A 280,000 Year Long Ice Age

UK weather forecast:

UK weather forecast: Britain to be hit with torrential rain for THREE more days

At least it isn’t snow.

I’ve been continuing with the development of my glaciation simulation model. It’s a model of heat flow up a geological column from the hot centre of the Earth through its surface and out into space. At the surface of the Earth the heat flows are very low: only about 70 milliWatts per square metre. But over many thousands of years this small heat flow adds up to sufficient heat to melt overlying sheets of snow and ice several kilometres deep.

I’ve now extended the model to have 18 radial geological columns at 5 degree intervals from the equator to the north pole.

And I’ve then been having snow fall continuously on all these continental geological columns at the same rate (about 10 centimetres per year) for tens of thousands of years.

The sequence of images below show the build-up of snow on the surface of the Earth at all latitudes from 0 to 90ºN over a period of 280,000 years, and the gradual heating of the surface rocks beneath the snow, and the consequent melting of the overlying snow. In the equatorial regions where snow doesn’t settle, the surface rocks cool slowly.

In this sequence snow never settles for long south of about latitude 30ºN, but at higher latitudes the snow settles and deepens quite rapidly. Surface rock temperatures rise highest beneath the deepest snow. Maximum snow depth at 90ºN reaches about 1200 metres.

The snow at the base of all these snow sheets is continually slowly melting, but because there’s snow continually falling on top of the snow sheets, they initially gradually get deeper, until the surface rocks beneath the snow have warmed up enough to melt the overlying snow faster than the rate at which new snow is being added, at which point the snow sheets begin to slowly thin.

So over 280,000 years the snow sheets first grow, and then dwindle back down to almost nothing. And that is the same sort of order of magnitude as the last 100,000 year long ice age, that only ended 12,000 years ago.

The snow sheets in this model extend as far south as 30ºN, which is the latitude of Cairo in Egypt. Most discussions of past northern hemisphere glaciations seldom show them extending further south than about 50ºN in Europe. Evidence of these ice sheets is found in unstratified gravel produced by the friction of ice sheets on rocks beneath. But there must need to be a considerable depth (several kilometres) of ice for this to happen, and it’s unlikely that relatively thin layers of snow will produce similar moraines and drumlins, or indeed any of them at all. And in my model the snow is mostly only about 100 metres deep between latitudes of 30ºN to 50ºN.

I’ve been wondering whether these relatively shallow snow sheets extended over the entirety of Europe, as well as Spain and Italy and Greece, and that the reason human civilisation first emerged in Egypt and Mesopotamia and only later in Greece and Rome is that for a long time the latter remained under snow as the glaciers gradually retreated northwards.

I’m hoping next to get almost all the snow to melt and produce an almost completely snow-free interglacial period during which the hot surface rocks gradually cool back down, eventually allowing a new period of glaciation to commence.

In the meantime I’m hoping that all the CO2 that’s being added to the Earth’s atmosphere will raise air temperatures enough to forestall the re-glaciation of the northern hemisphere any time soon. It’s one of my future projects to try to find out if CO2 can do this.

About Frank Davis

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8 Responses to A 280,000 Year Long Ice Age

  1. virtualbarman says:

    Amazing once again…

  2. I remain impressed with this theory, which seems very plausible. Thank you for this update.

    • Frank Davis says:

      Fortunately I’m not using Navier-Stokes equations in my simulation model. I’m using a simple steady-state conductive heat flow equation:

      in which Q is heat flow rate, k is thermal conductivity, A is area, L is thickness, and T1 – T2 is temperature difference. It’s one that is used by engineers all over the world to calculate heat flow.

      From your link:

      In the simplest terms, even the slightest infinitesimal input variation in these computer what-if scenarios at the start will result in the most lopsided results at end.

      That was certainly true of my orbital simulation model. A very slight change in the initial velocity of an orbiting body can (and regularly will) result in it ending up millions of kilometres away after a few years. But if anything in my ice age simulation model, this seems not quite so true. It’s actually very well behaved most of the time.

      But there are problems. For example the thermal conductivity of granite can vary over a wide range, depending among other things on how wet it is. And the temperatures in the interior of the Earth vary from place to place, and have never been physically measured at depths below 12 km. We know a lot about our solar system, and next to nothing about the Earth a few metres beneath our feet.

  3. narbanor says:

    Climate alarmist messages on the MSM, at least here in France, are often followed by an nth promotion of automotive or air transport, and occasionally (but not infrequently) followed by an nth bout of antitobacco prejudice, obviously aimed at distracting attention from urban air pollution’s negative effect on human health.
    In the case of the ozone layer depletion narrative, did the banning of CFCs (chlorofluorocarbons) in the late 80s really restore it to its primeval state, or have we also been ‘fed a line’, that just happens to be slightly – or vastly – more tricky to unravel than the ludicrously false LC-to-tobacco-consumption statistical link?

  4. smokingscot says:

    Regards humanoids, my understanding is there were at least 3 distinct types of “human” that they know of. One may have been pretty small with a fragile skeleton and it’s assumed they did not evolve.

    The two they are sure of is us lot and the Neanderthal. And the Neanderthal was wonderfully adapted to the cold, so while I agree 100% with your speculation that human civilization only made its way north once the ice had retreated, humans did just fine living on the the stuff.

    We know they were hunter gathers and they’d have had the smarts to fish. Their diet would most likely have been very similar to the Eskimo; raw fatty meat, with the fat being prized for its calorific content.

    Almost nothing survives from the Neanderthal, which is understandable, they too used caves and did the drawings bit, but no writing. But they were human.

    It was thought we killed them off. Now they know we didn’t; we inter married – and all Europeans have between 1 and 3% Neanderthal DNA in us.

  5. Fred says:

    Another theory of how ice ages are initiated, from Bill Bryson’s A Brief History of Everything.

    “Evaporation is a swift process, as you can easily gauge by the fate of a puddle on a summer’s day. Even something as large as the Mediterranean would dry out in a thousand years if it were not continually replenished. Such an event occurred a little under 6 million years ago and provoked what is known to science as the Messinian Salinity Crisis. What happened was that continental movement closed the Strait of Gibraltar. As the Mediterranean dried, its evaporated contents fell as fresh-water rain into other seas, mildly diluting their saltiness—indeed, making them just dilute enough to freeze over larger areas than normal. The enlarged area of ice bounced back more of the Sun’s heat and pushed Earth into an ice age. So, at least, the theory goes.
    What is certainly true, as far as we can tell, is that a little change in the Earth’s dynamics can have repercussions beyond our imagining. Such an event, as we shall see a little further on, may even have created us.”

  6. Pingback: I Hope Michael Gove Isn’t Our Next Prime Minister | Frank Davis

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