Open Thread Weekend

A Fascinating story on the discovery of the causes of Ice Ages
Milutin Milankovitch was born in the politically volatile Balkan nation of Serbia—later incorporated into Yugoslavia—in 1879. Milankovitch came from a relatively privileged background. His family owned extensive farmlands and vineyards, and several of his relatives were university graduates. For a time, he gave in to family pressure and studied agriculture in preparation for taking up the management of the Milankovitch estates. But he was more interested in the sciences and went instead to Vienna, where he earned a doctorate in engineering in 1904. After working for five years as an engineer in Vienna, building such things as dams and bridges of reinforced concrete, he gladly returned to his homeland to accept a post at the University of Belgrade. There he lectured on mechanics, astronomy and theoretical physics, and yearned for a challenge that would permit him to make his mark in the world of science.
In 1911, during an evening of wine tippling with a poet friend, Milankovitch selected his challenge: He would develop a mathematical theory that would enable him to determine not only the temperature of the earth at different latitudes and at different times but also the climates of other planets in the solar system. It was to be an ambitious scientific sojourn in what
Milankovitch called “distant worlds and times,’ and the young professor had picked an ideal stage of his life to begin. “I set Out on this hunt in my best years,” he recalled later. “Had I been somewhat younger I would not have possessed the necessary knowledge and experience. Had I been older I would not have had enough of that self-confidence that only youth can offer
in the form of rashness.”
Milankovitch pursued his goal with single-minded devotion. As he later observed: “When a scholar stands before a scientific problem, he becomes like a hunting dog that has sensed the game.” His first step was to make a thorough survey of work that had already been done in his chosen field. He was fascinated by James Croll’s astronomical theory, but concluded that Croll, for all his considerable accomplishments, had lacked the precise data required to deal adequately with a problem of such magnitude. Luckily, though, Milankovitch came across the more recent studies of the German mathematician Ludwig Pilgrim, who in 1904 had published minutely detailed calculations of the precession of the equinoxes and changes in the earth’s orbital eccentricity and angle of tilt. Indeed, Pilgrim had even gone so far as to chart the relationship between orbital eccentricity and the presumed chronology of past ice ages. Milankovitch judged that Pilgrim’s understanding of climatology left much to be desired, but could find no fault with his mathematics; he used the German’s figures to work out his own calculations of past climates of the earth and other planets.
His progress was interrupted in the fall of 1912 by the outbreak of the First Balkan War, in which Serbia joined its neighboring allies to expel the Turks from southeastern Europe; a reserve Army officer, Milankovitch was called to active duty with his regiment. Hostilities were short-lived, however, and Milankovitch soon returned to his civilian desk. During the next
two years he published several papers outlining the emerging results of his work, which indicated that glacial advances and retreats could indeed be brought about by changes in solar radiation due to the precession of the equinoxes and to variations in the earth’s orbital eccentricity. (His calculations became considerably more accurate after 1913, when American scientists at the Smithsonian Institution were able to establish the solar constant, or the intensity of the sun’s radiation.) He also showed that variations in the planet’s angle of tilt influenced climate to a far greater degree than James Croll had believed.
In the summer of 1914, war intruded once again on Milankovitch’s affairs. He was visiting his home village of Dalj—then a part of Austria Hungary—when World War I began, and was promptly interned as a prisoner of war. But his studies would not be hindered: In his suitcase, he carried the papers on what he called “my great cosmic problem,” and during his first night of confinement, he whipped out his fountain pen and turned to his calculations. “As I looked around my room after midnight,” he recalled later, “I needed some time before I realized where I was. The little room seemed like the nightquarters on my trip through the universe.”
Milankovitch did not stay long in his cell. Learning of his imprisonment, a Hungarian university professor who knew of the Serbian’s accomplishments prevailed upon the authorities to parole Milankovitch to Budapest, where he could have access to the library at the Hungarian Academy of Sciences. There he spent the rest of the war years, developing a theory for predicting the earth’s climate and completing a description of the climates of Mars and Venus. In 1920, his results were published in a work titled Mathematical Theory of Heat Phenomena Produced by Solar Radiation, in which the author demonstrated mathematically that widespread glaciation could be induced by astronomical changes that alter the amount and distribution of solar radiation reaching the earth. He also maintained that it was possible to determine the amount of radiation that had reached the earth at any time during the past. In short, Milankovitch was claiming he could prove that astronomical processes caused ice ages.
Among the many scientists who were impressed by Milankovitch’s work was the eminent German climatologist Wladimir Koppen, whose son-in-law, Alfred Wegener, had startled the scientific world in 1912 with his theory of continental drift. Now, Koppen and Wegener were in the process of writing a book about past climates. Invited to contribute to this project,
Milankovitch readily agreed, and set out to plot a curve that would show the variations in radiation that he believed were responsible for the succession of ice ages.
James Croll had believed that variations in solar radiation at very high latitudes during the winter were the dominant factor in the onset of glaciation. But Milankovitch saw the matter otherwise. After lengthy correspondence with Köppen, he had become convinced that the decisive factor in glaciation is the diminution of summer heat in the temperate latitudes, not a reduction of winter radiation at the Poles—where temperatures even today are low enough to preserve a permanent snow cover. Working from morning until night, he drew curves showing how summer radiation in the middle latitudes—between lat. 55° N. and lat. 65° N.—had varied during the past 600,000 years. Finally, after 100 days, he finished his calculations and mailed the results to Koppen.
When the German scientist examined the work of his Serbian colleague, he was immediately struck by the marked similarity between the lines on the Milankovitch chart and the sequence of European glaciations established years before by the geographers Albrecht Penck and Eduard Bruckner. Koppen informed Milankovitch that his astronomical theory had thus been confirmed, and asked him to attend a scientific conference to be held in
Innsbruck, Austria. There, as Milankovitch listened from an inconspicuous last-row seat, Alfred Wegener presented a spirited lecture on continental drift and ancient climates, illustrating the section on the Pleistocene epoch with Milankovitch’s painstakingly computed radiation curves. So well received was this new explanation for ice ages that Milankovitch slept that night “on a bed of laurels and soft pillows.”
Köppen and Wegener included Milankovitch’s work in their 1924 book, Climates of the Geological Past, and many geologists were convinced that the ice ages had at last been explained. Milankovitch, meanwhile, continued to elaborate and refine his theory, computing curves for latitudes both higher and lower than those that he had previously plotted. In 1930, he published his clearest statement yet on the causes of ice ages: Mathematical Climatology and the Astronomical Theory of Climatic Changes. In it, he demonstrated that radiation curves calculated for the higher latitudes are dominated by the 41,000-year tilt cycle, while curves for latitudes closer to the Equator are more heavily influenced by the 22,000-year precession of the equinoxes.
Aside from the fact that they corresponded with the assumed periods of glacial advances and retreats, Milankovitch’s curves did not offer definitive proof that they delineated the causes of ice ages. But this correspondence seemed far too striking for mere coincidence. Scientists the world over came to accept the Milankovitch explanation for climate changes, and Milutin Milankovitch was convinced that his life’s great work was done. For the first time since 1911, when he had set his lofty goal of scientific discovery, he was without a great challenge to face. “I am too old to start a new theory,” he remarked wistfully to his son in 1941, “and theories of the magnitude of the one I have completed do not grow on trees.”
Planet Earth
Ice Ages
By Windsor Chorlton
Time Life Boks
1983
Milankovitch noted that as the earth spins and moves around the sun, both its orbit and its attitude change slightly. The orbit varies from almost circular to strongly elliptical and back again every 93,000 years or so. The earth’s tilt in relation to the plane of its orbit—the cause of earthly seasons—changes from about 22 degrees to more than 24 degrees and back every 41,000 years. The earth also wobbles, rocking in a circular motion around its axis like a slowing top, and this too has a cycle: One full wobble consumes 25,800 years. By altering the distance between the sun and earth or changing the angle at which radiation strikes particular points on the earth, these moves alter the amount of solar energy reaching certain latitudes in certain seasons.
Evidence that supports the critical role Milankovitch attributed to these cycles has accumulated steadily. For instance, scientists from the Lamont Doherty Geological Observatory in New York discovered that variations in the type of oxygen and in the distribution of the remains of minute marine life—found in sedimentary samples taken from the floor of the
Indian Ocean—indicate periodic and severe climate changes. The sea-core record suggests that some of these changes have peaked every 23,000 years, others every 41,000 years and still others about every 100,000 years. It seems highly unlikely that the similarity to the span of orbital variations is mere coincidence.
Planet Earth
Atmosphere
By Oliver E. Allen
Time Life Books
1983

Ric Werme says:
March 31, 2012 at 10:40 am
If you indeed found it at The Register, then I don’t see why you were shocked unless you aren’t familiar with El Reg and their style. I don’t understand why you didn’t include a link to that quote. Well, if you found it on Pravda, I could understand….
@Ric
You’re right, it’s from the Reg and I had meant to include the link below the headline of the piece.. don’t know what happened.
Thanks for posting it.
I’m still looking for the actual paper and any video from the panel..
Cheers!

it seems the drug companies hare having a hard time reproducing the “discoveries” claimed by universities, prior to trying to create new drugs based upon said “research: http://news.yahoo.com/cancer-science-many-discoveries-dont-hold-174216262.html
do you all think there is any chance “climate research” might be similarly plagued? 😉

May I draw everyone’s attention to the fact that there has been a major reversal in climate science reported at Realclimate here: http://www.realclimate.org/index.php?p=11329
REPLY: This is a badly executed April Fools Joke, ignore it. Here’s why I didn’t do one this year:
http://wattsupwiththat.com/2012/04/01/how-peter-gleicks-skullduggery-killed-my-april-fools-posting/
With so much deception going on, you’d think RealClimate would know better. I guess not. – Anthony

@Bobl
bair polaire says: I can not find a simple comprehensive scientifically sound demonstration of the CO2 effect on the internet.
Best explanation is to not think thermal, but to use a more familliar example of the same phenomenon. Consider a fluorescent light bulb. …
PS, its clear here by the way that CO2 should reduce day temps and increase night ones such that the average temp might be higher but the diurnal range should be lower. IE a warming world will be more tropical, less dynamic, and safer for all lifeforms. Global warming must reduce the instance of extreme temperatures, either daily max, or nightly mins, has to.

Thanks a lot for your explanations! This really helps. I think your fluorescent light bulb is so far the best everyday life example of back radiation. Even though the reemission/afterglow does nothing to make the bulb brighter or reduce energy consumption as it is in a different wavelength than the source.
I would like to read more on your notion that the CO2 effect would make the climate milder and life more pleasant. Is this effect visible in the temperature records?

“Is the Sun’s radiation around 10 micron really lower than the Earth’s outgoing radiation at 10 micron?”
I provide Bair Polair with a calculation that shows it indeed is, by a factor of 4 million. He says he doubts it. Now, if I doubted something as fundamental as that, I would immediately check it. I mean it isn’t hard. Planck’s Law is widely available on the internet. All you have to do is plug in a wavelength of 10 micron for the Sun’s surface temperature (5800K) and the Earth’s 288K and see what values you get. Then you need to remember the inverse square law, since the Sun is 150 million kilometres away. I would check these calculations if I had doubts, but Bair Polaire simply says he doesn’t believe it. What doesn’t he believe? Planck’s Law? the formula for the surface area of a sphere? Mathematics in general? or the accumulated scientific knowledge of the last millennia?
I am willing to help anyone who has a genuine problem understanding but, as Andrew Judd says, Bair Polair like so many others is not interested in finding out. They ask questions rather in the hope that there is no answer and thus they have discovered something that every physicist since Isaac Newton has overlooked. That’s not going to happen.
Arguing against proven science, that which can be measured and verified, simply gives all sceptics a bad name.
So, Bair Polair, this puts you firmly in the Sky Dragon cuckoo club. I suggest you visit Tallbloke’s website where I am sure he will tell you exactly what you want to hear.
Bye.

Mike Jonas ….. Shushhhhhhhh.

tallbloke says:
March 31, 2012 at 6:25 am
I really like the new “Transendental rants and far out theories” section. A couple of good site links there. I’m thinking of adding a “lukewarm junkscience” section on the Talkshop. 😉
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LOL! Good move, Tall Bloke! Many will chafe at being categorized into the the margins…the Pale of Hypotheses… but will appreciate the offer of a soapbox. At the same time, science purists may grumble over the perceived legitimising, but will enjoy piling into the claims to debunk. Interesting it will be to see if any make it out of the ghetto into the mainstream, or vice-versa.
Perhaps avoiding the term “junk-science” will calm nerves. A word like “speculative” may be better, I don’t know. I was impressed by the way the late Carl Sagan subtitled one of his books as “speculations.” The one in which he called our brainstem “reptillian” and compared it to Siggy Freud’s Id, the mid-brain to the Ego and what he called the “neo-cortex,” the Super Ego. Plausible and poetic mind-candy and no one got angry or jumped down his throat for that because “speculation” tends to disarm rather than raise hackles, I guess.