Great Intro To Ice Ages and Global Warming

Ice Age Historical Temperatures

Ice Age Historical Temperatures

The present is on the right in this image. If you look at the height and width of the interglacial warm periods, you will notice that we are nearing the end of the present warm period.

This page:

Does a marvelous job of showing our place in the scheme of things. From the very long ice age cycle perspective, down to the present-day rate of CO2 emission and the irrelevancy of it.

It would be a great introductory paper to give to anyone just starting out on a journey of discovery about the Global Warming Scare and a nice read that pulls together a lot of disjoint bits for those of us who have been looking at things for a while.

For example, in one minor place it mentions the 206 year solar cycle. There is a link to a PDF file. No fanfare, no big deal about it. But the paper is about how the Maya had problems from droughts that happened on a roughly 206 year period … and postulates that a major drought driven by cycles of the sun may have been the cause of the collapse of their civilization. That’s one of the minor links…

More importantly, the research shows, the droughts — one of which is thought to have contributed to the collapse of the Maya civilization — appear to have been caused by a cyclical brightening of the sun. “It looks like changes in the sun’s energy output are having a direct effect on the climate of the Yucatan and causing the recurrence of drought, which is in turn influencing the Maya evolution,” said David Hodell, a UF professor of geology and the paper’s lead author.

I’ve not yet explored the other links to see what treasures they might provide. In the body of the paper, there are wonderful graphs of the ice age cycles and great renditions of the temperature peak of the Medieval Warm Period with the Little Ice Age for perspective, with references.

There is a wonderful little map of the world during the last ice age showing both the extent of the ice, and equally important, the much larger area of desert that comes with the cold. Cold is dry. Warm is wet. Warm and wet is very much better for humanity AND all the other life on the planet than cold and dry. Comparing that map to the one of the present makes it very clear just how precious is this moment in time, this interglacial.

The case is made, and rightly so, that the only ‘tipping point’ is to the downside, back into a glacial period. The only looming catastrophe is death by ice. And there is bugger-all we can do to stop it. (Though the good part is that we probably have a couple of more thousand years of the present regime before things get bad, so plenty of time to contemplate it.)

I would also point out that the historic warming in past interglacial periods has been higher than our present temperatures, but not by much. There is something that slaps us back down whenever the planet tries to warm up above this point. My guess would be the fact that IR radiation will increase with the 4th power of temperature, and trying to beat a 4th power function is a very hard hand to play. (Google the Stefan–Boltzmann law for thermodynamics details…)

For what it’s worth, with the theoretical impact of CO2 being a log function (so decreasing impact with each added unit) and with the Stefan–Boltzmann law putting a 4th power lid to the upside, the conclusion I draw is that the best thing we could do for the planet is to raise the CO2 levels. We can’t make it hotter, but we might be able to dampen some of the downside cooling.

About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
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13 Responses to Great Intro To Ice Ages and Global Warming

  1. Gary says:

    The orbital parameters are such that the cycles combine for warm interglacials only for a relatively short time over the long term. That’s what “slaps down the temperatures.” The 4th power lid is an upper bound.

  2. BlueIce2HotSea says:

    Nice to see geocraft has had a face lift and is still around. It was one of the earliest popular sites a few months after Dr Seitz’s blasting of IPCC corruption, circa 1996.

    Note the biome maps which show the rarity of trees during an ice-age. Not only is lack of rain and cold a serious problem, but also aphyxiation due to lack of CO2.


  3. Larry Geiger says:

    I read a book from the library that had this graph across the bottom of two pages. The book listed all sorts of bad stuff that was coming because of AGW. What I noticed, at the time (many years ago) is exactly what you are saying here. We don’t need to worry that much about warming. It looks like COLD is coming! I need to try and find that book again.

  4. mbabbitt says:

    I am happy I will not be around to witness the return of the next ice age. I always hope that the little warming the C02 provides could prevent this from happening. At least Lovelock said something like this recently. But are we to trust the rants of a Gaiain?

  5. peter c says:

    Just finished Dr Spencer’s excellent book The Great Global Warming Blunder, which makes the case for negative feedback via low level clouds. The upper limit is surely just the cloud thermostat kicking in.

    Also are you sure Milakovitch is correct? Negative feedback of a small forcing makes it unlikely. Now if there was a massive forcing – I can only think from a large oceanic change, well that would be scary. Like a large La Nina you might not see it coming.

  6. Doug Jones says:

    Hello, Ed- speaking of tying various threads together (and blatantly hijacking this one :) -I was at a science fiction convention this weekend, and was on a panel titled “Anthropogenic Global Warming: I’m skeptical of poor scientific practices- are you?”

    I slapped together a quick presentation with a few of Eschenbach’s Darwin Zero slides, Long’s rural vs urban adjustments, and some station survey pics, and got a positive reaction from the audience. Only one person claimed that the climate scientists were impartial and unbiased, and I could almost *hear* the crowd’s collective eyeroll at that.

    Jordin Kare asked me a good question, though. After I showed the Darwin Zero slides, he wanted to know if this was an outlier, or do many other stations have neutral or negative temperature adjustments? If many others have minor cooling adjustments, the global effect of the Dzero adjustments would be damped out. I had to admit that I didn’t know, but said that an independent survey can be done to check.

    So here I am, asking if you or a cohort can do that analysis- I could do it myself, but it would probably take me 10-20 times as long as it would for you, given your greater experience. In your copious spare time, could you extract some statistics on the GHCN temperature adjustments, comparable to the Darwin Zero presentation?

  7. Doug Jones says:

    oops, I reread the WUWT post

    and noticed this illustration- generated by NOAA no less!- that gives the result I was looking for:

    Now THAT’s what I call a smoking gun…

  8. E.M.Smith says:

    @Doug Jones: A word at WUWT will find several postings about the ‘wrong way’ adjustment of GIStemp too. It’s about 1/3 of the stations get adjusted the wrong way. I think it was covered at Icecap too. It’s pretty well known (though I can’t point at a particular reference at the moment) that the adjustments are “often wrong” and increasing in magnitude.

    If you need more, let me know.

    And yes, I’d call that “smoking”… in more ways than two…

    @Gary: the orbital shifts happen on a very long slow schedule. There is something else that happens on a much faster schedule. Don’t know what it is. Might just be an accidental timing artifact of the orbital effects. Just barely get over to the warming side, when BLAM, we tip down again. FWIW, I’ve read an excellent little book that goes through the history of Ice Ages and includes a very readable explanation of the Milankovitch cycle. The title was, I think “Ice Age”.

    google google google…

    Ah, there it is, “Ice Age” by John & Mary Gribbin:

    At Amazon, about $10 new and a bit over $3 used:

    So I’m familiar with the whole orbital / tilt / wobble interaction process. But that’s not enough for the shape of the onset / exit process. There is some hysteresis in there two. And I’d assert that at the top end, the restraint is probably the 4th power thing, while at the bottom end it may well be that loss of plants lets the CO2 build up enough to halt further freezing (as a WAG – Wild Ass Guess) or it just reaches thermal equilibrium? I donno…

    FWIW, the core of Milankovitch is that for a brief period of time the North Pole is pointed at the sun at the same time the orbital obliquity is just right and the pointing happens at just the right position in the orbit AND the nodding of the poles has us ‘tipped over’ just enough for the north polar ice to melt.

    At all other times, it does not melt, and we get an Ice Age Glaciation (inside an ongoing Ice Age Epoch).

    So all the folks wailing about how the N. Pole might melt and just praying for the whole thing to freeze over and stay that way are actually praying for the return of the Ice Age, as that is the definition.

    The wiki page isn’t too bad:

    though it has the obligatory ‘interglacial will last a long time’ so things must be our fault near the bottom. Though I note that the page is presently marked with a ‘being disputed’ flag that was not there last time I looked.


    I like to point out to folks (especially when the accuse me of being a promoter of ice age panic) that the nice thing about the Ice Age Catastrophe is that it takes several thousand years to be noticed. It’s even quite possible that we are already IN the next glacial phase. The chart of ice volume (red line up top) shows it takes 100,000 years to build up. So the remaining ice is on Greenland, and the max extend last time was about New York City. Draw a line, measure the distance, divide by 100,000 years. It’s about 800 FEET a year.

    I like to say you can outrun the Ice Sheet by taking a small stroll one Saturday per year… On Average.

    As we oscillate down into the next ice age, it is, for example, quite likely that the Little Ice Age was one of the lower going excursions. The rise into the present Modern Optimum is not quite as high as prior rises. So if we roll down into a New Little Ice Age, it would likely be a little worse than the last one. Then the New Future Optimum would be a bit cooler than now. Repeat about every few hundred years… oh so slowly … over the next 100,000 years. Then a Very Sudden Very Fast rise back into the next interglacial and a new Great Flood myth…

  9. E.M.Smith says:

    peter c
    Just finished Dr Spencer’s excellent book The Great Global Warming Blunder, which makes the case for negative feedback via low level clouds. The upper limit is surely just the cloud thermostat kicking in.

    On my someday list… And I could easily see a low level cloud increase in a hot world (and a large increase in hurricanes convecting heat to space) as dampeners to the upside.

    Also are you sure Milakovitch is correct? Negative feedback of a small forcing makes it unlikely. Now if there was a massive forcing – I can only think from a large oceanic change, well that would be scary. Like a large La Nina you might not see it coming.

    Very sure. The only “odd bit” is a moment in the history when we shift from a 40,000 year period to a 100,000 year period that is ill explained. Then again, the continents were somewhat different then and who knows what the oceans were doing. BTW, the present series of glaciations that folks call Ice Ages are really individual glaciation events in one Ice Age (that is more properly called an Ice Epoch – the term Ice Age being a bit ambiguous). So we have that periodicity of the Glaciation / Interglacial cycle in our Ice Epoch, but there have been several Ice Epochs, and those look to be connect to our position in the galaxy…


    BTW, there is very likely a Large impact from ocean changes. ( I generally avoid using the word ‘forcing’ as I find it non-physical. I like to speak in terms of real things found in physics books, not some vague ‘forcing’ catchall). One example:

    At the peak of an ice age, the Arctic Ocean will be cut off from the Pacific side. Both the ocean dropping and the ice grounding will assure that. As ice melts, eventually the ice sheet will be lifted from the land and the Pacific can supply warmer water to the underside of the sheet. POOF! You get rapid onset of melt. Something similar will happen on the Atlantic side, but less dramatic (not complete). Also, as the ocean depth changes by several hundred feet, I’d expect the Gulf Stream to change. What happens when the English Channel is land, for example.

    One of the key bits of Melankovitch is that the N. Pole Ice Cap is the critical bit. It is the one that ends up in just the right position to start melting. And once the melt begins, you get the positive feedback of albedo change. But you would get that at the S. Pole too… So what’s different between the two? Which one is over water vs land… (And notice that the surviving bit is on land in Greenland…) Which one has warm currents aimed at it and which one has an isolating cold circumpolar current?

    So what I think is the set of positive feedbacks is the following:

    1) More heat on northern oceans. (Orbital changes) Ice melt begins.
    2) Water can get under the ice. Flow volume increases.
    3) Albedo change, leading to more water warming.
    4) As warming happens, the drought conditions of an ice age start to ameliorate. This increases rainfall dramatically. Nothing like a bunch of tropical rain headed north to melt the ice sheet in Chicago… or New York … or Anchorage…
    5) Stronger Gulf Stream forms and is distributed more toward the polar sheet. England gets a thaw. Scandinavia melts.
    6) As the ice retreats, you get a step function as the ice is lifted off the ground in key places. Trans polar currents form.
    7) Wind driven break up and flushing begins (as we have now, but would not exist under a solid ice cap a mile thick).

    Several of these have a positive feedback to them.

    Eventually, when the drought conditions are gone, we can get enough clouds to have some low cloud negative feedback, but that’s long after the ice is on it’s way to gone.

    And, of course, if we stop having #7 as the AGW crowd wants, and get a little ocean cooling from orbital position being a bit late in the game, then we’re well on our way to going backward down that stack…

    The very LAST thing I want is dropping sea levels and a permanent ice cap at the north pole….

  10. GregO says:

    “The very LAST thing I want is dropping sea levels and a permanent ice cap at the north pole….”

    Amen brother. Watching the ice-melt in the Arctic every summer has become a sort of spectator sport – ice is melting AGW is true! Ice is holding AGW is false! That’s a broad generalization I admit, but has a grain of truth. A good question is “What good is all that ice?”

    I managed once in my life to get up on a glacier in Alaska. It was the deadest, driest, and in a way the most unearthly place I have been. Glaciers growing without bound would be a bad thing.

    So if we had an ice-free Arctic summer what terrible thing would happen? (Other than a blogospheric war of words of Biblical proportions…). I know the warmistas predict a “tipping point” and a “death spiral” and of course the poor, poor polar bears. Would it upset the thermohaline cycle? Floods? Famines? Four Horsemen of the Apocalypse anyone?

    Have we considered that an ice-free Arctic in the summer might be a nice thing? Easier to navigate, explore, vacation, etc? What is so good about all that ice?

  11. Bruce of Newcastle says:

    Doug Jones – if you see Ken Stewart’s blog you’ll get a lot on adjustments in Oz along the lines of Willis’ Darwin-zero posting.

    I think he’s currently focussing on the local Bureau of Meteorology adjustments, but has looked at GISS’s efforts before that:

  12. Gary says:

    Chiefio, you wrote:

    the orbital shifts happen on a very long slow schedule. There is something else that happens on a much faster schedule. Don’t know what it is. Might just be an accidental timing artifact of the orbital effects. Just barely get over to the warming side, when BLAM, we tip down again.

    Although the cycles are slow, in combination they add and subtract to the height and choppiness. If you’ve seen wave trains on the ocean coming from different angles you know what I mean. It’s the rogue wave phenomenon. Combining the major orbital cycles at 100Kyr, 41Kyr, 23Kyr, and 19Kyr produces a curve similar to the proxy records with relatively steep rises and fall. Certainly there are feedbacks, such as the amount of ice on the continents, that come into play and probably delay change until the tipping point is reached. Then it’s all down (or up) hill relatively quickly.

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