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frank_davis


Frank Davis

Banging on about the Smoking Ban


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Milankovitch and the Ice Ages
frank_davis4
frank_davis
While attention is on the Copenhagen climate conference and the measures it will agree to combat global warming, I thought I'd take a look at the past few ice ages.

The Foresight Institute provides some historical perspective showing the ambient temperatures going back 50,000 years as recovered from a Greenland ice core. It shows (see below) that temperatures were around 20 degrees C lower only 15,000 years ago. We are currently living in an interglacial period that's been going about 12,000 years - the plateau on the right of the chart below.
greenland-icecore

In fact, over the past 2.5 million years or more, the earth has been flipping in and out of ice ages with considerable regularity (see second chart below). In general, the periods of glaciation have been long relative to the warm interglacial interludes. And the periods of glaciation have been getting longer and deeper.
ice ages

Over the past 400,000 years, there have been 4 interglacial periods, including our own. The previous one was about 120,000 years ago, and it lasted about 10,000 years, and was 2 or 3 degrees warmer than our current one. The one before that was about 240,000 years ago, and that only lasted about 2,000 years. And the one before that was 320,000 years ago, and lasted 7,000 years. So, The earth has spent only about 30,000 of the past 400,000 years - 7.5 percent of the time - in warm interglacials. All of recorded human history is crammed into the second half of our current 12,000 year warm spell. Yet anatomically modern humans have been around for for 150,000 years.

Looking at the temperature data from the Vostok ice cores from Antarctica, two of the previous three interglacials have begun with temperatures peaking fairly early in the interglacial before gradual cooling resumed. In the subsequent ice age, the lowest temperatures come at the end, just before the next interglacial starts. The pattern of glaciation is a sawtooth with sharply rising temperatures followed by gradually falling temperatures. And our present interglacial seems to be following the same pattern, with peak temperatures about 8,000 years ago, and about 2 degrees C warmer than now. Over the past 6,000 years temperatures have been falling. So we are on the down-slope into the next ice age. If it follows the same pattern as before, it won't freeze over suddenly. It'll just get colder and colder as the centuries go by.

0rbital variationBut that supposes that there's a metronomic regularity to what happens. At present, the main theory about what governs ice ages is that of the Serbian mathematician Milutin Milankovitch. His theory was that cyclic changes in the obliquity or tilt (in a 41,000 year cycle) and precession (~23,000 year cycle) of the axis of the earth combined with changes in the eccentricity (0 = circular) of the orbit of the earth (100,000 year cycle) would bring a varying regime of northern hemisphere insolation (sunshine). And this would sometimes result in cool summers during which ice that had formed in winter would not entirely melt. As a result, ice sheets would gradually grow from one year to the next.

In the 1930s Milankovitch's theory met with scepticism for a number of reasons. In the first place, his predictions did not concur with the accepted ice age chronology of the time. Furthermore, during ice ages the ice sheets had expanded at both the poles, and not just the north pole. It was only when ice cores and ocean deposits revealed a 100,000 year cycle that the theory began to gain acceptance. But even then there were problems. The variations in the tilt of the the earth's axis and the eccentricity of the earth's orbit were very small, and the consequent variations in insolation in the northern hemisphere were also very small. Not enough in themselves, it was felt, to cause the cycles of glaciation. There had to be some way in which their effect was amplified. And one candidate for this amplifier was the greenhouse gas carbon dioxide. As the earth cooled, the cooling oceans would absorb carbon dioxide from the atmosphere, cooling the earth further. And when the earth warmed, carbon dioxide would be released by the warming oceans, warming the earth further. Ice cores revealed that carbon dioxide had indeed risen and fallen in this manner during previous glaciations. Carbon dioxide now made its appearance as a climate change amplifier, leveraging the Milankovitch insolation variations to produce a considerable effect.

There were other causes of concern. Milankovitch did not include another cycle, which is the inclination of the earth's orbit to the plane of the solar system. This is another 100,000 year cycle. And why did a 41,000 year cycle change to a 100,000 year cycle about three-quarters of a million years ago?

Apart from the question of the agreement of the predictions of the cycle with past glaciations, there was also the matter of future glaciations. Previous interglacials had only lasted a few thousand years. How long would our present-day interglacial continue? In 1966, Emiliani predicted a new glaciation would "begin in a few thousand years". A decade later, Kukla thought that the next ice age was "due very soon", perhaps even beginning within a century or so. The current view, using the latest models seems to be that:

The long-term cooling trend which began some 6,000 years ago will continue for the next 5,000 years; this first temperature minimum will be followed by an amelioration at around 15 kyr A.P. (after present), by a cold interval centered at 23 kyr A.P., and by a major glaciation at around 60 kyr A.P.

So the current view is that our modern interglacial has another 60,000 years to run, and we're still near the beginning of it.

But, now that the greenhouse effect of carbon dioxide had been invoked to explain how the small variations in insolation predicted by Milankovitch had been amplified to produce a sequence of ice ages and interglacials, carbon dioxide took on a new life of its own. If natural cycles of warming and cooling could be thus amplified, then the same would surely happen with the carbon dioxide added to the atmosphere by human industry. The threat of Anthropogenic Global Warming (AGW) was born.

What's to be made of it all? The most obvious point is that climate science has been clearly been undergoing rapid development over the past century, and this is continuing. It's not a settled science. For about 40 years Milankovitch was ignored, but new data from the sea bed brought his rehabilitation. A new ice age was then felt to be imminent. But now the carbon dioxide amplifier which was invoked to make his theory work has elbowed aside its parent, and Milankovitch has, so to speak, been returned to the gulag.

But now that we know that climate scientists have been busy "hiding the decline", and abolishing the inconvenient Medieval Warm Period, one has to wonder whether Milankovitch may also have been secretly buried for the exact same reason. After all, what is more inconvenient to the global warming hypothesis than a global cooling hypothesis which has, as we now know, led some experts to predict the return of ice age conditions within a century or so? When Global Climate Models (GCMs) can have their sensitivity adjusted to conform to the expectations of researchers, what is to stop the sensitivity of Milankovitch prediction models having their sensitivity cranked upwards or downwards to conform to the same expectations? And do the latest Milankovitch prediction models have the currently-fashionable AGW hypothesis built into them? Is that why the current interglacial is now expected to last another 60,000 years - 60,000 years longer than any previous one?

The worst of it all is that, as the climate debate ebbs and flows, the entire global political establshment is now in lockstep with it, and busily issuing decrees to reduce carbon dioxide emissions to ward off the global warming predicted by the current 'settled' science. But in a decade or so, it's perfectly possible that some new hypothesis will have emerged, reversing previous advice. Governments now act as amplifiers of the fragile climate science consensus in much the way that carbon dioxide is supposed to amplify the Milankovitch cycles. They're blowing hot at the moment, but could well start blowing cold any time, as climate fashion changes yet again.

But all is not lost. It may be possible to predict when the next flip in the political climate will take place. Milankovitch first enjoyed a brief burst of interest in the 1930s, and then was largely ignored for the next 40 years until the 1970s, when his theory enjoyed a brief revival, before being asphyxiated by carbon dioxide for the next 40 years. That's a 40-year cycle of waxing and waning interest. This being climate science, and all about extending trends into the future, we may confidently use this 40 year cycle to predict the return of Milankovitch's star sometime in the 2010s. In addition, the sun no longer seems to have any sunspots, which is historically correlated with periods of cold. And, above all, it's darn cold in Devon this afternoon.

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Tinfoil hat mode.

(Anonymous)
This is a bit of pure paranoid speculation on my part, pure conspiracy-theory stuff, but...

Suppose those politicians and their wealthy pals know the world is actually cooling and approaching an ice age. I'm sure they already know global warming is a scam so that part's not such a stretch. What would they do?

They'd want to move south to warmer countries. They won't want us all going with them. So they'd tell us it's warming and that those other countries will be either deserts or underwater while we'll get palm trees and olive groves.

The other thing they'd want to do is to move as much money into those warm countries as possible before they move.

One more thing - they'd want to move the pesky commoners from those countries out of the way. So they'd bring them all here...

I know, it's madness and pure tinfoil hattery but the chilling part is, it makes sense.

Re: Tinfoil hat mode.

(Anonymous)
Here is a bit more information to feed your paranoia. "Global Warming" first appeared at the 1972 Earth Summit BEFORE the actual start of the current warming trend and BEFORE the 1974 CIA report on how to handle a coming Ice Age. Second, Maurice Strong (Father of Global Warming) bought a ranch in Colorado that is sitting on what will be a prime piece of property during a coming Ice Age (it had a mild & well watered climate during last Ice Age). It sits on not one but THREE huge aquifers (ice ages are dry) not to mention large oil reserves. Third, Strong, the Rockefellers and the Council on Economic Development have intentionally DE-industrialized the USA since 1972, starting with OSHA and progressing through Equal Rights, EPA, World Trade Organization and soon Cap and Trade. Fourth Protesters were PAID ($10/hr) to protest nuclear plants closing the door on the cheap energy needed to fuel industry. The Rockefeller Foundation funds Greenpeace and Strong paid their way to that 1972 Earth Summit. He told them and other groups to go home and raise hell. Strong is a Rockefeller Foundation trustee and Senior Adviser to the World Bank. He hooked up with the Rockefellers in the fifties as a dead broke high School dropout. (David Rockefeller directs the World Bank and IMF at a yearly meeting in his home in Westchester NY after the "official" yearly meeting) The Central bankers have been steadily stealing the wealth from American citizens since 1913. Now 100% of your US taxes goes to the privately owned Federal Reserve according to the Grace Commission Report. David Rockefeller has very bluntly stated he wants a world government run by the bankers and intellectual elite. quote "...The supranational sovereignty of an intellectual elite and world bankers is surely preferable to the national auto-determination practiced in past centuries." http://www.newswithviews.com/Cappadona/heidi5.htm

Re: Tinfoil hat mode.

(Anonymous)
It's a little soon to be moving people around. Somebody likened Global Warming as snake oil, and I think it's probably so. Only this snake oil is is not just about money it's about power as well.

Whoops. It was me. Forgot I wasn't signed in.

That it is indeed tinfoil hat stuff, yet also perfectly rational.

I think the problem with it is that it's a line of reasoning that only really works if a new ice age starts very suddenly. You'd want to be living in someplace like Belem on the Amazon in Brazil when it all kicked in.

But from what I can see of the ice core record, while interglacials start when temperatures rise very rapidly (in geological terms), they end with temperatures gradually falling. They're like islands with high cliffs on one side, and the land then drops away slowly to wide flat sandy beaches on the other side. And this gradual fall seems to me unpick the logic of what you're suggesting. There isn't going to be a rush to live in tropical countries, but a very slow movement. And there may be hardly any at all, if we gradually change the way we live, building better insulated houses. And also we don't know what kind of technological innovations there will be in the long term future. There are huge energy resources of one sort or other that remain largely untapped - geothermal energy, solar energy, and many others.

Underlying a lot of doom-mongering there always seems to be an implicit assumption that the technology we've currently got is all we'll ever have. And that when the oil runs out, we'll all have to die, fighting over the last drop. I don't think history is quite like that. I think us humans are wonderfully inventive when we have to be. It's one of the reasons why a lot of technological innovation takes place during wars (although it's almost always of military hardware).



New Scientist had an article recently suggesting that the last mini-ice age happened within months.

Temperatures dropped gradually to a tipping point until one winter, there was no spring to follow.

Temperatures can continue to go down gradually after the ice has set in. It makes little difference to life once the ground is frozen anyway.

If that happens, I say we bury all the climate changers up to their necks and let the permafrost deal with them. As a warning to the climate changers of future generations.


From the ice core data, it seems true that while temperatures gradually fall during interglacials, it does eventually accelerate. The flat sandy beach eventually falls off a cliff.

I used to be a fairly regular reader of New Scientist. I bought one a few months ago, and it didn't seem to be at all the same as it used to be. I've heard a lot of people say that it's fully signed up to global warming. The same is apparently true of Nature. And the Royal Society. 'Tipping points' are a big feature of the global warming orthodoxy. They're the result of their view of the atmosphere as being unstable and liable to get caught in positive feedback loops, either warming or cooling. Rapid cooling is just the flip side of CO2-driven rapid warming.

Abrupt cooling can happen. Look at this: http://i43.tinypic.com/1zoanbc.jpg

It was online about a week ago, American Thinker blogsite I think, had someone familiar with computer programming go down through the lines of code from the emails and here they put in a .75 multiplier from about mid-1990's on - so that even if you ran the program using no data, it created a flat line and then a hockey stick at the end - with no data - that's what it did.

Of course AGW is a fraud, the same way SHS is a fraud.

And I still say at the very root and core of it lies the SHS Fraud and smoking bans - at the root core. As long as a lot of people feel empowered by wagging their fingers around at "those smokers" and it gives them a big feeling of "better than thee" - then by the same token of belief, they are in fact forced to accept the AGW Fraud now - plus whatever next one comes after that - perhaps the one-baby-per-couple fraud or the forced-euthanasia-at-age-50 fraud.

Bully for them. The same ones who made anti-smoking a big hit will now make the AGW Fraud a big hit along with the carbon taxes and one-world-government that goes with it.

And to think, this originated with the "left" - who were supposed to be "for the people" - but I guess all along, really they never were.

I think the American Thinker article maybe appeared on What's Up With That here, although that article seems to be about "hiding the decline", which was when they just snipped off the last 20 or 40 years of Briffa's tree-ring temperatures.

I read about the code you may be talking about on WUWT here. Basically this code multiplies temperatures over the 20th century by a set of nubers to make the early 20th century temperatures lower, and the late 20th century temperatures higher. What isn't clear is whether this code was used to create published results or not. It certainly looks very bad, though.

What gets me is that pretty much ALL temperature data from anywhere gets 'adjusted'. WUWT have an article that looks at what happened to the data for Darwin in Australia.

And yes, there's a deeper problem - a moral problem - with the finger-wagging righteous. And the finger-wagging pretty much started with smoking.

P.S. I've been a computer programmer for quite a few years now. I started out writing in Fortran. So I have some idea about computing, even if I don't know everything.

I heard a programmer today commenting on Climategate. I'm not a programmer, so I only had a limited understanding of what he was saying. What I took away was that rather than writing equations using variables for models, they were punching in data to be used as a hard part of the equation. For example, to find the area of a circle, one uses pi time the radius squared. My interpretation was that these researchers were taking fudged data and putting them into the equations, but treating the fake data as a known and fixed number, just like Pi is used to find the radius of a circle. If anyone here can tell me, I'd like to know if I understood this correctly.

On another note, I watched some news coverage of the protests at the G20 summit. If I heard correctly, over 700 people were arrested, but the reporters were eager to give legitimacy to the concerns of the protesters. Meanwhile, here in America, no one to my knowledge was arrested when the Tea Party protests took place, but the media eagerly painted any and all protesters as mean spirited racists and radical extremists.

When I watch these things, I understand the consequence of them. People don't want any of this ugliness in their lives, so it's going to be difficult to say to them "Look, you're going to have to learn to accept being hated now."

Personally, I wonder how far I'm willing to go. Will I be willing to accept losing my job, losing my home, or arrest and jail time? I think it's a very serious consideration in a world that's going to demand mandatory requirements that most of us never even thought possible.

I guess what I'm saying is that there's either an unawareness or a suspension of disbelief regarding how bad the current trends really are. So, do people realize what it will really take for these trends to be stopped or reversed?

Personally, I never expected in my life to be equated with a flat-earth theorist for denying that ETS causes lung cancer, or questioning the dire predictions of global warming theorists. So the ordinary world I expected is now a thing of the past, and I have to deal with this new world. But I can't see any place for me in this new world. So, I now live in two worlds; the world's world and my world. I could survive with that if the two worlds peacefully coexisted, but they don't, because the world seems to expect much more of me lately than I expect from it.

On the computing side, see my response above to previous comment.

As for Copenhagen arrests, I've heard it was 1,000 arrests, but these were climate activists being arrested, not sceptics and 'denialists'. But I could be wrong. I only listen to radio news once a day these days.

Personally, I never expected in my life to be equated with a flat-earth theorist for denying that ETS causes lung cancer, or questioning the dire predictions of global warming theorists

The odd thing about this is that most of the people who call other people flat-earthers have never actually looked at the research themselves. They rely on experts. On authorities. And I don't. Or at least I try not to.

Yes, it's no longer the ordinary world I knew either. The one where you could go down to your local pub and drink a pint of beer and smoke a few cigarettes and feel more or less at peace with the world.

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(Anonymous)
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Source Data for Orbital Parameters

(Anonymous)
I have never seen the source data for the predictions of the change of Earth's eccentricity, which should be in the literature somewhere. The graph you show would indicate an extended period of low eccentricity but where does that information come from? The graph also seems to show a minimum in the variance of the precession cycle but where is the source data for that?


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