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THE MECHANISM OF THE HUNDRED-THOUSAND YEAR CLIMATE OSCILLATION
The proposed theory of the mechanism of the hundred-thousand year climate oscillation is based on three main postulates:
All the three postulates are attempted to be explained below item by item.
A) Gradients, not the absolute quantities. Why gradients run the hundred-thousand year oscillation.
There has been no coherent theory to explain the mechanism of the hundred-thousand year oscillation yet. It is generally accepted it happens due to solar forcing variations explained by action of Milankovitch cycles. That means the explanation goes along the following mechanism pattern – interglacial happens as the result of the ascending cycle and the ice age results from the descending one. In short: insolation increase leads to interglacial, insolation decrease leads to onset of the glacial period. Such straightforward theory has many loopholes , though, and some scientists have already pointed out that although it generally reflects the solar forcing pattern it misses some points of paramount importance and, therefore, while the theory is generally not false it is simply incomplete.
There must be also other factors that regulate the ups and downs of the hundred-thousand year oscillation otherwise the shape of its temperature curve would be different. The points where warming leads to warming and cooling leads to cooling theory is weak are:
Obviously, other factors must be acting on the atmosphere than only Milankovitch cycles. The only "cooling leads to cooling and warming leads to warming" theory is the source of one more quite profound fallacy. It is called "never ending Holocene" (a.k.a. "the ice age never again" or "Pleistocene, the closed period" or "the Anthropocene") and part of it is the idea of the "anthropogenic" global warming. This theory claims that the ice age is the thing of the past as cooling caused by the diminishing solar forcing in the solar forcing cycle will from now on be counterbalanced by the current global warming which will last forever as it is mostly the result of both human-made energy and carbon dioxide released into the atmosphere and our only trouble is not to make these too abundant as in that situation it would lead the Earth to overheat. This is the reason all human efforts are now (in quite narrow minded way) directed to fight against the local, most probably of the resonant nature, global warming without seeing the broader picture of the hundred-thousand year oscillation threats. The reason of those fallacies is the people’s minds are generally in paradigm of the absolute characteristics. People think of climate in terms they think about weather. Is it going to be colder or warmer? Is it going to be wetter or drier? In case of the climate changes the absolute values do not work, though. It is the GRADIENT that counts and the hundred-thousand year oscillation climate change is not about only getting warmer or cooler. It is mainly about what is getting warmer and what is in the same time is getting colder, or, and that is very important, even if both entities are warming up they can do it at different rates which is going to result in growing temperature difference(!). Once this is comprehended the picture of the sudden collapse of temperature in the middle of a global warming becomes much less a reason for a sarcastic forehead touch.
Many factors indicate the purpose of the hundred-thousand year oscillation is to naturally keep Earth’s heat in balance. In this situation it has to operate based on the thermostat principle. A thermostat is a simple device used in heaters and coolers and the purpose of which is to keep the temperature of the thermally controlled containment between two preset levels. If the heating is the objective the thermostat turns the heater on any time the temperature falls below a pre-determined level in order to make the temperature rise to the preset upper level. As soon that temperature is achieved the thermostat turns the heater automatically off to allow the temperature to drop naturally down. This pattern is repeated over and over just to make sure the temperature is always kept within those two threshold values. If the containment’s temperature is attempted to be kept colder than the ambient one the cooler is employed. It works like the heater but in reverse.
Let us imagine a chamber that is constantly exposed to an action of both a cooler as well as a heater. If the heater provides more heat to the chamber than the cooler can remove from it, the chamber will slowly warm up. If the cooler removes more heat from the chamber than the heater supplies to it the chamber will slowly cool down. If the heater provides equal amount of heat to the chamber as it is removed from it by the cooler the chamber’s temperature remains steady. If then we want the chamber to cool down we can simply turn the heater off but if we want to speed up the process we can also turn the cooler on. And vice versa, if we want the system to warm up we will definitely turn the cooler off but if, in addition to that, we want that process to be accelerated, we will also turn the heater on.
The Earth is like that chamber; it is both heated as well as cooled at all times. The Sun is the heater and the space above the atmosphere is the cooler. The intensity of the solar radiation is not steady over the time. It depends on the sun rays angle, on clouds, on reflection from snow and ice. In the very long period the solar forcing term is used that is based on calculations made by M. Milankovitch. Solar forcing concept amalgamates the influence of sun’s eccentricity, obliquity and precession. Everyone knows how it works so I am not going to dwell on it. The bottom line is sometime the Earth receives more energy from the sun, sometimes less. The Milankovitch cycle insolation curve tells us quite precisely how much and at what latitude. Another factor that affects the heat received from the sun is the presence of water in the atmosphere. The clouds really affect the amount of heat both reaching the earth as well as leaving it. Then there is a cooler: the space. It is absolute zero temperature environment. The heat can radiate from the atmosphere fast. It can be really cold on the cloudless sky night on Sahara. It is very cold over the North Pole in winter because the sun is not warming it and the heat radiates away to the space freely as there is not much clouds above. On top of that the heat runs away through the tropospheric/stratospheric polar vortex structures.
As in case of the temperature controlled chamber mentioned before the Earth either cools down or warms up depending on the balance between its cooler and the heater. If the Sun provides more heat than the space removes from it the planet warms up, if it is otherwise the planet cools down. I mean the total heat balance, not the local ones – it is known the lower latitudes have permanent heat surplus and the higher ones, permanent deficiency (Fig. 3A2).
Fig. 3A2 Imbalance of the solar energy received on different latitudes.
As already has been mentioned, the temperature of the Earth follows the curve of the solar forcing at 65N latitude but not accurately. All solar forcing curve ups and downs are reflected on the Earth’s temperature curve (Fig.3A1) but it is obvious that some very strong ups do not bring an interglacial on while sometimes even relatively small ones do. The theory that says the ice ages are the result of fluctuating solar forcing as calculated by Milankovitch is not complete then and the scientists are aware of it. Something is missing.
What is definitely missing is the regulator of both the heater as well as the cooler: the master driver of the hundred-thousand year oscillation - the gradient. More precise, the gradient of temperature and water contents in atmosphere. The temperature gradient (definition also pertains to other gradients, like humidity gradient, air pressure gradient, etc.), following the Wikipedia, is a physical quantity that describes in which direction and at what rate the temperature changes the most rapidly around a particular location. The temperature gradient is a dimensional quantity expressed in units of degrees (on a particular temperature scale) per unit length. The SI unit is Kelvin per meter (K/m). Temperature gradients in the atmosphere are important in the atmospheric sciences (meteorology, climatology and related fields). Assuming that the temperature T is an intensive quantity, i.e., a single-valued, continuous and differentiable function of three-dimensional space (often called a scalar field), i.e., that:
T = T ( x , y , z )
Where x, y and z are the coordinates of the location of interest, then the temperature gradient is the vector quantity defined as:
∇ T = (∂ T/ ∂ x, ∂ T/ ∂ y, ∂ T /∂ z).
The action of the temperature gradient in atmosphere is very discrete and it is quite independent on the absolute temperature values. Two air masses one of +30 degree and another of +31 degree temperatures are of the same temperature gradient as the two air masses one of the +60 degrees and another of +61 respectively and therefore the direction of the heat flow between them (and the air flow, ceteris paribus) will be similar although in absolute numbers the temperatures of the first pair is much different than the second. Two air masses one of the +31 degree and another of +30 respectively, have different gradient than the both pairs above so the heat flow will be reversed and even if the absolute difference of the temperature of the third pair is so minute with respect to the first one the vector is reversed.
The rate of heating up and cooling down of water and land is different and that fact leads to temperature gradient between the two. The reason the lands and oceans warm up and cool down at different rates is both water and the rocks/soil blends have different heat capacities. Again, following the Wikipedia, the heat capacity of a defined system is the amount of heat (usually expressed in calories, kilocalories, or joules) needed to raise the system's temperature by one degree (usually expressed in Celsius or Kelvin). It is expressed in units of thermal energy per degree temperature. The specific heat capacity, often simply called specific heat, is the heat capacity per unit mass of a material. In the table of the materials heat capacity we find water’s being of 4.18 J/g K and the land (soil and rock) roughly equal to 0.81 J/g K. That means water can store roughly 5 times more heat than the soil and rock and therefore it takes much longer for water to cool down than rock and soil blend. The same pertains to oceans and lands of the Earth. The oceans tend to warm up slow as they absorb much more heat than the lands.
There is an abundance of temperature, pressure and moisture gradients in the atmosphere. The biggest one is, of course, the one between the air of the Poles and the Equator. But there are others: there is a gradient between the temperatures of the polar air and the moderate zone air, there is a difference between the air temperatures over the oceans and the lands, there is a gradient between the temperatures on the same latitude on the ground and 10 thousand miles over it etc. etc. All these gradients make the air move constantly.
Fig.3A3. Major gradients of the Earth.
The set of the most important gradients for the glacial onset is located at the northernmost part of the northern hemisphere.
The high latitudes of the northern hemisphere share relatively equal areas of land masses and waters. It includes Canada and Alaska in the Western and Northern Siberia on the Eastern hemisphere on the land side and Northern Atlantic, Northern Pacific and Arctic Ocean with neighboring seas on the ocean side. That quite even proportion is very important as those lands and oceans can absorb different amounts of heat. As the result they warm up and cool down at the very different rate. Under the same sun radiation the lands warm up much faster than the oceans and as the sun radiation is reduced the oceans cool down much slower than the lands. That creates the temperature gradient between the two entities. As the temperature of the oceans is changing slowly the temperature of the lands fluctuates over a particular year. In the fall the lands cool down fast and in the winter they become colder than oceans. As the result, the atmospheric circulation becomes winter-specific. The low pressure systems form over warm oceans as the warmed air raises and flows over now colder lands where it is dropping down, creating high pressure system. As the warm and humid air rises over the ocean it cools down and the rain precipitates there. The air that flows towards the land on high altitudes is already dry as the ascending air has already precipitated its water. This is the reason the amount of precipitation is so low over the northern lands in winter. As the air drops over the lands it is cold and dry. When it descends at the ground level it spreads in cyclonic way towards the sea carrying the land moisture away along with it. The climate of the winter on the northern lands is therefore dry. Then it comes the springtime and the sun starts to shine up warming the surface. In early summer the temperature of the lands starts to exceed that of the oceans and the air circulation reverses to summer-specific. Now, warmer than the oceans lands build up their low pressure systems, the air raises, cools down, the rain falls, the air flows over towards now colder oceans, drops down there building high pressure systems. As the air now flows along the sea surface towards the lands it absorbs moisture on its way. This is why the precipitation in summer months in the north is twice as high as during the winter ones. This is an annual situation but in the much longer time it can extend to centennial and even millennial gradient changes.
The above graph shows the falling temperature of the late interglacial while the CO 2 levels stay high for at least 7 or 8 more millennia. It is the proof that the oceans cool down at the much, much slower rate than the lands. The CO2 levels stay high in the atmosphere as the gas does not dissolve well in the warm water. It takes another few thousand years for the oceans to cool down before eventually the gas will start to dissolve in then much cooler oceans. The CO2 curve shape is an indirect proof that the temperature curve is showing the average temperature of both lands and oceans.
If so, let us try to split that average temperature curve into separate temperature curves of both the lands and the oceans (Fig. 3A4) then, starting from the point the average temperature begins to fall while the interglacial is ending. It can be assumed that at the end of an interglacial when the solar forcing is diminishing, humidity of air is reducing, the albedo on northern, now more and more ice covered lands growing the temperature of the lands will keep decreasing much faster than the temperature of the oceans. That will be continued for very, very long time, for thousands of years until both curves finally reach the minimum. That practically means that after an unimaginably long time of the Earth’s cooling the temperatures of both oceans and the lands will finally equalize. Again, even more practically, it means that everything (both lands and oceans) will be, by then, equally dead cold. Before that point the oceans were still slightly warmer than the lands and that kept the temperature gradient (vector) directed steadily the same way. If at this point the insolation starts working a bit stronger (solar forcing curve starts to go up) both entities will start warming up but the lands will start to undergo the process much faster than the oceans. As the result the gradient will change its direction.
What are the consequences of those gradient reversals?
Let us examine the gradient reversal point marked S1 – over the vastly long period of the ice age both lands as well as the oceans cooled down steadily. Because of the differences of thermal capacity the lands cooled down faster and the oceans slower. Therefore the oceans were always warmer than the lands. In this situation the winter-specific air circulation was prevailing. The cold and dry air descended on the lands building high pressure systems. The air flew towards the low pressure system over warmer oceans on low altitudes carrying with it the water particles removed from the lands. Over the long time such type of circulation slowly deprived the continents of the humidity making them both cold and arid. At the end of a glacial period the continents were bone dry and the air was just filled with dust that settled in tens of feet thick layers of loess soil. The clouds were non-existent and the sky was white from suspended dust. And in this very cold and dry environment that looked as if it only could get colder and drier something changed; a strong warming solar forcing cycle began. The lands started to become warmer than oceans and the summer-like circulation would become prevailing over the length of a particular year. The gradient reversal changed the air circulation pattern. The air over colder oceans became cool and heavy. The high pressure systems started to build there. The now fast warming lands started to pass their heat to the air above them and that air started to rise up building low pressure at the ground level. The cold and moist air moved from the ocean side towards the low pressure systems located over the lands where it raised and as it cooled down ascending kept precipitating its moisture. The rain came back to northern lands freeing them slowly from the suspended dust. The more abundant rain, very rare so far, would also fall over the glaciers helping to melt them more than just warm but dry air would do. The glaciers started to melt slowly, initially very slowly, but the overall ice building trend was stopped: from the S1 point on it was less and less ice not more. That’s why the point S1 is called the Glacial Maximum. For another 7-8 thousand of years the ice plates would continue to melt although quite slowly. Then, more and more warm and humid air started to flow into the lands, at first only at the coasts but it was enough to start melting the glaciers at their banks. Since then the atmosphere began to fill with moisture both as humidity as well as other forms like water droplets and ice crystals. The friction within the atmosphere increased which was very important for the atmospheric changes and the interglacial onset. At the certain moment the threshold value of the temperature, air humidity and water particle contents has been crossed and the enormous acceleration of the processes occurred. The temperature shot up like a rocket. The speed of the event was astonishing. It is quite possible it all happened just in one year and is also quite possible it could be even momentary. Just like a one big storm (if it was momentary it had to be a storm of biblical proportions). The interglacial burst out. It happened like that in all last 8 interglacials - exactly the same way both in the Eem as well as in the Holocene. The similarities are so striking; there is no doubt both processes, although separated by nearly one hundred thousand years were due to exactly the same mechanism. The repeatability of those phenomena also implies their inevitability. If both, so distant in time, started that way than, logically, it is very probable the second one will end up the same way as the first possibly within the similar time frame as well. In the second part of this chapter I will try to explain the nature of this extremely vigorous phenomenon but let us continue now with the temperature curves of the interglacial. As the increase of the temperature in the interglacial onset is so fast it can be assumed the temperature of the lands rises much faster than that of the oceans. The temperature gradient assures the warm rains fall over the glacial plates now speeding up the rate of their melting substantially. It would take 6000 years to fully melt such enormous amounts of ice, though. As the interglacial approaches its maximum the solar forcing (Milankovitch) curve starts to fall down, slowly at first. As a consequence the lands cool down again and it happens faster than the cooling of the oceans. At the certain point the temperature curve of the lands will fall under the temperature of the oceans. On the graph it is marked as the point S2. The point S2 denotes the next reversal of the major temperature gradient. From the point S2 onward the air over the lands becomes cooler and cooler, drier and drier. After another 10 thousand of years the ice plates will be completely rebuilt and the Earth will turn to a cold desert again.
It is the temperature gradient reversal, not absolute temperature change that acts as a cooling/warming switch within the one-hundred thousand year oscillation and that’s why it is so difficult to apprehend that the ice age can theoretically start in the apex of even most vigorous global warming.
The table below presents the gradient direction and their reversal points in the synthetic form. Gradient direction when lands are warmer than oceans is called "positive", and "negative" when opposite.
The snow melting season is very short at 65N latitude. It lasts only 2 months. In those 2 months all the snow of the just gone winter must melt. If for some reason it had not happen, then some of that snow would have been left until another winter. If it had not happen for a several winters in the row then we would have had the onset of the glacial period in the making as the snow would have started to turn into ice as the result of the weight pressure of the upper snow layers on the layers below. The paleo historical research of isotope traces seem to confirm that the winter of the ice age is not that different than the winter of the interglacial in terms of the average temperatures. It is the summer that is eliminated from the picture. Neither the interglacial start nor the onset of the ice age happens immediately after the gradient change. Those two points only mark the point that triggers the conditions necessary for the two grand events to happen – start and demise of an interglacial. As we currently live around the time of the S2 point of the gradient reversal, the first cooling of the new ice age may unfold even right in front of our eyes. The reversal of the atmospheric gradient has an imminent influence over the further climatic changes. Both their fast appearance as well dynamic, accelerating development once the gradient is reversed confirm it possess characteristics of the sensitive dependence of initial conditions (the feature popularly known as the "butterfly effect").
So far, only the temperature gradient has been reviewed in detail. Other atmospheric gradients are also important, though. Two most important ones are gradients of the atmospheric pressure and the atmospheric water presence (water vapor and air humidity). The air pressure gradient is extremely important in setting the direction of air circulation. Creation of the low pressure systems over the warm surfaces (oceans or lands) and high pressure systems over the cold ones is an engine that makes the air to circulate either in the summer or winter specific pattern. The temperature and the pressure gradients generate the buildup of the third, also absolutely important, gradient of the water contents in the atmospheric air masses. The water contents term is used here to differentiate between two distinct states of air humidity: uncondensed and condensed. In its uncondensed form the water vapor is invisible but represents a very powerful, omnipresent heat retention medium (a.k.a. greenhouse gas). The proportion of the water vapor to carbon dioxide in the atmosphere is like 96.9 to 3.6% (!). It is so powerful in this aspect it overwhelms all other natural and man-made greenhouse contributions. Although it is difficult to calculate power of atmospheric heat absorption of the water vapor as it has a profound infrared absorption spectrum with more and broader absorption bands than CO2, and also absorbs non-zero amounts of radiation in its low absorbing spectral regions, its global warming potential is difficult to calculate but based both on those spectra width and strength (Fig.3A5) it can be assumed the water vapor heat retention can be from 30 to 100 (or even more) times as high as that of the CO2.
If so, the influence of the carbon dioxide on the global warming processes (contrary to the widespread, popular belief) may not only be very small but quite possibly even infinitesimally small as well. The influence of the water vapor in the condensed state (clouds) is also paramount and will be discussed in the next part of this work.
Understanding the importance of the water vapor gradient in the atmosphere can never be complete without realizing that it works in a positive feedback loop with the temperature gradient. As the warming trend commences the rising temperature makes the ocean waters to evaporate more strongly and the air becomes more humid. As the circulation also becomes positive, (summer specific) the lands become wetter. There is more and more water vapor in the atmosphere – more powerful greenhouse gas and it makes the air temperature to go up. The same is true in the opposite direction: as the temperature starts to drop the air cools down and can only retain less water vapor. More clouds form and that prevent sunshine from warming up the lands first. Then, as the cooling process continues the air can retain less and less moisture. The water precipitates from the clouds and the snow precipitation form prevails over the rain one. As the snow melting decreases on the cooling land the water evaporation rate decreases too and the humidity of the air decreases as a consequence. Eventually, the air circulation becomes negative (winter specific) and the humid air at the ground is being carried away by the dry air towards the oceans. The lands slowly become arid. As much as warming and atmosphere wetting, the cooling and drying go hand in hand as well. Cooling and drying go together like the proverbial "horse and carriage"; not only that: it is the feedback loop - the cooler it gets the dryer the atmosphere becomes and the dryer the atmosphere becomes the cooler it gets. It is a classic feedback: the less water vapor in the atmosphere, the most powerful greenhouse gas, the colder the atmosphere becomes. The colder the atmosphere becomes the more water vapor condenses and then precipitates. At some point the precipitated water falls on the ground only in form of snow and if the glaciers have already formed the fallen snow will not evaporate again. This is the one way feedback street – colder, dryer, then even colder, even dryer, etc. etc. The following chapter explains this process in detail.
B) True Earth’s atmospheric circulation and the hundred-thousand year oscillation
The process of early glaciation cannot be explained with the classic, three-cell model of the Earth’s air circulation. That model assumes the continuous equatorial Hadley and Polar cells are separated by also continuous but rotating in the opposite direction mid-latitude Ferrel cell. The assumed continuity of all cells implies there is a very little direct air exchange between the Polar and Hadley cells. Ferrel cell, in that model is just a passive, rolling heat exchanger, an entity resulting from the acting Coriolis force. The model looks and works great on paper. In reality, the Ferrel cell does not exist at all, the Polar cell is far from being continuous and even Hadley cell which is the closest to possessing the attribute of the regular, continuous air circulation entity has its own points of direct air influx and outflow not at all in line with its allegedly perfect configuration. The three-cell air circulation model is not even a simplification or generalization of the actual state of matters. It is just a pure science fiction.
In fact, the allegedly separated polar, Ferrel and Hadley cells are just one big cell with two partitions that complicate the air flow leading an observer to the trap of the apparent three closed, independent circulations. The Fig.3B1 shows partitioned but still one-cell air circulation.
First major characteristic of such presented air circulation is the air of the mid altitudes never returning towards tropics under the tropopause as the three-cell model postulates. No single blow of the wind ever moves in that direction. There is no reason for that. No positive gradient of temperature, no pressure gradient either. The cooled air at that altitude cannot move that way at all. Any amount of dried and cooled air catapulted from the slope of the polar front and thrown by the jet stream that direction immediately sinks and is captured by the westerly winds back to north as the strong westerlies blow only pole ward at that altitude. This fact alone already kills the idea of the three-cell model. It is quite intuitive yet the fiction of the three-cell model still persists. The westerlies blow on every altitude there. The higher it is the stronger they are. The weakest westerlies are actually at the ground level. All those westerlies of the temperate zone finally meet the cold air of the arctic origin. The polar front is the interface of the two big air masses, one warm and humid coming from the south and another, cold and dry, from the north. The two air masses create big gradients of both temperature as well as humidity. As they meet they form an interface of very strong, laminar winds so the air masses do not mix there. The interface is never perpendicular to the ground plane as the three-cell model implies. The polar front is always tilted. It looks like a slope of a mountain and the westerlies actually hit that slope along its all height. As they cumulate on it the resulting air stream flows upward the slope and the relatively warm air cools and compresses. The water contained in such cooling and compressing air condensates and precipitates releasing heat. The heat magnifies the gradient of temperature between the air masses and that keeps the polar front from further expansion. The dry air is then grabbed by the polar jet stream, pushed eastward and thrown over into the polar front side where it continues its journey towards the North Pole cooling gradually. As it reaches the pole it cools down radically and descends creating very cold and dense lens of the very cold air. Such dense and cold air moves away from the pole outward in form of easterly winds. Those winds reach the polar front and they permeate it at the ground and mid-altitude level. Then they collide with the warm ground westerlies creating a formation of cold anticyclones that move southbound. This is the environment of the mass and the heat exchange that reaches the Hadley cell at its bottom feeding it with colder air from the north. That is how the northern hemisphere air circulation loop is closed in just one, grand cell of the global atmospheric circulation.
Once the idea of the Ferrel cell in form of the clockwise rotating air is dismissed we can see the clear picture of one mega-cell with two gradient-produced partitions – one, with the limited mobility (at the tropics) and the other, able to move either north or south bound as well as freely tilting (at higher latitudes). As the polar front partition is an entity located within one air rotating system we can see how much freedom of movement and flexibility it has within it. Not only it can move north and south but it can also tilt depending on the temperature, pressure and the humidity gradient of horizontally flowing air masses. The three-cell model implies the position of the polar front depends on expansion of one cell at the expense of the other i.e. as the polar cell expands the Ferrel cell shrinks and vice versa. The one-cell model explains how the warm air can wander deep north at high altitudes while, at the same time the polar air can expand down south at the ground and mid altitudes. It all can happen because of the polar front tilt. As the result, the area of the land under the polar front can expand from a couple hundred to a few hundred miles. With the warm and moist air on the top and the dry and very cold air below the resulting precipitation has a very good chance to end up on the ground as the snow or ice than the rain. In the time of Eemian interglacial it happened at the end of the 118 millennium before present, just before the end of the 12th thousand year birthday of that interglacial. The Eemian interglacial was very warm – the pressure of the warm air pushing as the result of the expanding Hadley cell was enormous yet with the same time the rapidly cooling northern lands strengthened the cold air flow south. What followed, it was not what the three-cell model would imply – a head-on collision of the two fronts. The collision did not occur – the dry and cold air at the low level made its way south and the warm and humid at the high level – north; as the pressure of both was increasing the radical tilt of the polar front resulted. At the certain moment large areas of northern lands found themselves virtually under the horizontally stratifying air masses of enormous temperature, moisture and pressure gradients (see the Fig.4A1 in the Chapter 4). That contact had to result in large area of increased precipitation in the very north latitudes of the hemisphere resulting in mostly snow and ice fall. The area under the tilted polar front found itself under of one, powerful storm. As those monumental area storms happened the snow kept accumulating and as the consequence the glaciers started to build up. As soon the first glaciers started to form the air above them cooled down, got dense and dropped in form of anticyclones (high pressure systems). That, eventually, created cool spots, even colder than the North Pole.
The steady process of accumulation of ice in the North America and in the northern Asia is one of the characteristics of the ice age onset. If the ice fails to melt within one summer time the next such failed season may double the ice amount. Perennial snow brings big climatic changes. The land covered with snow all year round will not be warmed in the summertime by the sun – the sunrays will be reflected back into space. The air above the ice will be cooled by the ice and the cold, heavy air will be descending on the ice keeping it cold. Such cooled area immediately starts to assume the role of the center of the high pressure cyclone with the surface wind blowing away from it. The high pressure cyclone will spread this cold, dry air over the land depriving it from humidity. Normally, the dry, descending air would immediately reduce the precipitation but at the end of an interglacial as it dwells right under the tilted polar front under a huge mass of warm and humid air (westerlies) being in contact with the cold, returning air will produce heavy snow precipitation. As the descending in an anticyclone air is cold it provides low temperature for the just fallen snow. If the slanted polar front is a snow making machine, then the produced by it ice cold dropping air high pressure centers are like freezers that conserve that ice and snow preventing them from melting. Once this process has started there is no way out. From that point on glaciers will start to build up steadily. The negative temperature gradient, the trigger of the process, is now well established.
If this situation becomes permanent it means the lands will not convert to their summer circulation in the summer and the winter will start to be there perennial. No more summer at 65-70N latitude means onset of glaciations which in case of Eem started in the 117th millennium back from now. The period from the still warm 119th millennium to the 117th millennium is characterized by the slow reversal of the temperature gradient between northern oceans and the northern land masses. The gradient started to reverse some time during the 118 millennium and that’s why the first great sudden cooling period happened at that time. The attempt to date it more accurately indicates it was in the beginning rather than the end of that millennium and subtracting it from the date of the beginning of the Eem interglacial (the beginning of the 130 millennium) gives the result close to 12 thousand years. The Holocene is now about 11.750 years old so it is very much in line with that. For skeptics (nomen est omen) who may claim that due to the global warming it is now too warm to start to cool down I would like to remain that the 119 millennium before present was the time of the very strong global warming in the Eem and the temperatures by then were much higher than now in the Holocene. Again, it is not about the absolute temperatures – it is all about the temperature gradient.
C) Polar vortex split as the builder of the ice age strength and its re-merge as the phenomenon that starts an interglacial.
Polar vortex is an anticyclone ever present over the Earth’s axis on each hemisphere. In fact, each polar vortex consists of two separate vortices – one hovering above another. The lower is the tropospheric polar vortex and the upper is the stratospheric (and mesospheric) one. The tropospheric polar vortex is wider and basically it is synonymous with what is described as polar cell – an entity with a boundary where it meets the warm air of the south forming the polar front and the northern jet stream at its top. The stratospheric polar vortex (called that way although in fact it reaches far into mesosphere) is an anticyclone of much smaller diameter, appearing in late fall and disappearing in the beginning of the spring. It attempts to center right over the tropospheric polar vortex and it usually floats right over it hardly ever leaning out of its boundaries. Some claim both entities have no continuity and, even more, they are completely independent without any relation between the two whatsoever but it is definitely incorrect. Even if there is no continuity between them, the heat transfer takes place from one to another and it is basically the reason for the stratospheric polar vortex to appear – to remove the heat from the tropospheric polar vortex in winter to assure the existence of the necessary temperature gradient that it is lacking in the cold season when the air of the lower latitudes is much colder than it is in the summer. If not for the stratospheric polar vortex the temperature of the tropospheric one would not vary that much from the temperature of then also much colder air that surrounds the polar front and the rotation of the lower polar vortex would slow down allowing it, in consequence, to spread south in search for the stronger temperature gradient which would, in turn, accelerate the rotation of the boundary again but then at much lower latitude. That would result in freezing temperatures in Canada and the northern states of the USA. As the stratospheric polar vortex removes the heat from the tropospheric one the high temperature gradient of the polar front is maintained which gives the boundary a faster rotation. As the vortex rotates faster it constrains its boundaries. Obviously, as the boundaries constrain they also move to higher latitudes preventing the cold air from spreading southward. In the summer, when the southern air warms up and the gradient of temperature is naturally high the polar cell is cold enough to rotate fast and to be constrained to avoid any dangerous expansion of the polar front south. As, paradoxically, the polar vortex needs less cooling in the summer, only the tropospheric polar vortex exists. When more cooling is needed in winter the stratospheric polar vortex comes in with help playing the role of an auxiliary cooling amplifier. Because the polar vortex is a very cold entity it tends to naturally position itself in the coldest area of the far North - as soon as the bottom of the polar vortex meets a warmer spot the temperature gradient moves it away from that spot towards the colder place. This coldest place in the time of interglacial is at or in the vicinity of the North Pole. It is like that now but it does not mean it will be the same in future. As long as the North Pole is the coldest place on the Northern Hemisphere the stratospheric polar vortex will wander around it. But even now the North Pole is not the coldest place on the northern hemisphere. This is the reason the tropospheric polar vortex of the northern hemisphere is not circular in shape; it is oblong with two centers rather than one. Those centers seem to be already located over the northern islands rather than over the Arctic Ocean waters. One tends to position itself over the Ellesmere Island of the northern Canada, the other over the Malaya Zemlya Island off the Siberian coast. The reason those centers are there indicates both locations may begin to match the coldness of the North Pole area.
Why is the polar vortex configuration change important for the process of glacial onset? It is because it can extend southern range of the polar air. What is really striking when one is looking at the pictures of the glaciation range of the last ice age is how far south the ice was extended. The immediate question that follows such observation is about the nature of such a deep freeze. The root cause seems to be the temperature gradient reversal and subsequent growth of such reversed gradient causing the tilt of the polar front with all further climatic changes resulting with the accelerated snow accumulation and further cooling of the northern lands. The monumental scale of the continuing cooling, though, must be contributed to subsequent fundamental reconfiguration of the northern atmospheric structure. As observed even in interglacial the developing negative gradient situation (lands colder than oceans) make the polar vortex (both tropospheric as well as the stratospheric) to attain an oblong planar shape with two centers instead of one. As the negative gradient grows over the time of the ever cooling ice age the polar vortex keeps changing its shape and at the certain time the elongation will pass its critical layout. The result will be the split of the stratospheric polar vortex into two separate ones which will be followed by the split of the tropospheric one afterwards. Is there any proof or even a hint such a situation already happened before and could it also happen in future? Yes, it is. A similar phenomenon (that I believe can harbinger the development of the major reshuffle of the glacial period climatic order) can be occasionally experienced over only a few days of a contemporary winter. It actually happens almost every winter - the event is short lived now, in the interglacial, but as the ice age is the time of a permanent winter it is quite possible this configuration may become permanent in the world of the perennial coldness. Let us see how it happens now in the coldest time of a winter usually at the end of February or early March. The polar vortex is a very sensitive entity and its shape can be affected by some atmospheric events. For example, it can be prompted by means of a powerful stratospheric wave. It happens according to the following pattern: as the tropical lands warm up the world deserts accumulate lots of heat but the mid latitude westerly winds cannot pass any more energy north than they are capable of to naturally reduce the temperature gradient. As it cannot be released gradually it forces its discharge in stratospheric energy pulses or bursts. The single burst may initiate from the edge of the west Sahara. Then, as it propagates along the desert eastwards picking up more energy it swipes the heat from Iraqi and Iranian deserts then Chinese ones and as it reaches south of the Tibet the temperature gradient (gradients, gradients and more gradients) in respect to colder north is at its maximum. The wave cannot progress any further in the troposphere but right above these latitudes there is a discontinuity in the troposphere’s ceiling - the tropopause. In this no-constrain environment the wave catapults into the stratosphere and then there is only one way – north, towards the cold – the entropy call! The wave cannot shoot southward – the troposphere ceiling towards equator is much higher than it is on the northern side. So the wave, launched from this enormous slingshot travels over the troposphere north in the curved way course (Coriolis). After a few days of travel it hits the stratospheric polar vortex somewhere from the side of eastern Siberia like a projectile. The stratospheric polar vortex will absorb this energy with the slowdown or even complete stop of its rotation. Not rotating anymore air will start to collapse. As it falls it gets denser warming up radically. The tropospheric polar vortex is now affected too. It also slows down behaving erratically. The jet stream slows down starting to wander deep down south. The polar cell spreads bringing harsh winter to Canada and the USA on the western hemisphere and to north Siberia on the eastern one. In the language of popular journalism this phenomenon is called "polar vortex" which quite accurately reflects the level of ignorance the contemporary press is famous for. In the scientific agenda it is called a SSW – a Stratospheric Sudden Warming. In the wave’s primary collision some energy may bounce away and continue its anticlockwise route hitting the stratospheric polar vortex also on the other side usually somewhere in the Greenland area. If the double hit happens the polar vortex is affected from both sides in close succession. In this situation, instead of being pushed away from the North Pole (which sometimes happens too) the stratospheric polar vortex is squeezed to the point it splits – the two independent polar vortices appear. That situation lasts only a few days. It is very interesting that when it happens one of those new vortices usually locates itself over the Northern Labrador and the other near Ob river valley in Siberia. (Fig 3C1)
As the North Pole cools back very quickly (it is still interglacial time) both vortices merge into one soon again. That tells us that as the result of stratospheric sudden warming (it can be called the nature’s "climatic experiment") the North Pole is momentarily far from being the coldest point on the northern hemisphere and that’s why the split vortices wander temporarily to new colder places and find them to be over the land masses which sometimes rival in coldness with the North Pole even in contemporary average winter times but over the time of the stratospheric sudden warming they become distinctively colder than the North Pole area.
The SSW then represents the "nature’s experiment" and it shows that:
The structural changes of the atmospheric circulation of an ice age will virtually follow the steps listed above with the exception of the gradual temperature gradient reversal, instead of the fast, a few days long stratospheric sudden warming. Obviously, everything that is to happen will happen in the completely different time scale. When the northern oceans become distinctively warmer than the adjacent lands their temperature gradient will reverse magnifying continuously afterwards. As the result of the gradient magnification the centers of the polar vortex will continue to spread apart. At the certain point the centers will find themselves so much far away one from another they will meet the glacial spots forming under those monumental snow storm mentioned in the previous, true air circulation, chapter. They will settle there. These are the excellent spots for the individual polar vortices to dwell as the anticyclones hovering over the proto-glaciers already spin the descending cold air. Eventually, two completely independent polar structures will form (Fig. 3C2) and their range will be strikingly coinciding with the confirmed range of the monumental glaciers plates of an ice age.
What would be the climatic consequence of such formation? The cardinal one will be polar front spreading much, much further south. The difference of the range of the polar cell of the single polar vortex located at the North Pole and the new polar vortex located over the Hudson Bay would be around of 300 – 400 miles.
Fig. 3C3: The range of the polar front in glacial and interglacial periods.
The expansion of the polar front would mean ruthless cooling in Canada and serious cooling in the USA. On the other side of the North Pole it would mean even further freezing of Siberia and radical cooling in China. The temperature of the Arctic Ocean water below 7 feet of the surface ice cannot get any lower than 28.4 F and at larger depths can be even warmer. Once the water is turned into glacier, though, its temperature can drop even down to -50 or even -60F degrees. Such glacier can be a gigantic heat sink cooling the air above radically (like over the Greenland today). To reverse the gradient it does not take the Arctic Ocean to warm up distinctively, it does not even take to warm it up at all. As long as the glaciers start to cool down the air above them their temperature will inevitably become lower than the temperature of the air over the oceans covered only by relatively thin ice crust. The drying air will amplify the process as diminishing atmospheric thermal Rossby number will contribute to the split by making the Earth’s atmospheric circulation equable. Finally the one cell system with two polar vortices will be established on the Northern Hemisphere and the similar changes will eventually follow on the Southern one as well. That configuration will be set relatively quickly. The glacial plates are fully built over only 7 thousand years since the first major cooling event of the S2 gradient reversal. The stereometric analysis of the glacial plates tells us a lot about the location and the form of the separate polar vortices: the American one being larger and circular in shape placed almost directly over the Hudson Bay and the Siberian one being more flattened latitudinally with at least three internal sub-vortices within it. The two polar vortices configuration will last until the interglacial return. For seven thousand years after the S1 gradient reversal the air will start to slowly fill with moisture. With the solar forcing, the thermal Rossby number increasing and the North Pole becoming the coldest point on the northern hemisphere again, the polar vortices will start to slowly wander north and, at some threshold value crossed, they will re-merge vigorously back into a single one. Almost in an instant the polar front will be shifted north by a few hundred miles, the mid altitude westerlies will re-appear starting to transport large amounts of humidity and heat towards north sprinkling the northern glaciers with warm rains. Another twelve thousand years of Garden of Eden will commence. This pattern has repeated itself eight times in last one million years. There is no reason it should not repeat again.
Should our interglacial start 11,744 thousand years ago we, the people, have lived in it for almost 12 thousand years. The previous interglacial started in the same way, lasted twelve thousand years and then ended. It is now time for our interglacial to follow suit. There is no reason to be otherwise as these climatic changes are of the oscillatory nature and therefore are following the pattern of the same mechanism.
The process of permanent Polar vortex split is basically complete in the first 7-8 years after the glacial onset. As the Eem started to cool down in 118th millennium ago the ice plates were fully built by the 110th one. By 110th millennium double polar vortex configuration was also established permanently. The dual polar vortex lingered until twelve thousand years ago although the conditions leading to its demise and return to the single polar vortex started around twenty thousand years ago around the time of the Glacial Maximum – the point of the S1 gradient change.
So the fully developed and formed Ice Age lasted between the 110th and the 20th millennium ago. It then took 90 thousand years for the oceans to cool down to match the temperature of the cooling lands. Why so long? By comparison of the heat capacity coefficient of lands and water it should be only approximately five times as long. We have to remember, though, than the lands had no supply of heat (except for the Eurasia) but the northern seas were still supplied with warm waters of the ocean currents from the south and for quite a long time. For 90 thousand years the world looked like this: most of the lands were cold and very dry. The rain was a complete rarity, in many areas nonexistent, the sky was cloudless but it was not blue – it was milky white. The sun did not shine, permanently obscured by a thick cloud of dust. The wind was not moisture generated, rather, like on Mars was set in motion by the gradient of the varying temperatures of dust clouds. The latitudes north of 65N were covered by the ice (very thick) and snow. The grassland was the prevailing vegetation over most of areas of the mid-latitudes and only the equatorial areas retained some rainforests in South America and Indonesia. The rainforest in Africa was practically extinct. Generally, the Earth was extremely hostile environment giving no chance for developing any civilization. People lived only in nomadic groups in the world areas that life sustain was possible. The number of men in Europe was dwindling. The Neanderthal man vanished around the Glacial Maximum time. The Homo-sapiens barely hanged around but made it to the interglacial in which it truly re-bounded. It took advantage of it quite efficiently so far. It is a good question what will happen to him when it finds itself back in the cold time.
Here is the point where all the three pillars of the proposed theory meet – the gradient, the one-cell atmospheric circulation and the polar vortex split.
All three together, made it possible to uncover a specific climatic mechanism of the hundred-thousand year oscillation working along the following chain of events:
The mechanism of the interglacial onset after 90 thousand of the glacial epoch will be of the reverse nature in respect to the glacial onset but the speed of it will be much faster, especially when some threshold values will be exceeded.
Fig. 3C4 Climate changes associated with the interglacial phase of the one-hundred thousand years oscillation:
1) Glacial Maximum – two independent polar atmospheric structures exist, each with individual tropospheric as well as stratospheric polar vortex. The structures are so far away one from another that the North Pacific – North Atlantic cross polar air flow occurs over the North Pole.
2) Intensifying solar forcing at high latitudes (Milankovitch cycle) causes the continents to warm up and the glaciers melting at their banks. As the mid-latitudes become warmer (especially south of the glacier’s range) the polar front starts to back off.
3) The polar front centers keep moving north and loose concentricity with the high pressure anticyclones hovering over the glacial plates.
4) Immediate pre-interglacial situation: as the North Pole is now the coldest point on the hemisphere the tropospheric polar vortex centers accelerate in their northbound drift towards one, common spot. The shape of the vortex becomes circular. The respective stratospheric polar vortices follow the drift’s direction.
5) Interglacial start: as all the conditions pass a threshold point in (possibly) one mega-storm a gigantic change of the atmospheric circulation takes place: the tropospheric polar vortex centers find their common center near the North Pole. The separate stratospheric polar vortices merge. The Hadley cell shrinks and warms up. The westerly winds start to blow away from the Hadley cell towards the polar cell carrying heat and moisture to so far cold and dry mid-latitude areas bringing rains that from now on will accelerate the process of glaciers melting although the high pressure system will stay over the glaciers until the ice is completely melted.
6) The atmospheric circulation is now specific to interglacial and will stay like that for another 12 thousand years. Until the glaciers are not fully melted the continental high pressure systems will stay over them slowing down their melting substantially. In spite of higher air temperatures and prevailing summer-like circulation it will take another 6 thousand years for the continental glaciers to melt fully. The main reason for that is the protective action of the high pressure systems above them (Greenland-like situation).
7) After 6 thousand years the glaciers are gone and the high pressure cyclones disappear. The continents are not overheating, though, as the solar forcing cycle is on the downturn now.
8) For the last 6 thousand years of the interglacial the temperatures of the lands have been diminishing and at some point the gradient would reverse. As the lands are now colder than the oceans the North Pole is not the coldest place on the northern hemisphere again. As the consequence, the tropospheric polar vortex becomes oblong again as its centers start wandering away from each other towards the colder spots over the lands. The polar cell will spread south over the continents and the warm and humid westerlies will slide over the cold front increasing the snow and ice precipitation. The glaciers will start forming, the high pressure systems will form over them and the glaciations process will resume.
9) At the certain moment the centers of the tropospheric polar vortices will atone with the high pressure cyclones and the separate stratospheric polar vortices will form over them. This situation will eventually match the configuration as on the illustration 1) and the whole interglacial sub-cycle will be completed. The small timeline graph is drawn below on the background of an interglacial profile. It indicates the loop presented lasts about 25 thousand years. Each vertical, intermittent line represents the climatic situation described by the pictures above.