observations that is in current use.
Given the observations, the description of the system, the usual procedure is to look for physical processes to provide an explanation of the systems observed behavior. The present explanation MAY be replaced by a better one. But I see no evidence that Hertzberg attempts to provide one. He just seems to disparage Hansen for using the current explanation.
Re; A-CO2 emissions variations swamped by seasonal cycle. –
“On this, in particular, in inter-annual variations are at a completely different frequency. They cannot “swamp” anything at another frequency. ”
Okay I take your point, it was badly expressed on my part. Because the magnitude of seasonal variations is greater than changes in A-CO2 emission rates I would not expect the system to show a close correlation between input and output for those variations.
I compare this to what is admittedly a MUCH more complex system, but it gives me a ‘metaphor’ at least for how such a system might behave.
If someone has a increased intake of calories then I would expect that they would put on weight faster and to a level not seem before . There may be other metabolic factors that link weight to cal. intake, but while these may cause small variations I would expect to see a first order correlation between calorie intake (CO2 emissions) and weight. (CO2 levels) I would not expect minor variations in cal. intake to show up in matching variations in weight. The observed small scale variability shows there are storage/dissipation processes that can impose variation, or suppress it.

Bart says:
January 26, 2011 at 11:02 pm
“I am telling you the way natural systems work, izen. This is non-negotiable. It is known. The input must show up in the output.
…If you want to understand the issues better, I suggest you study frequency domain analysis and estimation of power spectral densities. I mention this because your talk of “correlation” suggests to me that, like so many others, think that you can analyze cyclical systems using statistical techniques intended for simple polynomials whose measurements are corrupted by white noise. Those are the wrong tools, and that is precisely the kind of thing I was talking about at January 25, 2011 at 12:45 pm when I said “in something rather more rigorous and mature, and sorely needing to be applied in that field”.”
==========
I don’t doubt you have better math chops than me when it comes to analysis, but I would doubt your first assertion that ‘the input must show up in the output at all time domains and amplitudes in natural systems.
I can think of several biological systems where that is certainly not true and it is quite possible for a varying input to generate a smooth trend with its own independent inherent variations. The fact that the small variations in input do not show up in the output does not refute the contribution of that input to an observed trend. True such biological systems are much more complex than the A-CO2 => atmosphere, ocean and biosphere system under discussion here, but the presence of a biological component in this system give me some grounds for the suspicion that you cannot dismiss the causal link between the emissions and observed rise in this system.
Certainly not on the basis of the lack of detectability of variation in the observed atmospheric CO2 level that matches the variation in the emissions.
The attribution of maximum summer insolation at 65N during summer to glacial age warming is not arbitrary. It is the result of observation.
What causal chain links those two factors is open to question. But if you have an alternative causal parameter that you can derive from the Milankovic cycles and a physical process that explanians that link, then by all means provide it.

izen says:
January 27, 2011 at 8:54 am
“I would doubt your first assertion that ‘the input must show up in the output at all time domains and amplitudes in natural systems.”
I did not say amplitudes. You are putting your own words in my mouth. Yes, as I explained, every system has a frequency response which modulates the amplitudes as a function of frequency. If there are significant nonlinearities in the system, you also get harmonics of the input fundamental frequencies. But, such filtering must also obey certain laws in a causal system, to wit, as I explained, the lower the frequency you want to attenuate, the longer the lag between input and output.
“The attribution of maximum summer insolation at 65N during summer to glacial age warming is not arbitrary. It is the result of observation.”
The devil is in the details, buckaroo. Scientific investigation begins with observation, then hypothesis, then experimental confirmation. In this instance, as in the ice core samples of Co2, there is no avenue for conclusive experimental confirmation, and the hypothesis can not be proven given the available data. The math shows the effects of precession of the equinoxes are equal to first order.
“But if you have an alternative causal parameter that you can derive from the Milankovic cycles and a physical process that explanians that link, then by all means provide it.”
I gave you one. The smoothing of temperature due to thermal time constants means the peak temperature for perihelion is less than it otherwise would be. The entire waveform is attenuated and spread out. It is the spreading out that does it, because otherwise, the integrated temperature would still be the same over the orbit. But, there is a threshold of 0 degC below which ice no longer melts, so the spread out waveform translated into rate of melt gets chopped, and the integration is reduced relative to the summer aphelion case, so you get less melt. It actually is faster than I thought last night, though I still think the link I provided’s reference to other changes in orbital variable are probably more powerful. And, that’s another explanation for the different rates of melt: other processes, like the changes in orbital eccentricity and obliquity of the rotation axis.
Funny how you go on demanding I provide you with alternative explanations after I already have, but you are content with an airy dismissal of my observation that CO2 emissions spectra are not observable in measurement spectra.

BTW: I LOVE this contorted logic
“In fact, warming during the winter season has negligible effect on the melting of the ice sheet and, in fact, tends to be accompanied by higher precipitation, which favors ice sheet growth.”
So, a warmer winter causes more ice. Kind of like Global Warming causes record cold winters.
Here’s some direct counterevidence to your assertion:

“Rain is very corrosive to glaciers and at least in part the reason this glacier is retreating,” David Vaughan, a British Antarctic Survey glaciologist, said on an inflatable speedboat in a bay that had been blanketed by ice for thousands of years.

Joel,
What you lack in subtlety, you certainly don’t make up for in discretion. Common sense is the sense of the common layman. On scientific matters, it is most often wrong. If it weren’t, we never would have had any Dark Ages.
It’s Antarctica, Joel. The temperature rarely gets above 0 degC all year long.
Here’s another randomly selected google:

The Rhône-Sion hydrograph shows more runoff in wintertime and spring, but less in summer and autumn. This indicates a shift from winter snowfall to winter rain and means, a part of the winter precipitation is not any more stored in the seasonal snow cover, but becomes promptly effective to the runoff. This amount of water is not available during the summer. Furthermore we can observe a seasonal shift of snowmelt from summer to spring time, both due to the temperature increase. The runoff contribution from the glaciers is increasing. This process will continue as long as the main part of the glaciers is melted.
Next time, save the lecture, and do a little digging.

Bart,
It is on the Antarctic peninsula, which is the warmest part of Antarctica, as your link shows. So, your logic seems to be that the issue of rain in the warmest season on the warmest part of Antarctica somehow has a lot to say about rain being a problem in the coldest season in cold continental interiors of the arctic?
I am not even sure what you are arguing anymore since it has become so contorted. It seems to be that some vague armchair theorizing and handwaving overturns decades worth of careful empirical and theoretical study.
By the way, if you don’t respect common sense and you do not respect scientific authority, what exactly do you respect outside of your own intellect and those who you can find who basically agree with you (and disagree with the rest of the scientific community)?

I really need to proofread BEFORE posting… (corrections in italics)
Dave Springer says:
Your comment is awaiting moderation.
January 27, 2011 at 7:36 pm
“It ignores the fact that Hertzberg has no evidence whatsoever to support his hypothesis that the duration dominates”
This is hardly controversial. Even wikipedia notes that when northern hemisphere winter happens at aphelion that is the most extreme conditions for triggering an ice age.
Duration of winter probably is more important than distance from sun. As far as total insolation goes it’s a wash. The thing is, when looking for an ice age trigger, any temperature below 32F is important because that produces snow cover and snow lowers albedo which in turn lowers insolation in a vicious positive feedback cycle. You get the most snow not when temperatures are brutally cold but rather just cold enough so it doesn’t melt during the day. So the lower surface temperature from greater distance is mostly wasted because it decreases rather than increases snowfall. Conversely 8 extra days of winter and 8 fewer days of summer makes for deeper winter snowpack and less time to melt completely through in the summer. Northern hemisphere snowfall over land is the key to interglacial/glacial periods. Nothing else matters a whole lot other than how much snow cover survives the summer. Maximum snow survival happens (no serious dispute exists with this as the beginning of all glacial cycles lines up) when axial tilt is the lowest which diminshes the difference in summer and winter average temperatures – warmer winters and cooler summers. That’s empirical evidence that colder winters are counter-productive to ice age conditions if accompanied by warmer summers.

I mean… dude. Did you read this?

The Rhône-Sion hydrograph shows more runoff in wintertime and spring, but less in summer and autumn. This indicates a shift from winter snowfall to winter rain and means, a part of the winter precipitation is not any more stored in the seasonal snow cover, but becomes promptly effective to the runoff.

What part of this is not making sense to you? Do you understand the word promptly means not waiting until summer and higher temperatures?
I’m genuinely nonplussed by your seeming imperviousness to facts. Do you think the water pools up somewhere and refreezes? Do you think most glaciers are static and level? Where are you getting your ideas?

I did some searching on the polar ice pack in particular. I found little besides an offhand comment that rain turning to ice versus snow increases heat absorption in daylight because of the lower albedo. Does that mean more of the ice pack will melt come summer? I will leave that for the reader to decide.
Then, I was reminded that one of the results of the AGW computer models is that warming should be most pronounced on winter nights at high latitudes. And, that means that, according to Joel, there should currently be more rain at the pole, and the arctic sea ice should be expanding.
I think that pretty much seals off all his avenues for retreat, at least until the sea ice rebounds convincingly. I’m off on extended business tomorrow so won’t be commenting again for a while.

“…nor do we have a particularly good idea how often it happens…”
Missed a tag…

Should be “to” not “from” after “resignation” I think. Damn I’m not so sure any more!

lmao

It may have been a mistake for me to write down my thought processes as I tried to figure out what the heck point Joel was trying to make. So, let’s recap to soothe Quentin’s aching head.
1) Total insolation is the same regardless of precession of the equinoxes. Temperature is a low pass filtered variable proportional to the insolation. Glacial melt should be proportional to the integrated temperature above 0 degC. Glacial accumulation occurs at temperatures below 0 degC. If accumulation has a consistent mean rate, then it should be proportional to the integrated temperature below 0 degC. To first order, there should be no difference in glacial melt due to equinoxial precession alone.
However, the smoothing of input energy to output temperature via the Earth’s thermal time constants should result in lesser melt in the summer perihelion case. Altogether, the result marginally favors Hertzberg’s interpretation over Hansen/Tamino. However, other varying parameters, such as orbit eccentricity and obliquity of the rotation axis to the orbit plane, could have greater impacts. And, now we have rain to consider.
2) Hansen/Tamino/Shore insist that warmer winters in the NH and cooler summers favor glacier and ice sheet growth. Hertzberg argues the opposite, which is, in fact, what we are seeing. But, HTS argue this is because of the additional effect of AGW.
In the Antarctic, the seasons are flipped. HTS position would therefore have to be that, in the absence of AGW, the ice sheet should be retreating, and with AGW, retreating even more. In fact, we are not seeing this at all, except in the coastal regions where there has been more rain in summer.
A key consideration in all of this is the effect of rain. Rain significantly shrinks glaciers and ice sheet/pack where it occurs. So, in fact, what we observe is consistent with the Hertzberg hypothesis: glaciers and ice pack retreating in the NH, advancing in the SH except where there is substantial impact of rain. It appears to be summer rain, which is consistent with Joel’s suggestion that there is greater precipitation in warmer times. Thus, what we are observing in the SH appears to be inconsistent with the HTS hypothesis, even more so with AGW factored in.

This so called Tamino is a shallow poseur. By his own math, he is wrong.