Causes of Warm and Cold Phases and Sea Level Fluctuations as well as the Role of CO2

Causes of Warm and Cold Phases and Sea Level Fluctuations as well as the Role of CO₂

Heinz Kothen and Hans-Udo Knufinke

As to the Discussion on the Anthropogenic Greenhouse Effect

In scientific publications and reports of the mass media it is assumed that the small anthropogenic CO₂ portion of 0.01 % in the atmosphere is to blame for the present slight increases in the global average temperature of the near-ground air. Although the correlations observed between CO₂ and temperature graphs indicate a causal connection, cause and effect, however, remain open for the moment. As shown by the following example, contradictions between the fundamental physical effect of CO₂ and climate changes in the past need to be clarified: The period of approx. 20,000 to 10,000 years ago had experienced a rise of 65 ppm in the CO₂ content and of more than 6 °C in the average temperature. In the last 10,000 years, however, the CO₂ content in the air rose by 100 ppm, although the average temperature of today is more likely to be somewhat lower than the temperature recorded at that time. In the following, these circumstances and other possible causes of the rise in global average temperatures and the sea level are discussed using well-documented, prominent events of the last 130 million years.

The fluctuations of the alpine glaciers in the last 10,000 years and the CO₂ content in the atmosphere

As a supposed evidence supporting the increase of the global temperature since 1850 due to anthropogenic CO₂, the retreat of the alpine glaciers is, inter alia, taken into account. In the case of a somewhat closer look at the glacier oscillations of the last 10,000 years, it, however, becomes obvious that they take a largely cyclical course (Fig. 1). On a nearly equal scale, they are advancing and retreating. The periods of the advances and retreats are relatively short, with each of them taking place within approx. 1,000 years. The last glacier advance with a maximum extension was completed in 1850 (Figure 1).

Fig. 1: Glacier oscillations in the Alps and in the Bernina region (according to [ 1] )

Since that time - interrupted by standstills and temporary advances - a general retreat has been observed. Until the turn of the century, the Rhone glacier, e.g., - with an only slight CO₂ increase - had already retreated by 1,300 m (Fig. 2a u. b); this means more than in the subsequent time down to the present day, which is twice as long as that period and during which the anthropogenic CO₂ increase is higher by far. If we compare the CO₂ concentration in the atmosphere and the alpine glacier oscillations in the entire period from 1850 until today

Fig. 2a: Rhone glacier about 1850 (from [ 2] )

Fig 2b: Rhone glacier about 1900 (from [ 2] )

and in a more differentiated approach in the 20th century, the correlation is very slight. Before 1850 - during the Little Ice Age, which lasted 400 years - any correlation between CO₂ and glacier oscillations is not possible either: The CO₂ content in the air as well as the glacier oscillations increased in general. In the Middle Ages, it was more likely that the extensions of the alpine glaciers, among these also that of the large Aletsch Glacier, were even somewhat smaller than today [ 3] . The same is true for the Roman age, which is demonstrated by 300 years old tree trunks that had been buried under the advancing Gepatsch Ferner (glacier in the Oetztal Alps) in the fourth century and were recently exposed due to the retreat of ice at an altitude of 2,300 m above the present tree line [ 4] . Almost just under 25% of the Swiss glaciers was in a stationary phase or about to extend in 1994/95. Worldwide the glaciers are behaving in an unsteady way; some of them are retreating, while others are advancing, as e.g., the large Jostedalsbreen glacier in Norway and glaciers of New Zealand or Greenland.

Also these findings show that the CO₂ content in the air that has been rising for 10,000 years in general has not exerted any significant influence on the climates.

Climatic Contrasts and Different Sea Levels

In the Lower Rhine Embayment, sophisticated surveying that had been performed in respect of the tectonics in the advancing lignite opencast mines during many years allowed the movement rates of relevant geological periods to be determined in detail. For the Tertiary and Ice Age strata series, they range from clear extensions to the almost extension-free subsidence of the Embayment during the main seam formation [ 5] . It is striking, that soft and active tectonic phases in the Lower Rhine Embayment coincide with worldwide movements of the same kind, especially in the sea, but also in parts of the continents and point at connections with the climate.

Beyond it, comparisons of climatic contrasts and different sea levels between the Cretaceous Age (135 to 65 million years ago)and the Ice Age (for 2.5 million years), but also fluctuations of the same nature during the Tertiary, provide some information about their causes and CO₂'s role in geological history. Of fundamental importance here is the extent to what magma, which after being heated by the centrosphere rises and thus causes dominant processes, such as drifting-apart of continents and orogenesis (Fig. 3 and 6), triggers climatic and sea level fluctuations as well:

Fig. 3: Topographical consequences of ascending magma and descending lithosphere: Ocean ridges, subduction zones (deep-sea channels) and mountains (Westermann 1988)

During the Middle Cretaceous Age, a particularly hot and heavy flow of ascending magma reached the surface and involved increased formation of oceanic crust (Fig. 4), with volcanism being stepped up correspondingly [ 6]. Due to the increasing of uplifts, above all that of the ocean ridges, associated with the growing amount of ascending magma (Fig. 3), the sea level rose by 250m, with the ocean spreading [ 6], [ 8] . 85 % of the earth's surface was covered by the sea; today, it is 70 % [ 8] . Compared with today's level, the global temperature of the near-ground air increased by 10°C [ 6] . At the end of the Cretaceous Age, the sea area was again reduced by the recession of the ascending magma flow and the accompanying decrease in the sea bottom, and volcanism diminished. Even the global average temperature of the near-ground air dropped at that time [ 6] .

Fig. 4: Formation rate of oceanic crust, sea level and temperature fluctuations as well as reversals of the magnetic field in the last 150 million years

20 to 10 million years ago, the formation of oceanic crust not only in the Atlantic Ocean, but also in all oceans reached an all-time low in those days (Fig. 4). During that period, the sea level declined by 200 m - down to 70 m below the present level (Fig. 4). This was largely due to the fact that there was a considerable decrease in the uplifts of the ocean ridges associated with the ascending magma flow. The increase in the Antarctic ice volumes 15 to 10 million years ago, it is true, only partly explains that decline - even if we take account of the glaciation that was heavier than that of today. Under the present glaciation conditions, the sea would increase by only 70 m, if Antarctic (90%) and Arctic (10%) thawed off together [ 9] . In that period, the global average temperature of air dropped noticeably (see Fig. 4 as well).

But it was not only below the oceans where the ascending magma flow declined. That phenomenon was also observed in parts of the continental crust. The spreading of the Red Sea and the Gulf of Aden stagnated [ 10] . Hardly any extension movements were still recorded for the Lower Rhine Embayment, it even subsided by approx. 350 m [ 5] . In parallel with this, volcanism stopped on the periphery of the Lower Rhine Embayment (Neugebauer, kind information rendered in 1993).

The increased glaciation of the Antarctic 15 to 10 million years ago was not accompanied by glaciation of the Arctic. Only in the last 2.5 million years has coincidence in terms of tendency been noted for the glaciation in the Arctic and Antarctic. This suggests that the climate is not determined by atmospheric CO₂spreading over the earth.

Ten million years ago, the ascending magma flow and volcanism started to increase again. The Antarctic ice decreased. With considerable fluctuations the sea level in general rose, and 4 to 5 million years ago it reached another all-time high of almost 100 m above the present level (Fig. 4). Even the extensions in the Lower Rhine Embayment grew again in intensity terms [ 5] , and furthermore the spreading of the Red Sea and the Gulf of Aden (Fig. 3) was reactivated [ 10] .

During the cold phases of the Ice Age the sea level is considerably dropped due to the reduction in the sea water volume as a result of cooling and glaciation in the northern and southern hemispheres. In view of the assessment of the continental ice masses during the cold phases of the Ice Age it must be concluded that those masses did not offset the sea level drop of >130m below the present level [ 11] . For the cold phases, the continental ice volume was estimated at approx. 65 million km³; and today, this volume still amounts to approx. 30 million km³ [ 8] . The 35 million km³ of continental ice that has thawed in the meantime has caused a sea level drop of only 80m in the cold phases. The remaining 50m is due to the lowering of the sea bottom, above all in the area of the ocean ridges, which was caused by the decrease in the ascending magma flow. In the area of the ridges, the lowering must be much higher than the average amount of 50m.

Although the correlation between the CO₂ and temperature graphs for the last 150,000 years which were based on ice core investigations indicate a causal connection, the transition from a warm phase to a cold phase, however, reveals a considerably delay in the CO₂ concentration decrease compared to the temperature decline (Fig. 5) [ 12] . Thus, the warm phase is not finished by decreasing CO₂ , but the other way round - the CO₂ content decreases because it is getting cooler.

Fig. 5: Temperature changes and CO₂ content of the near-ground air for the last 160,000 years (according to [ 13])

According to these findings, both fluctuations of sea level and the climate are linked with magma processes. A climatic influence of the atmospheric CO₂ content, on the other hand, cannot be determined, although there is a physical effect in principle.

Mechanism of Climate Change

Because of all facts and findings in question following mechanism of climate change can be derived:

The centrosphere heats the lowest earth mantle to such temperatures that the resulting decrease in its density triggers hot ascending magma flows. These hot magma flows result in drifting-apart of continents, uplifts, above all of the ocean ridges (Fig. 3 and 6), and new crustification. As a consequence the sea level rises [ 6] . Near-ground, cold sea water is heated by the hot magma. Due to its lower density the heated water rises while in the meantime cold water masses sink to the sea bottom at high latitudes [ 14] . Both processes are linked with one another and involve deep currents. In the wake of cold water masses sinking to the ground at high latitudes, near-surface, climate-shaping convection currents - solar heat stored in the sea, such as the Gulf Stream - are reaching the northern and southern regions (see also [ 14] ). If the ascending magma flow is very strong - as e.g. during the Cretaceous Age, when in particular the ocean ridges were much higher than today - the sea level will rise again and the seas will spread; the volcanism associated with the ascending magma flow will reach correspondingly higher intensities. The global average temperature of the near-ground air rises. As a consequence of warming, above all of the seas, the CO₂ content of the atmosphere increases, without, however, having a noticeable effect by itself on the climate.

The alternation between extreme warm and glacial periods and ice ages is due to the following: If - as e.g. in the Cretaceous Age - larger amounts of magma which was heated by the centrosphere to particularly high temperatures reach the surface at a comparatively quick rate and increasingly form oceanic crust, larger amounts of heat are released to the sea. As a result, the amount of rising heated water is stepped up so that at higher latitudes bigger cold water masses can sink to the sea bottom, which in turn leads to a growth in the resulting deep currents (see below). The rising suction of the cold water masses which are increasingly sinking to the ground must in turn lead to an increase in the near-surface, climate-relevant ocean currents in the northern and southern regions.

On the other hand, correspondingly larger amounts of cooled lithosphere are sinking into the lower earth mantle (Fig. 6). The residence time required for warming by the centrosphere forces the circulation of rock to slow down. The slackened ascending magma flow causes the deep currents in the ocean to decrease, and less and less solar heat stored in the sea near the surface is reaching the high latitudes (see below). Due to the unstable intensities of the ascending magma flow, the deep currents in the sea are again and again stopped in some regions. Northern and southern regions are only temporarily reached by near-surface sea currents fed with solar energy. This results in an alternation of colder and warmer phases like in the Ice Age lasting for 2.5 million years.

Fig. 6: Ascending flow of magma heated by the centrosphere and sinking of the cooled lithosphere into the lower earth mantle (according to [ 15] )

Finally, slowing-down of the circulation must step up heating of magma sunk to the centrosphere so that circulation will speed up again. Since ascending magma flows are feasible by plumes only here and there or in a wide-meshed, global network of extension zones, some kind of heat accumulation must temporarily occur. These particularly hot magmas increase the ascending flow. With their arrival at the surface, a new extreme warm phase will start. Thus, glacial periods and extreme warm intervals condition each other. The last 1,000 million years experienced seven glaciation periods [ 16] , during which either both polar regions or only one of them were covered with ice - in fact with a CO₂ content in the air, that was some orders larger than today. As stated by LARSON, it is already today that the lower 100 to 200 km of the earth mantle are heated to such temperatures that - according to geological standards - stepped-up ascending magma flow and volcanism will be imminent in the relatively near future.

In addition to the varying intensity of the magma flow, which is to a large extent reflected in the formation rates of oceanic crust and the sea level fluctuations (Fig. 4), the location of its ascending zones being active at the time and the temperature of magma reaching the crust surface are playing a major role in terms of the climatic effect. Thus, the specific heat amount released by the ascending magma flow to the sea in conjunction with the location of the active heat exchanging zones determines the amount of sinking, cold water masses and their sinking zones, as well as the course and the intensity of deep currents. The location of the sinking zones and the amount of sinking water masses are in turn decisive in respect of the intensity of near-surface sea currents fed with solar heat and, finally, in respect of the global air temperature. This becomes particularly clear when we consider glaciation of only one polar region. During such glaciation, there is an obvious lack of active ascending magma zones in this region, preventing sufficient solar heat from reaching this area together with the sea current.

Although compared with the solar heat reaching the earth, the heat amount of ascending magma is very small, the latter, however, steps up the climatic effect of solar heat: It increases its transport from the zones of intensive insolation to high southern and northern latitudes, or makes it possible at all.

The circulation models of the climate-influencing sea currents, on the other hand, which are described in the literature [ 17] and are due to different salt contents in the water, give rise to some contradictions: Thus, without the heating of deep water by magma processes, it is difficult to explain the energy starting and sustaining the sea currents. Here also the question arises whether the severe cold phase of the Younger Dryas starting 11,000 years ago, which for a thousand years had once again given Northern Europe a tundra-like appearance [ 8] , may be due to glacial waters flowing from the Canadian continent to the North Atlantic, which are said to have interrupted the Gulf Stream [ 17] .

In order to answer this question, it is primarily to be declared up what factor had caused thawing of the widespread ice and how large the glacial water quantities were which flowed from the continent to the Atlantic. The latter are assumed to be in no proportion to the water masses of the Gulf Stream, a factor which is no indication of their lasting influence on the Gulf Stream. The reason for the general retreat of the widespread ice (with high albedo) in the northern and southern hemispheres, which had started 18-19,000 years ago and reached its present level 4 to 5,000 years ago, was due to the consequences of a newly stepped-up ascending magma flow, which had slowed down in the preceding marked, extreme cold phase. But the resulting gradual increase of > 130 m in the sea level, which was partly caused by thawing of the continental ice and partly by the rise in the sea bottom, was again and again interrupted; then the sea level sank again for some time (Fig. 7). Also the air temperatures, which in some respect are linked with the sea level fluctuations, dropped in those phases. This is reflected in the advances and retreats of the alpine glaciers that can be largely correlated with the sea level fluctuations (cp. Fig. 7 and Fig. 1). In the sequel, fluctuations in sea level, temperature and alpin glaciers proceeded in the same way.

Fig. 7: Fluctuating sea levels according to different authors in the last 18,000 years. 4,000 to 5,000 years ago, glaciation had decreased almost to its today's level

Accordingly, the Younger Dryas together with further, less pronounced, colder and warmer phases forms a transition from the extreme cold phase ending 18,000 years ago to the more balanced warmer phase continuing for a 10,000 years. The temperature gradient obviously changed temporarily between the sea surface and the sea bottom in the northern region so that the sinking of cold water masses and the resulting suction for the Gulf Stream declined temporarily, and possibly even stagnated during the Younger Dryas.

Also these mainly small climate changes and the alterations in the sea level thus involved can be explained by not completely regular ascending magma flows. First, as a result of the pressure relief the mobility of the otherwise very slowly flowing magma increases near the surface - for its 3,000 km long way from the base of the earth mantle to the crust, it is generally assessed to take millions and millions of years. Secondly, during the drifting-apart of the plates and the new crust formation, varying large amounts of new hot magma are almost periodically getting in contact with the sea water. As a consequence, the heating of sea water is changing again and again, a phenomenon that in the final analysis has similar effects on the atmosphere. Corresponding to the fluctuating ascending magma flow, the sea bottom is rising and falling.

It is, however, not only during glacial periods but also in extreme warm phases and all other climates that the ascending magma flow reaching the crust surface is constantly changing in terms of intensity. An evidence of this is, inter alia, the sea levels of the Cretaceous and Tertiary Ages that were permanently fluctuating by larger and smaller amounts. In 200,000 years the sea level experienced fluctuations of up to 100 m (Fig. 4), and - to be more precise - with ice-free poles, i.e. the entire change in the sea level was due to the varying intensity of the ascending magma flows!

Fig. 4 shows that the crust formation rates largely correspond to the sea levels and the sea surface temperatures although above all the location of the ascending magma flows being active at the time plays a climatic role and, furthermore, the density of the data network is still rather limited at present. This Figure, however, does not take adequate account of the rapid rotation in the last five million years. So, the average values shown in the diagram conceal the comparatively high crust formation rates at the start of this period and during the interglacial intervals of the Ice Age as well as the small rates in their cold phases.

Also the reversal intervals of the terrestrial magnetic field correspond in some way - as shown by Fig. 4 - with the oceanic crust formation rates. The reason for the differently long reversal intervals is assumed to be changes in the temperature gradient of the outer centrosphere [ 6] . During the Middle Cretaceous Age, the terrestrial magnetic field had kept its (normal) direction for 40 million years [ 6] . Especially hot magma, which after all produced extreme global air temperatures, left the zone surrounding the centrosphere. Less hot magma taking its place triggered a steep temperature gradient in the outer centrosphere. At present, it is less pronounced due to the already far advanced heating of the lower 100 to 200 km of the earth mantle [ 6] , and more than once per one million years the terrestrial magnetic field changes its poles (Fig. 4).

Can the emissions reaching the atmosphere due to lava eruptions have a lasting influence on the global climate?

Due to the observations made nowadays, the volcanic particles emitted are reported to seriously impede insulation and give rise to lasting cooling phases [ 18] . Examples of the geological past give an insight into this correlation: It is in the nature of things, and all findings support this assumption, that the intensity of volcanism is linked with the intensity of the ascending magma flow and the latter with the climate (see Fig. 4 as well). During extreme warm phases, volcanism was stepped up, while it declined in colder phases. An example of the former is given by the Cretaceous Age with its extreme temperatures and relatively strong volcanism [ 6] . Today, in an interglacial interval, volcanism is clearly weaker than in the Cretaceous Age. And it was obviously even weaker in the cold phases of the Ice Age. This was indicated by the Eifel volcanism that was mainly confined to the interglacial interval (Fig. 8). But also in the period some 15 to 10 million years ago, when the Antarctica glaciation stepped up, the global temperature dropped and the extension of the Lower Rhine Embayment declined, volcanism discontinued on the periphery of the Embayment [ 5] .

Fig. 8: Activity phases of the Eifel volcanism (according to [ 19]), temperature fluctuations derived from plankton shells in equatorial Pacific 800,000 to 160,000 years ago (according to [ 8]) and temperature changes derived from ice core drilling for the last 160,000 years (according to [ 13]).

These data lead to the conclusion that in terms of its global climatic effect the impediment to insulation caused by the particles emitted by volcanoes cannot be compared with the consequences of a stepped-up ascending magma flow, which is accompanied by increased volcanism.

According to LARSON [ 6] , on the other hand, the stepped-up lava eruptions in the Cretaceous Age - above all in the Pacific - were reported to have caused increasing CO₂ amounts, which could no longer be absorbed by the sea, to enter the atmosphere, thus causing warming.

All the data supported by facts, which within the scope of this brief overall survey mattered to the individual problems, speak against the assumption of a significant influence of CO₂ exerted on the climate - at least in terms of the magnitude to be considered here.

Do the periodicity of the ecliptic elements and the size of the land areas at the poles play a major role in the global scenario?

In addition to different other theories there is also one meaning that in the course of the geological history Ice Ages emerge whenever larger land areas are situated near the poles. In that case, the snow would not - differently from what is happening when it falls into the sea - thaw, but due to the reflection of insolation would finally lead to glaciation in a self-energizing process. For the glacial warm and cold phases, however, the ecliptic elements are said to be causal [ 18].

	The ecliptic of the sun is subjected to insignificant changes in cycles of 100,000 years. On the balance of insolation the effects of these cycles are minimal. Furthermore, the earth's axis inclination varies by 2.6° during a cycle of approx. 40,000 years. Finally, as a result of changes in earth's axis position in a cycle of approx. 21,000 years, the point of the ecliptic that is most distant from the sun and that closest to the sun shift according to the season. The two last cycles involve regional redistribution of insolation on earth [ see also 18] . While the various model calculations of the ecliptic elements for the last 950,000 years do not yield any fundamentally different variation of insolation from that obtained for the older phase of the Ice Age, the climatic data derived from ice cores and the ¹⁶O/¹⁸O ratios of plankton shells in sedimentary cores are totally different for theses two periods (Fig. 9): In the course of the Ice Age the intervals and temperature differences between the warm and cold phases changed enduringly. Fig. 9: d ¹⁸O-fluctuations from plankton shells in equatorial Pacific [ 12] (above) and model calculations of the fluctuations on insolation caused by the ecliptic elements for the month of June [ 20] (below)
	18,000 years ago, the relative maximum of the last extreme and marked cold period ended. 11,000 years ago, the following warming phase interrupted by short, colder phases was succeeded by an again severe cold period of 1,000 years (Younger Dryas). Long-period ecliptic elements do not explain this phenomenon.
	In the last 10,000 years, the ice in the northern and southern hemispheres has slowly retreated. Despite still extensive ice occurrence with high albedo (see also [21] ) the beginning of that period was worldwide more likely marked by higher temperatures than today although the CO₂ content was nearly 50% lower (see also Fig. 5) This phenomenon can either be due to the period of astronomic elements since according to the model calculations it would have to be warmer today than formerly.
	First, the stepped-up Antarctica glaciation 15 to 10 million years ago declined considerably in order to finally extend again sizably in the cold periods of the Quaternary Ice Age. This cannot be justified by the changing size of the land areas at the South Pole, for such changes did not occur. Thus, it was not the snowfall on land with a self-energizing glaciation process that entailed climatic consequences, but the changing intensity of the ascending magma flows in connection with the parallel transport of solar heat by means of near-surface sea currents to these regions (see also "Mechanism..."). On the other hand, large continuous land areas can indicate lacking active ascending magma zones and thus impede the transport of solar heat.

All these findings speak against a fundamental influence exerted by the ecliptic elements and self-energizing glaciation of polar land areas on the global average temperature of the near-ground air. They could not be the cause of either the Ice Age or the strongly changing intervals and temperature fluctuations between cold and warm phases in the course of the Ice Age (Fig. 9). Also the sun's luminosity and radiation being on the increase since the Precambrian - 10% in the last one billion years [ 16] - failed to prevent the generell cooling of approx. 15°C from the Cretaceous Age to the cold phases of the Ice Age.

What is also speaking against the postulated considerable climatic influence is the polar ice-adjusted rise of the sea level in the interglacial intervals and its decrease in the cold phases, which of course are not attributable to the ecliptic elements. The syme is valid for the proved volcanism during the warm phases and the relative rest during the cold phases of the Ice Age (see also [ 22] ), which are causal linked with the intensity of the ascending magma flow at the ocean ridges.

Résumé

The reason for changes in the global average temperature of the near-ground air is the changing ascending intensity of adequately hot magma flows, above all in the ocean ridges: it results in correspondingly differentiated water heating in the oceans. This is the determining factor on which the absorption capacities for sinking cold water masses in the northern and southern seas as well as the extent of the associated deep currents are dependent. In the wake of the sinking cold water masses, near-surface solar energy-fed sea currents, such as the Gulf Stream, will finally reach these regions. The larger the quantities and the higher the speed at which sun-heated water will reach the high latitudes, the higher the global average temperature of the near-ground air. It is not only the temperature in the polar regions that rises for this reason; but also the temperature up to or down to the equatorial latitudes increases due to smaller cool air supplies from the North and South. In the case of decreasing near-surface heat flows, the effect is reverse: In the northern and southern regions, it becomes cooler, and the same is true of the zones with intensive insolation.

In the Cretaceous Age, stepped-up ascending magma flows led to a rise of 10°C in the global average temperature and of 250 m in the sea level. Compared to the present level, slowed-down, less hot ascending magma flows produced a decrease of > 6°C in the global average temperature and of > 130 m in the sea level during the phases of the Ice Age. Between and during the Cretaceous and Ice Ages - viz. also in the case of ice-free poles - the sea levels fluctuated by small and larger amounts at short and longer intervals.

The oscillations of the alpine glaciers in the last 10,000 years largely correspond with the rise and decrease in the sea level. Obviously they are the consequence of not completely steady ascending magma flows getting in contact with the sea and the thus adequately fluctuating deep currents and near-surface heat flows in the seas that in the final analysis have an influence on the global air temperature. Neither ecliptic elements nor "building-up" theories are suitable explanations: "Building-up" theories (snow accumulation in polar land areas) are questionable since they point in one direction, i.e. towards the cold period. Cold and warm periods, however, are alternating at short intervals. Because of their much longer cycles alone, the ecliptic elements are out of the question.

A present quasi-periodic increase in the ascending magma flows lifting the sea bottom and heating the sea water also accounts for the current rise in the sea level and air temperature as well as the regress of ice masses, which started after the Little Ice Age, at about 1850, and are without any anomalies.

The doubts about the CO₂ influence are becoming particularly obvious when we compare the conditions nearly 10,000 years ago with those prevailing today. Then the global near-ground average temperature was somewhat higher than that of today (Fig. 5). The CO₂ value, on the other hand, amounted to about 255 ppm (Fig. 5), viz. approx. 100 ppm below the present value of 360 ppm. During the extreme cold phases of the Ice Age - the last ended 18,000 years ago - the CO₂ values were varying between 180 and 200 ppm (Fig. 5), and the global average temperature was > 6°C lower than that nearly 10,000 years ago and that of today. While in the first interval with a temperature rise of > 6°C the CO₂ content in the air thus grew by approx. 65 ppm, the CO₂ increase of some 100 ppm in the second interval did not give rise to any climatic consequences. According to the calculated influence of the ecliptic elements, the present temperatures would have to be higher than those nearly 10,000 years ago [ 16], [ 18]. In fact, however, the circumstances are reversed (Fig. 5). These findings alone show that the rise of the CO₂ content to 0.036 % has not exerted an important influence on the climatic scenario.

The authors want to express their thanks to: Prof. Dr. Horst J. Neugebauer, Bonn, and Dipl.-Ing. Klaus Reichenbach, Brühl, for their revision and suggestions. ______________________________________________________________________

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[ 22] Mc Guire et al. (1997): Correlation between rate of sea-level change and frequency of explosive volcanism in the Mediterranean.
Nature, Vol. 389 (2. Oktober 1997), 473-476

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